ISTS42 Program/Agenda

Overview and details of the sessions/events of ISTS42. Please select a date or location to show only sessions/events held on that day or location. Please select a single oral or poster session for a detailed view of each submission (includes abstracts).

Session Overview
Poster Display
Tuesday, 26/Mar/2024:
9:00am - 6:00pm

Location: Napalai D & E

Session Abstract

*Denotes Archie Carr Student Award candidate; ^ Denotes Grassroots Award candidate; Presenting author is underlined

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*Human-wildlife interactions and their consequences for sea turtle health in Malaysia

Syamsyahidah Samsol1, Mohd Uzair Rusli1, Jeethvendra Kirishnamoortie2,4, Hideaki Nishizawa3, Juanita Joseph2,5, Tsung-Hsien Li6

1Sea Turtle Research Unit, Institute of Oceanography and Environment, Universiti Malaysia Terengganu, Malaysia; 2Borneo Marine Research Institute, Universiti Malaysia Sabah, Malaysia; 3Graduate School of Informatics, Kyoto University, Japan; 4Tropical Research and Conservation Centre, Pom Pom Island, Sabah, Malaysia; 5Small Islands Research Centre, Faculty of Science and Natural Resources, Universiti Malaysia Sabah, Malaysia; 6National Museum of Marine Biology & Aquarium, Checheng, Pingtung, Taiwan

Human-wildlife interactions, including wildlife provisioning and ecotourism, are increasingly prevalent, raising concerns about their effects on wildlife welfare and coexistence. This study investigates the impacts of these interactions on the health of sea turtles in Terengganu and Sabah, Malaysia, and their implications for the conservation of these iconic marine species. Drawing upon a body of research in terrestrial and marine ecosystems that has examined interactions involving various species, including tigers, macaques, dolphins, and tiger sharks, our study focuses on understanding the dynamics of these interactions. We also assess the potential co-benefits of combining conservation and economic valuation. Our hypothesis centres on the effects of provisioning activities, such as swimming and feeding with sea turtles, on sea turtle health and the balance between tourism-related interactions and conservation. We conducted this investigation in two prominent locations: Teluk Dalam in Terengganu, known for swimming and feeding activities, and Semporna in Sabah, where tourists engage in swimming and diving with sea turtles. To comprehensively assess sea turtle health, we conducted detailed examinations that included measurements of weight, morphometric data, physical evaluations, and clinical pathology analyses. We examined ten green turtles in Teluk Dalam and 36 turtles (32 green and four hawksbill) in Semporna. Our results revealed that the turtles exhibited blood values within expected ranges compared to previous studies, and they displayed no clinical signs of ill health based on body condition scores and index. A significant finding emerged when comparing provisioned (Teluk Dalam) and non-provisioned (Semporna) turtles. Provisioned green turtles exhibited significantly higher levels of Blood Urea Nitrogen (BUN) and Creatinine (Crea), with a mean of 88.71 (±44.58) mg/dL and 10.14 (±10.59) mg/dL, respectively, while non-provisioned green turtles had a mean of BUN 8.94 (±6.68) mg/dL and Crea of 0.29 (±0.09) mg/dL, suggesting an early diagnosis of kidney diseases. This highlights the potential detrimental effects of provisioning activities on sea turtle health. This study highlights the importance of achieving a balanced approach to human-wildlife interactions where meaningful encounters are maintained while safeguarding the vital ecological roles that sea turtles play in marine ecosystems. By shedding light on the potential impacts of provisioning activities, we emphasise the need for responsible management of these interactions to protect the well-being of sea turtles and preserve their essential ecological functions in the marine ecosystem.

*Physiological changes in blood parameters of sea turtles across nesting episodes

Afif Aiman Azmi, Faizah Aplop, Mohd Uzair Rusli

Sea Turtle Research Unit, Institute of Oceanography and Environment, Universiti Malaysia Terengganu, Malaysia

Sea turtles are capital breeders, where the accumulation of energy and resources is necessary to go through an extended period of breeding season. An adult individual does not provide any maternal care to the incubated hatchlings, thus, justifying the necessity of providing sufficient resources for the developing embryos. In general, blood acts as the universal transporting media that carries these resources throughout the body, given the optimal internal physiological state of the individual. This study aims to investigate the changes in blood profile through blood gases, biochemistries, and hematology parameters of green turtles over a series of nesting episodes. We hypothesize that parameters that are highly demanded during egg production and individual health maintenance will show variability as the nesting period progresses. A suite of 16 blood parameters, classified into three groups; (1) nutrients and metabolites (glucose Glu, blood urea nitrogen BUN, creatinine Crea, and lactate Lac), (2) elements and electrolytes (Sodium Na, potassium K, chloride Cl, Calcium ion Ca2+, bicarbonate ions HCO3-, anion gap AnGap), and (3) blood gases (partial pressure CO2, partial pressure O2, total carbon dioxide TCO2, oxygen saturation sO2, base excess BE, and pH), were analysed using a portable clinical i-Stat analyser, with CG4+ and Chem8+ cartridges. Hematology parameters include hemoglobin Hb, packed cell volume PCV, erythrocyte counts, and estimated and differential (%) leukocyte counts were analysed using standard hematologic techniques. The analyses were performed for all blood samples collected from individuals over consecutive nesting episodes. Analysis of variance (ANOVA) with repeated measures showed a significant difference (p<0.05) in blood parameters of individuals (n = 5) nested consecutively; pH, pCO2, pO2, sO2, TCO2, K, Cl, and Ca2+. Hemoglobin (Hb) and PCV are among hematology parameters that significantly differ (p<0.05) as the successful nesting episodes proceed. The reported findings of this study correspond with previously reported values, thus expanding the reference values for blood profiles for this particular nesting population. Being one of the important nesting grounds in the South China Sea rookeries, the health assessment of adult individuals is crucial for conservation. We suggest further study into finding the possible association between maternal blood profiles and reproductive output/success to elucidate maternal provisioning as a potential contributing factor to the hatchling success in the first few days, given that individual health would influence reproductive outcomes.

Endoscopy and rectal enema for fecal collection in wild sea turtles (Chelonia mydas, Eretmochelys imbricata) in a field setting

Kristina L. Kaleel1, Patricia L. Secoura2, Juan Pablo Muñoz‐Pérez3,4,5,6, Daniela Alarcón‐Ruales3,4,5, Felipe Vallejo6, Cristina Miranda6, Gregory A. Lewbart2,3,4, Kathy A. Townsend5, Shelly L. Vaden2

1University of Florida College of Veterinary Medicine, Gainesville, Florida, USA; 2The Department of Clinical Sciences, North Carolina State College of Veterinary Medicine, Raleigh, North Carolina, USA; 3Colegio de Ciencias Biológicas y Ambientales (COCIBA), Universidad San Francisco de Quito USFQ, Quito, Ecuador; 4Galápagos Science Center (GSC), Universidad San Francisco de Quito (USFQ) & UNC‐Chapel Hill Galápagos Science Center (GSC), Galápagos, Ecuador; 5School of Science, Technology and Engineering, University of the Sunshine Coast UniSC, Hervey Bay, Australia; 6Equilibrio Azul, Puerto Lopez, Ecuador

Forty‐seven free‐ranging sea turtles (46‐ Chelonia mydas,1‐ Eretmochelys imbricata) were examined via novel use of an endoscopy combined with a rectal enema to obtain large fecal sample volumes. The cloaca was insufflated using an endoscope, after which the bladder and rectum separated, allowing access to the colon. Environmental conditions and location influenced the performance of the procedure initially, but after several attempts the procedure was successfully initiated. In all cases, fecal samples were obtained, and the animals were released to their respective locations. Fecal sample collection using this approach enhances the ability to obtain diagnostic information and perform other scientific analyses of sea turtles.

Increasing hypoxia progressively slows early embryonic development in the green turtle

David Morton Adams1, Sean A. Williamson1, Roger G. Evans2,3, Richard D. Reina1

1School of Biological Sciences, Monash University, Australia; 2Biomedicine Discovery Institute and Department of Physiology, Monash University, Australia; 3Pre-clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Australia

Green turtle (Chelonia mydas) embryos are in an arrested state of development when the eggs are laid, but in the presence of oxygen (generally 19-21% in new nests), arrest is broken and development resumes within 12-16 hours. However, the precise oxygen level at which embryos break arrest and continue development is not known. To better understand the impact of oxygen concentration on breaking of arrest and early embryonic development, we incubated freshly-laid eggs of the green sea turtle for three days at each of six different oxygen concentrations (≤1%, 3%, 5%, 7%, 9%, and 21%) and monitored the appearance and growth of white spots on the shell, typically indicative of embryonic development. As reported previously, white spots did not develop on eggs incubated in anoxia (≤1% oxygen). For all other treatments, mean time to white spot detection varied inversely with oxygen concentration and white spot growth rate increased with oxygen concentration. In nearly all cases the difference in time to white spot appearance and growth rate between eggs at different oxygen levels was statistically significant (p ≤ 0.05). This suggests that sea turtle embryonic development may respond to oxygen in a dose-dependent manner. Our results indicate that the development of green turtle embryos may be slowed if they are exposed to the most hypoxic conditions reported in mature natural nests. This work also has significant implications for conservation efforts, indicating that to ensure the safe transportation of eggs necessitates that oxygen availability be maintained at or below 1% if the eggs are to be in transit for 12 hours or more.

*Loggerhead sea turtle detection of ammonia odors: sensitivity to terrestrial stimuli

Lillian G. Prince, Kayla M. Goforth, Jadyn M. Sethna, Kenneth J. Lohmann, Catherine M. F. Lohmann

University of North Carolina at Chapel Hill

Loggerhead sea turtles (Caretta caretta) exhibit natal homing and feeding site fidelity following large-range migrations, a navigational phenomenon that is not yet fully understood. Previous studies suggest that turtles use Earth’s magnetic field to relocate their natal regions, but it is likely sea turtles use additional cues, such as olfactory stimuli, in combination with other navigation methods to localize specific beaches and islands. Migratory sea birds can detect and follow odor plumes of airborne ammonia, which is a volatile organic compound produced from seabird fecal matter and bacteria in marsh habitats, to relocate nesting islands. Given that sea turtles detect air and water-based odors, they may also rely on ammonia as an additional cue for local navigation. Previous unpublished data demonstrate that turtles can detect and respond to ammonium hydroxide (10µM & 100nM). In these experiments, turtles spent significantly more time with their nares out of water and took more breaths when odors of ammonia were present compared to odors of seawater; both of which are behaviors performed by turtles when they detect an odor of interest. Sensitivity to concentrations of any olfactory stimuli has yet to be investigated in loggerhead sea turtles and this study aims to determine their detection threshold of airborne ammonia. Turtles placed in an experimental arena were exposed to three additional concentrations of airborne ammonia (1mM, 1nM, and 10pM) spanning the previously studied concentrations, along with food (positive control) and seawater (negative control) odors. Preliminary analysis suggest that turtles take a higher number of breaths in response airborne ammonia, similarly as they do to food odors. Thus, it appears that sea turtles may be able to detect and respond to airborne ammonia at biologically relevant concentrations. Further work is needed to compare turtle responses to concentrations of ammonia in natural environments. While this response may be an innate cue, juvenile turtles likely learn or reinforce this terrestrial odor while spending time in nearshore feeding grounds. This may reinforce airborne ammonia as a navigation cue used later in life to locate nesting or foraging grounds.

*Evaluating the relationship between immune function and reproductive success in nesting turtles

Tiffany M Dawson, Kate L Mansfield

University of Central Florida, United States of America

Energetic tradeoffs between immune function and reproductive output are common in sexually mature females and can be exacerbated by extended breeding periods and/or multiple reproductive events. For sea turtles, reproductive hormonal shifts months prior to nesting, long migrations from foraging grounds to nesting beaches, and multiple mating and reproductive events in a single nesting season require heavy energy expenditures. Immune suppression is a common tradeoff for producing high quality offspring but is not well documented in large marine reptiles. To evaluate immune function tradeoffs in nesting sea turtles, we examined proxies for immune function relative to reproductive output for loggerhead turtles (Caretta caretta) during the 2020-2021 nesting seasons in Florida, USA. We evaluated n=122 blood samples for packed cell volume, differential white blood counts, and plasma protein fractionation; associated female reproductive output was measured by hatching success and the number of reproductive events were categorized as early-, mid-, or late-season based on sampling day. Generalized linear models showed significant relationships between immune proxies, sampling date and female size, indicating physiological changes within the nesting season and size-based differences. Decreases in immune function in reproductive females leave them susceptible to diseases and parasites, and exposure increases with changing habitats during migrations. Understanding the relationships between immune parameters and reproductive output is vital to developing best management practices and gaining insight into energetic tradeoffs for reproductive females.

*Effects of Incubation Factors on Loggerhead Hatchling Condition in the Gulf of Mexico

Allyssa Rose Hennessey1,2, Jake Andrew Lasala2, Frank V Paladino1

1Purdue University Fort Wayne, Indiana, United States of America; 2Mote Marine Laboratory, Florida, United States of America

Over the course of the marine turtle nesting season on the Gulf of Mexico, female turtles will lay approximately 3 to 6 clutches of eggs every 10 to 14 days. Subsequent clutches of eggs decline in resource quantity over the course of the season as females fast during the nesting season and egg contents are leached from their bodies over the course of the summer. The effect of suboptimal nutrients on the developing hatchlings could influence developing hatchlings' size, body condition (BCI), and may cause anomalies of the carapacial scutes. Variations in the number of scutes of the carapace of hatchlings are becoming increasingly common but are understudied.

The Sea Turtle Conservation and Research Program (STCRP) at Mote Marine Laboratory has monitored sea turtle nests on 56km of Sarasota County, Florida beaches since 1982. This nesting population is the largest loggerhead (Caretta caretta) rookery in the Gulf of Mexico. Annually, STCRP staff identify and tag nesting turtles in the region and have a database of over 5,500 unique nesters collected over 40+ years. For the project presented here, hatchlings were collected from known repeat loggerhead nesters on three beaches in Sarasota County from 2020-2023. The vertebral, costal, and marginal scutes were counted and anomalies were documented, along with hatchling length, body width, head width, body depth, and mass. Models were run to determine if the date the clutch was laid, incubation duration, or nest order had a significant effect on the presence of carapacial scute anomalies. Over the course of the study, a subset of nests were outfitted with temperature data loggers that logged every 15 minutes throughout development. Linear models were run to identify whether temperature fluctuations had a significant influence on the presence of scute anomalies. We will discuss how factors during clutch incubation can impact hatchling conditions.

The hatchling body condition index (BCI) was calculated using the method described by Lamont and Johnson. The date the nest was laid significantly affected the average hatchling BCI (p<0.001). This finding suggests that nests laid later in the nesting season have a higher chance of carapacial scute anomalies. The duration/length of clutch incubation also had a significant impact on the number of extra scutes per hatchling (p=0.034). Shorter incubation durations were directly tied to an increase in the presence of extra scutes. Interestingly, nest order also had an impact on the average number of extra scutes per hatchling. The third or fourth known nest laid by individual females had a significantly higher likelihood of hatchlings developing extra scutes compared to hatchlings from her first or second nest. Average ambient temperatures increase throughout the nesting season, causing incubation duration to shorten, due to quicker development. Hatchlings’ carapace patterns are thought to be developed in the middle third of incubation, making it a crucial period of incubation to study. Increasing temperatures eventually have a negative impact on hatch success, and average to high temperatures may also increase the chances of hatchlings developing carapacial anomalies, yet their effect is unknown.

*Acoustic monitoring of nest escaping activity in sea turtle hatchlings

Pey Chen Lim1, Hideaki Nishizawa2, Mohd Uzair Rusli1

1Sea Turtle Research Unit (SEATRU), Institute of Oceanography and Environment, Universiti Malaysia Terengganu; 2Graduate School of Informatics, Kyoto University

The incubation period and subsequent emergence from the nest is a critical phase in the life cycle of sea turtle hatchlings, fraught with challenges that can significantly impact their survival. Understanding the behaviors and physiological responses of hatchlings during this stage is crucial for improving conservation strategies. However, insights into the effects of clutch size on hatchling emergence and energy expenditure remain limited. The objectives of this study were to investigate the impact of clutch size on the nest escaping duration, digging duration, morphological attributes, and fitness of sea turtle hatchlings, and to develop minimally disruptive methods for monitoring these factors in situ. This study was conducted at Chagar Hutang Turtle Sanctuary, Malaysia, employing a controlled experimental setup. Eggs from 45-day-old nests were transported to the laboratory, preserving their natural orientation. They were divided based on clutch size into 'large' and 'small' categories, with a ratio of 3:1. Artificial nest chambers equipped with lavalier microphones were positioned at three depths within the nest: bottom (just above the eggs, 60 cm from the sand surface), middle (25 cm above the bottom), and top (10 cm below the sand surface), facilitating the recording of digging activity. After emerging from the nest, hatchlings were measured for morphological attributes, and a randomly selected group underwent fitness testing. The nest escaping duration was not significantly different between large and small clutches but large clutches tended to emerge faster, with a moderate negative effect size of -0.49 (95% CI [-1.625, 0.677]). Straight carapace length and width were significantly larger in small clutches than large clutches, while no significant differences were found in the measurements of frontal flipper length, body depth, external yolk sac, mass, blood glucose concentrations, and self-righting capability. Both nest depth and clutch size, as well as their interaction, had significant effects on the digging duration. The digging duration for large clutches decreased across nest depths, with estimates of 25.6 (± 2.23), 21.8 (± 2.23), and 17.4 (± 2.51) seconds for nest depths at bottom, middle, and top, respectively. Deeper nest depths might have more compacted sand, requiring more effort and time to excavate compared to shallower depths. Significant differences in digging duration were observed between large and small clutches at the bottom and top nest depths (p < 0.05), with larger clutches exhibiting longer digging durations. Higher amount of hatchlings from large clutches involved in digging may accelerate the excavation process, but this faster emergence could potentially lead to smaller body sizes. At the middle nest depth, no significant difference was found between large and small clutches (p > 0.05), indicating unique challenges for small clutches during the digging process at this depth. The study offers valuable insights into hatchling behavior and physiology, highlighting a clear influence of clutch size on their development path and survival strategies. The minimally disruptive monitoring technique developed here provides a new avenue for observing hatchling behavior without disturbing the natural process.

Impacts of incubation temperature on loggerhead (Caretta caretta) sea turtle hatchling morphology and hydrodynamics

Alexis Moyle, Sarah Milton

Florida Atlantic University, United States of America

Nest incubation temperatures affect many physiological and behavioral aspects of sea turtle hatchlings, including body characteristics that may impact swimming efficiency. Hotter nest temperatures result in smaller hatchlings with larger yolk stores, which could affect buoyancy, thrust, and stroke rates, though how these factors are interrelated is not yet known in hatchling sea turtles. This project examined the effects of incubation temperature on body morphology, buoyancy, swimming kinematics, and blood chemistry to better understand variations in locomotor performance in loggerhead (Caretta caretta) sea turtle hatchlings of South Florida. Nest temperature, body measurements, and blood samples were collected in conjunction with swim trial force measurements and video recordings. Hatchlings from nests with higher incubation temperatures (mean > 33°C) were significantly smaller in size, less buoyant, and displayed lower power stroke frequencies. In addition to lower hatch and emergence success, the relationships between morphology and performance suggest hatchlings of high temperature nests may exhibit weaker swimming abilities. Combined with their smaller body size, poorer swimming efficiency would make them more vulnerable to predation than hatchlings from cooler nests. The results of this study provide a further understanding of the effect of increasing incubation temperatures, as with climate change, on hatchling physiology and survival during the frenzy period.

Variations in mean brevetoxin concentrations by tissue type in three Florida sea turtle species

Raschelli A. Linz, Sarah L. Milton

Florida Atlantic University, United States of America

Nutrient inputs from terrestrial sources and increasing global temperatures have raised concerns about the frequency and intensity of harmful algal blooms (HABs), as they can lead to population declines of keystone and endangered species as well as major economic losses. Karenia brevis is one of the main microalgae implicated in the HABs that occur in Florida coastal waters. K. brevis produces polyether neurotoxins called brevetoxins (PbTx), which are known to cause immunomodulation, oxidative stress, increased stranding incidence and mortality, in sea turtles that have been exposed via inhalation or ingestion. To better understand how different species are impacted by this biotoxin, it is important to characterize its distribution, storage, and removal from the body. This meta-analysis aggregated available data regarding PbTx concentrations in a variety of tissues and biological products across three species of turtles that utilize Florida waters and nesting beaches, including green (Chelonia mydas), loggerhead (Caretta caretta), and Kemp’s ridley (Lepidochelys kempii) sea turtles. Reported mean PbTx-3 concentrations from studies that measured concentration using enzyme-linked immunosorbent assays were systematically collected from the literature and grouped by species and sample type. Two-way ANOVA with interaction and Tukey multiple comparisons test were used to determine significant differences in PbTx concentrations between sample types and species. Mean PbTx concentrations were determined to differ significantly between sample types, with digestive tissues (stomach contents, and feces) containing significantly higher concentrations than other samples (bile, kidney, liver, lung, plasma, urine, whole blood), supporting conclusions that ingestion is the primary route of exposure and that these species can remove significant quantities of PbTx via excretion. Interestingly, there were no significant differences in PbTx concentrations between the three species, potentially indicating that exposure risk is similar across species despite differences in diet and spatial distribution in coastal waters.

Maximising captive releases of leatherback turtles using insights from simulated growth and reproduction models

Anna Antonia Ortega1,2,4, Nina Marn3, Nicola Mitchell1,2, George Shillinger4

1The School of Biological Sciences, The University of Western Australia, Australia; 2The Oceans Institute, The University of Western Australia, Australia; 3Rudjer Bošković Institute, Zagreb, Croatia; 4Upwell Turtles, California, United States of America

The longevity of a population hinges on the ability of its individuals to reproduce, which is dependent upon energy acquisition, constrained by access to suitable temperature and sufficient food resources. Leatherback turtles are highly migratory and globally vulnerable to numerous widely dispersed anthropogenic threats, though little is known about their energy acquisition. What is known is based on a few studies of leatherbacks in captivity. Relevant physiological data (length, weight, oxygen consumption, metabolic rate) can be extrapolated to the pelagic life phase using Dynamic Energy Budget (DEB) theory. DEB theory provides the basis of mechanistic modelling presented here to demonstrate that varying temperature and food availability has impacts on the ability of leatherback turtles to grow and reproduce. Our model will identify the range of food and temperature thresholds which maximise early life leatherback growth. As a leatherback hatchling migrates from its nesting beach through the pelagic ocean, there may be certain migratory paths that fall within these maximum growth thresholds. Identifying these paths could inform conservation actions and allow release of leatherback hatchlings into the most favourable conditions, maximising early life growth and enhancing conservation efforts.

Non-invasive heart rate measurement of green turtle embryos

Hideaki Nishizawa1, Tomoatsu Ijichi1, Shota Hyodo1, Satomi Kondo2

1Graduate School of Informatics, Kyoto University; 2Everlasting Nature of Asia (ELNA), Ogasawara Marine Center

Measuring embryonic heart rate provides important information about development and activity rhythm of embryos. Non-invasive heart rate measurement of embryos using infrared light has been a useful technique in birds and reptiles including snakes and freshwater turtles. In this study, we evaluated how green turtle embryo activity rhythms responded to different incubation temperatures using non-invasive heart rate measurements. We collected green turtle eggs from 12 clutches after they incubated in situ for approximately 40 d from egg deposition at Omura Beach, Chichijima Island, Ogasawara, Japan. After eggs were transferred to the Ogasawara Marine Center, 15 eggs from each clutch were separated into three incubators (5 eggs each; i-CUBE Hot & Cool incubators, AS ONE Corporation) where the temperature was constantly set to 26℃, 29℃, and 32℃. Eggs were separately placed on water-dampened sphagnum moss on a plastic dish. After an acclimatization period of at least 12 hours, the heart rate of each embryo was measured with a digital egg monitor Buddy Mk II (Avitronics). We measured the heart rate every 6 hours (00:00, 06:00, 12:00, and 18:00) for 3 consecutive days. The results clearly showed that heart rates of embryos increased as temperature increased. In addition, heart rates varied across clutches. We investigated the relationship between heart rate and incubation temperature in the field for 5 of the clutches before the collection of eggs. We also discuss whether green turtle embryos have a circadian rhythm that has been previously reported from freshwater turtles.

Plastic ingested by green sea turtles (Chelonia mydas) with Fibropapillomatosis (FP)

Rachel Theresa Southards, Heather A. Seaman, Sarah L. Milton

Florida Atlantic University, United States of America

Marine ecosystems face an escalating threat from plastic pollution, and among the most vulnerable inhabitants are sea turtles. Listed as either vulnerable or endangered on the IUCN Red List, sea turtles ingest plastics that can result in severe physiological consequences, including gut compaction, gut perforation, and leaching of toxic chemicals from plastics into their tissues. This study delves into the relatively unexplored domain of plastic-induced physiological impacts on sea turtles while extending its focus to elucidate potential disparities in these impacts between turtles afflicted with Fibropapillomatosis (FP) and those without this debilitating disease. Our study investigates the variability of plastic ingestion among green sea turtles and between ontogenetic stages and FP. During necropsies the gastrointestinal tracts from 46 green sea turtles were collected and placed in aluminum pans. The gastrointestinal contents were removed and digested by 10% KOH for up to ten days. After digestion of non-debris material, the contents were filtered to obtain marine debris greater than 2mm. The debris was then counted and categorized using ImageJ software. There were twenty-one FP turtles sampled and seventeen of them had plastic (81%), most were juveniles. There were twenty-four non-FP turtles sampled and fifteen of them had plastic (63%). A total of 742 pieces of marine debris (2mm or larger) were found in the turtles and 40% of this total was found in FP turtles. The highest number of plastic pieces found in one individual was 160 and it was a turtle without FP. Black and white pieces were the most common in FP (23% and 26%, respectively) and non-FP turtles (29% and 25%, respectively). Filament was the most common type of marine debris found in FP (69%) and non-FP turtles (72%). These preliminary results suggest that there are no significant differences in plastic marine debris consumption between FP and non-FP green sea turtles; this study builds upon our current knowledge of marine debris and FP in sea turtles.

Histological reconstruction of the olive ridley sea turtle hatchling head

Jesus Rodolfo Martin del Campo1, Joy Richman2

1Universidad del Mar, Oaxaca, Mexico; 2University of British Columbia, Vancouver, Canada

There are seven species of sea turtles in the world, of which six belong to the Cheloniidae family and one to the Dermochelyidae family. Studies of the head anatomy have been carried out for species of both families; however, these primarily exist for adult sea turtles. Interestingly, the craniofacial region is the most affected by congenital malformations in sea turtles, and histological analysis of the cranial structures only exists for freshwater turtle hatchlings. In this study, in order to have a reference for the head histology of normal hatchlings and to be able to compare them with abnormal specimens in future studies, we performed the first histological analysis of the olive ridley sea turtle (Lepidochelys olivacea) hatchling head. Our results concur with the anatomical descriptions previously reported for adult and juvenile turtles of the Cheloniidae family, although small variations exist. For example, the brain in the olive ridley sea turtle is proportionally larger in hatchlings and juveniles in comparison to subadults and adults of the same family. The division of the nasal cavities for hatchlings was also very similar to juvenile and adult sea turtles in the Cheloniidae family. Finally, in general terms, the histology of the olive ridley hatchling head was also very similar to that reported for freshwater red-bellied shortneck turtle (Emydura subglobosa). These findings are important because will serve as a basis for histological comparisons with hatchlings presenting congenital craniofacial malformations in future studies.

Why the long face? Hawksbill foraging strategies when sympatric with green turtles

Jeanette Wyneken1, Michael Salmon1, Tommy Cutt2, Don McGleish2, Alexander Gaos3

1Florida Atlantic University, United States of America; 2Marine Institute Maui Ocean Center; 3Marine Turtle Biology & Assessment Program NOAA Pacific Islands Fisheries Science Center

Sea turtle head shape varies with phylogeny, ontogeny, and ecology. Among the extant sea turtle species, the hawksbill (Eretmochelys imbricata) stands out from other cheloniid species as having a head that is twice as long as it is wide. The jaws form a narrow "v" in dorsoventral view. In comparison, the green turtle (Chelonia mydas) differs in the other extreme; its head is rounded in profile with a blunt snout and the jaws are "u-shaped" in dorsoventral view. We hypothesize these two very distinct head shapes reflect foraging differences. We tested this hypothesis with morphological comparisons as well as field observations. Head shape was quantified by measuring heads of live turtles, dead strandings, and skulls. The head is structurally and functionally formed by two parts: the facial component and the neurocranial component. The neurocranial part of the skull houses jaw muscles and the attachments of neck muscles. We focused on comparisons of facial proportions and neurocranial proportions at several life stages. Facial elongation was most pronounced in juvenile hawksbills. Interestingly, adult hawksbill facial proportions became proportionately shorter while the neurocranial component became more robust. In green turtles, facial versus neurocranial elongation differed less in juveniles to adults. The two species occur sympatrically on shallow reefs in the waters of Hawaii (U.S.A). Both forage on algae. The hawksbills feed on algal colonies in crevices, often removing obstructions with their jaws. We hypothesize that the elongation of the hawksbill neurocranium supports the muscular and biomechanical requirements for this behavior. In contrast, green turtles scrape algae from larger colonies growing on open flat hard surfaces. This foraging mechanism requires broad flat scraping or nipping jaws and likely less mechanical advantage to depress or elevate the head. The head proportions and shapes align with the differing foraging techniques of each species.

Novel biomarkers of environmental genotoxicity in green turtle (Chelonia mydas) on the coast of Quintana Roo, Mexico.

Aida M. Guevara Meléndez1, Mauricio Comas García2, Leticia Yáñez Estrada3, Vanessa Labrada Martagón4

1Facultad de Ciencias Agronómicas, Universidad de El Salvador; 2Centro de Investigaciones en Ciencias de la Salud y Biomedicina, Universidad Autónoma de San Luis Potosí; 3Laboratorio de Género, Salud y Ambiente, Facultad de Medicina, Universidad Autónoma de San Luis Potosí; 4Laboratorio Ecología de la Salud, Facultad de Ciencias, Universidad Autónoma de San Luis Potosí

Micronuclei and nuclear abnormalities are biomarkers of genotoxicity in wildlife caused by bioavailability and environmental exposure to chemical agents. The coast of Quintana Roo represents a critical foraging and nesting area of numerous species of sea turtles; however, it is a highly modified and disturbed habitat by the tourism industry. The goal of this study was to quantify nuclear abnormalities in erythrocytes of green turtles (Chelonia mydas) and to evaluate differences between age classes, sex, and size. Individuals were captured in 2019 in three feeding areas (Akumal, Xcalak, and Punta Herrero) of the Mexican Caribbean with distinct anthropogenic pressures; at each site, the capture method changed due to environmental conditions, the bay's characteristics, and the organisms' size. Once captured, blood samples were taken from the cervical venous sinus and the blood smears were prepared in duplicate and stained following a specific protocol for sea turtles using acridine orange staining. The cell count with nuclear abnormalities was performed on 20 digital photographs taken per animal with a fluorescence microscope, documenting the number of micronuclei and nuclear abnormalities in a total of 2000 erythrocytes per individual. To determine environmental quality, concentrations of organochlorine pesticides (OC's) and polychlorinated biphenyls (PCBs) were determined in samples of plasma of the same species, captured in the same areas during 2016 and 2017, which were processed using Gas-Mass Chromatography.

Four nuclear abnormalities were identified for the first time in sea turtles: lobed nuclei, notched nuclei, nuclear buds, and figure-eight nuclei. Nuclear abnormalities were not correlated with the size of sea turtles. No significant differences were found in the frequency of micronuclei (KW-H=2.98, p=0.22), buds (KW-H=2.66, p=0.26), and nuclear abnormalities (KW-H=3.13, p=0.20) between study sites. Although, the 90% of sea turtles from the most touristic site (Akumal Bay) presented ≤140 nuclear abnormalities in 2000 erythrocytes, while the same proportion of individuals from Xcalak and Punta Herrero presented no more than 90 and 60 nuclear abnormalities in 2000 erythrocytes, respectively. Micronuclei were not found in green turtles from Punta Herrero; and buds were more common in individuals from Xcalak. The frequency of genotoxic damage matches the concentrations of OCs and PCBs, which were significantly higher in Akumal and Xcalak, respectively. These results suggest that Akumal continues to be the most affected area with intense genotoxic damage (highest proportion of individuals afflicted), probably associated with the increase in chemical contaminants derived from the various tourist activities at the site. The presence of contaminants, such as DDE in plasma, confirms the bioavailability and persistence of contaminants in the environment that have affected biodiversity for years. The green turtle can reside for up to 10 years in these feeding areas prior to sexual maturity; the effect that the genotoxic damage observed in the individuals from Akumal and Xcalak may have in the long term on the population of the Mexican Caribbean is unknown. The new abnormalities detected can be used as a biomarker to determine the anthropogenic damage generated in the bays.

Epibionts associated with nesting females of black turtles (Chelonia mydas agassizii) from the breeding population of Michoacan, Mexico

Cutzi Bedolla-Ochoa1,2, Carlos Delgado-Trejo1,2, Miguel Angel Reyes-López2, Fátima Yedith Camacho-Sánchez2

1Instituto de Investigaciones sobre los Recursos Naturales, Universidad Michoacana de San Nicolás de Hidalgo, México; 2Centro de Biotecnología Genómica, campus Reynosa, Instituto Politécnico Nacional. México.

In order to identify the presence of epibionts in nesting female black sea turtles (Chelonia mydas agassizii) at Colola beach, Mexico, 93 individuals were examined. The most frequent epibionts were balanos (Chelonibia testudinaria) with presence in 100% of the turtles, leeches (Ozobranchus branchiatus) were recorded in 48 individuals, six turtles presented barnacles (Lepa anatiferas) and in 26 turtles were recorded algae of the genus Oedogonium sp, Enteromorpha flexuosa, Ectocarpus sp. Roicosphenia curvata, Navicula directa, Synedra ulna, Synedra dorsiventalis, Nitzschia sp., Gomphonema acuminatum. On the other hand, the presence of polychaetes was observed in the balanus samples and nematodes, bryozoans and crustaceans in the algae samples present in the black turtle individuals.

The present study found that the size of the turtles is a variable that does not affect the incidence of epibionts. However, their incidence varied in the different anatomical areas (carapace, plastron, head, flippers and base of the tail) of the turtles. Balans were more abundant in the carapace, leeches in the neck. In the case of barnacles, they were always found attached to the squid, mainly on the plastron. Algae were found only on the carapace.

Impact of multidrug-resistant bacteria on sea turtles and the marine environment

Daphne Wrobel Goldberg1, Fabio Parra Sellera2, Danny Fuentes-Castillo3

1Projeto Albatroz, Cabo Frio, Brazil; 2School of Veterinary Medicine, Metropolitan University of Santos, Santos, SP, Brazil,; 3Laboratorio de Microbiología Veterinaria, Departamento de Patología y Medicina Preventiva, Facultad de Ciencias Veterinarias Universidad de Concepción

Sea turtles are not only charismatic and ecologically important species, but they also play a pivotal role in the health of marine ecosystems. Their unique life history traits, such as long lifespan, broad habitat range, and migratory behavior, make them valuable indicators of environmental quality and ecosystem health. As marine reptiles, sea turtles have the potential to accumulate and transport biotical or abiotic pollutants, including antibiotic-resistant bacteria, across different marine environments. This role as environmental sentinels positions sea turtles as important bioindicators of antibiotic resistance in the marine ecosystem. Among resistant pathogens, extended-spectrum beta-lactamase (ESBL) and carbapenemase-producing Enterobacterales are considered of critical priority according to the World Health Organization. The emergence of these resistant strains presents a significant challenge in clinical settings and public health, as infections caused by ESBL- and carbapenemase-producing Enterobacterales are often difficult to treat and can pose serious risks to human and animal health. Several studies have highlighted the prevalence of antibiotic-resistant bacteria, including ESBL and carbapenemase-producing Enterobacterales, in marine environments. A recent study in Brazil, evidenced CTX-M-15-producing Enterobacter hormaechei ST114 and Citrobacter freundii ST265 co-infecting a free-living Chelonia mydas, shedding light on the presence of CTX-M-15-producing extended-spectrum β-lactamase (ESBL) in marine animals. In another study, also conducted in Brazil, a novel sequence type (ST264) of Citrobacter portucalensis, a metallo-β-lactamase (NDM-1)-producing strain, was isolated from the blood sample of an infected migratory olive ridley, found stranded sick on the Southern part of the country. Both studies revealed the wide resistome of these pathogens, contributing to treatment failure and the death of the infected animals along the Brazilian coast. These investigationsprovide significant insights into the clinical and environmental implications of human-associated bacterial lineages for marine ecosystems, including the impact on endangered free-living sea turtles exposed to marine-polluted environments. The reports of multidrug-resistant Gram-negative bacteria in sea turtles are widely spread, reflecting the global nature of this issue. The risk posed by these antibiotic-resistant bacteria to sea turtles, already endangered due to numerous anthropogenic threats, is substantial. The potential impact on the health and survival of sea turtles, together with the implications for the overall marine ecosystem,underscores the urgent need for comprehensive monitoring, research, and conservation efforts to protect these emblematic marine species from these pathogens. The linkage between sea turtles and antibiotic-resistant bacteria is of particular concern due to the potential impact on both the health of sea turtles and the overall marine ecosystem. Sea turtles may serve as reservoirs and vectors of antibiotic-resistant bacteria, influencing the health of other marine organisms and contributing to the spread of antibiotic resistance in the marine environment. The monitoring and assessment of antibiotic-resistant bacteria in sea turtles provide valuable insights into the distribution, prevalence, and potential impacts of antibiotic resistance in the marine environment. By studying these interactions, researchers can better understand the evolution and dissemination dynamics of antibiotic resistance in marine ecosystems and develop effective strategies for the conservation of sea turtles and the maintenance of healthy marine ecosystems.

Report of a green turtle (Chelonia mydas) impaction due to mangrove propagules in the Philippines

Lowee Lyn Castillo1, Sharah M. Barredo1, Marco Acosta2, Mario Ronda2, Geraldine Benavente2, Ian Echanes3, Jessica Labaja1, Kurt Ivan Mariano1, Glen Gonzales Rebong4, Frances Camille Rivera5, Rizza Araceli F. Salinas6, Alessandro Ponzo1

1Large Marine Vertebrates Research Institute Philippines, Philippines; 2Port Barton Marine Park (PBMP), San Vicente Palawan, Philippines; 3Municipal Agriculturist Office, San Vicente, Palawan, Philippines; 4Palawan Wildlife Rescue and Conservation Center - Crocodile Farm in Puerto Princesa City, Palawan; 5Oceanus Conservation, Manila, Philippines; 6Department of Environment and Natural Resources Biodiversity Management Bureau, Quezon City, Manila.

While foraging behaviour has been extensively studied in other countries, there is still a lack of understanding of their foraging habits in the Philippines although movement and genetic data highlight the country as an important foraging and development ground across the Indo-Pacific. The population of green turtles, particularly in Palawan island, is understudied, as is their foraging behaviour across the nearly 2000 km of coastline, ranging from small coastal seagrass beds to large foraging sites like Tubbataha Reefs Natural Park. Conflicts in the Western Philippine Sea, coastal development, and climate change potentially threaten these foraging sites. On February 23, 2023, the Port Barton Marine Park ranger found a stranded green turtle and necropsy was conducted on February 26, 2023. The carcass exhibited a distended distal colon, impacted with faecal matter, mainly composed of undigested propagules of Rhizophora sp. and several strands of synthetic string. The undigested propagule material was scattered throughout the small and large intestine. Collected samples (n=16) from the distal colon measured an average of 43.73 mm in length and 17.36 mm in width, with the largest fraction measuring 82 mm in length. The strings (n=31) ranged from 50 to 530 mm in length, and were identified to be polypropylene rope strands, flour sack strands, and nylon rope strands. The synthetic materials, while present across the intestine, did not seem to be the primary cause of impaction, nor did it cause other macroscopic pathologies like intussusception – a phenomenon often found in turtles with nylon fishing lines or ropes in their gastrointestinal tract. Intestinal impaction from the propagules was identified as the most probable cause of death. Previous necropsies of stranded green turtles in Palawan and the Philippines have reported seagrass, and algae as the main food sources, and this is the first report, to our knowledge, with large quantities of propagules ingested. While the reason for the ingestion of large quantities of propagule is unknown, days before the stranding, a mangrove planting initiative was coordinated by local groups and authorities a few kilometres from the stranding site.

While no previous records occur in the Philippines to our knowledge, green turtles found in estuaries in the Galapagos Islands (Pritchard 1971; Carrion-Cortés et al, 2010), Western Australia (Pendoley and Fitzpatrick 1999), and Shoalwater Bay, Australia (Limpus and Limpus 2000) have been reported to opportunistically ingest mangrove propagules (Nagaoka et al., 2020), particularly the cotyledon and roots from Avicennia marina, as part of their diet, although these species are softer, less fibrous, with less probability to cause impactions.

Since shifts in the green turtle diet often depend on the availability of food sources, caution and proper planning should be put in place to ensure proper habitat selection for mangrove greenings programs, avoiding existing seagrass beds and other important foraging habitats for local marine turtle populations.

Clinical and pathological findings of a geriatric green turtle maintained in captivity with restricted water circulation: a case report

Chayanis Daochai1, Saransiri Nuanmanee2, Rattanakorn Phakphien3, Khunanont Thongcham3, Ratchakul Wiriyaprom1, Watcharapol Suyapoh1

1Faculty of Veterinary Science, Prince of Songkla University, Thailand; 2Songkhla Aquatic Animal Health Research and Development Center, Department of Fisheries, Thailand; 3Marine and Coastal Resources Research Center (Lower Gulf of Thailand), Department of Marine and Coastal Resources, Thailand

This case study investigates the clinical and histopathological aspects of a geriatric green turtle (Chelonia mydas) that was kept in captivity with restricted water circulation for over 10 years. The turtle displayed indications of loss of appetite and depression for a duration of 1 to 3 months. The radiograph was carried out during the second week, and blood was collected in the third week. Subsequently, after a month of sampling, the turtle exhibited the emission of mucous through its oral cavity during respiration. Following three days of displaying this symptom, the turtle perished, and samples were procured from its liver, kidney, colon, stomach, and lung for histopathological analysis. The water quality of the tank where the turtle was housed was monitored and found to possess elevated salinity and hardness. The findings of the comprehensive blood count, blood biochemical parameters, and thoracic radiography did not reveal any significant abnormalities. Nevertheless, the pathological examinations did identify the presence of some lesions. The liver exhibited a dark brown pigmentation as well as sinusoidal congestion, apoptotic bodies, and the accumulation of lipofuscin, suggesting the presence of foreign materials, while the kidneys displayed renal fibrosis, hemorrhage, and infiltration. The mucosa of the ileum, colon, and jejunum demonstrated signs of inflammation and abnormal coloring. Moreover, the stomach manifested an orange-reddish hue and contained green material, which is suggestive of moderately widespread colon melanosis. Additionally, the lung was diagnosed with gastro-enterocolitis and bacterial infection, whereby pathogens such as Klebsiella oxytoca, Proteus vulgari, and Escherichia coli were cultured from the lung. This specific case study highlights the importance of implementing comprehensive husbandry procedures when caring for marine turtles in captivity, especially for geriatric turtles, even when the clinical signs are not remarkable. The study suggests that the conditions of captivity may affect the levels of bacteria in the water or the susceptibility of turtles to bacteria, and this aspect should be considered when managing sea turtles and other aquatic animals in tanks with limited water circulation. Further investigation is needed to determine the factors contributing to this phenomenon and establish the best practices for captive environments.

Evaluating the sub-lethal effects of red tide blooms and brevetoxin exposure on nesting loggerhead sea turtles

Kelly A. Sloan1, Andrew Glinsky2, Jack Brzoza1, Nicole I. Stacy3, Paul Julian4, Simona A. Ceriani5, Susan Fogelson6, Justin R. Perrault7

1Sanibel Captiva Conservation Foundation, United States of America; 2National Oceanic and Atmospheric Administration; 3College of Veterinary Medicine, University of Florida; 4Everglades Foundation; 5Florida Fish and Wildlife Research Institute; 6Fishhead Labs; 7Loggerhead Marineline Center

Blooms of the harmful algae Karenia brevis are a significant and persistent threat to sea turtles that inhabit the Gulf of Mexico. A bloom off the coast of southwest Florida, USA from October 2017 through February 2019 was the longest continuous bloom since 2006 and resulted in the largest number of sea turtle deaths ever attributed to a single red tide event. In 2019, we launched a study on Sanibel Island, Florida to investigate the long-term effects of this unprecedented bloom on health and reproductive success of nesting loggerhead sea turtles (Caretta caretta). Our objectives were to (1) quantify brevetoxin concentrations in plasma for loggerheads nesting on Sanibel Island, Florida, USA, following an intense and prolonged red tide bloom, (2) establish correlations with brevetoxin exposure and blood analytes, (3) determine brevetoxin concentrations in unhatched egg contents and dead-in-nest hatchling livers, and (4) identify impacts of brevetoxin exposure on hatching success. Between 2019 and 2022, we collected 428 blood samples from 305 nesting loggerheads without clinical evidence of brevetoxicosis. We also collected 276 dead-in-nest hatchlings and 1,593 eggs from nests laid by these females. Plasma, hatchling livers, and egg contents were analyzed for total brevetoxins. Hatching success was used as an index for reproductive output. Maternal plasma brevetoxin concentrations were low in comparison to animals that strand during red tide blooms, ranging from 0.1 to 24.6 ng/mL Stable isotope analysis indicated that loggerheads foraging in the Gulf of Mexico had significantly higher plasma brevetoxin concentrations than those using Caribbean foraging grounds. Several correlations of brevetoxins with blood analytes provided evidence of subclinical effects on immune functions and overall health. Mean hatchling liver brevetoxin concentrations ranged from 12.0 to 534.0 ng/g and were significantly higher in 2020 and 2021 compared to 2019. Brevetoxin concentrations in hatchling livers and eggs from the same nest were significantly correlated, but no correlations were observed between these values and maternal brevetoxin concentrations. Hatching success did not significantly correlate with plasma, egg, or liver brevetoxin concentrations. Histopathologic evaluation of hatchling tissues was performed, but indicated no relationship with brevetoxin concentrations in hatchling livers. Our results provide evidence that even when harmful algal blooms do not cause direct mortality of exposed wildlife, they can potentially act as a physiological stressor with long-term impacts on the health of sea turtles. Additionally, our data confirm that toxin transfer occurs from nesting female to egg/offspring, with high values reported in many hatchling liver tissues, but brevetoxins do not appear to impact reproductive success. The combination of global climate change, potential tropical cyclone intensification, and eutrophication will likely increase the incidence and intensity of harmful algal blooms. It is important to consider the impacts of these blooms on sea turtle health and reproduction when evaluating stressors on the population and developing management strategies.

Characterisation of gastrointestinal tract disorders in relation to marine debris in sea turtles using postmortem computed tomography

Brian Chin Wing Kot, Tabris Yik To Chung, Henry Chun Lok Tsui

Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, China

Sea turtles are often used as indicator species to evaluate the extent of marine debris as well as umbrella species to promote public awareness on conservation issues because of their propensity to ingest debris. Standardizing methods to facilitate spatial, temporal, and species comparisons are critical. Assessing the entire gastrointestinal tract during necropsy is considered the most effective sampling strategy compared to lavage or fecal assessments. Method choices for identifying debris items likely affect debris detection among gut contents and bias the size range of items discovered. Few studies provide clear descriptions and counts of lethal cases of debris ingestion, but all should.

Virtopsy has the advantages of being observer-independent, non-subjective, non-invasive, digitally storable and transferable in facilitating a second-opinion by expert or institute located anywhere in the world. In human medicine, postmortem computed tomography is used for the detection of bowel obstruction in natural cause of death. The yielded computed tomography dataset can be presented as virtual endoscopy that allows the evaluation of hollow gastrointestinal tract, offering fly-through and fly-around function based on 3D data subjected to surface or volume rendering. Debris ingestion in sea turtles can have a range of effects from a benign response, where items simply pass through the gastrointestinal tract, to lethal effects caused by gut impaction or perforation. Our study aimed to characterize gastrointestinal tract disorders in relation to marine debris in sea turtles, and assess the impacts of marine debris on the body condition, diseases, and mortality in sea turtles stranded in Hong Kong waters.

Various postmortem computed tomography signs of gastrointestinal tract disorders in relation to marine debris were characterized in 94 individuals, including whirl sign, coffee bean sign, bird beak sign, and u-shape sign. Contrast computed tomography was used to evaluate motility on live-stranded cases and to detect and characterize obstructions and other abnormalities such as radiolucent foreign bodies, obstructions, and plications. Virtual gastroscopy resulted by computed tomography volume rendering technique allowed detection of intestinal impaction, perforation, intussusception, parasitic gastritis, ulcerative gastritis and other gastric lesions, as well as subtle mucosal changes. Ingested foreign items including fishing gears were also identified using computed tomography in live-stranded cases and removed under imaging guidance.

In summary, marine debris such as different plastic items, fishing lines, and fishhooks were found in the gastrointestinal tract of 72% of deceased sea turtles, while the ingestion of marine debris was identified as the cause of death for one stranded green sea turtle where a latex glove was found obstructing the oesophagus with intestinal congestion associated with other ingested debris. Fifty two live stranded sea turtles were found with evidence of ingested or entangled marine debris, which potentially threatened their lives. This study demonstrated virtopsy is a potentially powerful tool, providing non-invasive and objective measurements to supplement the necroscopic findings for detection of marine debris in the gastrointestinal tract of sea turtles. The calibrated 3D documentation and analysis of virtopsy findings would lead to qualitative improvements in conventional necropsy for the impact assessment of marine debris in sea turtles.

*Characterizing harmful algal bloom-associated biotoxin concentrations and chelonid alphaherpesvirus 5 presence in the blood of nesting leatherbacks in Palm Beach County, Florida, USA

Raschelli Anna-Elizabeth Linz1, Annie Page2, Justin R. Perrault3, Sarah L. Milton1

1Florida Atlantic University, United States of America; 2Harbor Branch Oceanographic Institute, United States of America; 3Loggerhead Marinelife Center, United States of America

Leatherback sea turtles (Dermochelys coriacea) have long been considered to be primarily pelagic. However, recent research indicates that they also heavily utilize coastal foraging areas, where they may be exposed to coastal stressors such as harmful algal blooms (HABs). Many species implicated in HABs produce biotoxins, which have toxic effects on multiple sea turtle species and can possibly serve as cofactors in the development of diseases, such as chelonid alphaherpesvirus 5 (ChHV5), the virus associated with fibropapillomatosis (FP) in Cheloniid species. Limited reports of FP, ChHV5, and some HAB-associated biotoxins exist in leatherback turtles. This study aims to characterize the concentrations of HAB-associated biotoxins and presence of ChHV5 in Northwest Atlantic leatherbacks nesting in Palm Beach County, Florida, USA, to provide a better understanding of how leatherbacks are affected by these stressors. Blood samples were collected from leatherbacks nesting on Juno and Jupiter Beaches, Florida, during the 2023 nesting season. Plasma fractions will be screened for a suite of HAB-associated biotoxins (e.g. domoic acid, lyngbyatoxin-A, microcystin-LA, microcystin-LR, microcystin-RR, microcystin-YR, nodularin, okadaic acid, anatoxin-A, brevetoxin-B, brevetoxin-3, cylindrospermopsin, neosaxitoxin, and saxitoxin). Whole blood will be analyzed using quantitative polymerase chain reaction to detect the presence of circulating ChHV5. These data will allow us to establish a baseline relating health parameters and HAB stressors in coastal leatherback turtle populations.

Implications of low hatchling production from hatcheries for sea turtle populations in India

Arushi Arora, Jayant Pande, Andrea D. Phillott

FLAME University, Pune, India

Sea turtle conservation in India often involves incubating threatened eggs in protected spaces called hatcheries to improve hatchling production. However, not all hatcheries use best practices, so hatchling numbers may be low. Our research examines the implications of low hatchling numbers for local populations and, subsequently, recommends improvements for hatcheries.

Stage-based Leslie matrix population modelling is being used to obtain intrinsic growth rates of study sea turtle populations in India, with fecundity, survivorship, and stage durations sourced from published literature. Elasticity analysis against survivorship and stage duration will determine the contribution of each life stage (hatchlings, juveniles, sub-adults, adults) to population growth.

The study is in progress and is scheduled to be completed in January 2024. We anticipate that findings will demonstrate a threshold below which low hatchling production from hatcheries may result in the loss of local populations. Results will be used to recommend hatchling production targets over time for hatcheries.

Establishing a target hatchling production and success rate to ensure population longevity will motivate hatcheries to use evidence-based best practices for collecting, moving, and incubating eggs. Meeting targets over time will also be proposed to relevant government authorities as a requirement for permit issuance and renewal for hatcheries.

Protecting Indonesia's largest green sea turtle nesting rookery: A two-decade retrospective and key insights

Thomas Reischig1, Muhamad Jayuli2, Rusli Andar2, Meriussoni Zai2, Jatmiko Wiwoho2, Hiltrud Cordes1

1Turtle Foundation, Cologne, Germany; 2Yayasan Penyu Indonesia, Denpasar, Indonesia

The Berau or Derawan archipelago off the east coast of Borneo (East Kalimantan, Indonesia) is considered the largest nesting site for green turtles (Chelonia mydas) in Indonesia and the eighth largest globally. It is part of the Coral Triangle and encompasses 31 mangrove and coral islands, with about 90% of nesting concentrated on the five uninhabited coral islands Sangalaki, Bilang-Bilangan, Mataha, Belambangan, and Sambit. However, decades of unbridled commercial egg harvesting, combined with demand from the Balinese turtle meat market and the spread of destructive fishing practices, is thought to have caused the green turtle population in Berau to decline by more than 90% since the 1950s.

In 2000, Turtle Foundation (TF) and local partners launched conservation efforts on Sangalaki Island. Despite national protection of sea turtles since 1999, licensed egg harvesting persisted until late 2001. It wasn't until January 2002 that egg harvesting was prohibited on Sangalaki, allowing TF to secure the nesting beach year-round with dedicated rangers stationed in a newly erected facility. In 2008, TF was allowed to replicate the successful Sangalaki protection model on Bilang-Bilangan and Mataha, ensuring the protection of approximately 75% of the green turtle nests in Berau.

Since then, the remaining two important nesting islands Belambangan and Sambit were focused as the next targets for protection. In the meantime, however, different perspectives between local stakeholders have resulted in transferring responsibilities for Sangalaki to the nature conservation authority BKSDA (since 2012), and for Bilang-Bilangan and Mataha to a local NGO (since 2017). With three nesting islands now protected from what used to be almost 100% egg exploitation, we were particularly pleased for the opportunity to establish a protection programme for Belambangan and Sambit in 2019. However, the situation changed again when we had to transfer this programme to another local NGO by end of 2021 but returned to Bilang-Bilangan and Mataha in the beginning of 2023.

Since its inception, TF has benefited the local community by providing income to local people through turtle conservation work. Activities were later expanded to include environmental education, most notably extended school visits throughout the Berau district. Currently, the centre of our community activities is on the inhabited island of Maratua, where a dedicated community coordinator leads various alternative income, outreach, and education activities.

While accurate calculations remain difficult due to data fragmentation across organisations, the current average number of nests laid by green turtles in Berau is estimated to be around 15,000 per year. Collective conservation initiatives have likely saved over 15 million green sea turtle eggs over the past two decades, almost completely protecting a once severely threatened turtle nesting population. Throughout this long and challenging journey, one of the most important lessons learned is recognising the significance of working with local communities to achieve sustainable nature conservation. During this process, the Indonesian TF "Yayasan Penyu Indonesia" has emerged as a national charitable organisation that now stands as a renowned entity in the field of sea turtle conservation in Indonesia.

People’s perceptions on the conservation of sea turtles and their associated habitats along the Ponta do Ouro-Kosi Bay Transfrontier Conservation Area, Mozambique and South Africa, south-eastern Africa

Cristina Louro1, Ronel Nel1, Linda Harris1, Sue Ranger2, Peter Richardson2, Bronwyn James3

1Nelson Mandela University, South Africa; 2Marine Conservation Society, United Kingdom; 3Nature Connect, South Africa

The Ponta do Ouro – Kosi Bay Transfrontier Conservation Area (TFCA) encompasses the Maputo National Park (MNAP) in Mozambique and the iSimangaliso Wetland Park World Heritage Site in South Africa. This area serves as an important courtship and nesting ground for loggerhead and leatherback sea turtle populations in the South Western Indian Ocean. Despite its biodiversity richness, local communities face persistent social and economic challenges. Thus, this study aims to document the value of sea turtles, their conservation impacts on people, and their wider influence on the surrounding social and economic system.

Filmed interviews and participatory mapping were utilized to gather and interpret knowledge. Using the 'snowball' sampling method, interviews were conducted in English (n=35), Portuguese (n=35), Rhonga (n=23), and Zulu (n=16). These interviews were transcribed and analyzed using Nvivo software, employing the reflective thematic analysis and grounded theory approaches. Mapping interviews on occurrence areas (n=86), value (n=52), and threats (n=69) were assessed using QGIS 3.12.0 Bucaresti software.

The findings revealed concerns about declining agricultural and fisheries yields, unemployment, and limited access to healthcare, education, and transportation. However, the people recognize the value of sea turtles, particularly their economic significance (55%). Individuals residing near nesting and courtship sites benefit the most, either through employment (as monitors, tourism guides, etc.) or by enhancing their businesses (ocean safaris, hospitality, and informal markets). In iSimangaliso, employment opportunities linked to sea turtles serve as the primary income source due to restricted access to natural resources and limited business prospects.

Despite evolving values over time, sea turtles in iSimangaliso and the MNAP continue to be valued for their meat (approximately 49%) and eggs (about 19%). Notably, in iSimangaliso, sea turtle eggs are also prized for medicinal purposes (22.2%). Concerning threats, there is a shared understanding of reduced risks to sea turtles (52.3%), predominantly focused on onshore threats. In iSimangaliso, threats primarily involve poaching of nesting females and nest raiding (51.1%), alongside fishing and pollution (22.2%). In the MNAP, threats revolve around fishing (25%), natural predators (23.4%), and coastal development (21.8%). Notably, potential coastal developments like housing and access roads, and the deep-water 'ghost' port, were not extensively addressed, possibly due to a lack of awareness regarding their impact on sea turtles and their habitats. The study participants emphasized ongoing efforts to generate knowledge (33.3%) and improve enforcement (44.0%) by enhancing communication between authorities and communities. The main occurrence areas highlighted by respondents include the nesting beaches of Bhanga Nek and Ponta Malongane and the potential feeding grounds in Mangal, a seagrass bed within the MNAP. Identified threat areas encompass Maputo Bay, Ponta do Ouro, and the Kosi Mouth area, attributed to artisanal fishing, coastal development, and poaching, respectively.

In conclusion, while facing numerous social and economic challenges, people value sea turtles and their habitats due to the diverse direct and indirect benefits derived from their presence. This comprehensive understanding is essential for implementing sustainable conservation strategies that prioritize both the needs of the people and the conservation of these migratory species, the sea turtles

Community-led conservation: A decade of success in marine turtle volunteer programs in Vietnam

Thi Thu Hien Bui, The Cuong Chu

Marine and Coastal Program, IUCN Vietnam

Since 2014, IUCN Vietnam has engaged volunteers in conservation efforts across various sites, including Con Dao National Park (NP), Hon Cau Marine Protected Area (MPA), Bai Tu Long NP, Nui Chua NP, and Ly Son MPA. The primary objectives are to enhance public awareness of the crucial role in marine turtle conservation, assist rangers in relocating turtle eggs to designated incubator areas during the nesting season (June-August), and subsequently release hatchlings into the sea. Additionally, the volunteers aim to advocate for biodiversity protection and marine conservation at the national level.

The program has garnered significant interest, with over 12,000 applicants expressing their willingness to participate. More than 600 individuals were carefully selected from this list, with women comprising more than 60% of the participants. The IUCN marine turtle volunteer Facebook fan page has achieved substantial reach, boasting 176,000 post impressions (inclusive of repeat views), 165,000 post reach (reflecting individual views), and 34,700 interactions (including likes, comments, and shares). Furthermore, the initiative has generated extensive media coverage, thousands of stories, and photos featured on social networks, over 40 articles and 15 events featured in well-known national outlets, and 12 out of 60 videos and films have been aired on national channels.

When asked about the reason for participating in the program, the top motivation for participating in a marine turtle conservation volunteer program is to join hands in marine environment protection and marine turtle conservation work, accounting for 98.2%.

While the communication aspects of the marine turtle volunteer program have been commendable, certain challenges persist. Firstly, releasing hatchlings, common in many marine turtle nesting sites, is viewed as a potential revenue stream for NPs/MPAs and an opportunity for awareness-raising. However, adhering strictly to scientific guidelines and employing correct methods is imperative. Secondly, the influx of visitors eager to witness marine turtle hatchlings poses a risk to their well-being. Addressing this issue requires careful management to prevent any negative impact on their health, and the Volunteer could play a crucial role as a guide. Lastly, ensuring sustained funding for the volunteer program remains challenging as almost all funding currently comes via IUCN from the U.S. Fish and Wildlife Services (FWS). Given its proven low costs and high benefits, NPs and MPAs should take ownership of the program, proactively engaging in marine turtle conservation efforts more comprehensively over the long term.

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Protecting sea turtles through the Bern Convention

Nikolaos Simantiris, Konstantina Andreanidou, George Sampson

MEDASSET-Mediterranean Association to Save the Sea Turtles, Greece

Policymakers at local, national, and international levels are of vital importance. Biodiversity policies promote the protection, conservation, and sustainability of biologically diverse ecosystems and habitats and decide the implementation of protection measures. Established in 1979, the Bern Convention was the first international treaty dedicated to the conservation of European wildlife and habitats. The Convention's goal is to unite European countries towards the protection of endangered and vulnerable species of flora and fauna. Through the implementation of monitoring and reporting actions by its partners, the Bern Convention promotes conservation policies, pollution, legislative, and educational measures, and coordinates international efforts. The Convention organizes annual meetings (Standing Committee) where experts present reports and recommendations, and submit complaints regarding unlawful practices in hotspot areas (case files).

Since 1984, MEDASSET has been pushing/lobbying/advocating for the creation and implementation of legislation at national, EU, and regional levels. MEDASSET, in collaboration with other NGOs, monitors the implementation of the Convention's recommendations in two major sea turtle nesting areas in Greece (Zakynthos and Kyparissia) and three in Turkey (Anamur, Kazanli, and Fethiye-Patara). Laganas Bay (Zakynthos island) is one of the most important nesting sites in the Mediterranean region, reporting more than 1,800 nests in 2023. However, the island experiences uncontrolled anthropogenic pressure (touristic activities, coastal development, etc.). Kyparissia Bay constitutes the most important nesting location for Caretta caretta in the Mediterranean Sea, with more than 6,000 nests recorded in 2023. However, Kyparissia is subjected to many violations of the Convention's recommendations and the Greek legislation (uncontrolled tourism, construction, and agricultural activities). Fethiye and Patara Bays in Turkey have been monitored as they form important nesting habitats for Caretta caretta and Chelonia mydas. The region is affected by the lack of management and protection, and the rapid construction and touristic development of the area. Anamur Bay is the 4th most important nesting site in the Mediterranean Sea, reporting more than 1,000 nests of Caretta caretta annually, and an important habitat for Chelonia mydas and Trionyx triunguis. Anamur is negatively impacted by the lack of law enforcement, illegal sand extraction, and coastal development. The aforementioned sites are currently open case files at the Standing Committee of the Bern Convention due to continuous monitoring by MEDASSET officers. Moreover, Kazanli Bay, a significant nesting site for Chelonia mydas, has been subjected to the release of toxic waste from a Soda Chrome Factory since 2000. In 2023, the situation remains unchanged with widespread chemical pollution and lack of monitoring and conservation actions.

For more than 40 years, MEDASSET has been advocating for the protection of sea turtles and their habitats across the Mediterranean. In the future, MEDASSET is dedicated to continuing its efforts to monitor the Government’s actions and follow up with the Convention’s Recommendations to ensure adequate protection for the species.

Accuracy of local communities in identifying leatherback turtle nest locations at Jeen Yessa beach in the Bird's Head region of Papua, Indonesia

Petrus Pieter Batubara1, Deasy Natalia Lontoh1, Yusup Adrian Jentewo1, Yairus Swabra1, Arfiandra Andika Wanaputra1, Fitryanti Pakiding1,2, Manjula Tiwari3

1Science for Conservation Program, Research and Community Service Institute of Universitas Papua, Manokwari, Papua Barat 98314, Indonesia; 2Department of Agricultural Technology, Universitas Papua, Manokwari, Papua Barat 98314, Indonesia; 3Ocean Ecology Network, Research Affiliate of National Oceanic and Atmospheric Administration, Southwest Fisheries Science Center, La Jolla, California 92037, USA

Jeen Yessa Beach (formerly Jamursba Medi) is one of the largest nesting beaches for leatherback turtles (Dermochelys coriacea) in the Pacific. It is part of the Jeen Womom Coastal Park Marine Protected Area. Despite having relatively high leatherback turtle nesting activity, low hatchling production is thought to be one of the factors that impeded population recovery. To increase hatchling production, the nesting beach team of the Science for Conservation Program at the State University of Papua (UNIPA) protects nests in situ by shading nests threatened by high sand temperatures with palm leaves and fencing nests threatened by predation. For these nest protection methods to work effectively in situ, nest protection must be erected just above the nest. However, with an 18-km long beach and insufficient personnel, most nesting activities are missed during night patrols, and the exact nest locations are unknown. Therefore, we recruit people from the communities living in villages around Jeen Yessa beach as local patrollers to record turtle nesting activity and identify nest locations in the morning. The number of local patrollers recruited increased from 5 in 2018 to 6 in 2019 and 7 in 2021 and 2022. To measure these local patrollers' accuracy of nest location identification, we analyzed April to September nesting data from the 2018, 2019, 2021, and 2022 nesting seasons. Local patrollers at Jeen Yessa Beach correctly located 355 out of 375 (94.7%) leatherback turtle nests. With such accuracy, we can confidently erect in situ leatherback nest protection at nest locations identified by the local patrollers.

InGeNi-Caretta project: management of emerging nesting sites of loggerhead sea turtles, based on scientific knowledge and coordination between Mediterranean Spanish regions.

Irene Alvarez de Quevedo1, Mireia Aguilera1, Eduardo Belda2, Luis Cardona3, Carles Carreras4, Adolfo Marco5, Marta Pascual4, Cinta Pegueroles4, Jesús Tomás6, Elena Abella1

1BETA Tech Center, TECNIO Network, University of Vic-Central University of Catalonia (UVic-UCC), C. de Roda 70, 08500, Vic, Spain.; 2Institut d’Investigació per a la Gestió de Zones Costaneres (IGIC), Universitat Politècnica de València, València, Spain; 3Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona (UB), Av. Diagonal 643, 08028, Barcelona, Spain; 4Department of Genetics, Microbiology and Statistics and IrBio, University of Barcelona, Avinguda Diagonal 643, E-08028, Barcelona, Spain; 5Estación Biológica de Doñana, CSIC, C/ Américo Vespucio s/n, Sevilla. Spain; 6Instituto Cavanilles de Biodiversidad y Biología Evolutiva, University of Valencia, Apdo. 22085, E-46071, Valencia, Spain

The western Mediterranean is experiencing an increase in nesting events of the loggerhead sea turtle (Caretta caretta), which corresponds to a colonisation process of the species as an adaptive response to the increase in global temperature, due to climate change. This phenomenon is considered of significant importance for the species because of predictions of future feminization of populations and reduction of incubation viability on the original nesting beaches, while the new nesting beaches have more favourable conditions in the current global warming scenario. To date, an alteration of such magnitude in the distribution range of nesting sea turtles has not been detected for any species of sea turtles in response to global warming. Furthermore, this colonisation occurs in areas with high human occupation and frequent use. For this reason, a coordinated and well-organised management plan needs to be established to promote hatching success, in coexistence with human presence. In this context, we present the InGeNi-Caretta project, started in 2023, with the aim of understanding this colonisation process, and providing a solid base of scientific knowledge for its management and conservation along the Spanish Mediterranean coast. It is a multidisciplinary project, which brings together, for the first time under all the researchers who have worked in recent decades on loggerhead turtle nesting in Spain. The main objectives of this 2-year project are: 1) to evaluate and analyse the sand beaches along the Mediterranean Spanish coast for nesting activity of sea turtles; 2) to do research on the environmental and reproductive parameters of in situ nesting events; 3) to infer the number, origin and behaviour of reproductive individuals through genomic studies; 4) to study of dispersion and habitat use of both reproductive adults and offspring; 5) to evaluate ex situ conservation techniques applied in nesting management; and 6) to disseminate and transfer of results. During the first year, after a record season in numbers of nesting, research for this project has been started. First preliminary analysis, include: a characterization of Spanish beaches, based on their environmental characteristics and anthropic impacts, such as light pollution; the study of the nesting process in situ, as the main source of information and samples of the project; a genetic census of the reproductive individuals participating in the observed nesting, including an estimate of the sex ratio of the adult population; data analysis on turtle movement and habitat use via electronic satellite tracking tags; determination of parameters for both incubation and nest success (hatching rate and emergence of nests, embryonic development rate, incubation temperature, humidity, presence of microorganisms, etc.); and, finally, the dissemination and transfer of results, being a fundamental part of the project to promote management and conservation of the loggerhead turtle, and particularly its nesting, based on solid scientific knowledge. Thus, InGeNi-Caretta aims to transfer the knowledge generated by the project to managers and decision makers in all regions of Spain, to facilitate the planning and management of this threatened species in the immediate future, as it is increasingly affected by climate change.

From Poachers to Protectors: A community based approach on sea turtle conservation in the Lamu Archipelago, Kenya

Annabelle Brooks1, Teresa Jahangir2, Famau Shukry2, Atwaa Salim2, Carol Korschen2

1The Manda Projects, Manda, Lamu, Kenya; 2Lamu Marine Conservation Trust, Shela, Lamu, Kenya

The Lamu archipelago on the northern coast of Kenya is home to 68% of Kenya’s mangrove forests, coral reefs, and seagrass habitats that provide habitat for numerous marine mammal and fish species, as well as 4 species of sea turtle. Established in 1992, the Lamu Marine Conservation Trust (LaMCoT) is a registered Community Based Organisation (CBO) based in the Lamu Archipelago and was set up as a response to the unsustainable harvesting of turtles and their eggs. LaMCoT has maintained a focus protecting turtles whilst expanding its links with the local community to work for both conservation and local development. Through the bycatch program local fishermen turn in turtles accidentally caught in their nets. Turtles are then measured, treated for any health problems, before being tagged and released. Ex-poachers have been trained to patrol local beaches to prevent the illegal poaching of eggs, mark out new nest sites and monitor them until hatching. Guests and community members are invited to watch these hatchings, helping to protect hatchlings from predators encountered on their way to the ocean. Nest sponsorship also sustains turtle protection efforts. Through education programmes LaMCoT increases the awareness of why turtles should be protected, and this also encourages community members to inform us of any turtle exploitation or poaching activity. Between 2001 - 2023 LaMCoT tagged 1,224 turtles, and helped 102,251 hatchlings to the ocean from 892 nests. Here we present the size frequency trends, health and recapture data from green and hawksbills collected from the bycatch program, as well as nesting trends and success rates for 1997 – 2023.

Ras Baridi Turtle Conservation Initiative (RBTCI): a comprehensive Saudi Arabian approach for long-term conservation

Abdulrazaq Alatawi, Ali Algohane, Ali Alfaidi, Roxanne Whelan, Ricardo Ramalho, Hector Barrios-Garrido

Beacon Development, KAUST Innovation. KAUST. Saudi Arabia.

Ras Baridi beach holds the distinction of being the most crucial nesting site for green turtles in the Saudi Arabian Red Sea. However, this vital area faces numerous threats that jeopardize the survival of nesting turtles, their nests, and hatchlings. In response to these multifaceted threats, the Baa Foundation entrusted KAUST-Beacon Development with the task of developing and implementing a Saudi-led initiative to safeguard this essential turtle nesting beach along the Red Sea coast. The Ras Baridi Turtle Conservation Initiative (RBTCI) harbors the overarching goal of ensuring the long-term survival of marine turtle populations in the Red Sea and preserving this critical marine turtle rookery for future generations, guaranteeing its sustainability for years to come. To achieve these objectives, RBTCI's efforts are primarily directed towards mitigating direct human impacts and climate change effects, while simultaneously fostering an educational and awareness campaign that promotes engagement with the project among national and international stakeholders. Our conservation efforts can be categorized into two main phases: short-term (immediate) and long-term actions. Conservation issues that have been promptly addressed and managed include beach driving, human beach activities, and plastic pollution. Also, we promote the study of those ones that require further investigation before effective mitigation strategies can be implemented, such as loss of nesting habitat, beach erosion, artificial light, cement crusts, natural obstructions, and wind-blown cement dust. RBTCI also lends support to research endeavors aimed at enhancing our understanding of various aspects of nesting ecology at Ras Baridi beaches. To date, we have achieved the following: (a) removal of 581.8 kilograms of plastic from the turtle nesting habitat, (b) conduct of nine oral sessions to educate 106 participants, (c) rescue of 1,366 light-disoriented hatchlings, (d) assessment and tagging of 384 green turtles, and (e) georeferencing of 332 nesting events along Ras Baridi beaches. Moreover, Saudi Local Environmental Wardens have carried out the vast majority of activities in-situ, ensuring that talented locals take the helm in the country to foster continuity and local ownership of conservation efforts in the Kingdom of Saudi Arabia. RBTCI is an expanding initiative that advocates for the conservation of marine turtles as umbrella species, striving towards the long-term protection of the entire ecosystems utilized by these threatened species.

A comprehensive review of sea turtle nesting rookeries along Bangladesh coast

Mohammad Zahirul Islam1,3, Mohammad Sazedul Islam2, M. Foysal Ehsan4, Rafat Adnan5, Fariat Muntaha6

1Marinelife Alliance, Bangladesh,; 2Wilderness Conservation Research Centre, Australia; 3Tropical Marinelife Center, Bangladesh; 4EnvirosoftBD, Bangladesh; 5Wilderness Conservation, Bangladesh; 6Chattogram Veterinary & Animal Sciences University, Bangladesh


The Bangladesh coast spans from St. Martin Island in the southeast to the Sundarbans mangrove coast in the southwest, covering a coastline of 710 kilometers. Our study focuses on the sandy beaches, approximately 400 kilometers in length, for sea turtle conservation efforts. The sea turtle program targets three main regions: A) Southeast coast (including St. Martin Island, Teknaf Peninsula, Sonadia Island, Kaladia-Laldia-Dhalghata-Matarbari beach, Kutubdia, and Bashkhali-Gohira-Parki), B) Southcentral coast (encompassing Kuakata, Char Kukri Mukri, Sonar Char, Tuphania, and Shib Char), and C) Sundarbans mangrove coast (comprising Dublar char, Katka, Mandarbaria, Egg Island, and Hiron Point). These areas fall under nine districts and nine Forest Divisions. The southeast coast faces threats from indiscriminate development and alteration of sand dunes and beach habitats. Additionally, the government's establishment of Coal-Based Power Plants at Matarbari, several LNG (Liquified Natural Gas) offshore terminal west of Haserchar and Sonadia island immensely impacted the nesting habitat at Haserchar (Gholghata), Kaladia, Laldia and Sonadia during the recent years (2018-2023). The Rampal coal based powerplant in the Sundarbans area further jeopardizes the coastal environment with more marine traffic and pollution. The Bangladesh coast serves as a critical nesting ground for various sea turtle species, including the Olive Ridley, Green, and Hawksbill turtles. Despite their ecological significance, sea turtles encounter numerous threats, including coastal development, habitat degradation, light pollution, incidental capture in fishing gear, egg poaching, and climate change impacts. Efforts to conserve sea turtles include the establishment of protected areas, community-based restoration programs, habitat restoration projects, and research initiatives. Collaborative programs, such as the Community-Based Sea Turtle Restoration Program led by the Marinelife Alliance, engage local communities in conservation efforts through awareness campaigns, nest monitoring, and sustainable fishing practices. Research projects utilizing satellite tracking devices have provided insights into sea turtle migration patterns and nesting behaviors. However, challenges persist, necessitating continued collaboration among government agencies, NGOs, and local communities. Addressing climate change impacts and developing adaptive conservation strategies are essential for the long-term survival of sea turtle nesting rookeries. Despite challenges, there is hope for the preservation of sea turtle habitats through collaborative conservation efforts and community engagement. The review underscores the ecological importance of sea turtle nesting sites along the Bangladesh coast and the need for sustained conservation efforts to ensure their survival and contribute to global marine biodiversity conservation. Nesting occurrences vary across the coast, with green turtle nesting predominantly observed on St. Martin Island, while olive ridley nesting extends from St. Martin Island to the Sundarbans coast. The Sundarbans and some coastal islands along the south-central coast experience changes due to mainland siltation and climate change, impacting nesting occurrences. Approximately 800-900 nests are recorded annually in the current sea turtle program, with the possibility of nesting occurring on new sand bars formed seasonally along the south-central coast during winter months.

*Evaluating the sustainability of common approaches to sea turtle conservation.

Amanda Elaine Robbins1, Ronel Nel1, Andrea D Phillott2, Andrea Saayman3, Judy Mann-Lang4

1Nelson Mandela University, Gqeberha, South Africa; 2FLAME University, Pune, India; 3North-West University, Potchefstroom, South Africa; 4Two Ocean Aquarium Foundation, South Africa

In 2020, the global Society for Conservation Biology recognized the need for more community centered conservation wherein the economic and sociocultural aspects of conservation are equally evaluated and considered as the ecological (Armitage et al., 2020). In doing so they’ve developed a sustainability framework with a goal of converting current conservation practices to more sustainable ones by 2030 (Armitage et al., 2020).

This poster will summarize the scope of a PhD project that aims to evaluate the ecological, economic, and sociocultural aspects of four common sea turtle conservation approaches: aquaria, marine protected areas, and nesting shores in South Africa; and hatcheries in India.

Sea turtles have been selected as a representative taxa for examining this sustainability framework as the species 1) occur globally; 2) have life history stages occurring across three habitat types (terrestrial, neritic, and oceanic); and 3) are conservation dependent, with six of seven species listed as vulnerable to critically endangered on the IUCN Red List of Endangered Species, with the seventh species, flatback sea turtles, categorized as ‘Data Deficient.’

Sea turtle conservation practices in South Africa and India have been chosen as both countries exhibit globally recognized practices. In South Africa, sea turtles have been protected since 1963 (Hughes, 2010) and the Ezemvelo Wildlife turtle monitoring program is further celebrated as being amongst the oldest and longest running turtle monitoring programs in the world (Hughes et al., 1967; van de Geer, 2022). Furthermore, most of the South African coastline participates in a national turtle stranding network which includes four sea turtle rehabilitation centers (South African Association of Marine Biological Research; Two Oceans Aquarium Foundation). In India, sea turtle hatcheries are prevalent with the relocation of sea turtle nests to hatcheries being a common practice (Phillott, Kale, & Unhale., 2021). There are guided sea turtle walks (Arun, 2013) and sea turtle festivals (e.g., Pawar, 2016) associated with hatcheries in different parts of the country.

To evaluate the ecological and economic aspects of these four common sea turtle conservation efforts, relative reproductive values (Bolten et al., 2011) will be used to quantify the number of sea turtles each conservation approach is protecting, while a cost-effectiveness analysis will be used to determine the cost, benefits, and feasibility of each conservation approach (Klein et al., 2017). These two data sets will be complimented by sociocultural surveys to understand how various demographics directly and indirectly benefitting from the four sea turtle conservation approaches value sea turtles and their conservation approaches. Surveys will be conducted as i) semi-structured interviewers with direct benefiters (e.g., local community members and personnel) and ii) questionnaires with indirect benefiters (e.g., visitors). The responses from both survey methods will undergo content analysis using a phenomenological research paradigm.

The results of these three analyses will be compared to best understand the ecological, economic, and sociocultural benefits and challenges of each conservation approach. Understanding the trade-offs of these four conservation approaches will allow sea turtle conservationists to better curate and implement conservation approaches depending on an area’s biodiversity and human needs.

*Addressing bycatch through fishermen’s wives and children in the Kingdom of Morocco

Wafae Benhardouze1, Mustapha Aksissou1, John Dutton2, Manjula Tiwari3

1FACULTY OF SCIENCES TETOUAN, Morocco; 2Ocean Ecology Network, California, USA; 3Ocean Ecology Network, Research Affiliate of NOAA—Southwest Fisheries Science Center, California, USA

The Kingdom of Morocco extends from the Mediterranean into the Atlantic Ocean with a coastline of 3,446 km. Little nesting takes place in the country, but juvenile and sub-adults loggerheads are the most commonly encountered species in these waters. Evaluating and mitigating mortality of sea turtles in Moroccan fisheries and creating a greater awareness for their protection are crucial to the survival and recovery of several nesting populations in the Atlantic and the Mediterranean. Efforts have been underway since 1999 to organize sea turtle workshops at major ports, and recruit and train fishermen to collect data on turtles caught in their fishing gear. More recently, women’s groups were created in northwestern Morocco to promote the involvement of local women (fishermen’s wives, and women who go fishing and diving) in addressing fisheries issues and marine conservation. The women’s groups are engaged in beach clean-ups, ocean surface garbage clean-ups, and in education and awareness activities about plastics and the proper disposal of discarded fishing gear and garbage by the fishermen. A marine education program has also been started for their children by high school students and includes quizzes, drawing competitions, etc. Theatrical plays and short films by fishermen children were produced and published on social networks. Activities of the women and children have been filmed and will be played back to them and other communities to generate further discussion about marine issues. The goal is to gradually make this a national women’s and children’s network. By making marine conservation a family activity, where fishermen’s wives /children can begin to influence their husbands/fathers, the project hopes to have an even bigger impact on sea turtle conservation in Morocco.

Imagine that you are a sea turtle: Development of an early childhood learning activity

Andrea D. Phillott1, Aditi Renake1, Anuradha Batabyal1, Karishma Modi2, Melissa Coyle3, Prerana Shet4, Seh Ling Long5, Viraj Shah1, Wid Zuriana Wan Sulaiman5, Zameela Ahmed6

1FLAME University, Pune, India; 2Dakshin Endeavours, Bengaluru, India; 3Independent Consultant, Rockhampton, Australia; 4National Institute of Oceanography, Goa, India; 5Perhentian Turtle Project, Perhentian Islands, Malaysia; 6Live & Learn Environmental Education, Malé, Maldives

To support a future sustainable planet, young children need to be engaged with environmental education; it influences their own relationship with nature (see Ginsburg & Audley, 2020. International Journal of Early Childhood Environmental Education 7: 42-61), environmental literacy, and behaviours as an adult (see Ardoin & Bowers, 2020. Educational Research Review 31: 100353) as well as the attitudes and behaviours of their parents (e.g., Dammerell et al., 2013. Environmental Research Letters 8: 015016). However, most programs focus on environmental education in nature with less emphasis on environmental education for and about nature (see Ginsburg & Audley, 2020).

Imagine that you are a sea turtle” is a learning activity that fills this niche. It guides early childhood learners (~4-7 yo) through stages in the sea turtle life cycle and sea turtle biology and examines human-sea turtle interactions and threats to turtles at different times and in different habitats. The development team included collaborators from across South and Southeast Asia and Australia with experience in early childhood learning and environmental education. Our goal was to apply culturally relevant teaching practices (see Bennett et al., 2017. Early Childhood Education Journal 46: 241-248) and incorporate regional examples and illustrations that reflect those of countries in South and Southeast Asia. Written prompts were prepared for educators to invoke physical and verbal responses from children and facilitate physical expression, critical thinking, and problem solving. While text was initially developed and refined in English, the activity is being translated into local languages and includes illustrations by local artists.

This presentation will demonstrate the international collaborative process used in development of the learning activity and provide an opportunity for other educators from the region to become involved in translating the activity into additional languages. Imagine that you are a sea turtle will be available as an open-access resource online in formats that enable its’ use in both online and face-to-face learning spaces.

Addressing online trade of turtleshell products in Indonesia

Joana Nicolau1, Muhamad Jayuli2, Rosek Nursaid3, Hiltrud Cordes4, Meriussoni Zai2, Thomas Reischig4, Jatmiko Wiwoho2

1Fundação Tartaruga; 2Yayasan Penyu Indonesia; 3Profauna; 4Turtle Foundation

Indonesia has a history of exporting turtleshell and stuffed hawksbill turtles (Eretmochelys imbricata) in large quantities. Despite the protection laws established since 1990 for all species of sea turtles, their parts and derivatives, the turtleshell trade continues to thrive within the country.

Besides being offered in different kinds of markets and souvenir shops, nowadays, different types of jewelry (mostly bracelets and rings), and other products made from turtleshell can be found on online shopping platforms and social media.

To gain a better insight into this type of trade, in 2019 and 2020, Yayasan Penyu Indonesia and Profauna conducted an online survey to understand the scale of the illegal trade of hawksbill products on these selling platforms. The findings were shocking: a total of 1,574 advertisements were found on 11 online platforms, amounting to a total of 29,326 items, with an estimated value of USD 340,000. Most offers were found on Instagram (739 advertisements) and Facebook (486 advertisements), while 349 advertisements were distributed over various popular Indonesian selling platforms. During the survey, the location of one major seller was identified on the island of Nias, North-Sumatra, who had accounts on 3 of the most relevant shopping platforms, holding a huge amount of turtleshell products in stock.

Based on these results, two strategies were created to reduce the availability and purchase of products found online. Continuous and friendly contacts were made with the platform owners, asking them to remove the advertisements from their online shops. All platforms and online shops have a complaint mechanism and policies in place, that also mention the prohibition of trading illegal products, including wildlife. Through these mechanisms, users can report violations of the terms of use, but awareness of the fact that turtleshell products belong to the category of illegal wildlife products is generally low in Indonesia. Reports to the platform owners using these complaint mechanisms and through direct approaches by email were done, asking the platform owners to remove the adverts from their online shops. As a result, the number of advertisements decreased from 1,574 to 201 (87% decrease).

In parallel, a campaign for potential buyers was launched, with the aim of initiating a change in behaviour and reducing the demand for turtleshell products. The approach was to create an emotional connection with sea turtles by informing the public that killing hawksbill turtles to obtain their shell is not only illegal, but also very cruel, because the turtles are peeled alive and will die a slow and painful death. Through regular posts on Yayasan Penyu Indonesia's social media platforms and the production of a television and radio advertisement, a substantial audience of approximately 20 million people across Indonesia could be reached.

The campaign proved to be a success, but efforts must be maintained over an extended period. Continued action is essential to perpetuate the positive effects achieved, ensuring a change in buyers’ awareness, leading to a reduction in the purchase of products made from turtleshell.

Key words: hawksbill turtle, turtleshell, online trade, behaviour change, campaign

"Show us the turtle, learn the story": An interactive platform for personalised engagement with sea turtle conservation in a Mediterranean tourist hotspot

Kostas Papafitsoros1,2, Vincent Tarrit2,3, Lukas Adam4, Anna Stamatiou5, Galini Samlidou2, Aliki Panagopoulou2

1Queen Mary University of London; 2ARCHELON, the Sea Turtle Protection Society of Greece; 3School of Engineering and Management Vaud; 4Czech Technical University; 5MEDASSET, Mediterranean Association to Save the Sea Turtles

Laganas Bay on Zakynthos Island, Greece, hosts one of the most important breeding sites for the Mediterranean loggerhead sea turtles and it also supports a year-round resident adult male and juvenile population. In 1999, the area was declared a National Marine Park. Zakynthos is also a popular tourism destination with more than one million visitors in 2023. Turtle-watching is a popular activity for the tourists who can see the turtles via organised boat tours, private hired boats and/or snorkelling. Previous research has revealed a high risk of turtle trauma or mortality especially to resident individuals, usually as a result of immense ecotouristic pressure as well as the frequent violation of the 6 knot speed limit, a key regulation of the park. In an effort to quantify this pressure, a viewing pressure measuring tool for individual turtles has been developed based on the frequency of their appearance in photos uploaded by tourists in social media (Instagram). Even though, the COVID-19 pandemic reduced the tourist pressure on turtles by 75% (2020), pressure intensified during 2021-2023. A 10-day monitoring of Laganas Bay during June 2023 (low tourist season) revealed that typically 4 boats observe a single turtle at a given time with aggregations of more than 7 boats observing a turtle occuring every day (max=10 boats). Furthermore, out of the 10 resident turtles observed in 2023, that have been recorded for the longest time within Laganas Bay (mostly males), 8 (80%) have sustained a boat collision. In order to engage visitors and tour operators towards responsible sea turtle viewing and to highlight this problematic situation, an interactive web-platform ( was recently launched. Through this platform visitors upload images of turtles that they have observed. These are identified via photo-ID, based on an existing 24-year-spanning photo-database and the visitors receive information about them in real time, including number of years since first documentation, interesting stories and behaviours. They further receive a quantification of the pressure that their observed turtle has been subjected to, as well as any injuries it has sustained, increasing their awareness about the extent to which it is threatened. Finally visitors have the opportunity to comment on the ecotouristic activity that they participated in. The platform was launched in August 2023 receiving positive feedback both from tourists and tour operators. Up to 31 October 2023, 164 images were submitted and 46 unique turtles were identified. Notably, 43% of the visitors that submitted a photo taken during a boat tour expressed disappointment about their experience especially with regards to the number of boats aggregating around a single turtle. We anticipate that future scaling-up of the number of submissions will lead to a high number of tourists and tour operators perceiving the sea turtles as unique individuals, with their own life history and habits, eventually resulting to more responsible viewing behaviour. The proposed platform could be adapted for use for other charismatic wildlife frequently viewed at biodiversity hotspots globally, facilitating greater interactions between citizens and science and promoting responsible tourism.

Improved knowledge and capacity to combat sea turtle illegal trade, Cabo Verde

Alberto Queiruga1, Albert Taxonera2, Ukie Resende3, Christophe Eizaguirre4, Olavo da Luz2

1Biosfera, Cabo Verde; 2Projeto Biodiversidade, Cabo Verde; 3Fundação Tartaruga, Cabo Verde; 4University Queen Mary of London, England

The Cabo Verde population of loggerhead turtles is one of the eleven most threatened populations in the world, yet it has grown in the last decade. As the size of the turtle population increases, illegal trade persists, mainly for consumption. However, the real impact of this trade remains still poorly known. To address this challenge, a group of sea turtle conservation partners have implemented a nation-wide integrative approach that is:

i) Improving knowledge about the illegal trade and the consumer market by assessing the origin (terrestrial vs. marine) and entry points of turtle products into communities and profiling poachers, sellers and consumers through socio-demographic surveys;

ii) Proposing a roadmap of specific interventions to mitigate the impact of future reduction of illegal turtle products on vulnerable populations;

iii) Supporting the development and strengthening of the national sea turtle network (TAOLA), to become a strong actor linking governmental and non-governmental organisations to fight the trade in turtle products; and

iv) Testing detector dogs as an innovative method of law enforcement in identified trade hotspots.

This poster will share how, for the first time in Cabo Verde, a national coordinated effort is providing the necessary knowledge to design specific evidence-based strategies, involving a stronger network of conservation organisations and pioneering interventions, through an integrative approach that can be scaled-up and replicated elsewhere.

Communicating Without Borders Or How to overcome language, cultural and proximity barriers to increase a project’s outreach

Efi Starfa1, Wassim Amdrous2, Nikolaos Simantiris1

1MEDASSET-Mediterranean Association to Save the Sea Turtles, Greece; 2WWF North Africa, Tunisia


The importance of well-targeted communication activities in raising awareness of environmental issues and projects cannot be argued and with the rise of social media, the communication axis has become even more significant. One of the main challenges of environmental projects involving conservation activities in many countries is how to get their “messages through” and engage audiences in different countries of operation, taking into account the limited resources, the language, cultural and proximity barriers.

The Case of the Project “Conservation of Marine Turtles in the Mediterranean Region

The project “Conservation of Marine Turtles in the Mediterranean Region” aimed at reducing human induced direct mortality of marine turtles, through targeted research and conservation, policy, education and communication activities. Operating in 13 countries (Albania, Algeria, Cyprus, Egypt, France, Greece, Italy, Lebanon, Libya, Morocco, Spain, Tunisia and Turkey), the partnership of the project faced the challenge of how to engage audiences with different languages, cultures and awareness levels since the beginning. This poster aims to present the communication strategy that the partnership followed to try to overcome these barriers.

Think Globally – Act Locally

⮚ The communication team of the project embraced a multi-dimensional strategy including both overarching communication activities, as well as activities implemented in the specific countries. Smart KPI’s (Key Performance Indicators) were developed to measure success.

⮚ Beyond a simple translation of the communication material to local languages, specific activities were designed to target local audiences and were implemented with the participation of local NGOs. The aim was to engage local communities to marine turtle conservation.

⮚ Engaging local communities in primary data collection through well-designed “Citizen-Science” activities and making them part of the solution.

⮚ Embracing both traditional media and modern social media to increase the project’s outreach and share of voice. Making an extra effort to promote the project’s activities and messages to all countries.

⮚ A photo is worth a thousand words and spreads the message beyond any borders. The project invested in producing professional audio-visual material to showcase its conservation efforts across the Mediterranean.

⮚ Take the extra mile to establish, open, and direct communication with project partners. The project’s success and the reach of communication activities depend on disseminating the information among project partners.

Good collaboration is key, but it is not always the case.


Translating the communication material is not enough. Cross–border projects aiming to achieve a common goal should start thinking locally. Communication activities should be tailored to the unique characteristics of each country, maximizing effectiveness, and minimizing the risk of miscommunication or cultural insensitivity. This in turn involves the formation of a communication task force in constant collaboration and communication that will help guide efforts in each country.

Update on community outreach towards sea turtle conservation at Kalpitiya peninsula of Sri Lanka from 2020 to 2023.

Lalith Ekanayake, Yamuna Karunarathna, Kavishka Ekanayake, M.J.A. Nazeer

Bio Conservation Society (BCSL), Sri Lanka

Five species of sea turtles come ashore to nest in Sri Lanka, while their feeding habitats and migration routes are located around the island (Green Sea Turtle, Leatherback Turtle, Olive Ridley, Loggerhead Turtle and Hawksbill Turtle). The Kalpitiya peninsula is located in the Gulf of Mannar on the northwest coast of Sri Lanka. The fishing communities on the Kalpitiya peninsula depend on seasonal artisanal gillnet fishing for pelagic schooling fish. Sea turtles often get entangled in the sea and lagoon causing damage for fishing nets. In response, fishers either beat the turtles’ heads until they rendered unconscious, or hack off the turtles’ body parts to make disentanglement easier. The turtles are then either discarded at sea, or brought back to shore for illegal processing of their meat for local consumption. Fauna and Flora Protection Ordinance (FFPO, 1972; amendment 1993 and 2009) prohibit harming and killing the turtles, or possessing their body parts. Coastal communities need to be educated about the importance of protecting sea turtles and coastal ecosystems including various habitats such as coral reefs, mangroves, seagrass beds, etc. The objective of this programme was to educate and raise awareness of coastal communities such as fishermen, school children and other users of coastal resources about sea turtle biology and conservation, legislation and enforcement. Educational programmes for students and community members were conducted in schools, children's clubs and fishing community associations. Workshops were held for fishermen to train and sensitize them on how to safely release bycatch turtles in their fishing gear. The programmes continued from 2020 to 2023 with some restrictions during the Covid 19 pandemic. In addition, various field activities such as beach clean-ups and tree planting in home gardens were carried out. The community members (both adults and school children) actively participated in the above field activities and were very enthusiastic about the field activities. Many newspaper articles were published in two local newspapers, and about 200,000 copies of the newspaper were distributed with the news throughout the island. Therefore, a larger group read the conservation message. Most of the community members were very interested in the education programmes and received information about coastal biodiversity conservation. They understood how they can benefit from coastal biodiversity conservation, including sea turtles. The active participation of coastal populations (both adults and children) in coastal biodiversity conservation such as beach cleaning, mangrove replanting has increased, and fishermen attitudinal surveys confirmed that fishers are releasing more bycatch sea turtles in the fishing gears without harming them. This has been the most important result and more field work needs to be done to gain community attention for conservation.

Reducing poaching in Sal Island: a wide approach beyond traditional beach patrols

Artur Lopes, Kirsten Fairweather, Berta Renom, Anice Lopes, Albert Taxonera

Associação Projeto Biodiversidade, Sal Island, Cabo Verde

In Sal Island, Cabo Verde, traditional foot patrols have been the primary method of preventing poaching of Loggerhead turtles since 2008, further supported by sensitisation through an educational program introduced in 2015. In more recent years, alternative approaches have been initiated to enhance the anti-poaching campaign, from expanding the sensitisation program to reach other communities, to use of new technologies to monitor nesting beaches. Currently, the anti-poaching campaign involves the use of drones to cover more isolated beaches, to carry out targeted missions on beaches with higher levels of poaching and to support foot patrols on the principal nesting beaches. Outreach within the community, aside from the traditional school and youth group activities, involves working in partnership with local fishermen’s associations and other communitarian groups, which conduct voluntary foot patrols on their local beaches during the nesting season. A partnership with the military is well established, with soldiers supporting traditional patrols on beaches with higher mortality, as well as conducting patrols on their local beaches, both by foot and by quad bike. As a touristic island, sensitisation of the year-round tourists is conducted through the use of the conservation hatchery during nesting season, as well as year-round hotel visits. This several-tiered approach will be presented to share the lessons learned that helped reduce the mortality of an increasing nesting population.

*Seatru public viewing lab: bridging science and society

Tuan Emilia Tuan Mohd Noor1, Nur Izyani Amrang1,2, Lyvia Chong1, Nadhirah Syafiqah Suhaimi1, Mohd Uzair Rusli1

1Sea Turtle Research Unit (SEATRU), Institute of Oceanography and Environment, Universiti Malaysia Terengganu, Malaysia.; 2Conservation Management Solutions SDN BHD, Institue of Oceanography and Environment, Universiti Malaysia Terengganu, Malaysia.

The SEATRU Public Viewing Lab, established at The Taaras Beach and Spa Resort in Malaysia, represents a pioneering endeavor in integrating scientific research with public outreach and education in sea turtle conservation. This unique, glass-panelled laboratory, the first of its kind in Malaysia, enables the public to directly observe sea turtle research and the hatching process directly, thus fostering greater interest and awareness in turtle conservation. Initiated in 2018, the lab is a collaborative project between Universiti Malaysia Terengganu, Berjaya Hotels & Resorts, and supported by the Department of Fisheries Malaysia. It has engaged over 5700 individuals from various countries, demonstrating the effectiveness of combining tourism with conservation and educational efforts. The lab's activities, such as turtle hatchling release events, educational trips, talks, adoption programs, and merchandise sales, have significantly contributed to raising public awareness and participation in conservation efforts. The SEATRU Public Viewing Lab also functions as a vital link between the scientific community and the general public, facilitating knowledge transfer in an interactive and engaging manner. This initiative not only enhances the public's understanding of sea turtles but also underscores the importance of scientific research in conservation. Recognized for its impact, the lab received a Special Jury Award and a Gold Medal in a 2019 Invention and Innovation Competition, solidifying its role as a model for education, community, and social innovation.

The first Workshop on Veterinary Medicine for Sea Turtles in Colombia

Gilberto Rafael Borges Guzmán1,2,3, Albert Bassols Garcia3, Karen Pabón-Aldana4,5, Karen Novoa4,5, Sandra Barrera4,5, Jorge Bernal Gutiérrez4,5, Aminta Jauregui4,5

1Fundación AVISTA, Venezuela; 2Fundación Científica Los Roques, Venezuela; 3Asociación Mexicana de Veterinarios de Tortugas; 4Programa de Conservación de Tortugas y Mamíferos Marinos, Colombia; 5Universidad de Bogotá Jorge Tadeo Lozano

During November 3 and 4, 2023, the "First Workshop on Veterinary Medicine for Sea Turtles in Colombia" took place at the Marine Museum - Aquarium of the University of Bogotá, Jorge Tadeo Lozano, Núcleo Rodadero, Santa Marta, Colombia. This event was organized by veterinarians Gilberto Borges Guzmán from Venezuela and Albert Bassols García from Spain, along with members of the Programa de Conservación de Tortugas y Mamíferos Marinos (PROCTMM), and in collaboration with the University of Bogotá through Jorge Tadeo Lozano, from Colombia. The workshop, featuring the participation of The Turtleman Foundation and Artesanias Tortugas Sin Fronteras, consisted of 12 theoretical hours and a 3-hour practical session. A total of 55 participants from 12 locations in Colombia participated (Barranquilla, Bogotá, Cali, Cartagena, Chía, Medellín, Palomino, Rionegro, Santa Marta, Soacha, Tayrona and Turbo) and one participant from Costa Rica (Ojochal), including biology and veterinary students, as well as professionals from both fields, engaged in the workshop. The topics covered during this inaugural workshop on sea turtle veterinary medicine included anatomy, biology, major diseases, sample collection, diagnoses, stranding responses, headstarting, facility management, necropsies, surgeries, practical sessions with necropsies, facility visits, and drills for stranding response. Such activities play a crucial role in the conservation endeavors for sea turtles in Colombia, as there is currently a limited number of veterinary professionals in the country dedicated to the preservation of these threatened species. It is hoped that these workshops will contribute to the training of more veterinarians and professionals in Colombia, ultimately aiding in the recovery of sea turtles facing health challenges, and in the future, we hope to improve and continue giving these workshops annually to continue training future professionals in Colombia and Latin America.

Building local capacity for natural heritage conservation. Chelonia mydas in Sinaloa, Mexico.

Marla Dublyn Diaz-Gámez1, Melina Maldonado-Sandoval3, Alan Alfredo Zavala-Norzagaray2, Alejandra Sandoval-Lugo1,2

1Universidad Autónoma de Occidente, Mexico; 2Instituto Politécnico Nacional; 3Grupo Tortuguero de las Californias

The northern zone of the state of Sinaloa is an essential area for the feeding of five species of sea turtles, among them the leatherback (Dermochelys coriacea), hawksbill (Eretmochelys imbricata), loggerhead turtles (Caretta caretta), and at a more considerable extent the eastern Pacific green turtle (Chelonia mydas) and the olive ridley (Lepidochelys olivacea). This area is significant for its high biodiversity and very particular characteristics for which the lagoon systems of northern Sinaloa are listed as priority wetlands by the RAMSAR convention. Sea turtle populations face serious threats that put at risk their conservation, incidental and directed capture, contamination, and diseases, among others. We implemented three approaches as follows: 1) Workshop for fishers from two communities (Topolobampo and Lazaro Cardenas) for in-water monitoring of sea turtles (Chelonia mydas and Eretmochelys imbricata) in the Sinaloa region. 2) Initiate a community-based sea turtle monitoring program in the Topolobampo-Ohuira-Santa María Lagoon system, integrating new members from two communities (Topolobampo and Lazaro Cardenas). 3. Science camp for young leaders in the community. This is why this study will provide a platform to initiate a monitoring and conservation program carried out by community members from two fishing communities: Topolobampo and Lazaro Cardenas. Therefore, this work aimed to generate meaningful information about sea turtle habitat use of the Topolobampo-Ohuira-Santa Maria lagoon system, as well as for the population characterization, the temporality of migration and residence, and other ecological data.

Evaluation by the community on educational signboards for sea turtle conservation in Cambodia

Tharamony Ngoun, Chandara Tak, Matthew Glue

Fauna & Flora, Cambodia

Educational signboards are a common tool utilised by conservation practitioners to spread awareness and education in target areas on conservation issues. Fauna & Flora and project partners have deployed many signboards in coastal communities in Cambodia. However, the effectiveness of these signboards, once installed in the community is poorly understood. Rather than investing additional funding into more sign boards, the Fauna & Flora team wanted to assess the effectiveness of sea turtle conservation signboards that had already been installed. An evaluation system was developed to enable community members to score the usefulness of the signboards and gauge the understanding of the message that had been conveyed. The evaluation system included a rating system with several questions about the content of the signboard, with community members answering these during group sessions. The results from this assessment were then anlaysed by the team to ascertain key takeaways from the assessment. Communities responded that the signboard had improved their understanding of the importance of healthy marine ecosystems. However, important messages such as the sea turtle hotline were not memorable. The communities suggested that more awareness raising should accompany the signboards.

Benefits of House of Learning, an after-school program as part of a marine turtle conservation effort, to local students

Alberto Y. T. Allo1,2, Kartika Zohar2, Fitryanti Pakiding2,3

1Department of Education, Universitas Papua, Manokwari, Papua Barat, 98314; 2Science for Conservation Program, Research and Community Service Institute of Universitas Papua, Manokwari, Papua Barat 98314; 3Department of Agricultural Technology, Universitas Papua, Manokwari, Papua Barat 98314

Providing incentives to the local community is a tool to promote actions compatible with conserving natural resources. In addition to economic incentives, the Abun Leatherback Project of the Research and Community Service Institute of the State University of Papua (LPPM UNIPA) provides educational benefits to local communities living near important leatherback nesting beaches at the Bird's Head region of West Papua, Indonesia that support marine turtle conservation. Jeen Yessa (formerly Jamursba Medi) and Jeen Syuab (formerly Wermon) beaches, located in the Bird's Head region of Papua, Indonesia, have the largest leatherback turtle (Dermochelys coriacea) nesting activity in the western Pacific. Local communities legally owned Jeen Yessa and Jeen Syuab. Low Human Development Index (54,63 in 2022) characterized these communities. To improve local students' abilities and increase environmental awareness, the Abun Leatherback Project created the House of Learning. It is an after-school program where local students can improve their abilities and is a part of the project's Community Empowerment program. Four Houses of Learning are currently spread over five villages (Resye, Womom, Syukwo, Wau, and Weyaf) near Jeen Yessa and Jeen Syuab. In UNIPA's House of Learning, local students improve their reading, writing, basic arithmetic, basic English, basic computer skills and learn about marine turtles and their environment in environmental education. In addition, the students also learn to love reading through the mobile library and, medicinal plants around them, and habits for healthy living. Community workers placed in the villages for ten months out of a year facilitate the learning and conduct different activities. They also track each student's progress through the various learning indicators by conducting monthly assessments. We examined the educational benefits of the Houses of Learning using 2022 assessment data. The pretest was completed in April, and the last posttest in December. After eight months of learning, reading skills improved in 58 of 121 students (48% of total number of students assessed), writing in 49 of 119 students (41%), basic arithmetic in 64 of 113 students (57%), basic English in 29 of 108 students (27%), and basic computer in 54 of 105 students (51%). For environmental education, 71 of 123 students showed improvement. We also found that 50 students (44%) participated actively in the mobile library, learning about medicinal plants and habits for healthy living activities. In the end-of-year program evaluation, 100% of local community members (n=76 households) felt that the House of Learning benefitted the community, and the community workers implemented the activities satisfactorily. The House of Learning has benefitted many families in the villages because most households have elementary-school-aged children, and this, in turn, helped secure leatherback conservation at the Jeen Womom Coastal Park.

Community-based sea turtle bycatch mitigation in southwest Cambodia

Srey Oun Ith1, Srey Thai Sem1, Phallin Chea1, Sopheap Tum2

1Wild Earth Allies, Cambodia; 2Fisheries Administration, Cambodia

Along Cambodia’s southwest coast, green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles forage and rest in regionally important coral reefs and the largest seagrass meadows in mainland southeast Asia. These populations are highly diminished relative to historic levels and face continued pressures from habitat degradation and fisheries, particularly illegal bottom trawling. Urgent protection of sea turtles and their foraging habitats is needed to ensure they remain in Cambodia’s seas. Since 2017, Wild Earth Allies has documented and responded to sea turtle bycatch in collaboration with coastal communities in Kampot province. This project is part of our overall program to strengthen co-management of Marine Protected Areas (MPAs) and fisheries. Our collaboration with coastal communities centers on strengthening the capacity of Community Fisheries (CFis) to manage marine resources and protect at-risk biodiversity, including sea turtles. CFis are recognized under Cambodian Fisheries Law and comprise communities or groups of small-scale fishers who are granted management and use rights of resources within a marine area, including setting boundaries and permissible fishing gear and practices. There are now 45 CFis across 4 coastal provinces playing a central role in managing Cambodia’s coastal and marine areas. This community-based approach improves equity in access to marine resource management and protection. The CFi model has also provided an opportunity for developing collaborative, community-based sea turtle conservation efforts. Together with 10 CFis, we have launched community-led patrols to mitigate threats to sea turtles, namely trawling and other forms of IUU fishing. We have also developed a community-based response system in Kampot province for sea turtle bycatch incidents. Our team trained response teams in safe handling of sea turtles and individual tracking methods using external flippers tags. Response teams are composed of CFi committee members and Fisheries Administration officers at the provincial level. Our team and CFi committees use signage, in-person meetings, and digital communications (e.g., Telegram groups) to raise awareness about the program and how to contact the response team if a sea turtle is accidentally captured. Non-monetary incentives are used to encourage fishers to report bycatch incidents, such as t-shirts and certificates honoring their service. This has resulted in increased reporting of sea turtle bycatch in Kampot province, with a 200% increase in reported incidents in 2022 versus 2017. In total, the team successfully released 15 green turtles and 4 hawksbills between 2017 and 2022. The team also documented one dead green turtle, bringing the total bycatch record to 20 incidents over the 5-year period in Kampot province, Cambodia. Results are input into the national sea turtle database, which is managed by the Fisheries Administration. While these bycatch rates are low at a global scale, sea turtle bycatch and sightings are higher in Kampot relative to other provinces in Cambodia. Our results demonstrate the importance of engaging coastal communities in the protection of sea turtles and vital foraging habitats in southwest Cambodia. As a next step, we are improving community patrol effectiveness and data collection with SMART technology (Spatial Monitoring and Reporting Tool).

Mitigating loggerhead turtle bycatch in southern Peru: a collaborative ‘fisher scientist’ initiative

Mariela Pajuelo1,2, Sergio Pingo2, Eliana Alfaro2, Astrid Jimenez2, Javier Quiñones3, Jeffrey Mangel2, Joanna Alfaro-Shigueto2,4

1Florida Museum, University of Florida, USA; 2Pro Delphinus, Peru; 3Instituto del Mar del Peru, Peru; 4Universidad Científica del Sur, Peru

In the South Pacific, the loggerhead turtle (Caretta caretta) has experienced a significant decline in nesting population numbers at rookeries in Australia. Fisheries bycatch has been recognized as a major threat for loggerhead turtles not only around nesting and foraging areas in the southwest Pacific, but also on developmental grounds off Peru and Chile in the southeast Pacific, where these turtles migrate after hatching. Earlier studies have reported an annual capture of over 3000 loggerhead turtles in the small-scale longline fisheries in Peru. While a systematic assessment of loggerhead bycatch is still needed to understand the level of impact small-scale fisheries currently pose on loggerhead turtles, we recognize that for sustainable and impactful change, it is equally important to actively involve and create a sense of ownership within the fishing community. Thus, here we present our 'Fisher Scientist' program aimed at involving small-scale longline fishers in southern Peru in sea turtle data collection and fostering a sense of ownership in marine wildlife conservation. This program, initiated in 2018, has successfully trained 150 participant fishers in safe sea turtle and handling techniques, and provided them with tools (e.g., measuring tape and dehookers) for sea turtle biometric measurement and safe release. Trainings were conducted in coordination with FONDEPES (Viceministry of Fisheries). Information gathered by ‘Fisher Scientist’ volunteers were obtained via interviews at the end of their fishing trips and, while not as detailed as data collected by onboard observers, has proven valuable for acquiring location and biometric measurements of over 50 sea turtles, the majority of which were loggerhead sea turtles. To enhance community engagement, videos and photographs of safe release of turtles were shared with the broader community through various social media networks of the Peruvian non-profit ProDelphinus. Fishers are still reporting data, and these will be updated for the presentation next year. Our next steps include extending the reach of this program to small-scale fisheries in northern Chile in 2024 and promoting the exchange of fishers between these two countries. Ultimately, we hope that by actively involving fishers in scientific data collection, we not only empower the community but also strengthen the foundation for sustainable fisheries management and sea turtle conservation in the Southeastern Pacific.

*Plastic marine debris in stranded sea turtles in Florida, U.S.A.

Heather A Seaman, Sarah L Milton

Florida Atlantic University, United States of America

Over the years, plastic production has increased to an astonishing volume and is predicted to continue. Sea turtles are known to mistake plastic for prey, which can result in gut compaction, gut perforation, and chemical leaching. Over time, environmental plastic will degrade into smaller microplastics, which sea turtles also ingest and may affect sea turtle health through chemical leaching of toxicants. Chemicals associated with plastics have been identified in tissues of sea turtles, and some are suspected to be endocrine disruptors. This study examined plastic ingestion in stranded sea turtles from around Florida, U.S.A., to identify the types of plastic most ingested. We collected the contents from the gastrointestinal tract of freshly euthanized or dead sea turtle carcasses. This study included sixty-five gastrointestinal tracts from loggerheads (Caretta caretta) (n=12), greens (Chelonia mydas) (n=48), hawksbill (Eretmochelys imbricata) (n=1), and Kemp’s Ridley (Lepidochelys kempii) (n=5) sea turtles. The contents were digested with 10% KOH for up to 10 days and then filtered through a 2mm size metal filter. The plastic was then categorized and imaged. Thirty-nine of the sixty-five sea turtles (60%) had marine debris (2mm or larger) in their gastrointestinal tract. Most samples were from female, juvenile, green sea turtles, but marine debris was found in all species and age classifications that were sampled. We recorded 1782 pieces of plastic debris, including one green sea turtle washback with 779 pieces of plastic in the gastrointestinal tract. A female, juvenile green sea turtle had the longest piece of marine debris at 463.7cm in length, which was monofilament (fishing line). Clear marine debris was the most common color noted. Hard and filament marine debris were the most common marine debris ingested. There was no significant correlation between size and the number of plastic pieces ingested, but this could be due to having primarily juvenile sea turtles. Data is continually being collected to expand the size range and species to allow better conclusions to be made. This study will also be expanded to investigate if plastic additives are leaching into sea turtle tissues and identifying their potential to be endocrine disruptors. The long-term impacts plastic ingestion can have on sea turtle physiology is still unknown. This work is essential not only to sea turtles but also to all organisms.

*A scoping review on the impact of beach plastics on sea turtles, eggs, and hatchlings

Aditi Renake, Andrea D. Phillott

FLAME University, Pune, India

Since early concerns about the impacts of plastics on sea turtles were published (e.g., Wehle & Coleman, 1983; Carr, 1987; Groombridge & Whitmore, 1989), plastic pollution has been categorised as one of the five major threats to sea turtles and their habitats worldwide (Mast et al., 2005). Sea turtles can potentially be affected by plastics (macro- and micro-) in the marine environment (usually though entanglement and ingestion) and the nesting environment (including impacts on nesting success, nest substrate properties, hatching success, hatchling sex ratios, and hatchling survival) (reviewed by Nelms et al., 2016).

The potential effect of plastics in the nesting environment on sea turtles is less studied than that in the marine environment and there is a need to understand key knowledge gaps and standardise methods to focus research on this threat and prioritise appropriate conservation and management efforts. To facilitate this, we are conducting a scoping review following the methods of Tricco et al. (2018) to identify the spatial and temporal distribution of study locations, focal research areas, and method being used. The study is ongoing, and our presentation at the symposium will include all relevant literature published to 2023.

We have examined 40 papers to date following standardised scoping review methodology. Studies of plastics on nesting beaches are being conducted in many regions of the world where nesting occurs, with more studies conducted in USA than other countries and few to no studies in Australia, and countries in Southeast Asia and East Africa. Study locations encompass nesting areas of all species except the flatback turtle.

The most common research focus is quantification and categorisation of macro- and microplastics in the nesting environment and prediction of sources on nesting beaches. Other, less common, research foci are plastics as obstacles and potential entanglement threats to nesting sea turtles and hatchlings, and the influence of microplastics on nest substrate properties. Key knowledge gaps at this time are understanding if plastics on the nesting beach change nest substrate properties and adversely impact hatching success and hatchling sex ratios at the population level, and management options to remove current plastics and minimise further pollution.

Different approaches are used across the same research focus area, including sampling and isolation methods, categorisation, and estimation of weight, abundance, and/or density. The absence of standardised approaches when sampling, isolating, quantifying, and categorising plastics on nesting beaches makes it challenging to compare findings among studies but does provide baseline data for specific study locations.

Given the threat of plastic pollution to sea turtles in their terrestrial environment- for example, microplastic abundance on beaches is believed to have tripled over the last twenty years (Moore, 2008; Do Sul & Costa, 2014) and is projected to quadruple by 2050 (Tekman et al., 2022)- findings presented in this poster can inform future research directions and priorities.

*Incidental by-catch of sea turtles in coastal and offshore fishery in Kalpitiya Peninsula, Sri Lanka: Assessment of fisher knowledge, practices and attitudes

Tharushi Ekanayake1, Shwetha Abeywarna1, Rajitha. K. Subasinghe2, Lalith Ekanayake1, R.S. Rajakaruna3

1Bio Conservation Society (BCSL), Sri Lanka; 2Bialik College Limited, Hawthorn Victoria, Australia.; 3Department of Zoology, University of Peradeniya.

Of the seven sea turtle species in the world, five, namely, green turtles, olive ridleys leatherbacks, loggerheads and hawksbills, come ashore to nest in Sri Lanka. Despite their protected status, sea turtles are still under threat. The most serious threat faced by the turtle population inhabiting and migrating through the Kalpitiya Peninsula is incidental by-catch in fishing gears. This study investigated fishers' knowledge, practices, and attitudes towards incidental sea turtle by-catch in the Kalpitiya Peninsula through fisherman interviews. Eighty-two fishers from 10 villages were interviewed through phone and in-person using a pre-tested, structured questionnaire comprising 40 questions after obtaining verbal consent (snowball sampling method). Data were entered into a database, and the responses of the fishers were analysed. The main source of income for all participants was fishing. All interviewees stated that they had seen turtles; olive ridley (48%) and green turtle (37%) were seen more frequently. The majority (88%) of the fishers claimed that having turtles was important. Most of the respondents (77%) stated turtles do get entangled in their fishing gears; and all claimed that they release turtles without harming. Some fishers (34%) said that 10-50 turtles get accidentally entangled in their fishing gear and 38% admitted that ray nets catch the most number of turtles while 37% said all the types of nets catch sea turtles. More than half of the fishers (63%) claimed that they had consumed turtle meat, and few (15%) had consumed it recently. Some (62%) said that still there was a demand for turtle meat. Ninety percent of the respondents admitted that it is necessary to conserve turtles. The survey results show that although the turtle entanglement rate was high, the fishers were well aware of the legislation and therefore claimed that they release turtles without harming. Only a few fishers claimed that they had consumed turtle meat recently. This confirms that although fishers are well aware of the law, few people are consuming turtle meat if they could hide it. The survey shows that fishers have sufficient knowledge about sea turtle legislation and positive attitudes towards the conservation of sea turtles but claimed that their fishing practices lead to turtle entanglement and damage. This indicates incidental by-catch in fishing gear still exists in the Kalpitiya Peninsula and the turtle entanglement rate is very high. Although the fishers released the entangled turtles, the entanglement could harm the turtles, and hence this study confirms incidental by-catch in fishing gears is a severe threat to the sea turtles. Moreover, the information provided by the respondent during the study may not exact things happening in the sea especially concerning the release of turtles and consuming the meat. So it is highly recommended to continue the fishermen awareness programmes to encourage fishers to release the turtles without harm.

*Analysis of potential threats to marine turtles in Venezuela: a bibliometric analysis

Irama Beatriz Perozo-Díaz1,2, Verónica de Los Llanos Romero3, Natalie Elizabeth Wildermann1,2,6, Héctor Alonso Barrios-Garrido1,2,4,5

1Laboratorio de Ecología General, Departamento de Biología, Centro de Modelado Científico (CMC) de La Universidad del Zulia; Maracaibo, Bolivarian Republic of Venezuela.; 2Grupo de Trabajo en Tortugas Marinas del Golfo de Venezuela (GTTM-GV);; 4TropWATER, Centre for Tropical Water and Aquatic Ecosystem Research; College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia,; 5KAUST Beacon Development; King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia.; 6Red Sea Research Center; King Abdullah University of Science and Technology (KAUST), 23955,. Saudi Arabia.

In Venezuela, several documented human-related threats to marine turtles pose a great conservation challenge. However, there are significant gaps in knowledge about some of these threats (level of knowledge and impact). In order to inform future research efforts, we conducted a bibliometric analysis of the available literature on marine turtle threats in Venezuela. We defined and categorized each threat in detail in any source. The categories were: fishery bycatch, take, coastal development, pollution and pathogens, and climate change. The references analyzed focused 13.51% of the times on take, followed by fishery bycatch (8.19%), then, pollution and pathogens (3.49%), coastal development (0.46%), and climate change (0.15%). On the other hand, 80.97% of the remaining studies focused on the biology and ecology of these reptiles (29.74%), nesting (23.37%) and conservation (34.29%). Furthermore, the analysis indicated that 39.45% of the references correspond to all spp., while among those where the studied species was identified we found that the most studied species are Chelonia mydas (36.42%), followed by Dermochelys coriacea and Eretmochelys imbricata and (26.1% and 25.34% respectively). In this sense, identifying and evaluating the least assessed threats to marine turtles in Venezuela is essential to understanding their real impact and designing more effective and needs-based conservation and monitoring strategies. This will also motivate continued recording and publication of the progress achieved by conservation programs in Venezuela.

Key Words: Fishery; bycatch; nesting; human threats.

*By-catch(ing your help for the protection) of sea turtles in the East Central Atlantic

Andrea Fariñas-Bermejo1,2, Ana Liria-Loza2, Alejandro Suárez-Pérez3, Graham J. Pierce1

1Institute of Marine Research, Spanish National Research Council (IIM-CSIC) (Galicia, Spain); 2ADS Biodiversidad (Las Palmas, Spain); 3Department of Pathology and Food Technology, Faculty of Veterinary Medicine, Universidad de Las Palmas de Gran Canaria (Las Palmas, Spain)

Conservation of highly mobile and migratory marine species requires comprehensive assessment of population trends and impacts at a large-scale. The East Central Atlantic Ocean (ECAO) is characterised by a high biodiversity of marine megafauna including endangered species such as sea turtles, and it serves as an important fishing area for over 50 countries. This overlap results in substantial risk of fishery bycatch, which is the main known anthropogenic cause of mortality to marine megafauna worldwide. Bycatch monitoring programs, involving on-board observers, remote monitoring systems and stranding networks, compile essential information for the understanding and quantification of impacts. Sufficient and representative spatial and fleet coverage as well as long time series are crucial to ensure adequate assessment of the impact of bycatch, and to support and monitor the development and implementation of effective mitigation measures.

We present a review of the sources of information on threats to sea turtles, and the available assessments of bycatch impacts in the ECAO, including the Macaronesian region and North-west Africa. We compile information on existing monitoring programs and the methods applied to understand and quantify bycatch impact. We focus particularly on the utility of data collected by strandings monitoring programs, which can contribute to the assessment of population status, trends and threats, including bycatch among others. Thus, we consider the organization and resourcing of the networks, their sampling strategy, the criteria used to diagnose mortality due to bycatch – and to distinguish it from mortality due to entanglement in abandoned, lost or discarded fishing gear, and the efforts to identify the fisheries responsible. We review evidence on bycatch mortality rates and on what might represent “safe” limits for bycatch mortality, as well as information on existing and proposed mitigation measures to reduce bycatch mortality.

This will be an interactive presentation by which we will "bycatch you attention" and solicit input from the experts attending the International Sea Turtle Symposium, on past, present and planned sea turtle monitoring, research on bycatch impact, and conservation actions, to help us fill knowledge gaps on sea turtles in the region. We aim to facilitate future collaboration, including standardisation and optimisation of data collection for the assessment of population status and trends, in the context of current projects such as CIBBRiNA (Coordinated Development and Implementation of Best Practice in Bycatch Reduction in the North Atlantic region) and REDUCE (Reducing bycatch of threatened megafauna in the East Central Atlantic), and initiatives like the development of a European common stranding database.

Spatio-temporal distribution and associated threats of Loggerhead turtle strandings in Uruguay (2000-2023)

Gabriela Manuela Velez-Rubio1,2,3, Paula Marin Acevedo1, Alejandro Fallabrino1

1NGO Karumbe; 2Facultad de Ciencias-Udelar, Uruguay; 3Programa de Desarrollo de Ciencias Básicas (PEDECIBA), Uruguay

Loggerhead turtle (Caretta caretta) is one of the most abundant sea turtle species in Uruguayan waters, one of the main feeding and developmental area in the Southwestern Atlantic for large juveniles and adults. These individuals come mainly from Brazilian rookeries, and they prey on mollusk, crustaceans and fishes. Base on previous studies their main threat is the industrial fisheries, mainly trawlers. But more information is need it to understand the spatio-temporal distribution and possible changes in the last decade. In this line, the objective of this work is to update the information of stranding distribution, size, life stage and associated threats of this species in Uruguayan waters and to improve the knowledge of this endangered species in the Southwestern Atlantic Ocean.

A total of 1277 stranded Loggerhead were recorded between 2000-2023, from which only 591 were measured (mean ± SD CCL=73.8±14.6 cm, range= 8.0-123.0 cm; median=71.5 cm). Most turtles were found dead, with only 4.07% found alive (alive=52; fresh=184; rotten=393; very rotten=460). Regarding the life stage 60.7% were large juveniles (Adults=222; Juveniles=775; small juveniles (CCL<40 cm= 6; no identified=274). Based on tail size (adults individuals) or gonad examination, there were 132 females and 72 males identified (no identification, n=1071). Loggerheads were observed during all seasons, although only 44 turtles were documented in the Winter, with 61% registered during 2023. The highest percentages of strandings were recorded during the Summer (n = 691, 54.1%) and Fall (n = 359, 28.2%). The spatial distribution showed that the highest number of strandings occurred in the oceanic zone (OZ; 72.7%, n = 928), followed by the outer estuarine zone (OEZ; 25.6%, n = 327), and the inner estuarine zone (IEZ; 0.9%, n = 12). Cause of death was difficult to identified, only in 4.7% of the cases the cause of death was determined. The main threat identified in the area is fisheries interaction but most of the carcasses observed were badly decomposed; nevertheless, in the last years other threats have arouse raising concern such as marine debris interaction and vessel collision.

Taken together, these findings reinforce the importance of the large juvenile and adult Loggerhead turtle South American foraging areas (south of latitude 33º S). Additionally, the need to determine regional habitat use as well as migratory routes across the Southwestern Atlantic Region in order to develop effective conservation measures to mitigate threats both at nesting beaches and foraging areas was highlighted from this study. The next step will be to analyze the stranding seasonality and spatial distribution together with the industrial fishing fleet operating in the Common Fishing Zone between Argentina and Uruguay (ZCPAU, from its name in Spanish) and the ones operating in Uruguayan territorial waters.

Frequency of vessel strike injuries in sea turtle strandings along Sanibel and Captiva Island, Florida, U.S.A.

Jack W. Brzoza1, Andrew T. Glinsky2, Savannah M. Weber1, Kelly A. Sloan1

1Sanibel-Captiva Conservation Foundation (Sanibel Island, Florida, U.S.A.); 2Cooperative Institute for Marine and Atmospheric Research (Honolulu, Hawaii, U.S.A.)

Vessel strikes affect sea turtles at various life stages and remain a significant threat to population recovery in many regions globally, including the southeast United States. In Florida, the Sanibel-Captiva Conservation Foundation (SCCF) documents strandings on the beaches and surrounding waters of Sanibel and Captiva, two barrier islands in Lee County, Florida, USA. For the past four years in Florida, Lee County had the third highest annual number of registered vessels, a metric used to correlate boating activity and vessel strikes. According to Florida Fish and Wildlife Conservation Commission, vessel strikes are also leading cause of stranding for sea turtles in Lee County in 2023 (Florida Sea Turtle Stranding and Salvage Network). In this study reports and photographs of strandings from 2010-2021 were analyzed to assess the incidence of vessel strike injuries (VSI) and identify patterns among species and size class.

Approximately one-third of all strandings (n=627) documented in this analysis presented with VSI. Due to severe decomposition, 13.9% of strandings were indistinguishable for VSI. Of all identified vessel strike strandings, loggerheads (Caretta caretta) accounted for the highest number (n=125), followed by greens (Chelonia mydas: n=52), and Kemp’s ridleys (Lepidochelys kempii: n=16). Curved carapace length measurements suggest that, on average, vessel strike-stranded loggerheads ranged from subadults to adults while stranded greens and Kemp’s ridleys typically fell in the juvenile and subadult size range. Although loggerheads accounted for the highest total number of watercraft interactions overall, green turtles had the highest percentage of VSI (39.7%). Loggerheads stranded most often during summer months (June, July, August), but loggerheads with VSI were most commonly documented earlier (May, June).

Loggerheads regularly nest in the study area and are most prevalent at the subadult and adult lifestages, accounting for the most strandings among the three species. The higher incidence of VSI in loggerheads during late spring and early summer may be a result of turtles spending more time nearshore and closer to the surface during mating. Conversely, Kemp’s ridleys and greens nest less frequently in the study area. The frequency of juvenile and subadult strandings for these two species likely reflect the use of nearby neritic habitat as foraging grounds, and the monthly variation observed may suggest seasonal shifts in behavior. While roughly one-third of all analyzed strandings had VSI, this may be a conservative proportion as strandings were analyzed from reports and photos (which may not have always been high quality if present). Additionally, 228 strandings were documented in 2018 during an intense red tide event, and only 33 were observed to have VSI (the majority had no obvious injuries and were likely red tide related). This may have decreased the overall proportion of strandings with a VSI. Addressing and reducing mortality from watercraft interactions remains a recovery priority for loggerhead, green, and Kemp’s ridley sea turtles. Data from the twelve-year period suggest vessel strikes are a significant cause of stranding in Lee County, Florida and reinforce the need for initiatives to reduce the number of watercraft interactions among sea turtles.

Beach cliffs as an emerging hazard to nesting sea turtles in the face of sea-level rise

Natalie E. Wildermann1,2,3, Hector Barrios-Garrido4, Khuld Jabby5, Royale S. Hardenstine5, Takahiro Shimada6, Ivor Williams5, Carlos M. Duarte1,2,3

1Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology; Thuwal, Kingdom of Saudi Arabia.; 2Red Sea Research Center, King Abdullah University of Science and Technology; Thuwal, Kingdom of Saudi Arabia.; 3Computational Bioscience Research Center, King Abdullah University of Science and Technology; Thuwal, Kingdom of Saudi Arabia.; 4Beacon Department, KAUST Innovation; Thuwal, Kingdom of Saudi Arabia.; 5Red Sea Zone Authority, Red Sea Global; Tawala, Kingdom of Saudi Arabia.; 6Aquatic Threatened Species Program, Department of Environment and Science; Moggill, Australia.

Climate change is a significant threat to sea turtles, affecting their reproductive success through warming temperatures impacting hatchling viability and sea-level rise leading to increased beach erosion and flooding risks. We raise attention about an emerging hazard directly impacting nesting sea turtles: the potential expansion of cliffs due to beach erosion, an issue previously overlooked concerning sea-level rise. Our study presents evidence of mortality of green turtles (Chelonia mydas) that fell off cliffs at Jazirat Mashabah, situated along the Saudi Arabian coast of the Red Sea, observed between 2019 and 2023. We carried out on-site visits and used satellite imagery analysis to determine the map the extent of cliffs and incident locations. We recorded 9 incidents of deceased turtles, and one found alive on her back. The limestone composition of the island has historically formed raised coral terraces along the coast during sea level transgressions. In their current state, these cliffs pose lethal challenges for nesting green turtles during their return to sea, especially in high-density nesting areas adjacent to cliffs. In addition, the accelerating rate of sea-level rise in the northern Red Sea amplifies concerns about the long-term impact of this hazard in nesting beaches. A better understanding of local sea-level rise scenarios through predictive models coupled with restoration efforts like beach nourishment and strategic barrier placement are crucial to sustain these habitats and ensure the continued survival of nesting sea turtles in the region. This study emphazises the need to address unanticipated threats faced by sea turtles due to changing coastal landscapes, advocating for proactive conservation strategies to ensure their survival amidst escalating global climate change.

Investigating trends in cause-specific sea turtle strandings and mortality in the U.S. Virgin Islands: 2018-2023

Taylor Brunson1, Claudia D. Lombard2, Kelly R. Stewart3, Sean Kelly1

1Division of Fish and Wildlife, Department of Planning and Natural Resources, Government of the Virgin Islands, USVI; 2U.S. Fishing and Wildlife Service, USA; 3The Ocean Foundation, Washington DC USA

While anthropogenic interactions are often accepted as the most common cause of sea turtle strandings and mortality in the U.S. Virgin Islands (U.S.V.I.), sea turtle stranding reports have not analyzed trends in cause-specific mortality in the last 25 years. In this study, we reviewed and compiled the last 5 years of stranding reports from multiple sources, including the U.S.V.I. Division of Fish and Wildlife and the Sea Turtle Stranding and Salvage Network. Our main goals were to (1) define recent trends in stranding and mortality both temporally and spatially and to (2) identify specific threats faced by recovering sea turtle populations. The U.S.V.I. provides nesting and foraging habitat to juvenile and adult populations of hawksbill turtles (Eretmochelys imbricata), green turtles (Chelonia mydas), leatherback turtles (Dermochelys coriacea), and occasionally loggerhead turtles (Caretta caretta). All species of sea turtle found in the U.S.V.I. are considered of interest to the government due to their global and local conservation status, and protection of their populations via local management and regulations are critical to their recovery. This study was conducted in part to fill data gaps in the U.S.V.I. on impacts of human activities (boating, fishing, etc.), in hopes of identifying major threats to these species. Preliminary review suggests that anthropogenic hazards such as boat strike and entanglement are leading causes of mortality among stranded turtles, signifying an urgent need for conservation actions such as mitigative measures from local government and community engagement.

Ten years of marine turtle strandings in Palawan, Philippines: from historical data to action planning

Sharah Marie Barredo1, Myla Adriano2, Mark Philip Acosta3, Ariana Agustines1, Lorraine Aplasca1, Geraldine Benavente3, Titus Canete1, Lowee Lyn Castillo1, Lyca Sandrea Castro4, Rufino Clavecilla5, Karen Mae C. Galabay6, Floredel D. Galon7, Jessica Labaja1, Teodoro Jose S. Matta8, Ethan Manasan1, Rene Manibale9, Dixie Marinas10, Curt Ivan Mariano1, Azell Montederamos1, Arty Moreno10, Jhonamie A. Mabuhay Omar4, Clarissa Pador11, Glenn Gonzales Rebong12, Rizza Araceli F. Salinas13, Sally Snow1, Ma. Vivian Soriano14, Mildred Suza15, Dwight Justley G. Ulep6, AA Yaptinchay16, Alessandro Ponzo1

1Large Marine Vertebrates Research Institute Philippines, Philippines; 2City Environment and Natural Resources Office, Puerto Princesa City, Palawan.; 3Port Barton Marine Park (PBMP), San Vicente, Palawan, Philippines; 4College of Fisheries and Aquatic Sciences, Western Philippines University- Puerto Princesa Campus, Puerto Princesa City, Palawan.; 5Municipal Agriculture Office, San Vicente, Palawan; 6University of Manila, Metro Manila.; 7Palawan State University, Puerto Princesa City, Palawan.; 8Palawan Council for Sustainable Development, Puerto Princesa City, Palawan; 9Alimanguan Sagip Pawikan, San Vicente, Palawan; 10Club Agutaya, San Vicente, Palawan Campus Puerto Princesa City, Palawan.; 11Protected Area Management Office, Malampaya Sound Protected Landscape and Seascape, Taytay, Palawan, Philippines; 12Palawan Wildlife Rescue and Conservation Center - Crocodile Farm in Puerto Princesa City, Palawan; 13Department of Environment and Natural Resources Biodiversity Management Bureau, Quezon City, Manila.; 14Community Environment and Natural Resources Office, Puerto Princesa City, Palawan.; 15Protected Area Management Office, El Nido-Taytay Managed Resource Protected Area,, Palawan; 16Marine Wildlife Watch of the Philippines, Makati City, Manila.

The province of Palawan, Philippines hosts extensive seagrass beds, coral reefs, and sandy beaches along its nearly 2000 km coastline that are home to at least four species of marine turtles. Threats to these species come from natural and anthropogenic stressors, however, our understanding of the severity, frequency, and impact of these is still very limited, and hinders the implementation of targeted mitigation and informed management strategies. In this study, we analysed stranding data compiled through citizen science, online data mining, and government reports that occurred in Palawan between 2012 and 2022. A total of 574 individual marine turtles were reported stranded, consisting of 399 (70.4%) green turtles, 77 (13.6%) hawksbill turtles, 25 (4.4%) olive ridley turtles, 5 (0.9%) leatherback turtles. The remaining 61 (10.8%) individuals had no species information reported. Based on photographic evidence available for 179 reports, the species was identified correctly in approximately 70% of the cases. Reporting was biassed both geographically and temporally by individual (agency, municipality or group) initiatives, as the information provided greatly depended on respondent competency and personal motivations. Only in 44% (254 cases) of the total incidents (567) the cause of the stranding was indicated in the available documentation and fishery interaction was reported as the predominant cause of stranding (98%, 249 cases). While this is partially biassed by economic incentives provided by some municipalities to surrender and report bycaught turtles, 70% of the necropsies opportunistically conducted on carcasses code 2-3 across the last 5 years, identified signs of human interaction and reported fisheries as the main cause of death. When paired with information coming from a rapid bycatch assessment conducted by co-authors in Palawan in 2022-23, where only 2% of the bycatch events were reported by the fishers to the authorities, the scale of these interactions and their potential impact exponentially increases. Similarly, worth noting that only 15% (85) of the incidents reported involved turtles recorded to have been found dead. These data currently do not include over 150 individuals reported but undocumented, that were stranded in carcass code 3-4 between May and August 2021, along the northwest coast of Palawan and further supports that the scale of the stranding and mortality of these animals is currently greatly underestimated. Despite the bias in the current reporting system and data acquisition, this study highlights the municipalities of Quezon, El Nido, and the city of Puerto Princesa, as priority areas for further investigation, and underlines the role of bycatch in small scale fisheries as the primary cause of stranding. Priority of areas of intervention have been identified as 1) the reactivation and enhancement of the Palawan Marine Wildlife Stranding Network 2) the need for an organised and centralised digital reporting system and data repository 3) enhance medical capacity and infrastructure for rehabilitation 4) awareness campaign and training in safe release procedures and reporting bycatch in small scale fishers 5) the needs to identify feasible and effective bycatch mitigation strategies.

Fatal shark attack on a loggerhead sea turtle (Caretta caretta) found stranded off the coast of the Strait of Gibraltar, Spain.

Carolina Fernández - Maldonado1, Alejandra Cerezo Caro1, Cristian Suárez-Santana2, Martín Cara Egea1, Antonio Fernández2

1Seashore Environment and Fauna, Tarifa, Cádiz, Spain; 2Atlantic Cetacean Research Center, Veterinary Histology and Pathology, Institute of Animal Health (IUSA), Veterinary School, University of Las Palmas de Gran Canaria (ULPGC), Trasmontaña, s/n, 35413 Arucas, Las Palmas, Spain

Injuries inflicted by sharks are a frequent occurrence in stranded sea turtles worldwide. Studies on interactions between large sharks and sea turtle strandings, however, have practically no reports along the Spanish coast.

Shark predation can occur while the turtle is alive or may be postmortem. Care necropsy procedure should differentiated in the wounds were caused intravitally, by the analysis of the caused defect and the demonstration of tissue reaction to the injury. Scavenging of carcasses may also preclude a complete necropsy, obscuring the determination of the cause of death or stranding of the turtle.

The animal was a subadult female loggerhead sea turtle found recently dead on a beach off the coast of the Strait of Gibraltar, Algeciras Bay, Cádiz. The turtle was in good nutritional condition, weighing 59.7 kilograms. The decomposition status indicated that it was freshly dead (code 2 of 5), and the curved carapace length (CCL) measured 56 c,, compared to the expected 73 cm when accounting for the depredation area of the carapace.

Macroscopically, a large wound stands out, extending caudally from one end to the other of the carapace and penetrating completely, affecting from the surface of the carapace to the plastron. In this way, all the musculature, organs, and structure of the turtle become absent throughout the affected area. The injury was characterized by incised marks, triangular, measuring 4 cm by 3 cm each and with a semicircular arrangement, which correspond to the typical characteristics of a shark bite.

Post-mortem examination revealed evidence of exsanguination and a freshly bleeding bite, with the absence of the right kidney. Additionally, all the tissue from the caudal part of the carapace, starting from the fourth right lateral scute, was missing, exposing the coelomic cavity.

Bite characteristics suggest that the great white shark (Carcharodon carcharias) could have been responsible for the death of the sea turtle, although further tests are needed.

Previous studies in fisheries show that in the Mediterranean Sea, the white shark exhibits a broad diet. The most common prey found includes small cetaceans, tuna (Thunnus spp.), swordfish (Xiphias gladius), and loggerhead sea turtles.

Previous studies in the southeastern USA found that injuries primarily involving the carapace were never observed in scavenging cases. Flipper amputations often were incomplete (>80% of the flipper removed), and some turtles had more than one amputation. In our case, the right flipper was completely removed.

In this work, we emphasize the importance of conducting complete necropsies. It is crucial that these procedures are carried out by veterinarians with extensive pathology experience, supported by experienced pathologists who can perform histopathology analyses. Not only to determine the cause of death but also, in cases like these, to differentiate whether the attack occurred ‘in vivo’ or postmortem.

This case represents the first confirmed record of a loggerhead turtle's death possibly due to a great white shark attack in Spanish waters. Additionally, it also contributes to the limited records of this shark species in this area, thereby helping to generate more information regarding its distribution and abundance.

Sea turtles, sea users and collisions: how to improve monitoring and cohabitation in Reunion Island, Indian Ocean?

Anne Emmanuelle Landes1, Charline Fisseau1, Claire Jean2, Mathieu Barret2, Sylvain Delaspre1, Stéphane Ciccione2

1CEDTM, Réunion (France); 2Kelonia, l'observatoire des tortues marines, Réunion (France)

Reunion Island is home to a significant number of coastal sea turtles, which have increased and then stabilized over the past 15 years. This foraging population consists of green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) at juvenile stages. The breeding population is very rare and relies on a single regular nesting female. The significant demographic growth of the foraging population has been accompanied by a considerable increase in human recreational activities along the coast. And unfortunately, since 2014, a growing number of collisions between turtles and vessels has been observed. Almost all of them were fatal. There is an urgent need for a better understanding of the threat and how it is evolving, particularly in order to improve awareness-raising materials for sea users and recommendations for supervising activities.

After two pilot studies (Dalleau 2022; Fontaine 2022), an at-sea survey was initiated in 2022 to meet this need. Two transects were defined between the locations of L'Ermitage and Cap La Houssaye (west coast of the island) in the 300m coastal band, which is the most frequented by turtles and boats. A total of 14 transects (80 km covered) were carried out from a semirigid research vessel (5.7 m long with 70cv horsepower outboard engine) between January and October 2023, during which 43 turtles were observed (Cm=41, Ei=1, NA=1) at a frequency of 6.3 individuals per hour. The estimated length of the carapace of 56% of them was less than 50cm and that of 14% of them was greater than 1m. In total, 103 boats were encountered, with the average number of boats per hour varying between 7.1 and 23.9, depending on the time of day surveyed. The probability of encounter was highest between 10 and 11 a.m. The vessels encountered were mainly scuba divers (40%), passenger transporters (24%) and recreational vessels (9%). In 33% of cases, their estimated speed was greater than 5 knots, which is outside current regulations.

After a first year of testing, it is recommended that the survey be continued, and the protocol completed in order to improve the robustness of the analyses and the accuracy of the spatial representations of the cohabitation of turtles and uses. It also emerged that counting and characterizing boats, as well as assessing whether practices comply with current legislation, depend on a certain amount of experience on the part of observers, and subjective judgements that need to be refined. However, the consistency of the monitoring parameters and their maintenance over time will make it possible to reduce bias and more accurately reflect the risk of collision and its evolution. The aim is to disseminate this knowledge to institutions and users to raise awareness on the need to respect navigational speed, as it is essential to limit this emerging threat to protect sea turtle populations, and in particular the relict population of breeding sea turtles of the island.

The use of Circle Hooks to mitigate loggerhead Bycatch in bottom longline off the Gulf of Gabès

Imed Jribi1, Achraf Chouaibi1, Arij Sadraoui1, Asma Chaabane1, Hamed Mallat1, Maissa Louhichi1, Wiem Boussellaa1, Zouhour Bouain1, Mohamed Nejmeddine Bradai2

1FSS, Tunisia; 2ASCOB-Syrtis, Sfax, Tunisia

Interactions between fisheries and sea turtles, represent a global conservation issue, and mitigating the impacts of these interactions is a crucial step to ensure the sustainability of fisheries and the conservation of these reptiles.

Among the various fishing methods used in the Mediterranean, bottom longlines are particularly harmful to sea turtles. This method, rooted in ancient fishing practices employing hooks and bait, poses a significant threat.

In the gulf of Gabès, one of the most important foraging and wintering ground for sea turtles in the Mediterranean, bottom longlines is targeting mainly groupers and some bottom elasmobranches. Loggerhead sea turtles interact also with this gear.

This study, conducted within the framework of the EU co-funded LifeMedturtles project, aims to assess the effectiveness of circle hooks in comparison to traditional J hooks as an alternative method to reduce interactions between sea turtles and fishing gear in the Gulf of Gabès.

A total of 36 sets were carried out using 23,176 hooks, which included 6,665 C hooks and 16,511 J hooks. These sets were conducted under identical conditions, including the same depth, weather conditions, and bait, in order to evaluate their impact on both target species and sea turtles.

Preliminary results indicate no difference between the two hook types concerning the target species. However, a notable difference emerges concerning sea turtles. To be precise, all six sea turtle captures occurred with J hooks, resulting in a catch rate of 0.36 turtles per 1000 hooks, whereas C hooks registered no sea turtle captures. It appears that circle hooks may offer a promising alternative for reducing bycatch without compromising the catch of the targeted species.

More investigations are needed for adoption of circle hooks as an alternative mitigation ‎measure.

Nine years of stranding data for sea turtles in the northern Gulf of Mexico

Tabitha Renee Siegfried

Gulfarium CARE Center

The Gulfarium C.A.R.E. center is a non-profit organization that was founded in 2015 to specialize in sea turtle rescue and rehabilitation. Over the last 5 years we have seen an exponential increase in the number of live stranded sea turtles in the northern Gulf of Mexico. In 2023, we received 117 sea turtles ranging from juvenile to adult, comprised of Kemp’s ridley, greens, and loggerheads. 94 % (n = 110) of the 117 sea turtles we received in 2023 were brought in as incidentally captured individuals. Of those incidentally captured individuals 96% (n = 102) were captured from local fishing piers, only 4% (n = 4) were caught by fisherman from the beach. There are four semi-local fishing piers that are actively incidentally catching sea turtles; however, one pier, Navarre Beach Fishing Pier, has the highest catch rate in the state of Florida. In 2023, Navarre Beach Fishing Pier successfully rescued 54 sea turtles, accounting for 46% of our incidentally captured turtles. Our busiest months coincide with nesting season, May – October. Over the last three years we have seen an increase in recapture events. In 2023, we noted 45 recapture events, this includes individuals recaptured in the same year, across years, and individuals being caught three or more times. Here we provide summary of the last nine years of strandings in the northern Gulf of Mexico.

*Foraging patterns of more nourished green sea turtles (Chelonia mydas) migrating to high latitudes in Japan

Megumi Kawai1, Kazunari Kameda2, Lyu Lyu1, Tomoko Narazaki3, Takuya Fukuoka4, Katsufumi Sato1

1The University of Tokyo, Japan; 2Kuroshima Research Station, Sea Turtle Association of Japan; 3Meijo University, Japan; 4Tokyo University of Agriculture and Technology, Japan

Juvenile green turtles are generally considered to be primarily herbivorous and occupy narrow ranges in neritic areas. However, some previous research revealed that they perform seasonal long-distance migrations. Juveniles in the high latitudes of Japan where they forage during the summer also migrate hundreds of kilometers. These turtles are known to migrate south when water temperatures drop in autumn or winter. Such polymorphism in the behaviors and life histories of organisms is important to reveal diversity within the same species. In this study, we compared prey items and foraging behavior of the migratory turtles in the temperate region with resident turtles in the subtropical region and evaluated the effect of these differences on morphological and nutritional status. During 2013-2023, field studies were conducted in summer at Kuroshima Island, a small island with a diameter of about 4 km (24°14’13” N, 124°00’35” E, subtropical region), and the Sanriku coastal region, which spans approximately 150 km (38°55′-39°40′ N, 141°40′-142°05′ E, temperate region) in Japan. We investigated feeding behaviors using animal-borne data loggers attached to the turtles. They were released near the capture site or about 4 km (in Kuroshima) / 10-30 km (in Sanriku) away from the capture site. The feeding ratio was calculated as the ratio of feeding time to video logger recording time. Body Condition Index (BCI) was calculated as the ratio of body mass to straight carapace length (SCL), and nutritional status was examined through blood chemical analysis, including total protein (TP), albumin (ALB) and total cholesterol (T-CHO). Twelve turtles (SCL: 47.4-72.8 cm) were released in Kuroshima. All six turtles released at the capture sites stayed there spending most of their time foraging. Five out of the six turtles released at different sites returned to the capture sites. The feeding ratio during their return was low (0-2.0%), but it increased after returning (11.7-33.1%). They fed on macroalgae and seagrass. On the other hand, sixteen turtles (SCL:43.4-60.4 cm) were released in Sanriku. Nine out of eleven turtles released at different sites moved in the opposite direction of the capture sites, while the other two turtles returned near the capture sites. Two out of five turtles released at the capture sites left the area. The feeding ratio during migration was relatively constant (0.7-9.3%) and they also fed on gelatinous prey in addition to macroalgae and seagrass. BCI was significantly higher in migrating Sanriku turtles (1.11-1.97, median:1.46) compared to resident Kuroshima individuals (1.05-1.59, 1.33). TP, ALB and T-CHO levels were significantly higher in migratory turtles (TP = Mean±SD:4.2±0.7 g/dL, ALB = 2.1±0.3 g/dL, T-CHO = 263.5±88.4 mg/dL) than in resident individuals (TP = 3.6±0.4 g/dL, ALB = 1.2±0.2 g/dL, T-CHO = 150.6±40.0 mg/dL). It seems to be important for turtles to not only feed on macroalgae and seagrass within a specific area but also on gelatinous prey while migrating to obtain more nutrition. Although the high latitudes of Japan serve as a summer-restricted foraging area, it is suggested that they provide a better foraging environment for the growth of green turtles.

*Spatial ecology and conservation of foraging green turtles in the Northern Territory, Australia

Natalie Robson

Charles Darwin University, Australia

Identifying the foraging grounds and migratory corridors of threatened marine turtles is crucial for their conservation management. The complex logistical and safety challenges involved in investigating the at-sea behaviour of marine turtles in the Northern Territory create a considerable gap in the knowledge. Green turtles (Chelonia mydas) are an important food resource for indigenous Australians and a species of cultural importance across many areas of the Northern Territory. These turtles are considered conservation-dependent due to anthropogenic threats such as marine debris, climate change, chemical and terrestrial discharge, international take (turtles taken outside Australian waters), and indigenous take (DoEE, 2017). A general lack of ecological knowledge in the North Marine Region makes conducting effective conservation in this area difficult. This study compiles existing nesting green turtle satellite tracking data from across Australia, collected over multiple decades, and new data from foraging turtles in the Northern Territory. Spatial analysis of this turtle movement data with anthropogenic threats, marine parks and new habitat data will help identify priority areas and inform conservation management plans.

*Habitat mapping reveals resident areas and movement patterns of nesting leatherback sea turtles (Dermochelys coriacea) in St. Croix USVI

Arona N. Bender1, Christina I. Mauney2, Corey D. Garza3, Peter H. Dutton4, Claudia D. Lombard5, Andrew J. Read1, Kelly R. Stewart6

1Duke University Marine Science & Conservation Division, Beaufort, NC 28516; 2NCCOS Beaufort Laboratory, Beaufort, NC 28516; 3University of Washington Seattle, WA 98195; 4NOAA Southwest Fisheries Science Center Marine Mammal and Turtle Division, La Jolla, CA 92037; 5US Fish and Wildlife Service, Frederiksted, VI 00840; 6St. Croix Sea Turtle Project, The Ocean Foundation, Washington DC 20036

Understanding patterns of movement and distribution is essential to identify potential threats and creating effective conservation plans. For highly migratory species such as the leatherback sea turtle (Dermochelys coriacea), it is critical to have a comprehensive knowledge of the areas used by these animals to ensure their protection. This is particularly true for the Northwest Atlantic Regional Management Unit (RMU) of this species, which has experienced population declines since 2009. In this study, our objective was to identify nesting patterns, home range, and habitat use of leatherbacks in this RMU during their nesting season.

We deployed 20 satellite-linked transmitters (SPLASH 10, Wildlife Computers) on adult female leatherback turtles nesting at Sandy Point National Wildlife Refuge (SPNWR), St. Croix, USVI from 2020 – 2023. We processed Fastloc GPS-derived locations in the Wildlife Computers data portal and complemented these data with observations of haul-outs and nighttime nesting surveys, to identify nesting events. We estimated the home range of each turtle with the Autocorrelated Kernel Density Estimation (AKDE) approach in R using the ctmm package.

Most leatherbacks returned to nest every 9 to 10 days, but a few individuals chose to skip one or more nesting events, leading to average nesting intervals of 18 to 25 days. During the nesting season, leatherbacks spent most of their time near SPNWR, typically within 15 kilometers of the nesting beach. However, turtles also traveled to the northern side of St. Croix, the deeper oceanic region between St. Croix and Puerto Rico, and the southeastern coast of Puerto Rico. Notably, one individual also spent some time near the northern side of Culebra during the nesting season. By mapping home ranges in this manner, we identified offshore areas that could be critical habitat used by these turtles in April and May each year.

*Using an unoccupied aerial vehicle (UAV) to assess seasonal abundances of megafauna in front of an important sea turtle nesting beach in Costa Rica

Adam Yaney-Keller1, Verónica Valverde-Cantillo2,3, Diego Fallas-Madrigal2, Pilar Santidrían Tomilo3,4, Nathan J. Robinson5

1School of Biological Sciences, Monash University, Australia; 2Escuela de Ciencias Biológicas, Universidad Nacional, Heredia, Costa Rica; 3The Leatherback Trust, Goldring-Gund Marine Biology Station, Playa Grande, Costa Rica; 4Animal Demography and Ecology Unit, GEDA, Institut Mediterrani d’Estudis Avançats (CSIC-UIB), Miquèl Marques 21, 01790, Esporles, Spain; 5Institut de Ciències del Mar, Spanish National Research Council - Consejo Superior de Investigaciones Científicas, Barcelona, Spain

Nearshore environments play a crucial role as habitats for marine megafauna, yet these dynamic ecosystems face intense human activity. To effectively monitor these habitats, frequent sampling is essential. Recent studies have demonstrated the efficacy of Unoccupied Aerial Vehicles (UAVs or drones) for surveys of nearshore marine megafauna. In this study, we focused on Cabuyal Bay, located in northwest Costa Rica, near an important sea turtle nesting beach.

Utilizing a small, commercially-available UAV, we conducted video surveys from September to March in both 2017-2018 and 2018-2019. The survey transects followed a sawtooth pattern, transitioning between 0 – 100 meters and 100 – 200 meters from the shore. Post-hoc analysis of the footage revealed a total of 1,891 organisms, predominantly mesopredatory fishes and rays. Over 60% of species identified were listed as threatened by the IUCN Red List. Interestingly, most taxa were observed more frequently during the dry season (Dec – Mar) than the wet season (Sep – Nov), with the exception of Mobulid rays and green (Chelonia mydas) and olive ridley (Lepidochelys olivacea) sea turtles. Moreover, higher abundances were recorded within the 0 – 100m transects compared to the 100m – 200m transects.

Our findings underscore the effectiveness of UAVs for rapid and cost-effective monitoring of marine megafauna in nearshore environments. The observed higher abundances during the dry season correlated with upwelling patterns and local productivity, although these patterns exhibited variation among taxa. Sea turtle detections in the wet season may have coincided with the arrival of females at the beginning of the nesting period, but more surveys are needed. Given the region's high biodiversity and the presence of an important sea turtle nesting beach, we propose that Cabuyal Bay warrants consideration for future protection measures.

Decades-long monitoring of an individual male loggerhead sea turtle: AAJ723

Annessia Marie Michaels, Michael Bresette, Jeff Guertin, Cody Mott

Inwater Research Group, United States of America

Biologists have been studying sea turtles at the St. Lucie Nuclear Power Plant in St. Lucie County, FL, USA since its operation began in 1976. Nearly 50 years of research has been conducted on more than 20,000 turtle captures including loggerhead, green, leatherback, hawksbill, olive ridley, and Kemp’s ridley turtles. Loggerhead sea turtles are the most abundant species observed at this research site, accounting for more than 11,000 captures. A small number of individuals (7.7%) have been captured multiple times at this site with only 4% being turtles that were caught ten or more times. However, there is a single loggerhead that has been captured a record 53 times. Originally flipper tagged AAJ723, “AJ,” is an adult male loggerhead that was first captured in 1989. In a 34-year span, we have been able to monitor this individual’s growth rate, as well as his health and overall body condition. Although undersized, AJ was thought to be a maturing male at the time of his original capture. It was not until 2009 that he demonstrated physical adult male characteristics including a long tail that extends past the carapace, curved front flipper claws, and a soft, concave plastron. To date, AJ is still below the generally accepted size for an adult loggerhead (straight carapace length (SCL) of ≥ 85 cm), where his SCL has remained 78 cm over the last decade. To our knowledge, this turtle is one of the most studied, wild-caught, male loggerheads around the globe. In addition to our long-term monitoring of this individual, AJ has been sampled as part of several collaborative studies helping to answer questions on stable isotope analysis, the presence of fibropapillomatosis in loggerheads, and antibiotic resistance in sea turtle microbiomes. While this is only one individual turtle within the population, the data we have collected over such an extended period has been paramount to sea turtle conservation efforts. Further research could give insight into population dynamics such as the benefits of having a long-lived male in the highest-density nesting grounds and the extent of his paternal linkages across Florida’s beaches. Additionally, we could examine size at sexual maturity and whether it has been habitually overestimated for adult male loggerheads. It is our understanding that AJ can continue to aid in sea turtle conservation for many generations.

Fishery discards and long-term changes in the diet of loggerhead turtles (Caretta caretta) in the western Mediterranean as revealed by gut contents and bulk and compound specific stable isotope analyses

Luis Cardona1, Francisco Javier Aznar2, Maria Bas3, Jesús Tomás3

1University of Barcelona, Spain; 2Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Spain; 3Institut de Ciències del Mar (ICM-CSIC), Spain

Loggerhead turtles (Caretta caretta) larger than 40 cm curved carapace length (CCL) have skulls adapted to crush hard-shelled invertebrates, which explains why mollusks and crustaceans usually dominate their diets. However, several recent studies provide evidence of a more varied diet, often including variable amounts of fish. Fishery discards are often assumed to be the main source of fish for loggerhead turtles, but the actual relevance of fishery discards is poorly known, as loggerhead turtles can also capture healthy fish by themselves. Fishing fleets and fishery discards have declined steadily in the Spain’s Mediterranean coastal waters since the late 20th century. Accordingly, if scavenging on fishery discards was their main source of fish, the contribution of fish to the diet of neritic loggerhead turtles inhabiting the region would have also decline. Here, we analyzed the gut contents of 94 juvenile loggerhead turtles ranging 29-67 cm CCL and captured incidentally in neritic habitats off the Mediterranean coast of Spain in two different periods (1991 and 2010-2017) to assess the contribution of fish to their diet over time. We also used bulk and compound-specific stable isotope analyses of proteins and amino acids (CSIAA), respectively, of a subsample of the same turtles to assess their trophic positions in three periods: 1991, 2007-2009 and 2015-2017 (n=10 in each period). Gut content analysis revealed a shift in the dominant diet items, from fish, crustaceans and tunicates in 1991 to bivalves, tunicates and gastropods in 2010 and 2017. The δ15Nbulk of turtle bone also dropped from 1991 to 2007-2009 and remained low in 2015-2017, suggesting a drop in trophic position as the contribution of fish to the diet declined. However, δ15NPhe values indicated that 52.5% of that temporal variability in δ15Nbulk was due to a baseline shift, previously reported on the basis of the δ15Nbulk values in seagrasses. Surprisingly, CSIAA did not confirm the drop in the trophic position of loggerhead turtles suggested by gut contents analysis; indeed, TPCSIAA increased significantly from 1991 to 2007-2009, and decreased again in 2015-2017. Such disagreement could be caused by temporal changes in the contribution of terrestrial C3 plants and phytoplankton to the base of coastal food webs, as TPCSIAA is highly sensitive to the actual proportion of vascular and non-vascular primary producers as sources of organic matter. Furthermore, alternative habitat use which may differ in N biogeochemical cycling may explain some of the variability in the δ15NPhe values. Finally, the overwhelming dominance of tunicates in the diet of loggerhead turles might mask any change in the contribution of other prey to the trophic position of loggerhead turtles. In conclusion, fish consumption by loggerhead turtles inhabiting the Mediterranean coast of Spain is partially dependent on fishery discards, but bulk and compound specific stable isotope analysis fail to track temporal shifts in trophic position because of the combination of several confounding factors.

Coming out of their shells: Repeatable social preferences in green sea turtles, Chelonia mydas

Amy Feakes1,2, Julian Gervolino1, Isha Afeef1,3, Emma Cavan2, Stephanie Köhnk1, Jamie Dunning2

1Olive Ridley Project, 91 Padiham Road, Sadben, Clitheroe, Lancashire, BB7 9EX UK; 2Faculty of Natural Sciences, Department of Life Sciences (Silwood Park), Imperial College London, Berkshire, UK; 3Olive Ridley Project Maldives, H. Kaneerumaage, Dhonhuraa Goalhi, Malé, 20037, Republic of Maldives

Social behaviours are prevalent across the animal kingdom and can have significant implications for species survival and fitness. This study focuses on the associations and preferences of green sea turtles at a key resting site in the Maldives. Employing photo identification, the study explores individual engagement in social behaviour at the dive site Hithadhoo Corner, Laamu Atoll, Maldives. Over a three month period 76 surveys were carried out at the dive site, and each turtle resting was individually identified. The location of each individual was recorded, with reference to the 6 specific coral bommies at the site. Over the survey period we identified 51 individuals across 332 encounters, across all coral bommies. Individuals were split into life-stage, adult and juvenile, based on size less than or greater than 65cm, estimated by eye. In adults the observation of a tail extending past the carapace placed them in the male category. To see if there was presence of grouping and sociality we used the Gambit of the Group approach, whereby individuals resting on the same bommie in the same time period were considered to be associating.

Using this approach, the study found an inclination towards grouping (62%), where it is more likely to encounter multiple individuals on a bommie than just one. With a closer examination of sex and life-stage influences using a Bayesian analysis approach; it is highlighted that males have a higher propensity to participate in group behaviour. Repeatable social associations were also evident in some individual turtles, with certain pairs observed on 8 occasions. With insights from social behaviour studies in other species, this study works to shed light on potential mechanisms and motivations that underlie the observed social behaviours in sea turtles. Our study challenges the historical non-social generalisation placed on this species and contributes to the growing body of research on sea turtle social behaviour.

The Florida hawksbill project: A twenty-year review

Lawrence D. Wood, Anna Bennett

National Save The Sea Turtle Foundation, United States of America

In 2004, the Comprehensive Florida Research and Conservation Program, a.k.a. the Florida Hawksbill Project, was initiated with the goal of establishing baseline data concerning the abundance, distribution, and population dynamics of hawksbills in Florida waters. Because hawksbills do not reproduce with any regularity in Florida, the Project has focused on in-water populations primarily along the southeast coast from Palm Beach County south through Monroe County. Depending on the depth of the habitat, all hawksbills were hand-captured while using either scuba or snorkel gear and returned to a waiting vessel. Once aboard, standard morphometrics were recorded, internal and external tags were applied, samples were collected, photographs were taken and, when appropriate, external tracking devices were attached. The turtles were then released at the surface near the capture site. As of November 2023, 302 individual hawksbills have been identified, and 76 of those have been re-captured at least once over 472 surveys encompassing 48,670 minutes (811.2 hrs) of in-water surveys. The turtles ranged in size from 19.3 - 83.9 cm SCL (median 54.5). Sub-adults captured in Palm Beach County revealed a female-biased population of 2.5:1 female:male ratio representing 17 Caribbean haplotypes, with a strong bias toward Mexican stocks. From satellite tracking data, subadults captured in Palm Beach County all confined themselves to relatively small home ranges (0.01 - 1.2km2) at or near coral reef structures, and showed very consistent use of specific overnight refuges. Ethograms of in-situ foraging behavior revealed a highly discriminating process of prey identification, followed by the consumption of a narrow range of poriferan species. Reference intervals were established for hematological and plasma biochemical analytes, and differential colonization of barnacle epibiota between hawksbill and green turtles was noted. While the sampling effort continues throughout SE Florida, ongoing studies include stable isotope analysis and further investigations into gender ratios, movements, population dynamics, blood analytes, and environmental DNA. Though comparatively rare in Florida, hawksbill turtles are deserving of continued research and conservation efforts in Florida waters. This project has shed new light on the value of Florida’s coastal reef habitats to this species, contributed significantly to our understanding of hawksbill behavior and physiology, and helped bring attention to Florida’s hawksbill aggregation as a relatively small but valuable member of the overall Caribbean population.

Seagrass meadow collapse due to overgrazing green turtles in the Ryukyu Islands, Japan

Junichi Okuyama1, Naoya Noguchi2, Hideaki Nishizawa2, Iwao Tanita1, Sachia Sasano1, Motoya Tamaki1

1Japan Fisheries Research and Education Agency, Japan; 2Kyoto University, Japan

Green turtles (Chelonia mydas) have reportedly been recovering their abundance in several populations worldwide over the past few decades. In Japan, major nesting populations have shown an increasing trend, whereas foraging aggregations in the seagrass/seaweed meadows have also been reported to increase in abundance. Concurrently, with the rise in green turtle abundance, many seagrass meadows in the subtropical Ryukyu Islands, located in the southwestern part of Japan, have been reported to suffer collapse or severe degradation. To assess the current condition of green turtle and seagrass abundances, comprehensive surveys were conducted in seagrass meadows in Ishigaki (Fukido estuary) and Kume Islands (Maja and Ou coastal areas), which are part of the Ryukyu Islands, from July to October 2023. First, the population densities of grazing green turtles in the seagrass meadows were investigated using an aerial drone survey on both islands. Second, the distribution and coverage of seagrass species were examined through underwater observation. In the Fukido estuary of Ishigaki Island, the drone-based line transect survey revealed that the population density of grazing green turtles ranged from 0.08 to 1.98 individuals/ha. The dominant seagrass species were Enhalus acoroides, Pacific turtlegrass (Thalassia hemprichii), Cymodocea rotundata, and C. serrulata. The distribution range of seagrass meadows did not exhibit significant change compared to the data from the seagrass census conducted between 2018 and 2020 by the Biodiversity Center of Japan, Ministry of the Environment. However, the coverage of E. acoroides had notably decreased. Additionally, the leaf lengths of most E. acoroides, which are typically over 100 cm, were only 3–5 cm due to grazing by green turtles. In the Maja and Ou coastal areas of Kume Island, the population density of green turtles ranged from 3.95 to 5.18 individuals/ha. Seagrass meadows that previously consisted of large seagrass species (T. hemprichii, C. rotundata, and C. serrulata), as recorded between 2018 and 2020 by the Biodiversity Center of Japan, were currently no longer present. Instead, only several patches of small species (Halophila spp. and Halodule spp.) were observed. Our findings suggest that the seagrass meadows in the Maja and Ou coastal areas of Kume Island were largely consumed due to overgrazing by green turtles. Meanwhile, the seagrass meadows in the Fukido estuary of Ishigaki Island are currently experiencing heavy grazing pressure, which may lead to the collapse of the seagrass meadows in the near future. Our results highlight the need for wildlife management that acknowledges the coexistence of green turtles and seagrass meadows.

Residence of Male Black Sea turtles (Chelonia mydas agassizii) at Nesting Areas in Michoacan, México.

Carlos Delgado-Trejo1,2, Cutzi Bedolla-Ochoa1,2, Miguel Angel Reyes-López2, Fátima Yedith Camacho-Sánchez2

1Instituto de Investigaciones sobre los Recursos Naturales,Universidad Michoacana de San Nicolás de Hidalgo, Mexico; 2Centro de Biotecnología Genómica, Campus Reynosa, IPN

The black turtle population in Michoacán is the most abundant in the eastern pacific, breeding adults aggregate during the months of september to january when courtship and copulation interactions occur. breeding females exhibit polyandrous mating behavior and no intra-sexual sexual selection is observed among breeding males. the reproductive behavior of breeding males has been studied for a decade and they exhibit intense competition for females throughout this period. it has been observed through satellite tracking that males do not make long-distance movements as females do to their breeding areas in central america and northwestern Mexico (Sinaloa, Sonora and the Baja California peninsula). Once the nesting season declines in the ANP Colola sanctuary (the main nesting site for the black sea turtle population in the American Pacific), the males make movements to the south of the coast of Michoacan on the border with the state of Guerrero where a thermoelectric power plant is located, where some males enter the plant's refrigeration channels, apparently in search of warm water. On the other hand, through the study of stomach contents in breeding males, it has been observed that they use a variety of food resources found in the coast of Michoacan, among which are jellyfish, algae, diatoms, sponges, sea grasses and others. Captures of copulating and courting males and photographic records in continuous years have yielded information suggesting that male black sea turtles do not follow females to feeding areas for several reasons: 1) The reproductive condition in terms of receptivity of males ends once the females leave the nesting area and begin migrating to feeding areas in Central America and northwestern Mexico. 2) The males do not follow females to feeding areas in Central America and northwestern Mexico, 3) Males do not require considerable energy inputs for sperm production, 4) The reproductive cycles of females in the black turtle population in Michoacán are three and five years, while males reproduce continuously once they reach sexual maturity. Evidence accumulated from a decade of studies on the reproductive behavior of adult breeding black turtles in Michoacán suggests that males are resident in the nesting areas of Michoacán, which encompass approximately 80 km of coastline.

Habitat selection of post-nesting loggerhead turtles in the Northwest Pacific

Kei Okamoto, Haruka Hayashi, Shintaro Ueno, Daisuke Ochi

Japan Fisheries Research and Education Agency, Fisheries Resources Institute, Japan

Loggerhead turtles, Caretta caretta, in the North Pacific nest only in Japan. This population experienced a rapid increase in the number of nests in the early 2010s and is ranked as Least Concern in the current IUCN assessment. However, the number of nests has shown a gradual downward trend in recent years and conservation should continue. Loggerheads spend most of their time in foraging areas except for breeding seasons that occur every few years. Increased adult mortality and decreased quality of foraging habitat may be causing the decline in the number of nests. Therefore, it is important to investigate the foraging ecology of this species to better understand the factors that are contributing to its decline. Previous studies have shown that the Japanese loggerhead population is dichotomized by size, but little is known about the relationship between foraging distribution and the marine environment. In this study, we attached satellite transmitters to nesting females at Tanegashima Island, one of the largest nesting sites for loggerheads in Japan, and analyzed the relationship between the locations used by post-nesting females and associated environmental factors to clarify habitat selection by females and the factors that influence it. We attached satellite transmitters on 23 turtles (SCL: 866 ± 41 mm, mean ± SD), and analyzed habitat preference using six environmental factors: sea surface temperature, sea surface salinity, sea surface current velocity, chlorophyll-a concentration, seafloor depth, and slope. The tracking period was divided into two seasons, summer and winter, and the environmental factors at the seasonal locations were compared to the environmental factors of entire home ranges to determine the characteristics of each high-use area. Our tracked loggerheads showed seasonal differences in spatial distribution, using a limited area near Tsushima Strait, Jeju Island, and Taiwan in the summer, and a wider area within the East China Sea (ECS) in the winter. The summer habitat had relatively slower currents than the surrounding waters, while the winter habitat had faster currents but was temperate. Indices of primary productivity such as salinity and chlorophyll-a did not affect habitat selection. We conclude that the post-nesting females of the Northwest Pacific loggerheads select habitats in the ECS that conserve energy and have comfortable water temperatures. The ECS is an important area not only for loggerheads but also for humans, especially as it is the best fishing ground for east Asian countries. Therefore, loggerheads in the ECS face competition for resources with fisheries and are at risk of bycatch. The results of this study may be useful in establishing protection and management measures for loggerheads in this area.

Insights on sea turtle behavior and habitat use in New York’s coastal waters from movement tags deployed on rehabilitated animals

Joseph D. Warren1, Charleigh Kilgallon1, Maxinne A. Montello1,2

1Stony Brook University, United States of America; 2New York Marine Rescue Center, United States of America

Instrumented tags (Customized Animal Tracking Solutions) were deployed on rehabilitated sea turtles released back into the ocean to provide short-term, fine-scale data on how sea turtles are using the estuarine and oceanic waters of New York. The tags are equipped with a variety of sensors including: high definition video, audio, inertial motion parameters (acceleration, orientation, magnetic field), temperature, and pressure (depth) which can be used to quantify the movement and behavior of the animal in the wild. Tags are attached to the carapace using suction cups, set to detach from the animal after 12 – 48 hrs depending on deployment configuration, and then float at the surface for tag retrieval and data download. Test deployments were conducted on rescued and rehabilitated turtles at the New York Marine Rescue Center (NYMRC) during the summer of 2023 to determine best suction cup attachment procedures and document behavioral reactions of individual turtles to the tags. Two field deployments on rehabilitated sea turtles (one juvenile green, one juvenile Kemp’s ridley) released into the ocean were conducted in late summer / early fall 2023. Both individuals were documented feeding on aquatic vegetation within 30-60 min of entry into the ocean. Inertial movement data were different for the two animal’s movement characteristics (e.g., turtle pitch, roll, yaw, and accelerations) as they swam and dove. The juvenile green turtle had consistent behaviors (in terms of dive timing and profiles) throughout the tag attachment period. The Kemp’s ridley turtle did not dive as often or as frequently during the first 4-6 hrs of release, but then dives became more frequent and deeper. Camera footage shows a variety of interspecific encounters (juvenile skate, sharks) occurring during the turtle’s movements.

Tracking male turtles from Kyparissia Bay, Western Greece, the largest loggerhead rookery in the Mediterranean

ALan F. Rees1, Tasos Dimalexis2, Odysseas Paxinos3, Panos Batzios4, George Mikoniatis5, Yannis Vavassis5

1Turtles from Above, Plymouth, UK; 2Nature Conservation Consultants (NCC) Ltd, Athens, Greece; 3MOm/Hellenic Society for the Study and Protection of the Monk Seal, Athens, Greece; 4BIOTOPIA GP, Athens, Greece; 5HELLENiQ UPSTREAM S.A., HELLENiQ ENERGY Holdings S.A., Athens, Greece

Most sea turtle telemetry studies focus on the more readily accessible adult females that come ashore to breed at predictable times in predictable locations. Adult males are believed to undertake similar breeding migrations, but as they remain at sea the entire time, acquiring them for telemetry is more logistically challenging. The Mediterranean’s largest breeding aggregation of loggerhead turtles use Kyparissia Bay in western Greece to mate and nest. Following a successful project tracking several adult females we wanted to examine the movements of adult males from the same population, but to additionally investigate their use of the water column during migrations and residency periods. During May 2023 we deployed three SPLASH10-385 Argos transmitters (Wildlife Computers, USA). Male turtles mounted on females were selected. They were captured using the rodeo technique where the researcher launches from a vessel onto the turtle which is then landed to be processed for the project. Turtle locations were gained from the standard Argos positioning system. Location accuracy is predicted to a few hundred metres but may be more accurate. Depth data were sampled and stored every 5 seconds. These were transmitted as raw data points subsampled at 75s intervals, in 1hr-long blocks. The turtles departed from the breeding site between 1 and 11 days after transmitter deployment. Tracking lasted a minimum of 98 days. Two turtles established residence in relatively shallow coastal waters and the third turtle, until the time of writing (Nov 1, 2023) did not settle. Turtle A was not recorded as diving deeper than 48.5m, during its 42-day migration, despite swimming through waters that were more than 200m deep for over 14 days. During his residency in a coastal foraging area, he remained predominantly in the top 10m of the water column, despite remote sensed bathymetry data suggesting the sea depth was often nearer 20m. Turtle B undertook a shorter 21-day migration incorporating coastal and open water sites. His diving was generally restricted to less than 10m with occasional dives no deeper than 30m. There was one exception to this, near the end of his migration he dived to 56.5m. From then on, during the restricted-area foraging period, the turtle increasingly dove deeper making regular dives to 75m or more with the greatest depth recorded as 119.5m. Turtle C has not settled into any one restricted area foraging site but instead has roamed the northern Ionian, with periods in both coastal and open waters. Despite often traversing waters over 1km deep the turtle was recorded as making only five dives deeper than 100m, with two of those dives occurring consecutively on 27 August. However, the turtle regularly dove between 50 to 100m deep. This turtle’s deepest dive (the second on 27 August) reached 202m. Our results indicate that loggerhead turtles in the Mediterranean habitually use only a few tens of metres depth of water, making them most susceptible to threats at or near the surface. These data will further improve our knowledge for the species distribution and ecology in the study area.

A multidisciplinary approach give insight on loggerhead turtle (Caretta caretta, Linneus 1758) trophic ecology in the Tyrrhenian Sea (Central Mediterranean)

Monica Francesca Blasi

Filicudi Wildlife Conservation, Italy


Marine turtles are key indicator species of ecosystem function and environmental health, however, many of their life-history features remain cryptic. The understanding of their year-round feeding habits is critical to establish the effect of contaminants exposure through the marine food web and their adverse health consequences. Here, the results of a long-term study on wild-caught alive loggerhead turtles in the Tyrrhenian Sea (Central Mediterranean) were reported. Primary, isotope stable δ13C and δ15N were determined in blood and epidermis samples as well as concentrations of metals and plastic additives. Then, antibiotic resistance of gram-negative bacteria and polymer composition analysis of plastic debris (FTIR-ATR) were analysed in faecal samples. Finally, epibionts and microbial communities which colonized carapace scutes were assessed. The results of Bayesian mixing models suggested that, generally, turtles sampled in Sicilian waters prey at low trophic levels but high concentrations of different chemical elements were found as a result of plastic ingestion. The presence of antibiotic-resistant strains also in healthy animals confirmed the role of the loggerhead sea turtles in spreading antibiotic-resistant bacteria. The differences in microbial diversity and composition between anterior vs posterior carapace scutes may be related to the different macroalgae settlement or growth at these locations as a consequence of the health status (hydrodynamics) of the individual. Our results support the utility of a multidisciplinary approach from wild-caught alive animals to investigate simultaneously different ecological features of sea turtles. Further studies should aim on investigating animals in both good health and with detectable disease issues, to understand how much different threats and healthy status can influence Mediterranean loggerhead turtles’ feeding ecology.


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Olive ridley internesting behaviour in northeast Brazil based on high resolution tracking data

A C C Melo1, A J B Santos1,4, R S Garcia1, C Pulita1, F L C Oliveira1, M I Weber1, A C D Silva1, E L Fonseca1, R M A Ramos2, E A P Santos3

1Fundação Projeto Tamar, Brazil; 2Engeo Soluções Integradas Ltda, Brazil; 3Centro TAMAR-ICMBio, Brazil; 4Florida State University, United States of America

In Brazil, the Sergipe and Bahia states comprises the main nesting grounds of olive ridley (Lepidochelys olivacea). To evaluate the specie internesting and post-nesting movements we deployed 22 FastGPS Platform Transmitter Terminal-PTT (Sirtack FastGPS F6G 376A). The deployment occurred from August 2018 to August 2019. The PTTs FastGPS sample rate was one location every 30 minutes. 10 olive ridleys started their post-reproductive migration immediately, 2 turtles stranded dead and 10 remained in the internest area for 34 days (average), ranging from 10 to 119 days. The average internesting core has 176km2 (72 to 324km2). Two females were recaptured, and locations were downloaded directly. The internesting core area was defined as 50% Kernel Density Estimation contours (KDE 50%). The internesting interval, distance and movements were described. The first nest of olive ridley #57952 was recorded on 08/16/2018, and after, the female traveled 11 km in 8 hours, reaching to the Port of Sergipe, and starting restricted movements for 9.6 days. For this phase, the internesting core area totaled 22 km2, located between 20 to 30 m depths, about 6km from the coast. After the restricted movements, the turtle returned to the area near the previous nesting site. This movement lasted 7 days with 47 km traveled. For 48 hours, the turtle remained within 2 km from the coast, with a false crawl, followed by a successful nesting on 09/04/2018, after 18 days. The internesting distance was 6 km. The first nesting of olive ridley #57986, was recorded on 04/02/2019, when the PTT was attached. Then, the turtle moved along the continental shelf for 6 days, until reaching the Port of Sergipe area, located 12 km south of the first nest. The restricted movements totaled 5 days, with an internesting core area of 9.5 km2, located at 3.5 km from the coast, between 10 and 15 m isobaths. The active search for second nest area totaled 7 days with a distance traveled of 62 km. The second nesting occurred on 04/20/2019, after 19 days, with an internesting distance of 8.6km. The results indicated that the intenresting interval identified (18 and 19 d) is like the pattern described for the species in Sergipe (20 d), however the internesting distance was slightly higher (6 and 8 km vs 4 to 5.5 km). The present analysis shows a variation in the size of the internesting core (KDE 50%) when estimated only for the restricted movement phase (KDE 50% = 22 and 9.5 km2), in relation to the value obtained for the total set of locations (96 and 72km2). PTT direct download is an efficient way to get the high-resolution locations, critical to identify different movements performed during internesting. Of the 860 FastGPS locations directed downloaded, only 17% (149) were remotely transmitted. Accurate habitat identification during internesting is relevant, especially if use areas overlap threats such as fishing, ports, and hydrocarbon exploration. The identified movements demonstrate the susceptibility of olive ridley to interact with shrimp fishery, since the identified internesting area overlap the fishery ground.

On battered reefs - insights into foraging of hawksbill turtles at known hotspots in the Maldives

Enas Mohamed Riyaz1, Ahmed Leevan1, Afrah Abdul-Sathaar2, Isha Afeef2, Ali Shareef3, Aishath Shaiha1, Ibrahim Inaan2, M.M.R Polyak4, Stephanie Köhnk4

1Environmental Protection Agency, Handhuvaree Hingun, Malé, Republic of Maldives; 2Olive Ridley Project Maldives, H. Kaneerumaage, Dhonhuraa Goalhi, Malé, 20037, Republic of Maldives; 3Happy Side, K. Maafushi, 08090, Republic of Maldives; 4Olive Ridley Project, 91 Padiham Road, Sadben, Clitheroe, Lancashire, BB7 9EX UK

The Maldives hosts the seventh largest coral reef system in the world which covers an area approximately 8,900 km2 in size. Coral reefs are among the most threatened ecosystems in the country and have been impacted by severe bleaching events in 1998 and in 2016. Degraded reefs dominated by zoanthid cover have been linked to hawksbill sea turtles in the Maldives. However, little is understood about the dietary composition of hawksbill sea turtles in Maldives, which hosts a recorded population of at least 4686 individuals. There are reports of hawksbill predation on the anemone-like zoanthids, Zoanthus sociatus and Palythoa caribaeorum made in the US Virgin Islands and Southern Brazil respectively. During a sea turtle expedition carried out in August 2023 in Maldives, several known hawksbills hotspots were surveyed for benthic cover association with foraging ecology. The hotspots surveyed across three atolls (North Malé, Baa Atoll and Lhaviyani Atoll) supported hawksbill populations of 85 to 227 individuals and were found to be degraded reefs with low live coral cover, where the substrates were heavily colonized by Zoanthus sp. which appear to be favored by hawksbill sea turtles. A similar pattern was also observed in several other hotspots where the predominant substrate cover was of the carpet corallimorph Rhodactis sp. During the surveys, predation on Zoanthus sp. by hawksbills were observed on multiple occasions, with clear signs of undigested Zoanthus sp. also observed from a collected hawksbill fecal sample. The association is further supported by the number of identified individual hawksbills at these ‘patches of reef’ dominated by Zoanthus sp., with Makunudhoo reef in Malé atoll supporting a recorded 227 individuals, and Thanburaanu reef in Baa Atoll supporting a recorded 145 individuals. Although there were no observations made for hawksbill predation on Rhodactis sp. during the surveys, it has been suggested that this species may also be part of the diet of hawksbills in these reefs, as predation on corallimorphs have been observed in other parts of the world. Similar to the case with zoanthids, Muthaafushi reef in Baa Atoll consists of high Rhodactis sp. cover and is recorded to support at least 85 individual hawksbills. Although both zoanthids and corallimorphs are known to compete with corals for space, the distribution of Zoanthus sp. is generally known to be patchy with high abundances restricted to a few sites, while the corallimorph Rhodactis sp. is a reported invasive species that damage certain reef building coral families such as Poritidae, Acroporidae and Pocilloporidae in the Maldives. Our observations indicate that hawksbill sea turtles might play an important role in regulating the abundance of certain zoanthids and corallimorphs, and thus allowing more space for coral growth. The long term implications of the hawksbill predation on these benthic communities could have an impact on the recovery of coral reefs, reinforcing the importance of hawksbill conservation in the Maldives.

Dispersal of nesting marine turtles from NEOM Islands, Saudi Arabia, after breeding

Hector Barrios-Garrido1, Abdulrazaq Alatawi2, August Santillan2, Enjey Ghazzawi3, Abdulaziz Alkaboor2, Mishari Alghrair4, Paul Marshall4, Deni Porej4, Ricardo Ramalho2

1Beacon Development, KAUST Innovation. KAUST. Saudi Arabia. University of Zulia, Venezuela. TropWATER, Australia; 2Beacon Development, KAUST Innovation. KAUST. Saudi Arabia; 3Education, Research, and Innovation. NEOM. Saudi Arabia; 4Nature Reserve, NEOM. Saudi Arabia

Marine turtles are highly mobile and face multiple threats across their habitats. Green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles nest in the Red Sea, but little is known about their re-nesting success, intervals, or post-breeding displacements. NEOM Islands are priority zones for protecting marine turtle rookeries, as they account for 95% of turtle nesting evidence in the northeastern Red Sea. This paper aims to calculate the distances between nesting beaches and feeding grounds, and to identify migratory pathways and their duration. We focused our survey efforts in Shusha and Walah Islands, where we attached Platform Terminal Transmitters (FastGPS and Argos) to 17 marine turtles (11 hawksbills and six greens) in one season for each species. We then identified and mapped inter-nesting habitats, feeding grounds, and migratory pathways. Six feeding grounds (four within Saudi Arabian localities and two within Egyptian waters) used by NEOM nesting turtles were identified. Expanding existing or creating new marine protected areas in the Red Sea coastal zone could benefit marine turtle conservation for both studied species during and after their reproductive episodes. Our findings suggest that green and hawksbill turtles from the NEOM Islands share migratory routes and foraging areas with other green and hawksbill turtle rookeries in the region. More research is needed to fill in the gaps in our knowledge about these threatened species, but presented results can already be used to inform conservation actions and management plans for NEOM Islands in the short, medium, and long term.

Keywords: Migratory Pathways; Critical Habitats; Management Plans; Habitat Use; Marine Protected Areas.

First island wide survey of hawksbill sea turtles, Eretmochelys imbricata, in the waters of St John, U.S. Virgin Islands

Paul Jobsis1, Scott Eanes2, William {Alex} Webb2

1Univ. of the Virgin Islands, Virgin Islands, U.S.; 2The Hawksbill Project

In-water estimates of hawksbill sea turtle abundance and size distribution are critical to understanding the potential growth or decline of the population. However, these measures can be difficult, costly, and time-consuming. The ephemeral nature of their sightings, the cost of boating operations, and the difficulty catching these turtles are factors in why this data is often unavailable. The size structure of the juvenile population can be a powerful predictor of population growth or decline. To assess the population in the waters of St John, USVI, a team of trained volunteers spent 11 days over two weeks in the summer of 2023 catching and tagging hawksbill sea turtles. Typically, a team of four free divers spent 6 to 8 hours per day swimming much of the shallow waters (1m to 15m) of the approximate 65km of St John’s coastline searching for sea turtles. Seventeen individuals were captured, tagged, and released. The turtles’ SCL ranged from 21.2cm to 67.9cm (mean 47.1 ± 16.5) and 1.1kg to 37.6kg (mean 16.7 ±13.1), reflecting that most, if not all, were juvenile or subadult individuals. None of the turtles showed evidence of previous tagging (no PIT or flipper) despite tagging programs occurring on the neighboring islands of St Thomas and Tortola. Structuring the data into 10cm size classes, which likely reflect age classes, produced a population pyramid that could be used for population growth predictions on larger data sets. The small population sample, n=17, showed an hourglass shape, with most turtles being over 60cm (n=7) and the second largest size class being 20-29 cm (n=4). A population pyramid with large young populations can predict population growth in the future. The small sample size from this first-ever island-wide survey is too small for accurate predictions of population growth. Still, it is an example of the effort required and the potential value of intensive in-water tagging efforts.

Evaluating resource use patterns and partitioning in relation to changing prey abundance in co-occurring sea turtle species using molecular isotope geochemistry

Matthew D. Ramirez1,2,3, Justine Intemann-Milligan4, Larisa Avens5, Matthew H. Godfrey6,7,8, Susan G. Barco9, Kelton W. McMahon1

1Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882 USA; 2Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina 28403 USA; 3Center for Marine Science, University of North Carolina Wilmington, Wilmington, North Carolina 28409 USA; 4Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94720 USA; 5National Marine Fisheries Service, Southeast Fisheries Science Center, NOAA Beaufort Laboratory, Beaufort, NC, 28516 USA; 6North Carolina Wildlife Resources Commission, Beaufort, NC, 28516 United States; 7Duke Marine Laboratory, Nicholas School of Environment, Duke University, Beaufort, NC, 28516 United States; 8Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, 27607 United States; 9Virginia Aquarium & Marine Science Center, Virginia Beach, VA 23451 United States

Understanding how resource use patterns vary among sympatric species and in response to human activities (e.g., fisheries) is critical to predicting ecological responses to future ecosystem change. Sympatric Kemp’s ridley (Lepidochelys kempii) and loggerhead (Caretta caretta) sea turtles are ideal species to study resource partitioning under environmental change scenarios because the abundance of blue crab (Callinectus sapidus), a key prey species and one of high economic importance for regional fisheries, has fluctuated dramatically in recent decades. Using compound specific stable isotope analysis of individual amino acids applied to stranded sea turtle bone tissue, we compared multi-decadal Kemp’s ridley and loggerhead sea turtle resource use patterns—trophic position and basal production source—and partitioning and evaluated relationships with blue crab (Callinectes sapidus) abundance. Bones were obtained from turtles that stranded dead in North Carolina and Virginia (Kemp’s ridley n = 48; loggerhead n = 26) from 1992 to 2016. Bone and skin samples were also obtained from the North Carolina Museum of Natural Sciences for turtles stranded in North Carolina from 1952 to 1981 (Kemp’s ridley n = 8; loggerhead n = 4) for comparison of modern (1992–2016) to historical (1952–1981) turtle samples. For modern bone samples, we identified a similar overall mean trophic position (MTP), internally indexed to the baseline nitrogen isotope value, for both Kemp’s ridleys (MTP = 3.3 ± 0.3) and loggerheads (MTP = 3.3 ± 0.4). For loggerheads, historical MTP (3.4 ± 0.2) was similar to modern MTP. For Kemp’s ridleys, historical MTP (2.9 ± 0.6) was lower but within the range of modern MTP. Loggerhead MTP increased by ~0.5 trophic levels from 1990 to 2012, suggesting a shift in foraging strategies through time to higher trophic level prey. This timeline corresponds with the decrease in blue crab abundance and aligns with the results of diet content studies that observed an increase in loggerhead sea turtle fish consumption from the 1990s to early 2000s, likely sourced from fisheries bycatch. Modern Kemp’s ridley MTP did not change during the study period. Additionally, stable carbon isotope fingerprinting revealed that eukaryotic microalgae were the primary basal resources supporting both species’ food webs throughout the time series. However, distinct clustering of each species within the linear discriminant analysis indicated possible microhabitat partitioning. These patterns may align with recent research in the Chesapeake Bay that suggests there is fine-scale spatial partitioning between the two species, with Kemp’s ridleys using more shallow, nearshore estuarine habitats and loggerheads using deeper, offshore habitats. The fluctuation in blue crab abundance and potential for fisheries bycatch subsidies adds to impacts of climate change stress and fishing predation on sea turtle food web dynamics. Increased sampling and gut content studies are needed to further understand variation in this species’ resource utilization patterns across space and time to better inform conservation and management efforts.

Green turtle photo-identification improves mark-recapture efforts and provides evidence of habitat connectivity and fine-scale ontogenetic shifts

Annabelle Brooks1, Hannah Virgin2, Stephen Dunbar3,4, Dustin Baumbach4, Liberty Boyd2, Stephen Connett5, Ryley Mayoras2, Elizabeth Whitman2

1Cape Eleuthera Institute, PO Box EL-62029, Rock Sound, Eleuthera, The Bahamas; 2Institute of Environment, Department of Biological Sciences, Florida International University, North Miami, Florida, USA; 3Marine Research Group, Loma Linda University, Loma Linda, CA 92350 USA; 4Protective Turtle Ecology Center for Training, Outreach, and Research, Inc. (ProTECTOR, Inc.); 5Family Island Research and Education, Archie Carr Center for Sea Turtle Research

Photo identification (PID) is an efficient and increasingly popular tool that uses natural or acquired markings unique to an individual to track wildlife for population or ecology-focused studies. Issues of tag loss and capture-stress associated with traditional capture-mark-recapture methods may be resolved using PID. The accessibility of photographic equipment and photo identification tools also allows for data to be collected by both researchers and citizen scientists, which can be shared in collaborative databases. In prior sea turtle studies, PID has proven useful in the identification of individuals because scales on either side of the faces of green, hawksbill, and loggerhead turtles, as well as the pineal spots of leatherbacks have been found to be distinct and consistent to individuals. Green turtles (Chelonia mydas) have highly migratory behaviors, making it difficult to track individuals across multiple life stages. Additionally, external tags may foul or be lost, and internal tags (PIT tags) can be cost prohibitive and go undetected without tag-specific detection equipment. Western Atlantic green turtles may be too small to tag when they recruit to benthic foraging habitats at approximately 20 - 25 cm SCL. Thus, PID offers a potential technique to determine fine scale habitat use in neritic habitats for juvenile and subadult green turtles as they use coastal foraging grounds. We tested the use of PID as a supplement to physical tagging using photographs of juvenile and subadult green turtles in tidal creeks and nearshore seagrass meadows off Abaco Island, The Bahamas. We compared data from physical Inconel flipper tags to outputs from HotSpotter, an automated photo identification software, across 314 captures between 2013 and 2019. Out of 1,230 images, we manually verified matches and found HotSpotter to have at least a 92% match rate between the software output and a human observer for a subset of 90 test photos. However, match rates increased to 100% when image backgrounds were removed, leaving only the turtle head for matching. In addition to external tag-identified recaptures, HotSpotter correctly identified five recaptures, of which four were previously unrecognized as recaptures. This included one individual recaptured in a geographically distinct habitat and subsequent size class 1,786 days later, who also displayed a distinct color change at the recapture site. Another individual was recaptured after 2,191 days, but in the same habitat and at a different size class, however it did not display a noteable color change. We further investigated the importance of size class and movements on color variation in juvenile green sea turtles. Our results suggest that PID is a useful supplement to physical tagging methods and a key tool for identifying drivers of color pattern variations across size classes and habitats. Our results elucidate fine-scale ontogenetic shifts across interconnected habitats with implications for a multi-ecosystem conservation approach.

*Role of sea turtle eggs as a marine originated organic matter in the diet of terrestrial invertebrate ghost crabs

Hirotaka Tajima1,2, Hideaki Nishizawa3, Manabu Kume4, Junichi Okuyama5, Hiromichi Mitamura1,2,4

1Graduate School of Agriculture, Kyoto University, Kyoto, Japan; 2Distinguished Doctoral Program of Platforms (WISE), Kyoto University, Kyoto, Japan; 3Graduate School of Informatics, Kyoto University, Kyoto, Japan; 4Field Science Education and Research Center, Kyoto University, Kyoto, Japan; 5Fisheries Technology Institute, Japan Fisheries Research and Education Agency, Okinawa, Japan

Sandy beaches have low primary productivity because large plants are unlikely to grow naturally. Therefore, marine originated organic matter, such as seaweed and fish carcasses, supports the basis of the beach food web. Sea turtle nesting plays a role in the movement of organic matter from the ocean to the sandy beaches. Sea turtle eggs are known to be predated by a wide variety of taxonomic groups that use the beaches. Although they are a pulsed resource supplied over a limited period, sea turtle eggs are likely to support the food web of the sandy beach. However, few studies have been conducted on the effects of sea turtle eggs on beach food webs in comparison with seaweed and other drift materials. This study aimed to verify the role of sea turtle eggs in the food web of sandy beaches by estimating the contribution rate of sea turtle eggs to the food of ghost crabs (Ocypode spp.), which are predators of sea turtle eggs around the world. Sample collection site was Ishigaki Island, Ryukyu Archipelago, one of the main nesting sites for green sea turtles (Chelonia mydas) in Japan. Samples were collected in summer (July, October 2022 and July 2023) during the sea turtle nesting season and in winter (March and April 2023) when no sea turtle eggs are present on sandy beaches. Ghost crabs (O. ceratophthalma : n=24 in summer and n=14 in winter, and O. sinensis : n=38 in summer and n = 4 in winter) and prey candidates including sea turtle eggs were collected at three beaches in the Ibaruma area with different numbers of green turtle nests. Samples were analyzed for carbon and nitrogen stable isotope ratios. The contribution of each prey candidate to the diet of ghost crabs was estimated from the stable isotope ratios with a Bayesian statistical isotope mixing model. Differences in the contribution among beaches and between species of ghost crabs were investigated. Carbon isotope ratios were higher in O. ceratophthalma than in O. sinensis. In summer, ants and terrestrial plants contributed more to the diet of O. sinensis, while brown algae contributed more to the diet of O. ceratophthalma. The contribution of seaweed in the diet of O. ceratophthalma and the contribution of ants in the diet of O. sinensis tended to be lower on a beach with sea turtles nests than on a beach with no sea turtles nest. In addition, green turtle eggs contributed approximately 10% of diets of O. ceratophthalma in summer, whereas the contribution was replaced by ants in winter when there were no green turtle eggs. These findings suggest that O. sinensis utilize mainly terrestrial-derived food, while O. ceratophthalma utilize marine-derived food. Green turtle eggs are considered to be a significant food resource for O. ceratophthalma in summer, but their contribution to the diet of O. sinensis was almost negligible.

*Change in clutch depth and reproductive success of late-season green turtle (Chelonia mydas) nests on the East-Central Florida coast, USA

Olivia J. Hardway, M.S. Moonstone, E. E. Seney, K. L. Mansfield

University of Central Florida's Marine Turtle Research Group, United States of America

The depth at which sea turtle nests are laid in sand affects key factors such as moisture levels, temperature, and gas exchange, which impact sex ratios, and hatching and emergence success. Florida’s late-season nests, defined as those laid after 31 August and that may still be incubating past 31 October, are exposed to extreme weather events such as hurricanes, tropical storms, and exceptionally high autumn “king” tides. Extreme weather is known to heavily affect sand accretion and erosion on the beach. The change in sand depth and reproductive success of late-season nests on the Archie Carr National Wildlife Refuge (ACNWR) is unstudied. To better understand hatching success and challenges facing late-season nests, we measured change in clutch depth in 40 green turtle (Chelonia mydas) nests laid June through October. During nest marking (shortly after deposition), a HOBO MX2201 temperature datalogger was placed on the top of the clutch (“nest datalogger”), and depth of the nest datalogger from the surface was recorded. A second datalogger (“sand datalogger”) was placed south of the clutch at the same depth as the nest datalogger. During inventory of the nest, we recorded the final depth of both dataloggers. We calculated the difference in depth measurements recorded for the nest and sand dataloggers to determine if the clutch had experienced any accretion or erosion. Inventory data collected from these nests were used to describe hatching and emergence success, as well as incubation duration. Changes in depth and reproductive success of these late-season nests were further compared to those of nests laid during the main nesting season (June-August). Data collection is ongoing and is expected to continue into early 2024; early results indicate nests laid in August and September experienced higher rates of sand accretion, whereas nests incubating as of 8 November experienced higher rates of erosion and wash outs due to high tides. As the nesting of green sea turtles increases in Florida, the number of late-season nests can be expected to increase. Results from this study can help determine the best way to protect these understudied late-season nests and help inform future nourishment and dune restoration projects, as well as understand the role late-season nests play in overall population dynamics and recovery efforts. Sampling and data logger deployment is part of a larger ongoing late-season project by the University of Central Florida’s Marine Turtle Research Group and is funded by the Sea Turtle License Plate Grant.

*Long-term trends in reproductive output of marine turtles on the Archie Carr National Wildlife Refuge, Florida, USA

Jeena Prasertlum, Erin E. Seney, Kate L. Mansfield

University of Central Florida Marine Turtle Research Group, United States of America

Temperature plays a major role in phenology, the seasonality of life history events, by disrupting natural reproductive patterns. The consequences of these disruptions on population dynamics are not well understood. It is crucial to assess the climate effects on phenological shifts in ectothermic organisms, given their substantial contribution to global biodiversity. Oviparous reptiles are particularly susceptible to these disruptions as many of their life history traits are vulnerable to climate change due to their high physiological sensitivity to temperature, absence of parental care, and temperature-sensitive embryonic development. Sea turtles are particularly at risk from global changes, as populations are facing multiple threats such as coastal development, marine pollution, over-exploitation, and entanglement, in addition to global warming. For this study, we focused on the Brevard County section of the Archie Carr National Wildlife Refuge (ACNWR), 21-km of the Atlantic coastline in Melbourne Beach, Florida, USA. This area is of great significance to sea turtle nesting, hosting one-eighth of all loggerhead sea turtle (Caretta caretta) nesting and one-third of all green sea turtle (Chelonia mydas) nesting in Florida. Assessing the reproductive ecology of sea turtles nesting on this beach is important for providing demographic information to measure conservation success and population recovery efforts. The UCF Marine Turtle Research Group (UCF MTRG) has monitored the ACNWR for sea turtle nesting activities for over four decades, resulting in an extensive dataset that has yet to be analyzed for long-term changes in reproductive success and output. Our two primary objectives were: 1) to assess changes over time in hatchling emergence success in relation to temperature for each species, and 2) estimate yearly hatchling output for both species and test for changes over time. To determine if emergence success has shifted over time, nest data from 1988-2023 were analyzed with historical air temperature data to predict if changes in these air temperatures influenced emergence success. Using historical nest count and inventory data, the average number of eggs per year were calculated, and this value was used to estimate hatchling output per year. Fluctuations in emergence success occurred over time, which could be attributed to various factors like turtle species, storm activity, nest placement, and predation rates, in addition to temperature effects. We show a significant increase in the number of hatchlings produced per year for green sea turtles while hatchling output for loggerheads throughout the years remains consistent and shows no clear trend. To make sure this trend is not exclusively due to the increase in green nests and stable loggerhead nesting trends, multiple models were created to assess other variable impacts. Nest numbers alone did not predict emerged hatchling estimates. The interaction of both nest numbers and emergence success rates significantly predicted hatchling output (p<0.05). The survival of early-stage sea turtles is a powerful driver of sea turtle population numbers. Understanding how the threat of climate change impacts their early life stages is essential for the implementation of conservation strategies to protect sea turtle species on this important refuge.

*Loggerhead sea turtle hatchling size: then and now

Abigail Crowder, Erin Seney, Kate Mansfield

University of Central Florida, United States of America

Sea turtles, recognized for their longevity and extensive migrations, reach sexual maturity between 25 to 35 years of age. Throughout their lives, these creatures traverse a variety of habitats, from nesting on coastal beaches to inhabiting coastal waters and venturing into the open ocean. Monitoring sea turtles across these different life stages is a complex challenge due to their intricate life histories. Notably, young sea turtles, the cornerstone of the population, have remained enigmatic and underexplored. Recent research identified a reduction in the size of nesting loggerhead (Caretta caretta) sea turtles at maturity over time within the Archie Carr National Wildlife Refuge (ACNWR). The ACNWR, located on the east coast of Florida, USA was established to protect the most significant loggerhead rookery in the Western Hemisphere and hosts 12% of annual loggerhead nests in Florida, with more than 10,000 loggerhead sea turtle nests recorded annually within the northern 21 km of nesting beach. While nesting and reproductive output (clutch size, hatching and emergent success) have been continuously collected in the refuge by UCF MTRG since 1982, hatchling size has been intermittently collected since the 1970's. We examined the size of hatchlings over four decades, with a primary objective to assess whether shifts in hatchling size have occurred over time, similar to the shift observed in adult females. We tested whether there has been a shift in hatchling size over time by using historical hatchling morphometric data (straight carapace length, straight carapace width, depth, and weight) from 1977-1979 coupled with recent hatchling data (2021-2023). Measurements were collected for 3,897 hatchlings from 125 nests (1,760 hatchlings from the 1970’s and 2,137 hatchlings from the 2020’s). Using Bayesian ANOVA analysis, we compared the variance among the two groups in our morphometric data. Results suggest that hatchlings from the 1970’s were larger in every morphological measurement when compared to hatchlings from the 2020’s, following the trend seen within the adult females. Our results, while subtle, aid in understanding the nuanced dynamics of the loggerhead population within the ACNWR. The size of hatchlings is a critical parameter to monitor as it can provide insight into the viability of the sea turtle population. If smaller hatchlings are produced over time, this may reflect in the overall fitness and reproductive success of the species in the future. Understanding the implications of these size variations is vital for the conservation and long-term survival of sea turtles in the region.

*Emergence success of leatherback sea turtles in a changing climate on the Archie Carr National Wildlife Refuge, Florida, USA

Brianna Madison Nardelli, Jeena Prasertlum, Erin E Seney, Kate L Mansfield

UCF Marine Turtle Research Group, United States of America

Sea turtles face a variety of challenges across their life stages, with their nest environment being particularly susceptible to diverse environmental conditions like storm surges, erosion, washouts, and nest temperature conditions. Historically, reproductive success of the endangered leatherback (Dermochelys coriacea) is known to be low compared to green (Chelonia mydas) and loggerhead (Caretta caretta) sea turtles. Florida’s (USA) east coastline provides important habitat for leatherback nesting, embryonic incubation, and hatching. We used a long-term leatherback reproductive output dataset from the Brevard County section of the Archie Carr National Wildlife Refuge (ACNWR) to examine whether leatherback emergence success has varied over time in a changing climate. The ACNWR is a 21-km section of the Atlantic coastline in Melbourne Beach, Florida, USA where the UCF Marine Turtle Research Group (UCF MTRG) has consistently monitored since 1982. During this period, the UCF MTRG observed an increase in leatherback nesting, from 0 to 5 nests annually in the 1980s to about 30-60 nests annually in the 2020s. We assessed leatherback emergence success relative to air temperature overtime on the ACNWR. Our objective was to understand whether temperature has impacted leatherback emergence success on this nesting beach, thereby contributing valuable insights into leatherback hatchling output trends over time. To determine if emergence success has shifted over time due to changes in temperature, we calculated emergence success for each leatherback nest from 1996-2023 and obtained historical local air temperature data from NOAA’s National Center for Environmental Information (NCEI). Using iterative model selection, we conducted analyses in Rstudio to test if changes in temperature are associated with a change in emergence success over time. Elevated temperatures may push nest environments to their thermal limits, potentially resulting in decreases in emergence success, hatching success, and increased hatchling mortality. Understanding how climate change impacts leatherback emergence success is imperative for gaining insight on the future population dynamics of the species as their nests continue to face rapidly changing environmental conditions.

*Determining incubation duration and reproductive success of late-season loggerhead (Caretta caretta) and green turtle (Chelonia mydas) nests on the East-Central Florida coast, USA

Merope S Moonstone, Olivia J Hardway, Matt E Larsen, Kate L Mansfield, Erin E Seney

University of Central Florida's Marine Turtle Research Group, United States of America

Though sea turtle nesting on Florida’s east coast extends nearly year-round, nests laid in the last months of the loggerhead (Caretta caretta) and green turtle (Chelonia mydas) nesting season, especially after the official “end” of the season (October 31), are historically understudied. Late-season nests (laid after August 31 with possibility of incubating past October 31) are the most likely to be impacted by beach nourishment projects typically occurring from November-March. These nests are also exposed to lower temperatures, which will slow egg incubation duration and may reduce nest viability and hatching success. With the recent increase in green turtle nesting, it is likely that late-season nests will become more common and may have an important contribution to population dynamics. The beaches monitored by the University of Central Florida’s Marine Turtle Research Group (UCF MTRG) in south and central Brevard County are representative of nesting in the state, hosting about 1 in 6 loggerhead and 1 in 3 green turtle nests, making this an optimal study area. This study aims to describe incubation duration, viability, and reproductive success of late-season nests by species, compared to main-season nests (April-August), using nest emergence and inventory data. In 2021-2023, the UCF MTRG supplemented its reproductive sampling scheme to include more late-season nests. Nine loggerhead and 70 green turtle nests were marked during the 2021 late season (September-November), comprising 2% and 18% of total marked nests in 2021, respectively. During the 2022 late season, 9 loggerhead and 67 green turtle nests were marked, comprising 5% and 14% of total marked nests, respectively. As of 8 November, 13 loggerhead and 46 green turtle nests were marked in the 2023 late season, comprising 3% and 10% of total marked nests, respectively. Late-season 2021 nests incubated more slowly and were more susceptible to being washed out compared to those laid earlier in the season. In 2022, nests laid during August-September were heavily impacted by Hurricane Ian, with nearly all of the remaining nests and those laid in October, washed out by Hurricane Nicole. Only 33% of the hatched late-season green turtle nests in 2021 had an observed emergence date and therefore a known incubation duration. To better determine incubation duration of late-season nests, temperature of green turtle clutches and the adjacent sand were measured throughout the 2023 nesting season using HOBO MX2201 temperature data loggers. The drop in clutch temperature post-emergence due to loss of metabolic heat allowed us to estimate emergence date and calculate incubation duration for nests where emergence was not observed. Many late-season nests in 2023 experienced high levels of sand accretion, lowering hatching and emergence success, with data collection still ongoing. Results from this research will be useful for determining the contributions of late-season nests to reproductive output, as well as informing nest inventory protocols during cooler months and aiding managers overseeing beach construction and seasonal beach restrictions.

*Nesting ecology of leatherback turtles at buru island, indonesia

Retno Kusuma Ningrum1,2, Muhammad Idham Farsha3, Rendra Kurniawan3, Ranny Yuneni3, Yuliana Syamsuni3, Alexander R Gaos4, John Wang4, Michael Osmond5, Shaya Honarvar1,2

1School of Life Sciences, University of Hawaiʻi at Mānoa, 3190 Maile Way, Honolulu, Hawaiʻi 96822, USA; 2Pacific Cooperative Studies Unit, University of Hawaiʻi at Mānoa, 3190 Maile Way, Honolulu, Hawaiʻi 96822, USA; 3Yayasan WWF-Indonesia, Marine and Fisheries Program, Jl. Pemuda 1 No.2 Renon, Bali 80226, Indonesia; 4NOAA Fisheries, Pacific Islands Fisheries Science Center, 1845 Wasp Boulevard, Honolulu, Hawaiʻi 96818, USA; 5World Wildlife Fund (WWF) US, Washington DC 20037-1193, USA

Leatherback turtles (Dermochelys coriacea) are one of six species of sea turtle that nest in Indonesia. The leatherback turtle population in the West Pacific is critically endangered and fully protected in Indonesia. To support sea turtle protection efforts, in 2022 the Ministry of Marine Affairs and Fisheries of Indonesia created and ratified the National Plan of Action (NPoA) for sea turtle conservation. The NPoA has identified seven priority areas and seven national turtle conservation goals, with Buru Island (Maluku Province) as one of the priority areas due to its recent identification as a regionally important leatherback nesting beach. The NPoA also identified the generation of data through research as one of its main goals. In 2017 we began daily monitoring of leatherback nesting along the 13.7 km of Fena Leisela coast on Buru Island. Trained local patrollers collected data on leatherback turtle nesting activity including # of nests, # eggs, location of nests, # of crawls, as well as female turtle morphometrics. After the incubation period, hatching success was determined. We documented a significant decrease of illegal take of turtle eggs over the project timeframe. These nesting ecology data are currently being analyzed and the results will be shared during the symposium. The results of this work will also be shared with local community members, government agencies (provincial, national, and international), non-profit organizations, policy makers, and other stakeholders to support management decision making. Given the critically endangered status of West Pacific leatherbacks, this research will have major implications for recovery efforts on behalf of the population.

*Nesting trends of leatherback, green, and olive ridley sea turtles at Parque Nacional Marino Las Baulas, Costa Rica

Isabel Rodriguez1, Faridah Fatungase1, Pilar Santidrian Tomillo2, Frank V Paladino1

1Purdue University Fort Wayne, Indiana, USA; 2The Leatherback Trust, Goldring Marine Biology Station, Playa Grande, Costa Rica

Parque Nacional Marino Las Baulas (PNMB) in Costa Rica was established in 1991 and is well known as a nesting beach for leatherback turtles (Dermochelys coriacea) in the eastern Pacific Ocean, where green turtles (Chelonia mydas), and olive ridley (Lepidochelys olivacea) also nest. Here, we report the nesting trends of the three sea turtle species nesting at Playa Grande and Ventanas, PNMB from 2012 to 2023. These beaches were considered the fourth largest leatherback nesting area in the world, with 1,367 leatherback turtles estimated to have nested in the 1988-1989 season. Today the Eastern Pacific leatherback sea turtle population is critically endangered due to declines over the last 35 years. In the 2012-2013 season, 29 nesting leatherbacks were observed, but in the 2022-2023 season only three nesting leatherbacks were observed. This 90% decrease in 10 years is likely caused by high adult mortality rates from interactions with fishing gear, rather than terrestrial threats due to implementation of nest protection. The olive ridley sea turtle is listed as vulnerable, and their nesting numbers decreased by 48% over study time period from 85 nesting olive ridleys in the 2012-2013 season to 44 nesting olive ridleys in the 2022-2023 season. This decrease in nesting females might be caused by olive ridley turtles' low fidelity to nesting beaches as indicated by inter-annual fluctuation, however ridley turtles are also at risk for mortality associated with fishing activity. The green turtle is listed as an endangered species, with populations in the eastern Pacific struggling relative to other populations. Green turtle nesting numbers increased by 36%, from 14 nesting turtles in the 2012-2013 season to 19 nesting turtles during the 2022-2023 season. Trends indicate that PNMB is no longer among the most important leatherback colonies, but continues to be an important nesting site for the three sea turtle species. As such, the continued protection of these beaches is crucial. We will continue to monitor the changes in population dynamics of the three species.

Closing the knowledge gap: Contributing data from Sumatra about the Northeastern Indian Ocean leatherback sea turtle subpopulation

Meriussoni Zai1, Thomas Reischig2, Sarif Hidayat3, Thomas Amey4, Hiltrud Cordes2

1Yayasan Penyu Indonesia, Indonesia; 2Turtle Foundation, Germany; 3Ministry of Maritime Affairs and Fisheries of the Republic of Indonesia; 4Ecosystem Impact, Indonesia

There are seven subpopulations of leatherback turtles in the world, one of which is the northeastern Indian Ocean subpopulation. This subpopulation nests on the Andaman and Nicobar Islands, in India, Sri Lanka, Thailand and Sumatra (Indonesia), with the Andaman and Nicobar Islands being the centre of nesting activity in terms of nest numbers. Notably, the IUCN status for this subpopulation is currently listed as 'data deficient', but there is a significant threat of exploitation for meat and eggs, particularly in Indonesia. So far, nesting data from Indonesia for this subpopulation have only been published for Amandangan Beach, Bangkaru Island (Aceh). This informational void creates a pressing need for comprehensive research and monitoring.

Since 2017, Yayasan Penyu Indonesia has conducted surveys on offshore islands of Sumatra and discovered eight previously unpublished nesting beaches for leatherback turtles. Together with the national conservation authority BPSPL Padang, we initiated a leatherback turtle conservation programme on Sipora, Mentawai District (West-Sumatra), in the same year. In addition, in partnership with the conservation NGO Ecosystem Impact, two more protection projects have been launched on the island of Salaut Besar, Simeulue District in 2021, and on Along beach, Simeulue Island (Aceh) in the beginning of 2023.

At two of the monitored nesting sites, the nesting season runs from October to March, with peak nesting in December and January. As we've only just started monitoring Along beach, the season cannot yet be accurately determined, but preliminary observations suggest a similar range. On Sipora, during six monitored nesting seasons we calculated an average of 32 nests per season, but with a wide range from 0 to 65 nests per season. On Salaut Besar, two contiguous nesting seasons yielded an average of 18 nests per season; the first of the three seasons we covered was incomplete because we started monitoring in the middle of it. On Along beach, were we just started in the beginning of 2023, in this half season 52 nests were counted, which could be extrapolated very carefully to approx. 100 nests laid in that particular season. Taking all three nesting sites together, we estimate that between 100 and 200 leatherback clutches could be laid each year at these sites. Although the time frame is too short to estimate a population trend, the six seasons of observation on Sipora suggest a downward tendency.

Compared to an average of around 1,000 nests found each year on the Andaman and Nicobar Islands, which are thought to make up the bulk of the northeast Indian Ocean leatherback subpopulation, and numerous unexplored Indonesian nesting sites, we believe the Indonesian part of this subpopulation is very important for the health of the population. However, exploitation of the leatherbacks for human consumption is still rampant at all unprotected nesting sites. We therefore recommend that similar protection and monitoring programmes be established for the Indonesian nesting beaches of Babah Ngom, Aceh Jaya District (Aceh), Lhok Dalam, Simeulue District (Aceh), Moale beach and Simuk Island, South Nias District (North-Sumatra) and Siberut Island, Mentawai District (West-Sumatra).

Running out of sand: Sea turtle nesting activity on Félicité Island, Seychelles

Lara Kalisch, Martin Stelfox, Stephanie Köhnk

Olive Ridley Project, 91 Padiham Road, Sadben, Clitheroe, Lancashire, BB7 9EX UK

The Seychelles are home to one of five regional populations of hawksbill turtles with more than 1000 females nesting annually (Mortimer 2000). Cousin Island has observed an estimated emergence of up to 256 individual nesting hawksbills per season and has been identified as the most important nesting spot in the region (Allen et al. 2010). In Seychelles hawksbill turtles exhibit a distinct nesting period from October until March (Mortimer 2000).

Félicité Island, located in the inner islands of the Seychelles, harbors five sandy beaches, of which four are easily accessible. Six Senses Zil Pasyon resort was established on this privately owned island in October 2016, occupying one third of the island. In December 2021 the Olive Ridley Project partnered with Six Senses Zil Pasyon to establish a monitoring and conservation program to ensure long-term data collection and protection for nesting turtles on the island. In this study, we present the results from the first completely monitored nesting season in 2022/2023. During the reporting period 87 false crawls and 51 true nests were recorded on all five beaches on Félicité Island. The majority of nesting activity was recorded on Grand Anse, the longest beach on the island. 43 clutches were laid by hawksbill turtles, and an additional eight green turtle clutches could be recorded. Hatching success, the percentage of eggs within a nest that hatched, was 80.1% for green turtles (SD = 35.5, N = 7) and 76.2% for hawksbill turtles on average (SD = 30.1, N = 36). Limited availability of suitable nesting space, highly dynamic beaches due to monsoon related erosion, as well as predation by ghost crabs (Ocypode spp.) were identified as the main challenges to nesting success on the island. 12 out of 30 hawksbill turtle clutches on the main nesting beach Grand Anse had to be relocated due to erosion or inundation. No previous data are available to comment on a trend in clutch numbers for either turtle species on Félicité, therefore we recommend continuation of monitoring reproductive females at Félicité to compare with population levels and trends observed at other islands in Seychelles.

Which threats affect hatching success of the hawksbill turtle (Eretmochelys imbricata) in Fiji?

Shritika Shayal Prakash1,3, Ashmeeta Shalvina2, Ana Ciriyawa1, Susanna Piovano1

1Discipline of Marine Studies, SAGEONS, The University of the South Pacific, Laucala Campus, Suva, Fiji; 2Discipline of Biological and Chemical Sciences, SAGEONS, The University of the South Pacific, Laucala Campus, Suva, Fiji; 3Present address: Ika Bula Consultants, Suva, Fiji

Sea turtles face multiple threats and challenges during their life stages. The lack of comprehensive data, particularly in the South Pacific, often hinders the ability to implement effective conservation measures to minimize these threats. This study examines hawksbill turtle nests to determine hatching success and identify the threats faced by the small nesting population of Fiji. Annual surveys were conducted from 2014 to 2017 during the peak nesting season, which extends from November to April and coincides with the cyclone season. A total of 110 nests were documented at 19 sites over three consecutive seasons. Of this, 21.8% of the nests failed to hatch, resulting in no hatchling emergence, and 63.6% successfully hatched. Logistical constraints prevented follow-up examinations for the remaining 14.6% of nests, leaving their fate unknown. The mean hatching success was 56.5 ± 44.4 % (range = 0% - 100%). The Kruskal Wallis analysis revealed that there was no significant difference in the hatching success between nesting seasons (p = 0.372). A number of threats affecting nest success were identified; including predation by sand crabs and dogs (15.5%), illegal harvest (10.9%), and coastal inundation (13.6%). At the time of the survey, the remaining 60% of the threat to nests could not be determined. Findings from this study can enable local stakeholders to direct conservation efforts toward mitigating at least some of these threats.

An increased risk of predation for Caretta caretta nests in Calabria (Southern Italy)

Chiara Mancino1,2, Maria Denaro2, Pietro Giovannelli2, Eshna Gomes2, Romano Liotti2, Teresa Malito2, Giovanni Parise2, Salvatore Urso2

1Sapienza University, Italy; 2Caretta Calabria Conservation, Italy

Sea turtles’ nests are threatened by various anthropogenic and natural factors, including the predation of eggs and hatchlings by opportunistic species that frequently patrol the beaches in search of food. The Calabrian Ionian coastline (Southern Italy) ranks among the primary national nesting grounds for Caretta caretta. In this area, loggerhead nests are located through systematic shoreline patrols covering approximately 30-50 km daily, carried out by Caretta Calabria Conservation Onlus. This search is aided using drones and fat bikes, and it is conducted by skilled operators with expertise in identifying and interpreting the tracks of the species. The main predator of eggs and hatchlings is the fox (Vulpes vulpes) to which has recently been added the ghost crab (Ocypode cursor) found for the first time in the summer of 2020. The protection of the nest involves security to prevent predation by natural threats. It consists of placing a fox exclusion device (FED) (size 1x1 m, mesh 10x10 cm) on the egg chamber, under about 10 cm of sand. In cases of repeated excavation attempts by predators, additional dissuasion measures are opportunely employed. Annually, in the study area, we observe fox predation attempts on loggerhead nests. In the 2023 season, predation attempts increased, affecting 31% of nests. However, even with the utilization of the mentioned anti-predation methods, only 4 nests were entirely predated. Regarding the ghost crab, there have been n = 3 instances of predation detected since 2020. However, in only one of these cases, which occurred in the summer of 2023, it was possible to confirm the entire destruction of a clutch. The Ionian coastline features pristine beaches where both foxes and crabs thrive, thanks to the favorable ecological conditions that support their survival and, notably, their food search. The measures taken to prevent fox digging have shown only partial effectiveness thus far. In specific environmental conditions, such as after rainfall or when dealing with a compacted substrate, the predator can still dig and reach the most superficial eggs despite the presence of the FED. In more exceptional cases, it can even access the clutch through side tunnels. The impact of this threat is greatest in more natural stretches of coastline and generally seems to increase towards the end of the bathing season (late August) when human presence drops considerably. As regards the ghost crab, its presence represents a further concern for the safety of the nests of C. caretta in the studied geographical region. While the crab's distribution is currently confined to a small coastal area, the significant rise in its population density indicates the likelihood of its rapid expansion across the entire area in the future.

Hatching success and sex ratios of Chelonia mydas nests in Lang Tengah Island, Malaysia

Azrin Asyikin Mohd Shukor1,2, Tze Ning Cheok1,4, Seh Ling Long1,3

1Lang Tengah Turtle Watch, Lang Tengah Island, Terengganu, Malaysia; 2PULIHARA) Marine Conservation and Research Organisation, Malaysia; 3TRAFICC International Southeast Asia; 4Scuba Junkie SEAS

Climate change poses a threat to species with temperature-dependent sex determination, like sea turtles, potentially resulting in skewed female offspring. Among potential adaptions is their nesting behavior shifting towards cooler areas. This study aims to evaluate trends in incubation temperatures and incubation periods, estimate sex ratios, and determine the hatching success of Chelonia mydas nests on Lang Tengah Island from 2021 to 2023. Lang Tengah Island is vital for green and hawksbill turtles, serving as nesting and feeding grounds in Terengganu. Two nesting beaches, Turtle Bay and Lang Sari are patrolled nightly from March to October each year. Nests laid on Lang Sari were relocated to Turtle Bay to prevent poaching while nests laid on Turtle Bay were relocated only if below the high tide line. A data logger was deployed in 43 nests (13 in-situ nests and 30 ex-situ nests) to measure the incubation temperature for estimating hatchling sex ratios. All the nests were excavated at least 3 days after mass hatchling emergence to determine the hatching success. In total, 135 nests were protected, of which 85 nests were relocated and 31.9% had data loggers. The average hatching success rate of all the nests over the three-year observation period was 75.5% (SD = 24.01), while the nests equipped with a data logger had an average hatching success of 80% (SD = 12.83) (79.5% and 80.2% for in-situ and ex-situ nests, respectively). Logistical equations were used to estimate the hatchling sex ratio in each nest with a proposed pivotal temperature of 29.1°C for the Malaysian green turtle populations. Analysis of sex ratio of these 43 nests revealed an average of 7.5% female hatchlings (SD = 13.61), with an average incubation temperature during TSP of 28.3 °C (SD = 0.42) and incubation period of 55–65 days. Specifically, in-situ nests had an average of 7.8% female hatchlings (SD = 15.4), with an average incubation temperature during TSP of 28.3 °C (SD = 0.49) and incubation period of 57–62 days, while ex-situ nests had 7.4% female hatchlings (SD = 13.3) with an average incubation temperature during TSP of 28.3 °C (SD = 0.40) and incubation period of 55–65 days. This deviation towards more male hatchlings may be attributed to the triple-dip La Nina effect occurring over three consecutive years (2020-2022). Furthermore, all the in-situ nests were laid under vegetation which were fully shaded. Notably, nests were mainly moved to shaded or partially shaded areas due to the beach’s 70 m length, as the open space below the high tide line. These findings contrast with the prevalent high female bias reported in offspring at many rookeries worldwide and underscore the significant role that local beach characteristics play in influencing incubation temperature. The findings, of this study, have significant implications for sea turtle conservation. To mitigate the impact of climate change on sea turtle population, conservation efforts may need to focus on protecting and maintaining nesting sites that provide cooler incubation conditions for the production of males, and where necessary, relocating nests to such sites.

Loggerheads nesting in France mainland and Corsica in 2023: an exceptional year or the beginning of a new story?

Anthony Caro1, Sidonie Catteau2, Cathy Cesarini3, Françoise Claro4, Céline Ferlat5, Jacques Fretey6, Delphine Gambaiani5, Alexandre Girard4, Marc Girondot7, Antony Martinez9, Claude Miaud8, Pierre Moisson9, Jean-Baptiste Sénégas5, Charlène Thévenet9

1Office Français pour la Biodiversité; 2Association Marineland, Antibes; 3Association CARI (Cétacés Association Recherche Insulaire) and Société Herpétologique de France, Réseau Tortues Marines de Méditerranée Française; 4UMS PatriNat, Muséum National d'Histoire Naturelle de Paris; 5Centre d'Etude et de Sauvegarde des Tortues Marines de Méditerranée; 6Association Chélonée; 7Ecologie, Systématique, Evolution, Université Paris-Saclay, CNRS, AgroParisTech, France; 8CEFE, Univ Montpellier, CNRS, EPHE-PSL University, IRD; 9A Cupulatta, Vero, Corse

Although France is a major country for the presence of sea turtles thanks to its overseas territories (French Guiana, Guadeloupe, Martinique, Mayotte, New Caledonia, Polynesia, Saint-Pierre et Miquelon, for example), sea turtle nesting activity in mainland France was either non-existent or anecdotal in the past. Since 2002, between zero and two loggerhead nests per year have been observed on the French Mediterranean coast. The year 2023 has proved exceptional, with 14 loggerhead clutches observed on the Mediterranean coast of southern France, including Corsica (2 at the mainland West, 7 at the mainland East and 5 in Corsica). In a single year, we can estimate that we have seen more nests in the south of France than in the previous 500 years. The nests were monitored by an exceptional large team of around 800 people involved in protecting them day and night. (probably the highest ratio persons/nest in the world!). Nest temperatures were recorded, and incubation success was characterized. The sex ratio of these nests will be estimated using a methodology developed for this species (Monsinjon et al. 2022, doi 10.1016/j.ecolmodel.2022.110119). This situation is one of the few times that colonization of a new habitat has been monitored in real time. Colonization of new habitats could be a strategy that has been underestimated until now. Indeed, in a more or less stable environment, the strategy of returning to lay eggs where females were born and where they have already laid is favored. With this in mind, work on sea turtle resilience has focused on changes in phenology (Fuentes et al. 2023, doi 10.1111/gcb.16991). However, in a changing world, the strategy enabling sea turtles to be resilient in the face of climate change is more likely to involve colonizing new nesting sites at higher latitudes than changing their phenology.

Authors are listed by alphabetical order

First years of monitoring three potential key beaches for sea turtles on the Osa Peninsula, Costa Rica.

Lucia Heredero Saura, Laura Exley, George Grimmett

COPROT, Costa Rica

The Osa Peninsula has been recognised for its terrestrial and marine importance globally, supporting 2.5% of global terrestrial diversity and 50% of all marine species found in Costa Rican waters. The surrounding coastal environment provides nesting beaches for eastern Pacific green (Chelonia mydas), and olive ridley (Lepidochelys olivacea) sea turtles. COPROT (Comunidad Protectora de Tortugas de Osa) is a non-profit organization dedicated to the conservation of sea turtles through environmental education of the local community and monitoring of three key nesting beaches on the Osa Peninsula namely: Pejeperro, Rio Oro and Carate. These very remote beaches are adjacent and are located on the south Pacific coast of Costa Rica.

Prior to COPROT there was no consistent long term data collected on these beaches and therefore little is known about the nesting population here with its potential importance overlooked. COPROT has been carrying out continuous monitoring of these beaches since 2020 to determine ecological population trends for this region. Results from the last three nesting seasons suggest these are critical beaches and could become index beaches for solitary nesting eastern Pacific green and olive ridley turtles in Costa Rica.

Almost 700 nests were recorded annually, made up over 400 eastern pacific green turtles where 75% were placed in vegetated areas, and 6000 olive ridley nests where more than 93% were placed in intertidal zones. It is worth highlighting for green turtles that more than 50% of the activities were false crawls or abandoned nest attempts. Clutch fertility, hatching success and emergence success was found to be 93%, 84% and 82% respectively for green turtles and 83%, 64% and 62% respectively for olive ridley clutches. Green turtles had an average of 70 eggs per nest and a mean CCL of 87.5 cm whilst olive ridley clutches had an average of 96 eggs and a mean of 67 cm CCL. Clutch size for green turtles were similar to other nesting populations in the north pacific but smaller compared to the atlantic ones.

These populations, although still not fully understood, would suggest that these beaches with further monitoring could be well suited to serve as index beaches for both green and olive ridley turtles in Costa Rica because of the high number of nests and success of turtles here. Continued monitoring and further research of the ecology of the population could show that indeed these beaches have been overlooked.

With further recognition, better systems and funding could be in place to gain spatiotemporal data of the nesting population during inter-laying periods. This could include turtle interactions with fisheries, regions of coastal development and habitat destruction so that appropriate attention can be implemented efficiently. It would also boost socioeconomic standards in the local community through more funding for financing qualifications and infrastructure as well as increase ecotourism which would also increase local job opportunities. Together these factors will ultimately support the conservation of the nesting turtles on the Osa Peninsula.

Is there a future for loggerhead sea turtle (Caretta caretta, Linneus 1758) nesting in the Aeolian Archipelago (Southern Italy)?

Monica Francesca Blasi, Vittoria Fiandino, Michelle Gelippi

Filicudi Wildlife Conservation, Italy

Loggerhead turtles have started to expand their nesting range into the Western Mediterranean, which was known to hosted only sporadic nests until recently.

The Aeolian Archipelago, located in the Southern Tyrrhenian Sea (Sicily, Italy), provides optimal foraging grounds for loggerhead turtles (Caretta caretta). Based on local people’s report, sporadic nesting occurred along the beaches of Stromboli and Lipari, but in 2019 two nesting events were documented for the first time. Moreover, recently, several nesting attempts (2 in 2020, 21 in 2021, 8 in 2022 and 28 in 2023) were also recorded in the area. This may indicate suitability of these potential nesting areas as climate refuge for some individual. Indeed, from photo-identification analysis of scales around the face at least 2 individuals were identified to be involved in these attempts. In this study we analysed the characteristics and quality of these habitats, such as the composition of sand and beach location/morphology, as well as the related anthropogenic threats that may affect nesting success.

Analysis results indicated that only Stromboli and Vulcano islands could host potential nesting beaches. Nevertheless, all nesting attempts were performed in the south-eastern coast of Lipari, Salina and Stromboli, which are probably more protected by the dominant winds. In those areas only few sandy (artisanal or volcanic) beaches are present, however, in the proximity of the cost, sand lays underwater and the morphology of the sea bottom decreases were slowly compared to other areas. The chosen habitats are characterized mostly by gravel or large rocks, although in the past the sand was present before disappearing due to coastal erosion. We suggest that the complete absence of nesting attempts on Vulcano island could be related to massive tourism and/or underwater hydrothermal activity.

Based on our results, the Aeolian Archipelago may become an important nesting area if appropriate protection strategies are applied. Moreover, higher monitoring effort is recommended, especially in those coastal tracts identified as potential nesting habitats.

Leatherback haven in the Indian Ocean

Adhith Swaminathan1, Saw Thesorow1, Sushil Lakra1, Dr. Kartik Shanker1,2

1Dakshin Foundation, Bangalore, India; 2Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India

The Northeast Indian Ocean leatherback subpopulation mainly consists of nesting populations in India, Sri Lanka, and to a lesser extent, Thailand and Indonesia. In India, leatherback turtles only nest in the Andaman and Nicobar Islands; this population has been studied over the past four decades through surveys, tagging and nest monitoring programmes at various index beaches. Here, we present findings from two studies, one conducted on Great Nicobar Island with annual monitoring before and periodic surveys after the 2004 Indian Ocean tsunami, and the second a long-term monitoring programme on Little Andaman Island (2008-2023).

Despite previous concerns regarding the viability of this subpopulation, recent surveys of the Nicobar Islands indicate that the beaches have reformed after 2004, leading to an increase in leatherback nesting with numbers comparable to the pre-tsunami period. Our long-term data from Little Andaman Island indicate a stable nesting population with some inter-annual fluctuations, ranging from ~80-173 nests per year. The average nesting female size observed in the region was CCL 156 cm (±SD 8.3; n=450) with an average clutch size of 85 eggs (±SD 23.0; n=592). Satellite telemetry studies conducted between 2011-2014 on leatherbacks nesting in Little Andaman Island indicate that all the turtles started their post-nesting migrations by heading south of the Andaman and Nicobar Islands and dispersed in varied paths in the southeast and southwest Indian Ocean. Five turtles travelled southeast, some along the coastal waters of Indonesia, towards Timor-Leste and north-western Australia and four turtles travelled southwest with some reaching the eastern coast of Africa.

With over 1000 nests a season, the nesting beaches of the Andaman and Nicobar Islands host important nesting grounds for a significant population in the northeast Indian Ocean thus highlighting the critical need for conservation of these habitats.

Explorers and residents: dichotomic nesting and internesting behaviour of loggerhead sea turtles colonising the western Mediterranean

Eduardo Belda1, Sara Abalo-Morla2, Luís Cardona3, Elena Abella4, Lucas Belda1, Blanca Feliu-Tena1,5, Marta Pascual6, Carlos Carreras6, Jesús Tomás7

1Institut per a la Investigació i Gestió de Zones Costaneres (IGIC), Universitat Politècnica de València, C/Paranimf n° 1, 46730, Gandia, València, Spain; 2Instituto Español de Oceanografía, Centro Oceanografico de Vigo (COV-IEO), CSIC, Subida a Radio Faro, 50-52, 36390, Vigo, Pontevedra, Spain; 3Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona (UB), Av. Diagonal 643, 08028, Barcelona, Spain; 4BETA Tech Center, TECNIO Network, University of Vic-Central University of Catalonia ( UVic-UCC), C. de Roda 70, 08500, Vic, Spain.; 5Instituto Español de Oceanografía (IEO-CSIC), C.O. Murcia, C/el Varadero 1, Lo Pagan, 30740 Murcia, Spain; 6Departament de Genètica, Microbiologia i Estadística and IRBio, Universitat de Barcelona, Avinguda Diagonal, 643, 08028, Barcelona, Spain.; 7Instituto Cavanilles de Biodiversidad y Biología Evolutiva, University of Valencia, Apdo. 22085, E-46071, Valencia, Spain

In the present century, we are witnessing an increase in the number of loggerhead sea turtle nesting events in the western Mediterranean, an area supposedly out of the nesting range for the species. This increase has been hypothesised to be mediated by global warming. The increase in air and seawater temperature may have facilitated the possibility for loggerhead turtles to nest in previously unsuitable areas of the western Mediterranean. For a philopatric species, colonising distant beaches thousands of kilometres away from their natal beach is challenging. The western Mediterranean is known as a foraging developmental area for juvenile loggerhead turtles from Atlantic and Mediterranean regional management units. One of the hypotheses to explain this distant colonisation is that juveniles may reach sexual maturity in these developmental habitats and, under suitable conditions, nest in nearby beaches. In any case, the behaviour of these females in this new nesting area is unknown. In this study, we used satellite transmitters to track the movements of 13 adult female breeding loggerhead turtles (Caretta caretta) tagged on nesting beaches at the coast of Valencia (11) and Catalonia (2) from 2016 to 2023. Two of the females were tagged twice during this period, with an interval of four (2016-2020) and five years (2018-2023), respectively. The mean curve carapace length was 80 ± SD = 5.3 cm (range 73 – 90). Within the same season, four of the 13 females showed nest site fidelity, with successive nests found at the same beach or nearby beaches (< 10 km). Two of these four females made long-distance movements (> 100 km) between successive nesting events, while the other two remained near the nesting beach. Fidelity to nesting sites was also observed between seasons for two remigrant females. The other nine females used distant beaches, with successive nests up to 500 km apart within a season.

These results suggest that there are two types of female behaviour among the breeders in Spain. We classified them as explorers, the ones wandering throughout the coast, and residents as the ones using only one beach for consecutive nesting activity. These two alternative behaviours have been previously observed in well-established nesting rookeries, but distances between consecutive nesting events recorded in the present study almost double previous recorded distances elsewhere. We hypothesise that this dichotomic behaviour could be explained as follows: explorer females would be those coming from distant nesting populations that may remain in the western Mediterranean foraging grounds after reaching sexual maturity and, under suitable conditions, explore beaches nearby to nest. Alternatively, resident females may proceed from undetected nests laid in western Mediterranean countries years ago that returned to reproduce to the natal beach due to philopatry. Nonetheless, we cannot discard that the so-called residents may be explorers from distant populations who find a suitable nesting beach and use it for consecutive nesting events. Further research is needed since this information is crucial for managing and conservation in what seems to be a new-growing loggerhead turtle nesting population in the western Mediterranean.

Collaborative conservation initiatives: Preliminary assessment of the green turtle (Chelonia mydas) nesting ecology in Chakar Hutan, Terengganu, Malaysia

Nur Isandra Shazlynn Shamsul Azmil1, Wan Zuriana Wan Sulaiman1, Muhammad Afiq Karim1, Audrey Symplicius1, Seh Ling Long1,2

1Lang Tengah Turtle Watch, Malaysia; 2TRAFFIC International Southeast Asia

Four species of sea turtles are known to nest in Terengganu, located on the east coast of Peninsular Malaysia, with the green turtle being the only species showing a recovery nesting trend. Majority of the high-density nesting beaches are protected as turtle sanctuaries or reserves. One of the beaches is Chakar Hutan in the south of Terengganu. Two Terengganu State Department of Fisheries (DoF) rangers patrol this 1.4 kilometer stretch of turtle reserve between April and September, relocating nests to a nearby hatchery in Ma’Daerah for incubation. Apart from the number of nests and number of turtle individuals tagged, little was known about the nesting ecology of the green turtle population on this beach. Since July 2022, Lang Tengah Turtle Watch (LTTW) and DoF formed a collaborative partnership, in which LTTW sets up and manages a hatchery at Chakar Hutan. The nests are relocated to the hatchery on the same beach to reduce the relocation distance, travel time and egg movement. The nests were not left in-situ to prevent poaching, predation, inundation during high tide, and beach erosion. The primary objectives of this project were to (1) increase monitoring efforts, (2) understand the nesting ecology, and (3) implement conservation strategies. In 2023, monitoring effort was undertaken by LTTW staff, interns alongside the DoF rangers throughout the nesting season from March to early November. Nightly patrols were conducted to identify nesting and non-nesting emergences. Encountered individual nesting females were identified using the photo identification and/or tagging method. Retrieved clutches were incubated ex-situ and monitored throughout the incubation period, except for nests that were missed during night patrols. The nest content was excavated at least 3 days after mass emergence of hatchlings to determine the hatching and emergence success rates. The nest temperatures were monitored throughout the incubation period. These monitoring efforts in 2023 documented a total of 1,193 turtle landings, resulting in 504 nests and the protection of 46,598 eggs, with an average clutch size of 93 eggs (SD=20.55). A total of 40,206 hatchlings were released, with an average incubation period of 61 days (SD=3.45). Overall, the hatching and emergence success rates were 87.59% (SD=14.62) and 83.53% (SD=15.64), respectively. Nest predation incidents, which accounted for 9.89% of nests, involved fungal infections, ants, and maggots. Of the 27 nests monitored, the average nest temperature during TSP was 28.86°C (SD=0.97), estimated to produce an average of 63% male hatchlings. Throughout this nesting season, 129 nesting individuals were identified. On average, each female laid 2 – 7 nests, with a nesting interval between 9 and 11 days. Notably, two females nested up to seven times. This is the preliminary data for 2023 green turtle nesting monitoring in Chakar Hutan, the first year following the establishment of this project. The findings provide crucial insights into the nesting ecology of green turtles at Chakar Hutan beach, emphasizing the positive impact of collaborative initiatives on the conservation of this endangered species.

Olive Ridley nesting monitoring in the Osa Peninsula; threats and conservation measures.

Alba Lopez Bobadilla, Laura Exley

COPROT, Comunidad Protectora de Tortugas de Osa, Costa Rica

The study area covered by COPROT, Comunidad Protectora de Tortugas de Osa, extends along 3 sea turtle nesting beaches: Playa Pejeperro, Playa Río Oro and Playa Carate. These beaches are contiguous, with a total length of 8.3 km and are located in the south of the Osa Peninsula. The peninsula, which is in the southwest of Costa Rica along the Pacific coast, is renowned as one of the most biodiverse places in the world. The beaches are located within protected areas and have special relevance for olive ridley sea turtle solitary nesting.

The aim of this study is to describe relevant nesting aspects such as the number of nests per season, the predation percentage and compare the success rate for nests left in situ to the relocated nests in the hatchery. The data collection method of this study is based on patrols, nest exhumations and hatchery data. Rio Oro and Pejeperro beaches have been monitored continuously since 2020 by COPROT, whereas Carate beach has been monitored by different organizations intermittently since 2005.

The most evident threats in the study area are predation by domestic dogs and/or wild animals, illegal egg collection, and effects of climate change. To combat these threats, a hatchery has been constructed in Carate beach, providing a safe environment for the relocated nests and giving us the opportunity to monitor temperature, hatchling biometrics and hatching success.
Data, such as hatching success, from a sample of nests marked on the beach will be compared to nests in the hatchery to assess the effectiveness of this initiative. Hatching success is expected to be greater in nests within the hatchery than those left wild on the beaches, which is 64%.
The number of olive ridley (Lepidochelys olivacea) nests for these 3 beaches exceeds 6000 nests per year. The minimum number of nests per season is 2300 for Pejeperro, 2700 for Río Oro and 800 for Carate.
So far 2023, the percentage of predation is 7.24% in Pejeperro, 20.7% in Rio Oro and over 50% in Carate. Predation increases with proximity to the community of Carate, where there is a higher concentration of people and pets. The community of Carate is small and isolated with low resources and numerous environmental problems. Work in previous years suggests predation by domestic dogs to be an issue facing Olive Ridley nests in this area.
Another protection measure has been to put up bamboo nets to protect some nests in situ. The effectiveness of this measure is being studied and the results are expected to be similar to previous studies for this same beach which suggested the nets have a positive impact. In addition, COPROT carries out annual pet castration clinics and environmental education campaigns.

This study, and future research, will be essential in determining adequate protection and management measures for the species in the peninsula.

How important is sea turtle nest site selection in the context of climate change?

Holly Jayne Stokes1, Nicole Esteban1, Graeme C Hays2

1Swansea University, United Kingdom; 2Deakin University, Australia

The ability of animals to mitigate climate change impacts could be key to their future survival, such as altering breeding and migration timings. Climate change and sea level rise pose a serious risk to sea turtles by influencing nest temperatures that can increase sex ratio skews and embryo death. In theory, we could assume that sea turtles may be able to mitigate threats from climate change by shifting to cooler nest sites along the beach. For this study, we evaluated 48 green turtle (Chelonia mydas) laid nest location on Diego Garcia, Chagos Archipelago, in the Indian Ocean. Nest locations were generally (90%) at the back of the beach in vegetation, where the risk of over-wash and inundation was lowest and the 10% of nests on the open beach were still close (within 1.5m) to the vegetation. All nests were above the mean high-water line (range = 0.14-2.44 m; mode = 1.35 m). When crawl distance increased, nests tended to be further into the vegetation, although, some crawls were long and circuitous (up to 76 m) when vegetation was impenetrable.

Further, we compared our results to nest positions recorded from all seven sea turtle species around the world. We reviewed 53 sites (including this study) from 51 studies and found that turtles generally crawl far enough inland to reduce the risk of nest over-wash, ultimately reducing embryo mortality. We suggest that increasing embryo survival is the main consideration over hatchling sex ratios when it comes to nest site selection and so sea turtles are unlikely to switch to cooler beach locations to mitigate the impacts of climate warming.

Effects of rising temperature on sea turtle nesting outcomes - How TREE Foundation maintains the temperature along the Andhra Pradesh coast, India.

Prabhakara Rao Marabathina, Supraja Dharini

TREE Foundation, India

A warmer ocean and coastal environment poses challenges for sea turtles whose sex determination is temperature-dependent. Warmer incubation temperatures produce more female hatchlings and a reduction in the natural number of males one would expect. Warmer beaches will put sea turtle embryos at risk. During development, the sex of an embryo is determined by the nest temperature during incubation, with warmer nests producing more females and cooler nests producing more males. It should be noted that temperatures above 33°c will cause a nest to fail completely.

The Olive Ridley turtles nest along the Andhra Pradesh coast, East Coast of India and the green and hawksbill sea turtles forage offshore, using various habitats during their nesting, migration and feeding, including beaches, sea grass beds, coral reefs, near­shore bottom areas, and the waters of the open ocean. However a rise in temperatures is altering their nesting habitats. The density of nests protected over the past 15 years show that more nests these days are being laid later in the season and it is becoming warmer earlier than in previous years. Adhering to protocols for protecting nests from rising temperatures through hatchery- based conservation has helped in protecting incubating eggs and safely releasing the emerging hatchlings that they may make their way down the beach to the sea despite rising temperatures.

The poster illustrates the meticulous conservation protocols followed by the Sea Turtle Protection Force members of TREE Foundation in maintaining temperatures to ensure nest viability and the protection of todays hatchlings so they may produce further generations in the future when they too mature.

The poster also illustrates the awareness programs conducted to reduce the existing threats, such as incidental capture in commercial fisheries and artisanal fisheries and need for protection of the nesting habitats along the Andhra Pradesh coast.

Reproductive trends of loggerhead and green sea turtle populations over time: An analysis of a long-term nest monitoring dataset from Sanibel, Florida, USA

Savannah M Weber1, Andrew Glinsky2, Jack W Brzoza1, Charles LeBuff3, Kelly A Sloan1

1Sanibel-Captiva Conservation Foundation (Florida, USA); 2Cooperative Institute for Marine and Atmospheric Research (Hawaii, USA); 3Caretta Research Inc (Florida, USA)

Analyses of long-term nest monitoring datasets can reveal trends that can be used to evaluate how marine turtle populations respond to increasing environmental and anthropogenic pressures. These trends can also provide metrics to assess the success of conservation efforts. The nesting beaches of Sanibel Island, Florida, USA, have been monitored since 1959 to protect the local loggerhead (Caretta caretta) nesting population, as well as a growing population of nesting green (Chelonia mydas) turtles in more recent years. In this analysis, nest-monitoring and night-tagging datasets from Sanibel were analyzed to identify trends in reproductive metrics. These included nest counts and dates of first and last nesting emergences from 1980 to 2023, as well as incubation duration and hatch success from 1998 to 2023. The differences in years represented are due to discrepancies in data collection during early years of nest-monitoring.

Our results indicate that nest counts for both species significantly increased over time, which we attribute to early conservation efforts. Our results also showed that the date of first nesting emergence for loggerhead turtles and green turtles shifted significantly earlier in the season, while the date of last nesting emergence for both species did not significantly change. Additionally, there was a significant decrease in loggerhead incubation duration over time. However, there was no significant change in green incubation duration over time, though this is likely due to the comparatively small sample size of green turtle nests. There was also no significant change found in either species’ hatch success over time. Finally, a standardized tagging dataset was used to compare the average size of encountered loggerhead nesting females from 1972 to 1976 to those from 2016 to 2023. The results suggest that the local population has exhibited a significant decrease in size over time, as has been observed in previous studies conducted on other nesting beaches.

We explore how these trends may be a result of changes in population demographics and large-scale threats, such as the increasing severity of storms, rising temperatures, and predation. By bridging the gap between the past and present trends of demographics and reproductive activity, our investigation 1) provides insights into how these species have been impacted by environmental changes and human-induced impacts, 2) highlights the importance of the continuation of long-term studies, as well as the need for consistent and standardized methodology, and 3) demonstrates evidence of the effectiveness of conservation efforts, which can help promote the protection of endangered species for future generations.

A summary of twenty eight years of sea turtle nesting data on Topsail Island, North Carolina

Terry Meyer1, Jean F Beasley1, Kathryn A Zagzebski1, Matthew H Godfrey2

1The Karen Beasley Sea Turtle Rescue & Rehabilitation Center, 302 Tortuga Lane, Surf City, NC 28445; 2North Carolina Wildlife Resources Commission, 1701 Mail Service Center Raleigh, NC 27699-1700

The Karen Beasley Sea Turtle Rescue and Rehabilitation Center (KBSTRRC) is a nonprofit sea turtle conservation organization in North Carolina, USA. KBSTRRC’s Topsail Turtle Project (TTP) is permitted to monitor the beaches of Topsail Island for nesting sea turtles, protect the nests and hatchlings, and gather conservation data. Nesting data has been collected consistently for 28 years.

May 1 through August 31 is sea turtle nesting season in North Carolina. Each day during nesting season, TTP volunteers survey the 41.8 km (26 miles) of Topsail Island looking for turtle tracks. When tracks are found, an experienced volunteer is dispatched to determine whether the tracks lead to a clutch of eggs or represent a false crawl. If eggs are found, it is designated a nest and protected with tape and signs, and a wire grid is placed over the top to exclude predators. If eggs are deposited in an unsuitable location, volunteers will carefully relocate the nest. At this time, and for relocated nests only, data on the number of eggs are collected. Approximately 60 days after eggs were laid, TTP volunteers monitor the nest until hatchlings emerge. Three days after hatchling emergence, the nest contents are inventoried, and additional data are collected.

Over the past 28 years, the TTP has responded to 5,042 sea turtle crawls. Of these, 2,832 have been determined to be egg clutches while 2,210 have been determined to be false crawls. The highest number of clutches laid was 187 in 1999, while the lowest number was 53 in 2014. The average number of clutches per year is 98. There is an increasing trend in the number of false crawls. The average number of false crawls during the first five years is 58, and the average for the last five years is 109.2.

The majority of clutches (98.48%) are loggerhead turtles. Green turtles comprise 1.48% of the total clutches. There has been one documented Kemp’s ridley clutch (0.035%) and one unknown nest (0.035%).

The mean clutch count on Topsail Island during this time frame was 119.9 eggs. Annual mean clutch count ranged from 109.2 to 127.7 eggs. The mean incubation period was 59.5 days (range 52.9 to 66.8 days). An inventory was conducted on 86.9% of the clutches after the end of incubation, or after 80 days if no emergence was detected. The mean emergence success was 73.7% (range 0% to 83.7%.) Years of lowest emergence success were attributed to hurricanes.

These data are comparable with other sea turtle nesting beaches in North Carolina. This preliminary summary presents our first comprehensive review of the data. We hope continued data examination will offer additional insight into sea turtle nesting, emergence, and conservation.

17-year green sea turtle monitoring on Tetiaroa atoll, French Polynesia

Dr. Cécile Gaspar, Dr. Jade Gouin, Théo Guillaume, Romain Clervoy

TE MANA O TE MOANA, NGO, French Polynesia

Tetiaroa atoll holds a unique place in French Polynesia islands. Its cultural heritage is of the outmost importance but it has also become a very unique laboratory since 2014 through the innovative set up of the Tetiaroa Soicety Foundation in synergy with The Brando Eco-Resort.

However, Te mana o te moana biologists and veterinarians have started under Dr. Cécile Gaspar guidance in 2007, a long term green sea turtle monitoring on 3 islets of this atoll, inculding female indentification measures and tracking, nesting and hatchling success, nest temperatures and parameters collection, hatchling predation and beach erosion monitoring...

This presentation will highlight the key data collected and share long term vision for this monitoring that is expected to be exported in other key green sea turtle nesting Polynesian Islands.

Irresponsible tourism is a threat to the habitat of the green sea turtle on the northern coasts of the Sea of Oman Sea

Mahmood Sinaei1, Mehdi Bolouki2, Mohammad Talebi Matin2, Ashrafali Hosseini2, Mostafa Hasanian1, Farhad Salehzehi3, Mohammad Sadegh Saba2

1Department of Biology, Marine Environment Research Center, Islamic Azad University, Chabahar Branch, Chabahar, Iran; 2Department of Environment, Tehran, Iran; 3Chabahar Industrial Free Zone, Sistan and Baloochistan, Chabahar, Iran

With an average of 50 nests per year and a hatching rate between 35 and 40%, the northern coasts of the Sea of Oman host Iran's endangered green turtle species(Chelonia mydas). So far, about 30 beaches have been identified as green turtle nesting habitats on these beaches. 15 years of conservation efforts have protected the species' alleged habitats. During the COVID-19 pandemic, we saw a decrease in habitat destruction and more presence of turtles on these coasts. But with the end of the COVID-19 epidemic, the large number of tourists on different coasts, especially during the egg-laying season, increased several times, which greatly affected the desirability of the green turtle egg-laying habitat on the northern coasts of the Sea of Oman. Here we provide information to define the crisis that has occurred and discuss the best possible solution to deal with it.

Methods: The information on green turtles nesting on these coasts presented here comes from long-term annual monitoring surveys by the authors (2010-2022). During the 2022 nesting season, we patrolled the beaches daily from June to November. Turtle egg-laying information was collected on different beaches. Also, protective measures were taken to prevent nests from falling. In some cases, it was necessary to build a hatchery site to do this. Nests were monitored while the hatchlings were emerging to calculate the hatching percentage.

Results and discussion: The nesting season on the northern coasts of the Sea of Oman is from June to November. During the 2022 nesting season, 10 egg-laying green turtles were counted on the coasts. The average CCL = 106.12 ± 4 cm was counted. The average weight of green turtle eggs on the coasts was 40.5±5.2 gr and the average diameter was 34.6-±3.1 mm. The results show that the average incubation period of eggs in different beaches is 63-55 days, the lowest of which was 51 days and the highest was 70 days. One turtle has been found for every 2160 meters. The coasts of Poshat, Kacho, Lipar, Ramin, Pozm, Tang, Abkohi, Kohe Mobarak were monitored. The average number of hatchlings of the green species for these coasts was 600 in this season. coasts such as Lipar, which show the highest number of visitors, do not have nesting and egg-laying due to the large presence of tourists after the COVID-19 epidemic. Installation of signboards and production of educational content such as production of motion graphics and brochures have been done. However without implementing a strong project that requires the participation of all stakeholders and funding in the first place. Industrial development on the northern coasts of the Sea of Oman (Makoran coast) is on the agenda of the government of the Islamic Republic of Iran, and if the necessary measures are not implemented, industrial development and irresponsible tourism will cause the extinction of this species on the northern coasts of the Sea of Oman. Introducing marine coastal protected areas and intensive and strong management programs are recommended on coasts like Lipar where nesting has stopped.

Last strongholds of Iran’s largest hawksbill rookery: mice invasion on the Nakhiloo Island, Persian Gulf

Majid Askari-Hesni1, Mostafa Moazeni2, Mohammad Amin Tollab2, Hossein Jafari2, Abdolrahman Moradzadeh2, Amirmozafar Hosseini3, Mahdi Iranmanesh1, Somaye Zangiabadi4, Abolfazl Akbari5, Pejman Khalili5, Amir Ehsan Stansti5, Mohsen Rezaie-Atagholipour6

1Department of Biology, Faculty of Science, Shahid Bahonar University of Kerman, Kerman, Iran.; 2Department of Environment, Bushehr, Iran; 3Department of Marine Biology, Faculty of Marine Science, Khoramshahr Marine Science and Technology University, Khoramshahr, Khuzestan, Iran; 4Department of Biology, Tarbiat Modares University, Tehran, Iran; 5Persian Gulf Mobin Energy Company, Asalouyeh, Bushehr, Iran; 6Qeshm Environmental Conservation Institute (QECI), Qeshm Island, Hormozgan, Iran

With an average of over 210 nests per year, Nakhiloo Island (~0.3 km2) in the northern Persian Gulf hosts Iran’s largest rookery of Critically Endangered hawksbill turtles, which dominantly nest along almost all Iranian islands and some parts of the country’s mainland beaches. Conservation efforts have successfully protected the Nakhiloo’s nesting site for over a decade. However, in 2019, mice (Mus musculus L.) were introduced to the island, probably by the boats of recreational fishers camped there. In 2021, when conservationists returned to the island after the COVID-19 pandemic lockdown, the mice population had rocketed, feasting on migratory seabirds’ eggs and chickens and hawksbill hatchlings. Here, we presented some information to define the dimensions of the crisis and discussed the best possible solution to tackle it. The information on hawksbill nesting on the island presented here comes from long-term annual monitoring surveys by the authors (2014-2022). During the 2022 nesting season, we patrolled the island’s beaches daily from April to July. Data on nesting activities and mice density were collected. We used bucket traps to catch mice and estimated their density using the catch-per-unit effort method. Some nests were monitored while hatchlings were emerging to calculate the percentage of mice predation mortality. The nesting season on the island is from April to July, and the hatchling season is from May to August. During the 2022 nesting season, 188 nesting hawksbills (Mean CCL = 71.12±5 cm) and 310 nests were counted on the island. Nest density was 1.2±0.31 nest/10m2 of the beach. A total of 40 nests were randomly monitored to estimate the mortality rate of hatchlings caused by the mice predation. Mice preyed on at least 50% of hatchlings before they reached the sea. The estimated mean number of hawksbill hatchlings for the site is 8000 per season. Therefore, mice predation probably causes mortality of about 4000 hatchlings per season. Mice density was estimated as one to two individuals/50m2. Without an immediate and effective eradication project, which in the first place needs funds, the hawksbill reproduction success will have been reducing for years until a complete collapse occurs. A literature review showed that the best solution would be broadcasting brodifacoum baits, starting immediately after the last birds and turtle hatchlings leave the island by the end of summer.

The significance and challenges faced by the increasing number of nesting honu (Hawaiian Green Sea Turtles) on Oahu

Deborah Kay Herrera1, Sheldon Plentovich2, Kelly Goodale3, Joy Browning4

1Malama i na honu, United States of America; 2Pacific Islands Coastal Program; 3Pacific Islands Fish and Wildlife Service Office; 4Pacific Islands Fish and Wildlife Service Office

The honu or Hawaiian Green Sea Turtle once nested in large numbers on all the main Hawaiian Islands. Starting in 1800s and continuing until the 1970s, widespread, unsustainable harvest, primarily for consumption of adults and eggs by humans, constrained and eventually eliminated all significant nesting areas with one exception; Lalo or French Frigate Shoals. Hard-wired life history traits like late maturation and natal site fidelity work synergistically to impede recovery which will require expansion into previously used nesting areas. Although honu numbers have increased at ~5%/year, there is little evidence of any significant nesting outside of the low-lying atoll of Lalo. Expansion in nesting to high-elevation islands that will persist as sea-level rises is necessary for survival and recovery. A collaborative, community-based project using citizen scientists to find, monitor and protect honu nests on Oahu started in 2016 and revealed a dramatic increase in sea turtle nesting starting in 2020 and continuing through the present. Nest numbers increased from 0 – 2 nests found in 2016 – 2018 to a high of 58, 67 and 31 nests found in 2020, 2021 and 2022 respectively. Hatching success and emergence success were generally high (>85% & >75% respectively). However, many nests and hatchlings require protection from artificial lights, vehicles driving on the beach, invasive predators and discarded fishing line. Public education focused on these threats, especially on how to use artificial light responsibly, and management is needed to protect honu as they once again begin to nest on Oahu.

Unveiling a recently discovered loggerhead sea turtle nesting site in Greece producing a predominance of male hatchlings

Anna Lamaj, Galini Samlidou, ALan F. Rees, Dimitris Margaritoulis

ARCHELON, the Sea Turtle Protection Society of Greece

Greece hosts the largest reproductive aggregations of loggerhead sea turtles (Caretta caretta) in the Mediterranean, with temperature-dependent sex determination (TSD) being a critical factor in their population dynamics. This study focuses on Preveza beach, located in northwestern Greece, surveyed as part of the LIFE EUROTURTLES project initiated in 2017. The project involved beach monitoring, nest protection against predation, and post-hatch excavations and, additionally, an effort to understand the male-to-female ratio of sea turtle hatchlings. From 2017 to 2019, daily surveys were conducted to monitor sea turtle nesting activities, while from 2018 to 2021, temperature loggers were deployed to record beach temperatures, used as a proxy for incubation temperatures which play a crucial role in determining the sex of hatchlings. A total of 15 loggers were placed in strategic locations along the beach, with temperature data collected at regular intervals. Nesting activity on Preveza beach was regular but relatively low. The number of nests recorded increased over the years, with 3 nests in 2017, 8 in 2018, and 13 in 2019. In 2020, 16 tracks indicating nesting attempts were identified, but the exact number of nests remained undetermined due to limited surveying. Beach temperatures consistently remained below the pivotal temperature of 29.7°C, a threshold for balanced sex ratios in sea turtle hatchlings. This suggests a predominant production of male hatchlings. Peak sand temperatures are typically observed in July and August, and the data indicated that temperatures during June and early July were consistently below the pivotal temperature, contributing to a male-skewed hatchling sex ratio. The male hatchling bias, due to its cooler sand conditions, make the area significant for sea turtle conservation efforts. This is particularly important in the context of ongoing global warming trends, which are expected to lead to increasingly female-biased hatchling outputs on other beaches. The potentially increasing nesting activity and the extensive, relatively undeveloped beach suggest that Preveza beach may become a significant nesting site in the future, provided that loggerheads will consistently expand their nesting range towards cooler zones in the face of global warming. In the Mediterranean, this expansion is already observed in two directions: a northward expansion into Albania and a westward expansion into the western Mediterranean. These findings have implications for understanding and preserving the endangered loggerhead sea turtle populations and their emerging habitats in the region.

How sand grain size dictates sea turtle hatchlings’ destiny in the nest escaping?

Mohd Uzair Rusli, Lyvia Chong, David T. Booth, Nadhirah Syafiqah Suhaimi

Sea Turtle Research Unit (SEATRU), Institute of Oceanography and Environment, Universiti Malaysia Terengganu, Malaysia

Sea turtles are oviparous reptiles that deposit eggs in underground nests and provide no post-ovulatory parental care to their offspring. Upon hatched, hatchlings use the egg’s finite energy reserve to sustain embryonic development and the first few days of their post-hatch live, which includes nest escape, beach crossing, and swimming offshore. This study investigated whether the grain size of nest substrate can affect hatchling energy usage during nest escape. About-to-hatch eggs (incubated in-situ for 42 to 51 days) were collected from a natural nesting beach and further incubated in two separate laboratory chambers filled with either coarse-grain sand or fine-grain sand at 28°C. Open-flow respirometry was used to measure hatchlings’ oxygen consumption rate during the nest escape process, which was then converted to energy consumption. We found that hatchlings digging through the coarse sand took significantly shorter time (168 ± 13.9 h) to emerge from their nest chambers than those digging through the fine sand (233.21 ± 12.6 h) and consumed significantly less energy. Identifying the effects of nest substrate on hatchling energy consumption during nest escape can provide improvements in hatchery management practices by choosing to relocate “doomed” clutches into protected hatcheries located in coarse sand, which should maximise the energy reserves of hatchlings when they emerge from their nests. Additionally, we are investigating the influence of environmental noise on hatchling activities. Preliminary observations suggest that natural and anthropogenic noise may significantly impact hatchling orientation and energy use. This aspect of the study highlights the need for a broader environmental consideration in hatchery management.

Utilisation of the Spatial Monitoring and Reporting Tool to monitor nesting sea turtle activity and volunteer patrol effort at Cambodia’s only known nesting site

Chandara Tak, Matthew Glue, Tharamony Ngoun

Fauna & Flora, Cambodia

In March 2022 the first sea turtle nest in over ten years was discovered in Cambodia by the Fauna & Flora team during an expedition to the remote island group of Polou Wai. This ended a decade-long search for the last remaining sea turtle nesting sites in Cambodia by the Fauna & Flora team and counterparts from the Fisheries Administration. Following the discovery of this nest, a plan was formulated to concentrate conservation efforts at this site and other remote island locations. A relationship was established with the Royal Cambodian Navy Personnel based on the island. In close coordination with the navy base commander, a volunteer network was established on the island with eligible personnel selected to support sea turtle conservation efforts. These volunteers have now been trained in how to spot key signs of sea turtle nesting activity, how to confirm nests, nest relocation and tagging techniques. Importantly, they have received training from Fisheries Administration counterparts in how to utilise the Spatial Monitoring and Reporting Tool (SMART) to monitor their survey efforts and submit data on sea turtle nesting activity. Key metrics captured by the SMART tool include distance, hours and number of days patrolled. The Fauna & Flora team would like to share our experience using this tool to engage with sea turtle patrol volunteers, track their patrol effort and monitor nesting sites during the first two years of its implementation.

*The umbilical cord as a non-invasive sampling: genotype and applications

Gisela Marín-Capuz1, Elena Abella2, Marta Pascual1, Cinta Pegueroles1,3, Carlos Carreras1,3

1Departament de Genètica, Microbiologia i Estadística and IRBio, Universitat de Barcelona, Avinguda Diagonal, 643, 08028, Barcelona, Spain; 2BETA Technological Center, University of Vic - Central University of Catalonia, Carretera Roda 70, E-08500, Vic, Spain; 3Should be considered senior authors

High throughput sequencing allows obtaining a high number of genome-wide loci, revolutionising the field of conservation genomics. However, it is often difficult to collect samples from elusive species, and the quantity and quality of the DNA extracted can be compromised by the type of samples. Sea turtles spend most of their life in the open ocean, making them a difficult group to obtain biological samples. In addition, common methodologies to obtain biological samples on sea turtles (e.g., blood or tissue sample) are often unsafe or unfeasible to perform on newborn hatchlings. Thus, exploring new non-invasive methodologies on sea turtles is essential to improve the possibilities of studying them. Here, we evaluated the potential of the umbilical cord (UC) as a non-invasive methodology in newborn turtles. To do so, we assessed whether the DNA retrieved from both sides of the UC i) is adequate for genomic research, ii) belongs to the mother or to the offspring, and iii) identified the prevalence of this tissue under natural and artificial incubation conditions. In brief, we generated 2b-RAD libraries for samples from 5 Spanish sporadic nests, including both extreme regions of 13 UCs, 50 blood or tissue samples (4 of them corresponding to hatchlings with genotyped UC and the remaining to hatchlings of the same nests) and the blood of one female that laid 2 of these nests. We generated a genome-wide catalogue of loci by mapping our sequences to the loggerhead reference genome. We calculated the Percentage of Shared Genotypes (PSG) from the following comparisons: 1) both regions of the UCs (hatchling side and egg side), 2) the UCs and the corresponding hatchling sample, 3) the UCs and the female sample whenever available, and 4) among all pairwise comparisons involving the UCs and the rest of hatchlings genotyped of the same and different nest. We also conducted differentiation analysis to test the clustering of the UC versus the other samples. Regarding the prevalence of UCs, we counted the number of nests with UC samples found in naturally emerged nests in a hatchery of an established nesting population of loggerhead turtle (Boa Vista, Cape Verde) and also in incubator-developed hatchlings from the management program of sporadic nesting in Spain. Our results revealed that the UC genotype belongs to the hatchling and not to the mother, obtaining PSG values higher than 95% between both sides of the UC and between the genotypes of this tissue and the corresponding hatchling. In addition, the PSG values of the UC with respect to the nesting female (if available) and with respect to the rest of the siblings were lower and coincident with the values acquired among any pair of siblings. Our data reported a lower prevalence of the tissue in naturally emerged nests (6.7% of the nests) in comparison with incubator-developed hatchlings (100% of the nests). In summary, we obtained high-quality genomic DNA from the UC and unveiled that the whole tissue has the same genotype and corresponds to the hatchling, with notable occurrence in incubator-hatched loggerhead eggs.

*Identifying geographic locations where sea turtle species are likely to inter-breed and hybridize

Sierra Nicole Hershberger1,2, Mary M Brandle1,2, Sibelle T Vilaça3, Matthew D Ramirez1,2

1Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina 28403 USA; 2Center for Marine Science, University of North Carolina Wilmington, Wilmington, North Carolina 28409 USA; 3Instituto Technológico Vale, Belém, Pará, 66055-090, Brazil

Multiple sea turtle species are known to hybridize which occurs in particularly high frequency in Brazil. However, the ecological factors that promote sea turtle hybridization remain understudied, as is the possible prevalence of hybridization outside of Brazil. Current hypotheses suggest a combination of factors may lead to sea turtle hybridization including timing of reproduction, promiscuity, and population status. In this study, we aim to identify geographic locations where sea turtle species are likeliest to interbreed via a global literature review and data synthesis, using the ecological conditions in Brazil as a baseline for comparison. We specifically performed a systematic literature review of sea turtle nesting data—all 6 Cheloniidae species—to characterize the spatiotemporal overlap in sea turtle nesting seasons between species and evaluate ecological factors that may be linked to hybridization events (i.e.., length of temporal overlap, order of species nesting seasons, population status). We initially identified 1,317 papers pertaining to sea turtle nesting, which were reduced to 383 that contained data on sea turtle nesting season length. From these papers we extracted data denoting the start and end of nesting seasons, sampling effort, nesting female and nest count, nesting trend through time (if available), and geographic locations used to assign studies to Regional Management Units (RMUs). Resulting nesting data was used to quantify the length of overlap in nesting seasons between co-occurring species at local scales (e.g., state within country) whenever possible or RMU when data were limited. Additionally, our literature review yielded 154 records of sea turtle hybridization globally. Ongoing work is using binomial regression to identify the ecological conditions—species order of reproduction, length of temporal overlap in reproduction, population status, population size—that best predict the presence/absence of sea turtle hybrids. We are also identifying geographic hotspots with ecological conditions qualitatively similar to known hotspots such as nesting sites found in Brazil that may be important areas for further study. Our project aims to inform and guide research efforts to identify potential hybridization hotspots globally, holding important implications for where future research and conservation efforts should be concentrated. This is all the more pressing given recent findings that sea turtle hybrids can produce successful offspring, raising important questions about the conservation and management of hybrids.

*4-decades of loggerhead nesting trends and survey analyses at Marine Corps Base Camp Lejeune

Hailey Grossman1,2, Susan Piacenza1

1Fisheries, Wildlife, and Conservation Sciences, Oregon State University; 2Environmental Management Division, Marine Corps Base Camp Lejeune NC

Loggerhead sea turtles (Caretta caretta) have the broadest nesting range of any sea turtle species; however, very few long-term studies have been conducted at the geographic limits of the reproductive habitats. Climate change in coastal zones has impacted seasonality, storm frequency and intensity, high water events, and shifted the timing of weather conditions during the reproductive season. With these changes, it is unclear how nesting itself has changed throughout the range. Long-term loggerhead sea turtle nesting surveys at Marine Corps Base Camp Lejeune (MCBCLJN), located in southeastern North Carolina, USA, have been conducted continuously since the passing of the Endangered Species Act (ESA) in 1973. While military training operations occur on a portion of the beach, nests in active training locations are relocated; while other parts of the beach function effectively as a natural and undeveloped beach. MCBCLJN manages one of the longest running continuous surveys at the northernmost extent of the Northwest Atlantic loggerhead population. This study analyzed a 40-year dataset to determine change in nesting indicators and population trends over time while considering phenological shifts from longer summertime conditions due to climate change. To estimate population growth rate, the total nests observed each year were log-transformed and a linear regression was used over the time series. The loggerhead nesting season on MCBCLJN begins in May and typically ends in October, the number of nests over the past 40-years has ranged from a high of 92 nests to a low of only 7 nests in a single nesting season. To estimate the discrete rate of increase, λ, the slope of the linear regression was exponentiated. The loggerhead nesting population at MCBCLJN had a slight positive population growth rate from 1983 - 2023, with an estimated growth rate of 1.0063 (95% confidence interval 1.00218 - 1.0282); this translates to a 0.63% increase annually. In addition, the number of unsuccessful nesting attempts (false crawls) have decreased. There was no statistical evidence to support that the nesting season has increased in total number of days or shifted earlier in the year for nesting loggerheads. There was also no statistical evidence that the mean clutch size has changed over time. The results of the study suggest that the nesting population at MCBCLJN is at least stable and is slowly increasing, despite impacts from nest relocations and military training activities. While MCBCLJN’s nesting trend is estimated to be increasing about 0.6% a year. One possible explanation of an increasing population in North Carolina could be that nesting is very slowly becoming more successful and is slowly supporting the expanding nesting population on the northernmost extent of the loggerhead breeding range. The results from this study highlight the importance of monitoring loggerhead nesting throughout the nesting range, especially given concern about future impacts of climate change to this broadly distributed marine reptile.

*Size matters: how sample size and molecular marker choice affect mixed stock analysis

Gustavo D. Stahelin1,2, Katherine L. Mansfield1

1University of Central Florida, Department of Biology, Orlando, FL, USA; 2Fundação Projeto Tamar, Salvador, BA, Brazil.

Sample size is a fundamental aspect of scientific studies, but statistically derived results can be misleading due to an inadequate number of samples. Some publications suggest a minimum number of samples for regression models based on data variance, but there is a lack of guidance for several statistical approaches, in particular, genetic studies. Mixed stock analysis (MSA) is a powerful tool to evaluate the composition of mixed stock aggregations. Still, no direct guidance exists on the minimum number of samples needed for accurate estimates using such models. To address the sample size issue, we used computer simulations to better understand the effect of sample size on MSA and make recommendations for future studies. Our simulations considered three source sea turtle populations (rookeries) and four mixed stock aggregations. We ran 30,000 simulations using a combination of variables to understand the impact of sample size on mixed stock model estimates. Variables included: rookery size (500, 1,000, 10,000, and 50,000 individuals), mixed stock aggregation size (500, 1,000, and 5,000 individuals), and sample size from rookeries and mixed stock aggregations (as a continuous variable from 25 to 200 samples). In addition, we considered two different scenarios to simulate the use of different genetic markers to evaluate rookery contributions: use of genetic markers with higher and lower resolution to distinguish rookeries – 400 bp vs 800 bp mtDNA fragments. We compared the estimates from each simulation against the true contribution from rookeries to mixed stock aggregations to assess model accuracy. Our results indicate that, regardless of population size, 30-50 samples can accurately characterize mtDNA markers in the rookeries for MSA studies. We also found that model accuracy can be maximized by using a combination of higher-resolution molecular markers (e.g., 800 bp fragments to distinguish rookeries) and sample sizes from mixed stock aggregations of 100 samples or more. Using lower-resolution markers, model accuracy is only maximized by using >150 samples from mixed stock aggregations. Considering that large sample sizes may be hard to achieve in multiple regions, we strongly recommend the development of higher resolution markers to better distinguish rookeries. Simultaneously, rookeries must be reassessed using these higher-resolution markers, allowing future studies to use lower mixed stock aggregation sample sizes. Insufficient sample size associated with poor genetic markers can generate misleading MSA estimates, hampering our understanding of connectivity and sea turtle dispersal patterns across habitats and, ultimately, conservation efforts for specific populations.

Where do they come from? A genomic baseline for individual assignments in the loggerhead turtle (Caretta caretta)

Astrid Luna-Ortiz1, Anna Barbanti1, Adolfo Marco2, Silvia Giralt3, Daniela Freggi4, Cinta Pegueroles1, Alberto Abreu-Grobois5, Raúl Llera-Herrera5, Elisabeth Labastida-Estrada6, Salima Machkour M`Rabet7, Dimitris Margaroitoulis8, Oguz Turkozan9, Marta Pascual1,10, Carlos Carreras1,10

1Departament de Genètica, Microbiologia i Estadística and IRBio, Universitat de Barcelona, Avinguda Diagonal, 643, 08028 Barcelona, Spain; 2Department of Biodiversity Conservation, Estación Biológica de Doñana, CSIC, Americo Vespucio s/n, 41092 Seville, Spain; 3Fundación para la Conservación y la Recuperación de Animales Marinos (CRAM), 08820 El Prat de Llobregat, Spain; 4Lampedusa Sea Turtle Rescue Center, Punta Sottile, 92031 Lampedusa AG, Italy; 5Unidad Académica Mazatlan, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Apartado Postal 811, Mazatlan, Sinaloa 82000 Mexico; 6Colección Nacional de Helmintos. Departamento de Zoología. Instituto de Biología. Universidad Nacional Autónoma de México; 7Laboratorio de Ecología Molecular y Conservación, El Colegio de la Frontera Sur Unidad Chetumal; 8ARCHELON, the Sea Turtle Protection Society of Greece, Solomou 57, GR-10432 Athens, Greece; 9Aydın Adnan Menderes University, Faculty of Arts and Science, Department of Biology, 09010 Aydın, Turkey; 10Should be considered senior authors

Genomic techniques are becoming widely used in conservation, offering an unprecedented resolution to evaluate the behaviour, reproductive success, and impact of different threats on endangered species. In the case of sea turtles, there is an urgent need to identify the natal origin of individual juveniles in feeding areas or breeders colonising new nesting beaches to make scientifically-informed management decisions. In the case of species with large genome sizes, such as sea turtles, it is necessary to use genomic reduction techniques to optimise costs and it is fundamental to standardize protocols for reliable cross-comparisons. Additionally, it is crucial to build a genomic baseline with data from known regular nesting areas from where the individuals could have originated. To build a robust baseline for the loggerhead turtle, we analysed with 2bRAD a total of 278 samples, including individuals from nine regular nesting beaches in the Mediterranean from a previous study and individuals from three regular nesting beaches in the Atlantic. To test the effectiveness of the baseline for individual assignments, we analysed with the same methodology 114 individuals from four Mediterranean foraging areas (Catalano-Balearic Sea (CAB), Lampedusa (LAM), eastern Aegean Sea (EAG) and western Aegean Sea (WAG)) obtaining a total of 3,680 SNPs shared by 95% of the individuals. First, we conducted a genetic structure analysis with the baseline individuals and identified three groups corresponding to the previously described Regional Management Units (RMU). Additionally, we performed a hierarchical analysis with the samples from the Mediterranean nesting populations of the baseline and identified a clear differentiation between Greek nesting areas and the remaining populations, as reported in previous work. Finally, we carried out an individual assignment analysis of all individuals collected from the four feeding grounds, using the baseline and following a hierarchical approach from a global perspective (including the baseline of the three RMUs) to a more regional perspective (including only the Mediterranean nesting beaches as the baseline). We successfully identified the origin of each of the 114 individuals, both at the RMU level and at the regional level within the Mediterranean. All turtles were assigned to the Mediterranean RMU, except for some individuals from LAM and CAT. When analysing at the regional level, the individuals from Greece were more prevalent in WAG, while those from the other Mediterranean populations were more prevalent in the remaining foraging areas. Our methodology allowed us to perform individual assignments on all samples at the RMU and regional levels, opening new perspectives to the research and conservation of sea turtles. By using this strategy, it is possible to reliably identify the populations impacted by threats at great distances outside their nesting areas or to research on turtles from a specific origin found in mixed foraging areas shared by individuals from multiple populations.

New colonisers drive the increase of the emerging loggerhead turtle nesting in Western Mediterranean

Astrid Luna-Ortiz1,8, Gisela Marín-Capuz1,8, Elena Abella2, Jose Luis Crespo-Picazo3, Fernando Escribano4, Guillem Félix5, Silvia Giralt6, Jesús Tomás7, Marta Pascual1,9, Carlos Carreras1,9, Cinta Pegueroles1,9

1Department of Genetics, Microbiology and Statistics and IrBio, University of Barcelona, Avinguda Diagonal 643, E-08028, Barcelona, Spain; 2BETA Technological Center, University of Vic - Central University of Catalonia, Carretera Roda 70, E-08500, Vic, Spain; 3Fundació Oceanogràfic de la Comunitat Valenciana, Ciutat de les Arts i les Ciències, E-46013, València, Spain; 4Centro de Recuperación de Fauna Silvestre "El Valle", Ctra. Subida a El Valle, 62, E-30150, La Alberca de las Torres, Murcia, Spain.; 5Consorci de Recuperació de Fauna de les Illes Balears (COFIB) Carretera Palma- Sineu, Km 15,400, E-07142, Santa Eugènia, Balearic Islands, Spain; 6Fundación para la Conservación y la Recuperación de Animales Marinos (CRAM), E-08820, El Prat de Llobregat, Barcelona, Spain; 7Instituto Cavanilles de Biodiversidad y Biología Evolutiva, University of Valencia, Apdo. 22085, E-46071, Valencia, Spain; 8Should be considered first author; 9Should be considered senior authors

The loggerhead sea turtle (Caretta caretta) is particularly sensitive to global warming, due to its temperature-dependent sex determination, increasing hatchling mortality and the potential constraints to colonize new suitable areas due to philopatry. Despite these limitations, the species is colonizing the western Mediterranean, with a substantial increase in the number of nests year by year. To understand this rapid colonization in recent years in Spain, we sampled 45 hatchlings from 8 nests between 2016 and 2019. We build individual 2bRAD libraries from a variable number of hatchlings per nest (generating a dataset with 2,291 SNPs), sequenced the mtDNA D‐loop region of one sample per nest and collected data on clutch size, hatching success, and incubation duration. Our results confirm that this ongoing colonisation has a Mediterranean and Atlantic mixed origin and we showed that nests were laid by different females, except for two nests laid 213 Km apart within the same season in 2019. There are no records of returning females in the two periods analysed: present study (years 2016-2019) and past study (years 2001-2015), suggesting that the recent increase in nesting seems to be due to an increase in the number of colonising individuals rather than females born in the same area returning to breed. We hypothesise that this increase in the number of colonisers results from successful conservation, feminisation of the populations and earlier sexual maturation in foraging areas related to an increase of sea temperature. However, given the high degree of philopatry in the species and the high rates of estimated female offspring in some Spanish nests, some of them could return in the future as breeding adults. Consequently, the detection of re-emigrant females nesting in subsequent years would confirm the successful consolidation of a new rookery. Interestingly, some nests along the Western Mediterranean coast have more males, making it a key area for producing male offspring in the Mediterranean basin. In addition, regarding the male genetic composition of the nests, the relatedness analysis shows higher values among individuals in the same nest, except in one case where its pair of individuals shows lower relatedness values than those of other nests, suggesting possible multipaternity within this clutch. All these evidences confirm that we are witnessing a shift of species distribution at evolutionary level induced by climate change. These results allow defining the colonization process of a long-lived species and sets the current status of this emerging population to understand the patterns towards the establishment of a resident population under a global warming scenario. Detecting and studying these new events through genomic monitoring, is crucial for the potential expansion and long-term survival of the species.

Reimagining sea turtle conservation in India: insights from a long-term monitoring study

Chandana Pusapati1, Muralidharan Manoharakrishnan2, Nupur Kale3, Chetan Rao4, Alissa Barnes5, Vishrutha Rao1, Kartik Shanker1,6

1Dakshin Foundation, Bangalore, India; 2World Wide Fund for Nature-India; 3Swansea University, Swansea, United Kingdom; 4FLAME University, Pune, India; 5Wildlife Conservation Society-India; 6Indian Institute of Science, Bangalore, Karnataka, India

Odisha is a prominent nesting and breeding ground for the east coast population of olive ridley turtles in India. Historically, the population experienced drastic declines in the 1980s and 1990s due to direct take and fisheries by-catch. This resulted in policy changes and conservation initiatives that led to blanket fishing bans and the implementation of spatial closures. Over 2 decades later, we examine various population parameters to inform future conservation needs and directions.

We monitored the nesting and nearshore population of olive ridleys in Rushikulya, a major mass nesting site in Odisha, between 2008 – present. We conducted nearshore boat surveys, regular beach patrols for solitary nesting estimates, carried out arribada census, measured hatching success and hatchling sex ratios. We observed that this population is stable or even increasing, despite fisheries by-catch related mortality in the region. Annual arribada nesting numbers have increased from ~40,000 to >200,000 over the last 15 years. The density of turtle aggregations in the nearshore waters has remained stable with minor inter- and intra-annual fluctuations throughout this period. High hatching and emergence success, relative to other mass nesting beaches, indicates a potentially steady hatchling recruitment rate. The hatchling sex ratios, however, are found to be rapidly becoming more female-biased (71%).

These results underscore the need to reevaluate current perceived threats and conservation measures for this population. It also provides valuable empirical evidence to show that the olive ridley turtles in the region might be more resilient than earlier believed and suggests that future conservation efforts should address the effects of climate change and habitat loss that pose a bigger threat to the long-term stability of the population.

Genetic stock structure of Hawksbill turtle (Eretmochelys imbricata) nesting populations in Fiji

Erin L. LaCasella1, Susanna Piovano2, Shritika S. Prakash2, Malakai Tuiono2, Ana Ciriyawa2, Peter H. Dutton1

1Southwest Fisheries Science Center, NOAA Fisheries, United States of America; 2SAGEONS, The University of the South Pacific, Fiji

Little is known about hawksbill turtle (Eretmochelys imbricata) nesting populations across the Fijian archipelago, which is made up of more than 800 predominantly uninhabited islands and islets in the South Pacific that are difficult to access and monitor. In 2014, the University of South Pacific Sea Turtle Team began a concerted effort to assess nest abundance, distribution and collect genetic samples to characterize the nesting populations of hawksbill turtles in Fiji, and fill a critical information gap for hawksbills in the Pacific.

During the nesting season, beaches across four administrative divisions (northern, eastern, southern and western) of Fiji were monitored after initial reports of nesting activity. A total of 65 tissue samples were collected between 2014-2023 from adult females, hatchlings, or salvaged embryos for genetic analysis. DNA was extracted and ~800 base pairs of the mitochondrial (mtDNA) control region were sequenced using primers LCM15382 and H950g. Haplotypes were determined by comparing the sequences to known haplotypes (published and unpublished), resulting in the identification of five different mtDNA haplotypes (EiIP04, EiIP33, EiIP57, EiIP74, EiIP136) among the samples analyzed. EiIP33 is very common and widespread across the Pacific. To date, haplotypes EiIP04 and EiIP57 have only been identified in the North Queensland rookery while EiIP74 and EiIP136 have not been described at any nesting population, which illustrates the importance of this small nesting population as a potential source population to key foraging areas in the south Pacific.

We present the results of stock structure analysis to characterize the Fijian hawksbill nesting populations and determine the level of differentiation from regional nesting populations across the Southwest Pacific. These results demonstrate the importance of continuing sampling efforts around Fiji in order to improve our understanding of the hawksbill population structure in the region and achieve a robust assessment of population status on a local and regional level for better management and conservation.

Genetic stock identification of fisheries bycatch provides insights into differences in broad-scale distribution patterns of leatherbacks in the North and Southeast Pacific

Suzanne E Roden1, Erin L LaCasella1, Joanna Alfaro-Shigueto2,3, George H Balazs4, Nelly de Paz Campos5, Miguel Donoso6, Amy Frey1, T Todd Jones7, Jeffrey C Mangel2, Summer Martin7, Shawn Murakawa7, Patricia Zarate8, Peter H Dutton1

1Southwest Fisheries Science Center, NOAA-Fisheries; 2Asociacion ProDelphinus; 3Universidad Cientifica del Sur; 4Golden Honu Services of Oceania; 5ACOREMA; 6Pacifico Laud; 7Pacific Islands Fisheries Science Center, NOAA-Fisheries; 8Departamento de Oceanografía y Medio Ambiente, Instituto de Fomento Pesquero

Leatherback turtles use waters throughout the Pacific as foraging grounds where fisheries interactions occur, resulting in incidental catch in commercial and artisanal longline and gillnet fisheries. This bycatch is of concern due to severely depleted Pacific nesting populations, prompting leatherback conservation as an international priority. This study uses molecular genetic analysis to build on previous satellite telemetry research in order to advance the overall understanding of connectivity and migration patterns of Pacific leatherbacks. Analysis of a comprehensive set of samples collected by observers from US-based fisheries in the North Pacific as well as artisanal and commercial fisheries in the southeast Pacific (Peru and Chile) between 1995 and 2022 reveals that while almost all leatherbacks bycaught in the North Pacific originated from the western Pacific nesting population, a portion of the Chile and Peru leatherback bycatch originated from both western and eastern Pacific nesting stocks. The connectivity between the western Pacific nesting populations and the fisheries in the eastern Pacific is notable, and is something that satellite telemetry studies, largely based on tracking nesting females, has tended to overlook. We present details of these results and discuss conservation implications and future research directions that leverage new genomics resources for improving genetic stock identification of Pacific leatherbacks

Surviving the Northernmost waters: Genetic insights into green turtles' adaptation in Japan

Tomoko Hamabata

Graduate School of Information Sciences, Tohoku University, Japan

Green turtles (Chelonia mydas) have a global distribution encompassing tropical and subtropical regions. Japan serves as the northernmost breeding site and foraging habitat for this species. Previous studies have delineated distinct foraging habitats in Japanese waters based on turtles' natal origins, revealing a crucial distribution boundary. Coastal seagrass beds south of Japan's Ryukyu Islands are vital for low-latitude populations, while the coastal waters surrounding Japan's main islands are predominantly used by turtles from the northernmost nesting sites. Since the coastal waters around Japan's main islands are temperate, the water temperature seasonally varies. Especially in winter, it substantially drops compared to the tropical and subtropical waters, probably making the adaptive traits of green turtles in these regions crucial. In addition, the types of food resources for green turtles also differ in these two waters due to the differences in environments. The ongoing rise in seawater temperatures along Japan's main islands, attributed to climate change, may pose a significant threat to the future distribution of green turtles and their food resources, which have achieved local environmental adaptation. This study analyzed whole-genome sequencing data from individuals from the northernmost nesting populations (Ogasawara, Japan) and the low-latitude nesting populations (Southeast Asia and the western Pacific islands) to understand the genetic signatures related to distribution boundary and local adaptation. Several genomic regions were differentiated between the Northernmost and low-latitude populations, and 88 genes were included in these regions. Some of those genes are known to have functions relating to the metabolisms of energy, glucose, galactose, and fatty acids, suggesting that the adaptation has been enabled through the evolution of metabolic functions. This study aims to uncover the genetic underpinnings of the local adaptations in northernmost green turtle populations acquired through evolutionary history, obtaining valuable insights into their tolerance to varying environmental conditions and contributing to future monitoring.

Developing a cost-effective molecular method of sex determination of Northern Atlantic juvenile sea turtles using gene expression

Maxine A. Montello1, Patricia Ceseretti2, Andrew M. Wier2

1New York Marine Rescue Center, Riverhead, New York, USA; 2Dyson College of Natural Science, Biology Department, Pace University, Pleasantville, New York, USA

The New York Marine Research Center (NYMRC): a non-profit responsible for the rescue, rehabilitation, and release of stranded sea turtles along the New York coastline, rescues four different species of sea turtles that strand due to entanglement, vessel interaction, cold stunning and debilitation. These genera include Kemp’s ridley (Lepidochelys kempii), loggerhead (Caretta caretta), Atlantic green (Chelonia mydas), and leatherback (Dermochelys coriacea). Juvenile sea turtles do not have clear sexual dimorphism, which makes it difficult to determine their sex based on external characteristics. Sea turtles have temperature-dependent sex determination, which makes standard end-point PCR methods for amplifying gender specific genes found in chromosomal-dependent animals, useless. Current methods used to determine sex in juvenile sea turtles are costly and often inaccessible to non-profit organizations. Some of these methods include the Anti-Mullerian Hormone (AMH) test. The aim of this study is to develop a PCR based method that can be used on all four of the sea turtle genera that strand in New York State. From 2019-2023, 100 microliters of blood were obtained from three species of turtles, Kemp’s ridley, green and loggerhead. All samples were then transferred for offsite analysis at Pace University. The sea turtle primers developed were for the SOX9, EIF1AD and IFNGR2 genes and were chosen for their differential gene expression among males and females. Preliminary data shows that both the SOX9 and EIF1AD genes are strong candidate for sex determination in all three sea turtle species.

Genetic characterization and diversity of an undescribed loggerhead turtle (Caretta caretta) reproductive population and new insights on the genetic structure for the southwest Atlantic

Alberty Cleyton Gaspar Xavier1, Luana Alves Simões1, Sarah de Souza Alves Teodoro1, Sandra Ludwig1, Gabrielly Loretti Schultz1, Ana Carolina Barcelos Pereira Mariano1, Daniella Torres Almeida Pereira2, Tatiane Bittar Vieira2, Victor Patiri3, Gustave Gilles Lopez3, Romoaldo Sales Gaspar3, Sarah Maria Vargas1

1Universidade Federal do Espírito Santo, Brazil; 2Fundação Projeto Tamar.; 3Braço Social Consultoria

The loggerhead turtle (Caretta caretta) is a cosmopolitan species globally listed as vulnerable by the International Union for Conservation of Nature. This species is notable for its extensive migrations and its reproductive philopatry behavior, wherein it nests on specific beaches. In Brazil, the loggerhead turtle nests primarily on the coasts of Sergipe (SE), northern Bahia (BA), northern Espírito Santo (nES), and the extreme north of Rio de Janeiro (RJ), but secondary nesting areas can also be observed in the southern Espírito Santo (sES) and southern Bahia. Based on the control region of mitochondrial DNA (D-loop), this study aimed to characterize the genetic diversity of an undescribed nesting loggerhead turtle population in southern Espírito Santo, increase the sample size of the northern Rio de Janeiro nesting population, evaluate the genetic structure among Brazilian rookeries and test whether their genetic composition has changed over time. Epithelial tissue samples were collected from females from sES (N=33) over three reproductive seasons (2020/21, 2021/22, and 2022/23), and dead hatchlings (N = 43) from nests in northern Rio de Janeiro in 2023. The obtained data were complemented with sequences available in the literature from RJ (N= 49), SE (N= 35), BA (N= 62), and nES (N= 236) to perform the genetic structure analyses. The lowest haplotype diversity value was found for sES (0.316), followed by RJ (0.320), and the highest for SE (0.548). The haplotype CC-A4.3, previously found only in the nES population, was identified for the first time in the RJ region and in sES population. Pairwise FST analysis indicated genetic similarity between sES and RJ and among SE, BA, and nES, but significant genetic differences between these two groups of populations. These indicated two genetic stocks for Brazilian nesting loggerhead turtles (Genetic stock 1 = SE/BA/ES; and Genetic stock 2 = RJ), now expanded to include a population in the southernmost group (Genetic stock 1 = SE/BA/nES; and Genetic stock 2 = sES/RJ). The temporal analysis did not show any statistically significant difference between periods. This study emphasizes the low diversity and significant genetic differentiation of loggerhead turtle populations in sES and RJ compared to those further north, highlighting the relevance of molecular tools in understanding population limits. While mtDNA analyses are useful to characterize genetic diversity, we suggest analyses with biparental nuclear DNA in future studies for a deeper understanding of the genetic structure guiding future management and conservation initiatives.

Genetic composition and origin of undescribed leatherback turtles aggregations (Dermochelys coriacea) along the Brazilian coast

Gabrielly Loretti Schultz1, Werlanne Magalhães2, Sarah de Souza Alves Teodoro1, Ana Carolina Barcelos Pereira Mariano1, Alberty Cleyton Gaspar Xavier1, Alexsandro Santos3, Daniella Torres Almeida Pereira3, Tatiane Bittar Vieira3, Marta Cremer4, Camila Domit5, Sarah Maria Vargas1

1Universidade Federal do Espírito Santo, Brazil; 2Instituto Tartarugas do Delta; 3Fundação Projeto TAMAR; 4Universidade da Região de Joinville; 5Universidade Federal do Paraná

The leatherback turtle (Dermochelys coriacea) is widely distributed and occurs in tropical and temperate areas around the world, spending most of their life cycle in the open ocean. The species perform long migrations between nesting and feeding areas, and most genetic studies have analyzed only rookeries. In the Southwest Atlantic, the subpopulation of D. coriacea is Critically Endangered, comprises few individuals, and nesting activity frequently occurs on the northern coast of Espírito Santo (Brazil), although it can occur in other Brazilian states. This study aimed to characterize the diversity and genetic composition of leatherback turtles for the first time in one nesting area in northern Brazil (Piauí state) and three feeding areas, one in Southeast Brazil (Rio de Janeiro state) and two in Southern Brazil coast (Paraná and Santa Catarina states), and compare data with other published nesting and foraging areas around the Atlantic Ocean. Epithelial tissue samples were collected in 2012, 2019, and 2022 from dead hatchlings in Piauí (N = 6) and from stranded adult and juvenile individuals between 2016 and 2022 in feeding areas (Rio de Janeiro - RJ, N = 13; Paraná - PR, N = 19; and Santa Catarina - SC, N = 16). We sequenced 763 bp fragments from the control region of mitochondrial DNA and combined them with data from published studies on nesting areas for a regional perspective (Africa, Espírito Santo, and North and Central America) and from one feeding area in Southern Brazil (Rio Grande do Sul state, RS). For dead hatchlings samples from Piauí we found only Dc1.1 (the most common haplotype within Atlantic), for stranded animals from foraging areas we found five haplotypes (Dc1.1, Dc1.3, Dc1.4, Dc3.1 and Dc13.1), two of them exclusively found in African rookeries. The genetic diversity of the undescribed foraging areas evaluated varied from 0.20 for RJ to 0.45 for SC. Paraná, Santa Catarina and Rio Grande do Sul were grouped into a single aggregation due to genetic homogeneity (FST values between -0.005 and -0.056; p > 0.05) and presented a haplotype diversity of 0.493. The pairwise FST revealed that individuals from feeding areas in the southern region (PR, SC and RS) exhibited genetic homogeneity with those from Gabon (FST = 0.003; p > 0.05) and Ghana (FST = 0.020; p > 0.05), indicating a possible migratory flow between Africa and Brazil. The lack of genetic structure provides scientific information for conservation strategies, suggesting the critical importance of southern Brazil's coast, with about 1000km long, for African populations. While mtDNA analyses are useful to characterize the genetic diversity and trace the origin of individuals in feeding areas, we suggest further analyses with biparental nuclear DNA for a deeper understanding of the genetic composition, structure, and migratory routes for these populations, guiding future management and conservation initiatives.

Somatic growth rates of juvenile green sea turtles (Chelonia mydas) foraging in the Fijian Archipelago

Garrett E Lemons1, Calandra N Tuner Tomaszewicz1, Shritika S Prakash2, Katy Miller3, Jeffrey A Seminoff1, Susanna Piovano2

1NOAA, United States of America; 2School of Agriculture, Geography, Environment, Oceans, and Natural Sciences, The University of the South Pacific, Suva, Fiji; 3Vatuvara Private Islands, Suva, Fiji

Establishing key life history traits (i.e., somatic growth rates) for sea turtles produces insights into population demography and informs conservation efforts. Despite a plethora of studies on sea turtles over the past decades, there remain significant knowledge gaps for the demography of most populations. From 2015 – 2022, we measured size and somatic growth for 212 foraging green turtles (Chelonia mydas) captured at three foraging grounds in the Fijian Archipelago, tropical South Pacific. Mean size of all turtles was 57.3 ± 9.5 cm curved carapace length (CCL) with a size range of 41.1 – 104.0 cm ccl. We modeled a mean size-specific growth rate function for this foraging aggregation that was decreasing and non-monotonic. The mean growth rate for this foraging aggregation was 1.6 ± 0.1 cm/yr minimum CCL. We found variation in mean growth rates among the three foraging sites, perhaps owing to differences in habitat quality and/or the foraging ecology of growing turtles. Despite the observed differences, the range of Fijian juvenile green turtle growth rates align with those reported from foraging aggregations elsewhere in the tropical West and East Pacific. Establishing growth parameters for Fijian green turtles provides a baseline of information to inform ecological and health assessments vital to the development of future conservation plans.

Key Words

Sea turtle, South Pacific, GAM modeling

Assessing breeding sex ratios and relatedness among male and female breeders in a hawksbill turtle rookery

Kathryn Levasseur1,2, Cooper Oljeski1, Dyani Harrison1, Sylvia Stewart-Bates1, Phoebe Fowler1, Seth Stapleton2,3, Joseph Quattro4

1Davidson College, USA; 2Jumby Bay Hawksbill Project, Long Island, Antigua; 3University of Minnesota, USA; 4University of South Carolina, USA

Males are often missing from marine turtle demographic studies since they are absent from easily accessible nesting beaches. Genetic techniques provide a solution: male breeders can be identified indirectly by reconstructing paternal genotypes from the genotypes of hatchling cohorts and their known mothers. Breeding sex ratios can then be estimated by comparing the number of discrete paternal genotypes to the number of nesting females contributing to nests. This is especially important information for species with temperature-dependent sex determination to track potential shifts in sex ratios driven by climate change. These reconstructed genotypes can also be used to assess relatedness among male and female breeders. Here, we use microsatellites to reconstruct paternal genotypes from 12 nests sampled in 2014 from the Jumby Bay (JB) rookery in Antigua to strengthen a previous estimate of the JB breeding sex ratio, and to assess whether the breeding sex ratio is consistent in consecutive years. We then include these paternal genotypes in a pedigree reconstruction analysis with JB nesting females to assess relatedness among breeders, e.g. to determine if male breeders are offspring of long-term JB nesters. We report our findings on the updated JB breeding sex ratio and relatedness among male and female breeders, and discuss the implications of our findings on hawksbill population resiliency and male natal homing.

Genetic analysis of hawksbill sea turtle (Eretmochelys imbricata) by mtDNA sequences in the Yucatan Peninsula

Irlanda Esmeralda Gallardo-Alanis1,2, Fátima Yedith Camacho-Sánchez1,3, Blanca Idalia González-Garza4, Cesar Ley-Quiñonez5, Alan A. Zavala-Norzagaray5, Luis Angel Tello-Sahagún5,6, Mitzi C. Núñez-Solano7, Israel Llamas-Gonzalez7, Caterine E. Hart8, A. Alonso Aguirre9, José Alberto Narváez-Zapata110, Miguel Angel Reyes Lopez1

1Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Mexico; 2George Mason University; 3UAT-UAMRA; 4Mar y Sierra Salvaje A.C; 5Instituto Politécnico Nacional, CIIDIR Sinaloa; 6Estación Biológica Majahuas; 7Eco Mayto A. C; 8Centro de Investigaciones oceanicas del mar de Cortés, Mazatlán, Sinaloa; 9Warner College of Natural Resources, Colorado State University; 10Industrial Biotechnology Laboratory, Centro de Biotecnología Genómica, Instituto Politécnico Nacional

The biodiversity of sea turtles plays a significant role in Mexico, as it is home to 6 out of 7 existing species in the world. Hawksbill sea turtle (Eretmochelys imbricata) is endangered both in Mexico and globally. This study aims to increase the understanding of the genetic population for hawksbills obtained in females, hatchlings, and juveniles in the Mexican Caribbean and Pacific. The analysis of haplotypic and nucleotide diversity and genetic divergence in hawksbill populations in Mexico revealed 5 new Mexican haplotypes compared to those previously reported. The haplotype network confirmed the separation between Atlantic and Pacific populations. In the Atlantic, there was a higher overall diversity of haplotypes, with at least three groups of redundant haplotypes indicating better population conservation. In the Pacific and Mexican Caribbean, no redundant haplotypes were found, and an emerging haplotype diversity was observed, suggesting a potential population expansion. Genetic divergence in Pacific’s nesting turtles showed moderate haplotypic diversity (h= 0.4891) and low nucleotide diversity (π = 0.00057), while in the Atlantic Caribbean, populations exhibited below-average haplotypic diversity (h= 0.2356) and low nucleotide diversity (π = 0.00038). This indicates a vulnerability of hawksbill turtle populations. High FST values between Mexican populations in the Atlantic and Pacific (FST = 0.69741) suggest limited genetic flow between populations, emphasizing the importance of conserving individual populations of the hawksbill turtle. A better knowledge of the diversity and distribution of sea turtles can lead, based on these results obtained, to the implementation of better conservation strategies, such as a study of protection of the migration and feeding areas of the Mexican Caribbean, as well as aspects interaction of this population with others from the Atlantic or the Caribbean itself.

Updating haplotypes for Antigua & Barbuda and re-analyzing rookery structure in the Eastern Caribbean

Kathryn Levasseur1,2, Johana Monzon1, Dyani Harrison1, Cooper Oljeski1, Sylvia Stewart-Bates1, Seth Stapleton2,3

1Davidson College, USA; 2Jumby Bay Hawksbill Project, Long Island, Antigua; 3University of Minnesota, USA

Mitochondrial haplotypes have been used in marine turtle studies for decades to delineate rookeries and to link rookeries to foraging grounds, shedding light on population structure, natal homing, and habitat connectivity. These studies rely on robust sample sizes from many locations to accurately characterize haplotypes. New samples (n=74) were collected from hawksbills nesting in Antigua and Barbuda, including samples from the west coast of Barbuda and mainland beaches of Antigua that previously had low sample sizes. We sequenced the 740-bp segment of the mitochondrial control region, edited sequences with BioEdit, and matched our haplotypes with known haplotypes in BLAST. We then re-analyzed rookery structure (pairwise Fst) in the Eastern Caribbean using newly published data from the region. We found similar haplotype frequencies to those previously reported for Jumby Bay, mainland Antigua, and Barbuda. The Barbuda rookery contains only one haplotype (A20) that is rare in Antigua, even after increasing the sample size from 18 to 34. We also identified two new haplotypes for Antigua and Barbuda that are typically found in hawksbills nesting in Mexico (A23) and Brazil (A61). Lastly, we report on rookery structure in the Eastern Caribbean and discuss implications for natal homing behavior. These results, especially the Barbuda rookery with its regionally unique haplotype composition of 100% A20, could be helpful for updating mixed-stock analyses.

Evaluating the green turtle new colonisation of the Mediterranean through genomics and satellite telemetry

Gisela Marín-Capuz1, José Luís Crespo-Picazo2, Nathan J. Robinson2,3, Lucia Garrido4, Ana R. Patrício5,6, Simon Demetropoulos7, Dimitris Margaritoulis8, Jane Hardwick9, Imed Jbri10, Marta Pascual1, Cinta Pegueroles1,11, Carlos Carreras1,11

1Departament de Genètica, Microbiologia i Estadística and IRBio, Universitat de Barcelona, Avinguda Diagonal, 643, 08028, Barcelona, Spain; 2Fundación Oceanogràfic de la Comunitat Valenciana, Gran Vía Marqués del Turia 19, 46005 Valencia, Spain; 3Institut de Ciències del Mar, Spanish National Research Council - Consejo Superior de Investigaciones Científicas, Barcelona 08003, Spain; 4Fundación para la Conservación y la Recuperación de Animales Marinos (CRAM), E-08820, El Prat de Llobregat, Barcelona, Spain; 5MARE – Marine and Environmental Sciences Centre / ARNET – Aquatic Research Network, Ispa – Instituto Universitário de Ciências Psicológicas, Sociais e da Vida, Lisboa, Portugal; 6Centre for Ecology and Conservation, University of Exeter, Penryn, UK; 7Cyprus Wildlife Society, P.O. Box 24281. Nicosia 1703, Cyprus; 8ARCHELON, the Sea Turtle Protection Society of Greece, Solomou 57, GR-10432 Athens, Greece; 9Department of Environment, PO Box 10202 Grand Cayman KY1-1002, Cayman Islands.; 10BIOME Lab Sfax Faculty of Sciences, University of Sfax, Route Soukra 1171, Sfax, Tunisia; 11Should be considered senior authors

In the context of the global biodiversity crisis, it is crucial to identify management and conservation units of marine species as well as the potential colonisation of new habitats. The green turtle (Chelonia mydas) is a migratory species that can establish long-distance connections between widely separated areas while maintaining population differentiation due to philopatry. In the Mediterranean, nesting green turtle populations are concentrated in Turkey, Cyprus and Syria. However, in the last years, the species seems to be expanding its distribution as sporadic nests of this species have been found in new Mediterranean areas, and sexually mature individuals have been recorded in the western Mediterranean. To assess the origin of these potential colonising events, we genotyped with 2b-RAD individuals from the 3 green turtle Regional Management Units (RMU) that could potentially contribute to these events: North Atlantic, South Atlantic and Mediterranean (N = 15; 5 individuals from each RMU). With these genotypes, we assessed the current genetic differentiation among the three analysed RMUs to build a population genomic baseline. Additionally, we genotyped 7 hatchlings from 3 sporadic Mediterranean nests (2 in Crete, Greece and 1 in Tunisia), and 3 out of 4 adult individuals tagged with satellite telemetry in the western basin. By combining genetic and tagging information, we assigned tagged individuals to their potential source populations and assessed their dispersal patterns within the Mediterranean. The three RMUs were highly differentiated and all the individuals from the baseline clustered perfectly in the three RMUs, indicating the high potential of genomics for detecting population structure and for individual assignments. Furthermore, all the potential colonisers were satisfactory assigned to one of the source RMUs using genomic data. We detected that the breeders of one of the sporadic nests were from the distant South Atlantic RMU while the breeders of the two other nests were from the closest Mediterranean RMU, showing that this starting colonisation has multiple origins. The four tracked individuals (all of them larger than 73 cm CCL) comprised a potential adult male, one confirmed adult male and two females with mature follicles, indicating their potential to nest. The three adult individuals with genomic data also originated in these two RMUs, while an Atlantic mtDNA haplotype could be sequenced from the remaining individual lacking genomic data. Our combined telemetry and genomic data provide for the first time the movements of individuals of Atlantic origin along the north Africa coast, where we detected the nest of Atlantic origin, and its exit trajectories out of the Mediterranean. Additionally, our findings shed light on the movements of an adult of Mediterranean origin through the western basin, thereby unveiling new migration routes for both Atlantic and Mediterranean populations. These evidences suggest an incipient double colonisation of green turtles in the Mediterranean probably associated with climate change, by two distant populations without historical mixing. Finally, our study provides a proof of concept for the application of genomics in sea turtles, enhancing the current knowledge of population structure and individual assignments for its implementation in management decisions.

The mystery of bimodal nesting seasons in marine turtles

Marc Girondot

Université Paris-Saclay, France

The seasonality of egg-laying in marine turtles is a well-known phenomenon that has been exploited to determine population trends based on an integration of the number of female emergences or nests during a season. However, there are situations where several peaks in female emergence may have been detected during a season. We explore two such situations, one involving leatherback turtles laying eggs in French Guiana and another involving green turtles in the Indian Ocean. In both cases, we demonstrate the presence of bimodal nesting season with a new statistical model. Using this model, we show that estimates that do not take this bimodality into account can provide biased results both in terms of describing phenology and quantifying the number of nests. The origin of these different groups of females is discussed based on available information. This new model opens the door to a more rigorous analysis of egg-laying seasonality in sea turtles. Such rigor is essential in a context of climate change, where shifts in seasonality can have a major influence on these species, which have temperature-sensitive sex determination. Finally the presence of bimodal nesting season is analyzed worldwide.

Implications from low remigration rates of nesting females in the North Pacific population of loggerhead turtles.

Yoshimasa Matsuzawa1,2, Takashi Ishihara1,3, Kojiro Mizuno4,5, Mitsuharu Kume5, Ryoko Masuyama5, Shizue Mizutani5

1Sea Turtle Association of Japan; 2Shikoku Aquarium; 3AQUARIUM x ART átoa; 4Amami Marine Life Research Association; 5Turtle Crew

Nesting grounds for the North Pacific population of loggerhead turtles are restricted to beaches in Japan. Researches have been continued in some of the major nesting sites to identify individual loggerheads by tagging them. Those results indicate that only about 30% of the individuals remigrate to the same beaches after a few years of nesting. This means that either the tags have dropped off by the time of the return, they have shifted their nesting beaches, or the survival rate after nesting is low. Previous studies have shown that the percentage of all tags lost during the remigration interval is 2.3, 2.0, and 13.2% for 2-, 3-, and 4-year remigrations, respectively. Using PIT tags, which are unlikely to be lost, the effect of tag loss on individual identification will be reduced in this study. If many of the tagged nesting females had changed beaches, the new nesting sites should include beaches in Tanegashima Island, Kagoshima prefecture, which occupy higher percentage of total nesting counts in the population, and have not been surveyed for individual identification. Therefore, we began nighttime surveys for individual identification on Tanegashima Island since 2015, focusing on an area of high nesting densities. At the time females were found on the beach, flipper tags and PIT tags were attached after checking the presence of existing tags. Then, the straight carapace length (SCL) was measured. A total of 208 individuals were identified by the 2023 season. Remigrations over the years were confirmed 28 times by 21 individuals, with 3 individuals remigrating twice and 2 individuals remigrating 3 times. The remigration rate for loggerheads nesting on Tanegashima Island was estimated to be approximately 20-30%, taking into account areas and times when surveys could not be conducted. It was roughly at the same low level as other nesting sites. From the identification tags, the shift in nesting sites was confirmed for 5 individuals (2.4%): 4 from the neighboring Yakushima Island to Tanegashima Island and 1 from Tanegashima Island to Yakushima Island. It was strongly suggested that the low remigration rate was not primarily due to a shift in nesting sites. Thus, it is suspected that the main cause of the low remigration rate of nesting individuals is the low survival rate while remigration interval. The determinations of the factors that cause mortality after nesting need to be as specific as possible.

Where did they go? Alarming lack of juveniles raises concern at Tubbataha

Nicolas Pilcher1, Angelique Songco2, Rizza Araceli Salinas3, Maria Retchie Alaba2, Gerlie Gedoria2, Segundo Conales Jr2, Noel Bundal2, Jeffrey David2, Crisencio Caranay Jr.2, Rowell Alarcon2

1Marine Research Foundation, Malaysia; 2Tubbataha Reefs Natural Park, Philippines; 3Biodiversity Management Bureau, Philippines

The Tubbataha Reefs National Park is a World Heritage Site and an important foraging ground for green turtles Chelonia mydas. Since 2010 the population has been periodically assessed via in-water sampling that includes tagging, measuring, genetic sampling, and laparoscopy, with sampling of a average of 200 turtles of all age classes during each of the six seasons in which the study has been conducted. The data from the laparoscopy procedures is of critical importance to this presentation.

In the first three seasons of sampling (2010, 2014 and 2015) the population was primarily comprised of juvenile sea turtles (~79 to 90% juvenile) but by 2016 and 2019 notable changes were apparent: Juvenile turtles comprised only slightly more than 50% of all turtles, and by 2023 juveniles comprised only 25% of all turtles, and less than both sub-adults and adults.

Tubbataha was considered a juvenile development ground up until recently, and the smallest turtles on record were ~35cm which we classified as new recruits to the foraging area. No turtles smaller than this size have ever been recorded despite substantial diver and ranger activity, so that while there is a degree of nesting on the small islets in the TRNP, it is not believed these turtles remain resident from hatchling stages. It is presently unknown if turtles that hatch at Tubbataha return to Tubbataha in subsequent years as foraging animals. Laparoscopy data indicates that turtles previously classified as juveniles have progressed to sub-adults, and sub-adults have progressed to adults. We believe that Tubbataha continues to function adequately as a development feeding area.

The gradual shift in proportions of juveniles versus sub adults and adults is of grave concern, as this signifies that somewhere along the ‘production line’ juvenile turtles are being removed from the population, or are not being produced. The Turtle Islands Park and the Turtle Islands Wildlife Sanctuary, the largest combined green turtle rookery in SE Asia, and also in the Sulu Sea where Tubbataha lies, continues to increase in number of nesters and production of hatchlings. Similarly, we are unaware of any ‘new’ foraging area where turtles may have shifted to. We believe that hatchling production is not the culprit, and this points to either bycatch or intentional poaching as potential reasons behind the gradual loss of juveniles at this site.

Shout-out to loggerheads in Brazil: Nesting trends from 1991 – 2019

Gustavo David Stahelin1, Paulo Barata1, Paulo Lara1, Nathalia Berchieri1, Alexsandro Santos1, João Carlos Alciati Thomé2, Cecília Baptistotte2, Daniella Torres de Almeida1, Daniel Nascimento3, Jaqueline Castilhos1, Bruno Giffoni1, Danielle Monteiro4,5, Maria Ângela Marcovaldi1

1Fundação Projeto Tamar, Salvador, BA, Brazil.; 2Centro TAMAR-ICMBio, Vitória, ES, Brazil.; 3Reserva Particular do Patrimônio Natural – Fazenda Caruara, São João da Barra, RJ, Brazil.; 4Laboratório de Estudos para a Pesca Responsável – Instituto de Oceanografia – Universidade Federal do Rio Grande, Rio Grande, RS, Brazil.; 5Núcleo de Educação e Monitoramento Ambiental – NEMA, Rio Grande, RS, Brazil.

Population size is a critical metric for endangered species population assessments. Abundance can be particularly challenging to estimate for migratory and complex life cycle species, in which individuals may be distributed across an entire ocean basin. For sea turtles, one of the main parameters used for population assessment is the annual number of nests. Loggerhead sea turtle (Caretta caretta) nesting in the Southwest Atlantic Regional Management Unit (RMU) occurs along the coast of Brazil, where the main nesting sites have been monitored since the 1980s by Projeto Tamar. Here, we present a reassessment of nest abundance trends for the main loggerhead sea turtle rookeries in Brazil. Nesting sites were grouped into three areas, based on geographic distribution and genetic substructuring: Sergipe and northern Bahia states (SE/BA), northern Espirito Santo state (ES), and northern Rio de Janeiro state (RJ). Nest abundance was estimated using daily nest count data from each nesting season in the period 1991-2019 for SE/BA and ES and 2001-2019 for RJ. We evaluated trends in nest abundance for each rookery (SE/BA and ES from 1991 to 2019 and RJ from 2001 to 2019) and for all rookeries combined (from 2001 to 2019) using generalized additive mixed models with a negative binomial distribution. We observed an overall increasing trend in the number of nests for all evaluated areas over time. The number of nests increased from 1,464 in 1991 to 5,330 in 2019 in SE/BA, from 485 to 2,711 in ES during the same period, and from 809 in 2001 to 2,389 in 2019 in RJ. For all rookeries combined, the number of nests increased from 4,274 in 2001 to 10,430 in 2019. Clutch frequency and remigration intervals for this RMU have not changed since the 1990s, indicating that the increased number of nests observed could be linked to a greater abundance of nesting females. This is a major finding that supports the recent change in the conservation status of loggerheads in the Brazilian Red List from Endangered to Vulnerable. Fundação Projeto Tamar uses an adaptive threat management approach with environmental education and social inclusion as the backbone for local community engagement toward conservation. Eradication of nesting female killing and nest poaching are likely the main reasons for the nest abundance recovery reported here. However, other threats, such as fisheries bycatch, coastal development, and animal nest predation, require continuous monitoring and implementing adaptative mitigation measures to ensure persistent population growth.

Helminth Infection of the Loggerhead Sea Turtle Caretta caretta along the Tunisian coasts

Wiem Boussellaa1, Hamed Mallat2, Maroua Hrizi2, Imed Jribi2

1SZN; Stazione Zoologica Anton Dohrn di Napoli, Italy; 2Faculty of Sciences of Sfax

Despite their potential ecological and environmental effects, parasites of sea turtles remain an underestimated component of ecosystem functioning. In Tunisian coasts, despite the Gulf of Gabès is an important foraging and wintering area in the Mediterranean Sea, the parasite fauna of the loggerhead sea turtles, Caretta caretta, remain poorly known.

Here, we provide a new data on the presence of 9 parasite species in 10 individual loggerhead sea turtles Caretta caretta stranded along the Gulf of Gabès between June 2021 and August 2022. Analysis of variance (ANOVA) was applied among localities of stranded loggerhead sea turtles and prevalence of endoparasites was used to highlight any relationship between the parasites and the origin of the hosts.

The necropsies revealed the presence of three helminthic species found in the stomach and intestine (3 Digenea, 2 Nematoda and 2 Cestoda) and two species of ectoparasites (one Copepoda and one Annelida).

Among the Helminth parasites of Caretta caretta, Nematodes present the highest prevalence of infection (83.3%) followed by Digenea (66.6%) and Cestoda (33.33%). ANOVA showed significant differences (p < 0.001) among the data used.

This work provides valuable information on the parasite fauna of loggerhead sea turtles. Due to the scarcity of sea turtle parasite studies in Tunisia (only one, Karaa et al., 2019), it is reasonable to suppose that parasite species diversity in sea turtles of Tunisian coasts is considerably higher than reported to date. Further studies appear necessary to outline the parasitic fauna of C. caretta on Tunisian coasts.

Skin lesion in aquaculture green sea turtle, Chelonia Mydas

Muhammad Nasyrul Adly Mohd Afandy, Faizah Aplop, Mohd Uzair Rusli

Universiti Malaysia Terengganu, Malaysia

The green sea turtle, Chelonia mydas (C. mydas) travels thousands of ocean miles for most of its life, which makes it difficult for us to observe its physiological personalities and life histories. For that reason, sanctuaries are established to protect, closely monitor, and observe the various threats to the species and conserve the population of these species, given its current endangered status. In Malaysia, The Turtle Conservation and Information Centers (TCICs) was established by the Malaysia Department of Fisheries to provide information on sea turtles and support conservation efforts through rehabilitation, research, hatchery establishment, and awareness programs. Unfortunately, there has been an increase in skin lesion disease in the captive C. mydas population in TCICs especially in Segari, Perak which causes are still a biological mystery. Skin lesion is a complex group of diseases that can have a genetic-related basis which raises concern among the conservation team. The causes of the skin lesion may include external factors such as humidity, conservation center environment, water pollution, pool capacity, and diet. At the same time, genetic mutation may also be the contributing factor of the increasing skin lesion in C. mydas. As of to date, the genomic profile of the C. mydas has never been explored, which inquires whether the disease affects the species to its genome. To investigate this issue, blood samples from six C. mydas were collected where the DNAs had been extracted; two samples from the healthy wild C. mydas from Chagar Hutang, Pulau Redang, Terengganu and two samples from healthy and unhealthy captive C. mydas in TCIC Segari, Perak respectively. Using genome sequencing technology, the whole-genome sequence data of C. mydas were obtained from their DNA samples and the entire genome were reconstructed through genome assembly processes. In this study, we intend to explore and use two potential computational techniques based on deep learning methods known as DeepVariant calling and DeepSV calling to identify genetic variants that can unravel some clues on skin lesion issues of C. mydas in captive population. The predicted genetic variant results of all group of C. mydas genome sequences from both deep learning methods will be compared, integrated and validated accordingly. Variant annotation will then be conducted to interpret potential impacts of these genetic variants on C. mydas gene functions, disease risks and therapeutic responses.

Clinical and radiographic evaluation of mortality leading cause in accidentally trawled sea turtles: Drowning or Gas embolism?

Delia Franchini1, Stefano Ciccarelli1, Carmela Valastro1, Francesco Caprio1, Davide Bellomo1, Daniela Freggi1, Pasquale Salvemini2, Antonio Di Bello1

1Sea Turtle Clinic, Department of Veterinary Medicine, University of Bari, Italy; 2WWF Turtle Rescue Center, Molfetta Bari, Italy


In the Mediterranean, very intensive fishing activity has a strong impact on the marine ecosystem and represents one of the main threats to large vertebrates of conservation interest, such as sea turtles (Casale, 2011; Vasapollo et al., 2019). Trawling fishery results in the highest probability of incidental catches of sea turtles and a high mortality rate in these animals (18%) (Lucchetti et al., 2019); in reference to mortality, to date drowning has been recognized as one of the main cause (Stabenau et al., 2013). In 2014, a clinical-pathological condition called “Gas embolism” (GE) was identified and linked to a high mortality rate (30-41%) (García-Párraga et al., 2014; Fahlman et al., 2017).

The aim of the present study was to identify the main cause of death of accidentally trawled sea turtles in the south Adriatic sea, through clinical and radiographic evaluation, and to define their mortality rate in a significant sample.

Between November 2017 and April 2023, a total of 1440 Loggerhead sea turtles (Caretta caretta) were referred for clinical evaluation at Sea Turtle Clinic (STC) of the Department of Veterinary Medicine of University of Bari . All the turtles were caught in trawl nets along the coastline of the southern Adriatic Sea and, of these, 33% showed radiographic signs compatible with GE, 3% radiographic signs compatible with drowning and 9% radiographic signs compatible with GE associated with drowning.

Out of 1440 turtles accidentally trawled in the southern Adriatic Sea, covered by this study, a total of 61 died (overall mortality rate: 4.24%) of which: 38/1440 (mortality rate: 2.64%) died from GE, 2/1440 ( mortality rate: 0.14%) died from drowning, 13/1440 (mortality rate: 0.90%) died from GE associated with drowning, 8/1440 (mortality rate: 0.56%) died for other pathological conditions not related to trawling.

96% (1379/1440) of the turtles accidentally trawled and delivered to the STC over a 7-year period were released back into the sea. More precisely, the following were released: 697 turtles without clinical and radiographic pathological signs, 551 affected by GE or GE associated with drowning, 91 affected by other pathological conditions not related to trawling and 40 affected by drowning. 92% (591/644) of the turtles affected by GE, drowning and GE associated with drowning, recovered in a period of time varying from 2 to 13 days, without any supportive pharmacological therapy, but thanks to housing in tanks outside from water or with a low water level, inside a room with a temperature of approximately 25-30 °C. Only in 5 turtles that suffered from severe drowning was the bronchial tree washed with sterile water.

The present study suggests that the leading cause of mortality in accidentally trawled sea turtles in south Adriatic sea is Gas embolism.

A multidisciplinary approach on the health assessment of loggerhead turtles undergoing rehabilitation: supporting their role as sentinels of marine litter

Montserrat Sole1, Arnaud Legrand2, Edith Bigot-Corbel2, Maria El Rakwe M3, Enora Prado3, Gaelle Blanvillain4, Albert Martinez-Silvestre5, Jose Luis Crespo6, Lucia Garrido7, Claude Miaud8, Fabien Aubret9, Pauline Provin10, Arnaud Charlery-Adèle10, Jean-Christophe Auguet10

1ICM-CSIC, Spain; 2Nantes Université, France; 3IFREMER, Brest, France; 4Virginia Polytechnic Institute and State University, Blacksburg, USA; 5CRARC, Spain; 6Fundación Oceanogràfic, Spain; 7CRAM, Spain; 8UAR CNRS, France; 9CEFE, Univ Montpellier, CNRS, EPHE-PSL University, IRD, Univ Paul Valéry, France; 10MARBEC, Université de Montpellier, CNRS, Ifremer, IRD, France

Sea turtles are proposed as sentinel species through Descriptor 10 of the European MSFD on marine litter with the goal "Properties and quantities of marine litter do not cause harm to the coastal and marine environment" in the assessment of ocean health. In the marine environment, microplastics (plastic material of < 5mm) constitute an emerging threat by itself, but also for the additives they structurally contain and/or the organic pollutants from the surrounding media that may be adsorbed to their surface. Marine turtles are long-lived animals with a life style and pelagic habits that make them particularly vulnerable to plastic litter. In addition to the use of sea turtles as bioindicators, the combined efforts between fishermen, researchers, veterinary and recovery centers should act together in the direction of improving not only their survival rates after incidental bycatch but also improving their health status after rehabilitation and before entering the natural marine environment. In this sense, the cooperation so far between ten research institutes has led to the CAOUA project “Assessment of the impact of micro-plastic pollution on the intestinal microbiota and the vulnerability of loggerhead turtles (Caretta caretta) in the Gulf of Lion. This project conducted in the NW Mediterranean region focusses on the use of about 100 loggerhead turtles undergoing rehabilitation in recovery centers during the period 2021-2023. Its main goal is to determine the link between turtles’s overall health status assessed with the aid of 1) well-established biochemical blood parameters, 2) the activity of plasmatic B-esterases, 3) the intestinal microbiota composition and microplastics content on their excreta. The existence of an association between microplastic incidence and intestine flora alterations (dysbiosis) could consequently affect their health performance that could be traced through immune alterations and neurotoxicity. Given the evidences of the link between microplastic exposure, immune depression and neural disorders in other animal groups, it is our goal to test the adequacy of loggerhead turtles as sentinels of microplastic pollution in the Mediterranean. Not only for the health implications it reports to this IUCN Red List Threatened Species but also to humans in the frame of the One Health concept. CAOUA is a pioneer successful project, which will be followed by the TORPP One Health consortium initiatives encompassing human health. These new proposals will include hospital and researchers from Nantes in France (Europe) and an additional partner, the overseas Pointe a Pitre Hospitals in La Guadeloupe (French Antilles). These new MIGUD and MIPMAT projects are under evaluation.

Traumatic Fibromas in Lepidochelys olivacea during rehabilitation: case report

Denyielim Elias de Oliveira1, Ana Clara Rigoni1, Paolla di Cavallieri Rodrigues1, Clara Sardinha1, Daniela Nóbrega2, Renato Leite Leonardo3, Joana Ikeda1, Daphne Wrobel Goldberg4

1Ambipar Response; 2Laboratório Pat Animal; 3Dr. Fish Soluções em Aquarismo e Veterinária Ltda; 4Projeto Albatroz

Fibroma is a benign neoplasm of fibroblasts with abundant collagenous stroma, of unknown etiology. However, there are occurrences of reactive, non-neoplastic lesions related to irritations/chronic trauma, common in the oral cavity of humans, called traumatic fibromas. In July 2022, an adult Lepidochelys olivacea with a curved carapace length (CCL) of 63 cm was brought to the Rehabilitation Center of Araruama (PMP-BC/ES) in Praia Seca, Rio de Janeiro, Brazil. The animal displayed good body condition and clinical signs of drowning, which were later confirmed in radiographs. Additionally, the examination revealed the presence of free air in the coelomic cavity (pneumoceloma). Due to the complexity of the condition and the persistent buoyancy alteration and swimming asymmetry, the rehabilitation period extended for approximately 10 months. Although the clinical condition gradually improved, the animal started to show stress-related behavioral changes, including reduced appetite and repetitive movements, often bumping into the walls of the 10,000L tank. Upon being moved to a larger 60,000L tank, the turtle's appetite returned, and there was a notable improvement in its behavioral patterns. Nonetheless, the growth of skin masses was noted in areas that had experienced greater friction within the smaller enclosure. In May 2023, following the remission of the initial clinical signs, the skin masses were surgically removed from the animal using a high-power surgical laser. Macroscopically, the lesions were nodular, with well-defined boundaries, measuring between 3 and 8 cm, and had a pedunculated insertion, smooth surface, soft consistency, and a rose coloration when cut. Some of the masses were still ulcerated due to constant friction with the enclosure's edges. Samples obtained during the surgery were preserved in 10% buffered formalin, subsequently processed, embedded in paraffin, cut into 4 µm sections, and stained with hematoxylin and eosin. The microscopic analysis revealed the proliferation of spindle cells in organized bundles, with slight anisocariosis and no mitotic figures, amidst abundant collagenous stroma, dilated blood vessels, moderate irregular acanthosis, and frequent ulceration. The clinical-pathological findings are consistent with traumatic cutaneous fibromas. The turtle recovered from the procedure in two weeks and was successfully returned to its natural habitat. Cases of cutaneous fibromas in chelonians are uncommon, and most described lesions were not linked to chronic trauma. While sea turtles might develop visceral fibromas associated with fibropapillomatosis, the localization and clinical-morphological aspects differ from those in this report. However, the findings resembled traumatic fibromas found in the oral cavity of humans, with the etiology attributed to constant friction with the tank edges. In such cases, it is recommended to reduce captivity-related stress and eliminate the traumatic factor, followed by the excision of the lesions, thereby minimizing the chances of recurrence. This report underscores the significance of identifying behavioral changes and potential chronic injuries during the rehabilitation of sea turtles, as well as the accurate diagnosis and treatment of this condition.

Health and hematological evaluation of captive hawkbills sea turtle in a rehabilitation facility in Thailand

Sirawich Srisiri1,2, Komkiew Pinpimai3, Thanida Haetrakul1,2,3

1Department of Veterinary Medicine, Faculty of Veterinary Science Chulalongkorn University, Bangkok, 10330, Thailand; 2Veterinary Medical Aquatic Animal Research Center of Excellence (VMARCE), Chulalongkorn University, Bangkok, 10330, Thailand; 3Aquatic Resource Research Institute, Chulalongkorn University, Bangkok, 10330, Thailand

Ensuring optimal health for captive sea turtles poses a significant challenge due to difficulties in replicating their natural diets and environments. Routine health monitoring is crucial to evaluate health status and to reflect their husbandry. In this study, the health status and hematological parameters of 13 captive hawksbill turtles (Eretmochelys imbricata) were examined. The turtles were from a rehabilitation station of by-catch sea turtles in Chonburi Province, Thailand, consisting of 1 male and 12 female adults of unknown age. The average straight carapace length and width were 59.13 cm and 44.96 cm, respectively.

The overall mentation and health of the turtles were in average condition. Five out of 13 turtles have few visible external lesions on the head, neck, or flippers, which are possibly due to overcrowding. Some individuals have the presence of purulent exudates on the lesions.

Blood samples were taken from the dorsal cervical sinus in a heparinized tube. The samples were submitted for hematological, and blood chemistry analysis. The average hematological values were as follows; hematocrit 29.77%, RBC 1.03x106 cells/ul, WBC 9.22x103 cells/ul. Differential WBC counts showed that some individuals expressed low monocyte counts. The RBC counts in 11 turtles were slightly higher than the reference values. Other hematological values and Blood morphology were within the normal limits. No blood parasite was found.

For blood chemistry values, elevated Alkaline Phosphatase (ALP), blood urea nitrogen (BUN), and plasma albumin values were observed in all turtles, with an average ALP of 133.15 U/L, BUN of 52.15 mg/dl, and Albumin of 2.11 g/dl. Phosphorus and uric acid were observed to increase in 2 different individuals. On the other hand, the AST value was lower than the reference value in 4 individuals. An individual showed an increased phosphorus (P) level despite normal Calcium (Ca). The Ca:P ratio in most individuals was close to 1, with an average of 1.03. Two individuals show an inverted Ca:P ratio with a value lower than 1.

Hypernatremia was also observed in 4 individuals, which is usually caused by dehydration. The plasma chloride and potassium were within normal limits.

Captive sea turtles usually receive diets that are different from their natural preference. Hence causing alterations in hematological and plasma chemistry value, or consequently impairing health status. In our case, these turtles received only assorted fish chunks, which are high in protein and phosphorus contents. This can lead to an increase in plasma BUN and phosphorus levels, which are commonly reported from captive sea turtles. Both parameters are direct metabolites from protein catabolism. In many published studies, regarding high P intake and low Ca intake, the plasma Ca:P ratio of captive sea turtles can be as low as 0.5.

In summary, this population of captive hawksbills exhibited average health, with potential diet-related hematological alterations. Ongoing monitoring is essential for the overall well-being of captive turtles and establishing baseline blood parameters aids veterinarians in providing timely care and interventions for any future health issues.

Caring for long-term sea turtle patients: exploring the potential of Environmental Enrichment strategies through the experience of Lampedusa Rescue Center, Italy

Andrea Badaile, Daniela Freggi, Aethus Salvatore Tuccio

Lampedusa Sea Turtle Rescue Center, Italy

The goal of rescue and rehabilitation efforts is to provide assistance to injured sea turtles, primarily due to human interactions, with the ultimate aim of releasing them back into their natural habitat. Assessing the long-term well-being of patients is a challenging task, especially for those individuals that may not be suitable for release due to their specific conditions, such as amputated flippers or severe illnesses.

These turtles may exhibit various behaviors and adaptations to their disabilities, influenced by factors like the duration of captivity and the characteristics of their holding tanks. Additionally, it's essential to consider the outcomes of turtles released after extended periods of rehabilitation and those with pre-existing disabilities before being rescued.

Prolonged confinement and sedentary behavior in tanks, as well as enduring stereotyped movements, can lead to a decrease in muscle mass in turtles and, consequently, potentially lower survival rates after release. The impact of these factors on their overall well-being and behavior remains relatively unknown. One potential approach to address these issues may be represented by environmental enrichment, combined with spacious tanks that allow the individuals to move freely and choose whether to interact or not.

Environmental enrichment (EE) encompasses a range of strategies designed to improve the well-being of animals in captivity or during rehabilitation. There are few documented cases in the literature of EE applied to sea turtles (all concerning captive animals in aquariums). Our goal was to test this procedure and quantify the potential enhancement of sea turtles' well-being during rehabilitation activity and whether this strategy can be considered a tool to increase the chances of survival of the animals and potentially their successful reintroduction into the natural habitat.

In this research, we conducted an EE experiment involving four long-term resident sea turtles, each facing specific challenges, such as missing or damaged flippers. We implemented four distinct types of environmental enrichmen

In this research, we conducted an environmental enrichment (EE) experience involving four of our long-term resident sea turtles, each of them facing specific challenges, such as missing or damaged flippers. We implemented four distinct types of environmental enrichment, including food-based, tactile, sensory, and mixed approaches, to improve their overall well-being.

We closely monitored individual behaviors and interactions with the enrichments to assess their effectiveness and potential benefits for long-term residents. The EE sessions occurred over two week intervals, alternating with two-week silent periods, and they were repeated over a span of six months. Subsequently, we analyzed the animals' interactions during these sessions to determine their engagement with the enrichment tools, potential improvements in their skills and whether this strategy could offer support to permanent residents unable to be released.

Surveying antibiotic resistance of gram-negative bacteria isolated from wild-caught green sea turtles (Chelonia mydas) and loggerhead sea turtles (Caretta caretta) of Florida, U.S.A.

Christina Cortes, Isabella Donadio Pizzolato, Nada Maher, Sarah Milton

Florida Atlantic University, United States of America

Antibiotic resistance is a growing concern due to the improper use of antibiotics. Not only is antibiotic resistance increasingly occurring in human populations, but it appears to be spreading in wildlife populations as well due to their overuse and misuse in medicine, farming, and industrial settings, and their subsequent release into watersheds. This project examined the prevalence of antibiotic resistant bacteria in the hindgut microbiome of green (Chelonia mydas) (n=61) and loggerhead (Caretta caretta) (n=47) sea turtles in Florida, USA. Using cloacal swabs, wild-caught juvenile to adult turtles were sampled from two sites in Florida: wild-caught, apparently healthy turtles were netted at the St. Lucie Nuclear Power Plant and turtles in rehabilitation were sampled from the Gumbo Limbo Nature Center. Samples were plated and incubated using MacConkey agar to select for gram negative bacteria. Bacteria were then transferred to Mueller Hinton agar plates and tested for antibiotic resistance against six antibiotics. These antibiotics were selected to represent the main classes of antibiotics as well as the antibiotics frequently used in rehabilitation settings: (amikacin (30 μg), ceftazidime (30 μg), ampicillin (10 μg), tetracycline (30 μg), ciprofloxacin (5 μg), and azithromycin (15 μg)). 83.3% of samples were resistant or intermediately resistant to at least one antibiotic, and 27.7% of samples were resistant or intermediately resistant to three antibiotics. Of the specific antibiotics, 61.1% of samples were resistant to ampicillin, 27.7% of samples were resistant to azithromycin, 50% of samples were intermediately resistant to ciprofloxacin, 11.1% were resistant to tetracycline, and 16.6% were intermediately resistant to amikacin. There were no statistically significant differences between species regarding antibiotic resistance profiles. Interestingly, the greatest degrees of resistance were found to antibiotics used in human medicine, rather than those commonly used in sea turtle rehabilitation facilities. The concern was that turtles could spread pathogenic antibiotic resistant bacteria to turtles and other marine wildlife in their own habitats, especially since release back into the wild is the goal of wildlife rehabilitation facilities. Beyond aiding in digestion and nutrient uptake, the gut microbiome impacts host health by producing metabolic compounds, excluding pathogenic microbes, and contributing to the development of host intestinal immune homeostasis and systemic immune systems. The overall goal of this study is to provide more information about the relationship between health and the presence of antibiotic resistance in the hindgut of Florida sea turtles, determine the types of bacteria found in the hindgut, and determine the prevalence of antibiotic resistance in wild Florida turtles. All work was performed under FWC Marine Turtle Permit #053.

Community livelihoods development as a sea turtle conservation tool in Sri Lanka

Thushan Kapurusinghe, Shyama Wijekulasuriya, Deshapriya Saman Rathnakumara, Vasantha Pahalawattaarachchi

Turtle Conservation Project, Sri Lanka

Five of the world’s seven species of marine turtle come ashore to nest in Sri Lanka. They are the Green turtle (Chelonia mydas), Leatherback turtle (Dermochelys coriacea), Loggerhead turtle (Caretta caretta), Hawksbill turtle (Eretmochelys imbricata) and the Olive Ridley turtle (Lepidochelys olivacea). Coastal communities of Sri Lanka depend on their surrounding natural resources for their survival and as a result of this, very important coastal habitats and coastal biodiversity such as the coral reefs, sea grass beds, mangroves, marine turtles and other coastal vegetation are under the threat of extinction. Coastal communities continue to use the coastal resources in destructive manner by violating the existing environmental laws due to their poor income. This complicated socio economic problem causes a great challenge to the government of the country. Marine turtles are slaughtered for their meat in some coastal villages and turtle eggs are robbed by poachers for sale or personal consumption. Coastal habitats are rapidly degrading due to anthropogenic causes such as hotel constructions, coastal cultivation, fisheries activities and aquaculture projects etc.

TCP aims to provide alternative livelihood options to those coastal communities whose lives are dependent on coastal resources as a conservation and management tool. TCP has employed former turtle egg collectors as turtle nest protectors and trained them as tourists’ guides to show the turtle nesting activities to the visiting tourists in 1996. Furthermore, TCP has introduced community Batik, sewing, coconut coir products, ornamental fish breeding, soft toys making, organic farming, beauty culture training, food processing, and tourism initiatives etc. as community livelihood development programmes. These programmes are not limited to a training programme. After the training programme, materials are given to the beneficiaries and further training on accounting, packaging, marketing and branding is provided. Loan schemes have been introduced to provide the initial capital for local businesses. TCP links these community livelihood projects with tourism initiatives and TCP volunteer programme. Foreign volunteers and tourists are actively engaged with activities such as making batiks, farming, fish breeding etc. and also they purchase many community products. In addition, TCP forms community based organizations (CBOs) to enable the community beneficiaries to work and act as a group increasing their efficiency and capacity. TCP conducts capacity development programmes and exposure tours to enhance the community skills and capacities.

Diversification of community livelihoods is an important fact since there can be a conflict among the community members if too many community members are doing the same business. Furthermore, there can be a shortage of supply in raw materials if they are locally collected. Factors such as the Corona Virus Pandemic, financial crisis, lack of tourism etc. have caused problems and disrupted the financial flow of community businesses but regaining slowly.

In recognition of TCP’s community livelihood development initiatives, the Ministry of Environment has awarded TCP the “Green Employment Award” in 2009 and most of these community livelihood development activities are still continuing.

Incidental Discovery of Materials, Equipment, and Methods through the Words of a Carey Craftsman.

Gilberto Rafael Borges Guzmán1,2,3, Héctor Barrios-Garrido4,5,6, Pedro Vernet1,2

1ProOcean; 2Fundación Científica Los Roques, Venezuela; 3Asociación Mexicana de Veterinarios de Tortugas; 4King Abdullah University of Science and Technology, Saudi Arabia; 5TropWATER, James Cook University. Australia; 6GTTM-GV, Venezuela

The hawksbill sea turtle (Eretmochelys imbricata) is critically endangered according to the IUCN Red List and the Venezuelan Red Book of Threatened Species. As recognized globally, their populations have been significantly reduced, primarily due to the use of their carapace for utilitarian instruments initially (cutlery, buttons, pipes, brushes, combs, musical instruments, guitar nails, etc.), followed by jewelry, ornaments, and spurs for fighting roosters. In Venezuela, these crafts experienced significant growth from the late 19th century until the 1970's when the prohibition on capturing wild species, including sea turtles, came into effect. This prohibition includes the use of their products and by-products.Despite this, the illicit production of objects using hawksbill shell persisted. Interestingly, over time, artisans grew older and passed away, reducing the number of skilled craftsmen. The younger generations showed less interest, alleviating pressure on the hawksbill sea turtle. This trend began in the 1940’s when plastic gained popularity. Those who remained gradually focused almost exclusively on making spurs for roosters, partly due to an inability to compete with the prices of illegally imported jewelry from Cuba, and partly because of the ongoing illegal demand for spurs. Illegality surrounding this practice has hindered researchers from understanding the details and secrets of this art. Presently, in Venezuela, amidst political and economic challenges, some artisans are abandoning these practices. During a casual conversation with one of them and through direct observation, convenient sampling was conducted, yielding the materials and recordings as a gift. The artisan noted that due to the "level of difficulty and time required to work with the shell," as expressed by a fisherman and artisan from eastern Venezuela, a resident of Los Roques National Park, the most critical nesting area in the southern Caribbean and collaborator of the conservation project, "alternative sources of income must be sought quickly." Unfortunately, many of these alternatives are also illegal. The collaborator has generously provided us with a complete set of tools for working with the shell, including elements he personally crafted for cutting, shaping, and polishing garments. Additionally, he provided a detailed explanation in his own voice, allowing us to record how each instrument or material is used. Here, we present the transcribed recording and photographs of each component exactly as they were received, in order to generate knowledge for the general population, to have the ability to identify, based on the objects used, if there are carey craftsman in the locality, since it allows them to know the tools and instruments for their production. Even though in Venezuela this activity is disappearing, some processes were known, but to date the complete set of tools and their functions were not available. Knowledge of its production will help identify the artisan and then be able to report and suppress said illegal activities.

*Teeny Tiny Neon Turtles: A reliable, accessible, and scalable minimally-invasive remote tracking method for post hatchling neonate sea turtles

Jenna Contuchio, Rita Mehta

University of California Santa Cruz, United States of America

Due to the logistical difficulties of tracking true neonate post-hatchling sea turtles, there are considerable knowledge gaps in our understanding of their in-water behaviors and dispersal within this age class. Tracking technologies have historically been restricted by the small body size and rapid growth of post-hatchlings and pose accessibility constraints by being cost-prohibitive. Here, we present a pilot study for two novel, inexpensive, and minimally invasive tagging options to remotely track and quantify post-hatchlings' dispersal, oceanic movements, and dive depth profiles. Our study aimed to discover uncomplicated, cost-effective treatments that will result in long-term retention of tag attachment along with remote detectability. We tested UV, fluorescing, and retroreflector treatments on the carapace of a deceased red-eared slider (Trachemys scripta elegans) turtle shell. Although Trachemys scripta elegans is a semi-aquatic freshwater species, we found this to be an acceptable replacement due to the lack of required permits and access to sea turtle hatchlings. Triangular-shaped 1cm marking tags weighing between 0.073 g and 0.126 g were applied using clear aquarium silicone, a product currently used in sea turtles for solar tag attachment. After a short curing period, we submerged the shell into a continuous flow seawater tank at 0.76 m with treatments; treatment replicates, and controls. The shell was mounted on a mechanical arm with a synchronous rotating motor at 3 rpm to imitate vertical movement in the water column. In addition, we also submerged one 1.27 cm corner cube retroreflector in the same tank for underwater clarity and reflectance testing. We captured images throughout the study to test emission detectability, material degradation, and tag stability. We investigated UV, fluorescence, and reflectance detectability levels using corresponding UV, blue, and green LED lights and UV and green handheld lasers for excitation. We tested treatment degradation using ImageJ to quantify the percentage of treatment materials lost over time. We used ImageJ to analyze the area loss of tags over the initial eight weeks. All UV, fluorescent, and retroreflector treatments readily persisted and were detectable for eight weeks. When writing this, our preliminary calculated degradation rate is less than 10%. Due to the low rate of decay and ease in detectability of these treatments, our work identifies a high success rate in using UV, fluorescent, retroreflectors, and corner cube marking tags as novel and practical tools for accessible and scalable remote tracking of marine organisms. Hyperspectral or multispectral optic communications instruments on remote sensing drones, wave gliders, long-range AUVs, and a suite of additional marine-specific monitoring devices which can be programmed to detect UV, fluorescing, retroreflector, and corner cube pattern emissions for use in individualized tracking of oceanic movements and dive depths in many marine animals across the globe. Our methodology indicates a high probability of success in tracking initial dispersal patterns, oceanic movements, and dive depths of post-hatchling neonate sea turtles from nesting beaches across the globe. (Manuscript in prep.)

Drone fight to FAIR dataset

Nick Mortimer1, Milica Stankovic2, Mathew A Vanderklif1, Chris Jacket1

1CSIRO Environment, Indian Ocean Marine Research Centre, Crawley, WA, Australia, 6009; 2Excellence Center for Biodiversity of Peninsular Thailand, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, Thailand 90112

Drones have become an important tool in monitoring coastal and marine ecosystems, for researchers, managers and local communities. Currently there is a lack of standardization and automation in workflows. Delivering analysis ready datasets is a difficult and challenging task, especially with the rapid development of drone technology. Building workflows based on open-source tools to deliver standard products that are ready for use in machine learning can enable researchers and communities to deliver FAIR (Findable, Accessible, Interoperable, and Reusable) datasets. We present a workflow that has been developed using open-source Python tools, to accept images from a range of drones, apply corrections to their position estimates and stores images with meaning full names in a regular directory structure while providing quality data management metrics and feedback. For habitat assessment the system builds a series of machine learning ready geo referenced tiles using direct geo referencing. This approach is fast, efficient and allows for multiple looks at the same area. For object identification we have adapted a popular opensource tool LabelImg to allow for efficient human classification of marine objects such as turtles and sharks. The workflow then produces a training set ready to be shared for use in machine learning.

The potential of passive acoustic monitoring to help inform conservation strategies of northwest Atlantic leatherback sea turtles (Dermochelys coriacea)

Derek M. Aoki1,2,7, Annie Page2, Justin R. Perrault1, Jeffrey R. Guertin3, Scott Benson4,8, Andrew DiMatteo5, Claudio Quesada-Rodriguez6, Aimee L. Hoover7, George L. Shillinger7,9

1Loggerhead Marinelife Center, Juno Beach, Florida, USA; 2Florida Atlantic University, Harbor Branch Oceanographic Institute, Fort Pierce, Florida, USA; 3Inwater Research Group, Jensen Beach, Florida, USA; 4Marine Mammal and Turtle Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Moss Landing, CA, USA; 5CheloniData LLC, Berthoud, CO, USA; 6Ecology Project International, Pacuare Reserve, Costa Rica; 7Upwell Turtles, Monterey, California, USA; 8Moss Landing Marine Laboratories, San Jose State University, Moss Landing, CA, USA; 9MigraMar, Bodega Bay, California, USA

The northwest Atlantic leatherback sea turtle (Dermochelys coriacea) migrates vast distances between subtropical nesting grounds and high latitude foraging grounds. While satellite telemetry is often used to track long-distance migrations, acoustic telemetry also provides presence data when animal-borne transmitters pass within an acoustic receiver’s detection range. As a result, acoustic telemetry can generate more detections, improve spatial resolution, and reduce positional errors compared to satellite tags, when within the detection radius of an acoustic receiver. Leatherback turtles that nest in Pacuaré, Costa Rica and southeastern Florida, USA forage along the continental shelf and/or in the Gulf of Mexico, where numerous active acoustic arrays are present. These arrays provide a unique opportunity to use acoustic telemetry to identify post-nesting locations of tagged individuals. This study aims to understand long-term post-nesting leatherback presence within the northwest Atlantic Ocean (NAO) and Gulf of Mexico from acoustic telemetry. During 2019–2023, 23 leatherbacks were tagged with Vemco V16-4x (Innovasea Systems Inc.) in Pacuaré Nature Reserve (PNR), Costa Rica (N=8), and Juno Beach, Florida, USA (N=15). As of July 2023, four PNR leatherbacks have been detected 66,783 times (mean ± SD: 16,710 ± 28,642 detections/female) by six acoustic receiver groups in the northeastern Gulf of Mexico (N=3), Scotian Shelf (N=2), and Mid-Atlantic Bight (N=1), with detections occurring up to 2.5 years after tag deployment. Fifteen leatherbacks tagged on Juno Beach have been detected 1,260 times (mean ± SD: 84 ± 66 detections/female) by 17 acoustic receiver groups ranging from the southeast Florida Shelf to the Scotian Shelf, with detections occurring up to ten months after deployment. As we continue to receive acoustic detections from the Ocean Tracking Network, results indicate that acoustic telemetry can be a viable method to obtain leatherback presence data if individuals are foraging in areas with an abundance of acoustic receiver arrays, as seen in the Gulf of Mexico. So far, leatherbacks in the NAO have displayed fewer detections, likely due to transiting and foraging in areas devoid of acoustic receivers; however, acoustic tagging efforts should continue to gain a better representation of leatherback presence in NAO shelf waters. Additionally, acoustic telemetry should be incorporated with other research techniques (i.e., satellite tracking) to improve in-water monitoring methods, particularity increasing resolution of coastal movements in areas where leatherbacks are susceptible to human interactions (i.e., fisheries and recreational vessel traffic) . These data can also provide valuable information for the conservation and management of this endangered subpopulation. For instance, working with fishermen to affix acoustic receivers to crab and lobster fishing gear (i.e., crab pots) can help identify when and where leatherbacks are interacting with fishing gear, and expanding acoustic receiver coverage in proposed offshore wind farm sites can shed light on how leatherbacks and other marine animals could interact with these structures. As such, continued passive acoustic telemetry studies of leatherbacks is necessary to obtain animal presence and behavior data to aid in developing mitigation strategies that minimize potential negative effects on leatherback welfare.

Comparing aerial and boat-based surveys to monitor offshore aggregations of olive ridleys in India

Muralidharan Manoharakrishnan1, Sadhwi Sindura Behera1, Sejal Worah1, Shashank Srinivasan2, Nandini Mehrotra2, Chandana Pusapati3, Vishrutha Rao3, Kartik Shanker3,4

1World Wide Fund for Nature-India; 2Technology for Wildlife Foundation, Goa, India; 3Dakshin Foundation, Bangalore, Karnataka, India; 4Indian Institute of Science, Bangalore, Karnataka, India

Olive ridley turtles annually aggregate in nearshore waters adjacent to the mass nesting sites in Odisha. Estimation of their densities has traditionally been carried out using manual survey techniques such as boat transects in nearshore waters. With the advancement of the use of aerial vehicles to monitor wildlife populations, unmanned aerial vehicles (UAVs) can be used to conduct robust, safe, and cost-effective assessments of marine turtle populations in coastal ecosystems.

In this study, turtles observed on the surface were counted using aerial videos captured by UAVs. These followed a line transect mirroring the travel path covered during the boat surveys, enabling a comparison between both survey methods. The UAVs were flown at a height of 95m above ground level and the surveys were conducted during daylight hours (0600-1200 hours) in a Beaufort Sea State range of 0-2. The number of sea turtles observed during the aerial survey in each photograph was determined manually by three independent reviewers and the angle and distance from the transect line were calculated after identifying all the turtle locations on the imagery. This was compared with the results from the boat transects which were estimated through the line transect surveys. As the image frame of the aerial surveys was 140-150m in width, a fixed-width transect design was used for the analysis. In comparison, the boat transects had longer sighting distances (>100m), making the encounter rate higher in some transects.

As the offshore aggregations of olive ridley turtles are known to be quite dynamic prior to mass nesting, the usage of aerial vehicles can be instrumental in reducing the effort of field monitoring. In this case, the use of UAVs resulted in reducing the transect survey duration by 2 hours. Additionally, with the advancement in Artificial Intelligence and Machine Learning tools the data analysis from the aerial surveys can be automated, thereby reducing reporting time.

Adopt, track, protect: leveraging digitalization for sustainable sea turtle conservation in malaysia

Faizah Aplop, Tuan Mustaqim Rosdan, Arizal Shamsil Rifin, Muhammad Nasyrul Afandy, Muhd Uzair Rusli

Universiti Malaysia Terengganu, Malaysia

Digital tools are revolutionizing conservation efforts by providing innovative solutions for engaging the public. By leveraging the power of digital platforms, we can connect with people from all walks of life, inspiring them to take action and make a difference for the planet. As we move forward, it is clear that digital tools plays an increasingly important role in ensuring the success of conservation efforts by allowing efficient data collection, management and storage. The Sea Turtle Research Unit (SEATRU) of Universiti Malaysia Terengganu (UMT) is embarking on this digitalization journey, starting with the implementation of the Turtle Imprinting Database System (TIDES). This public web-based database application system brings a multitude of benefits to SEATRU conservation efforts by enhancing sea turtle data management and analysis of vast amount of data. TIDES gathers and stores data on sea turtles' movements and behaviors using tagging and tracking technologies and offers adoption programs to the public based on this data. Adopters of the program receive regular updates and educational materials about their individual sea turtle, which aims to inspire ongoing commitment to sea turtle conservation and raise awareness about the importance of protecting these animals and their habitats. With the implementation of this database, stakeholders, researchers, organizations and even communities can communicate, collaborate on projects, and easily share information that could lead to more effective conservation initiatives.

Nest domes: an innovative strategy to mitigate the impact of climate change in the sex determination of sea turtles

Zulema Alejandra Guevara Oviedo1, Sara Giraldo2, Sergio Tenjo2, Daniel Payan3

1Rancho San Cristóbal CSL; 2Banana Boat; 3VML Colombia

Temperature is an essential factor in the development and biology of sea turtles and is crucial for their sex determination; currently, critical scenarios are being experienced as a result of climate change.

A solution was required to this drastic scenario, so in collaboration between Rancho San Cristobal, the Program for the Conservation of Turtles and Marine Mammals of Colombia (PROCTMM) and Banana Boat, Nest Domes were created: the first natural domes that have the function of regulating the sand temperature, whose purpose is to serve as a tool for protection of sea turtle nests. Six specimens were placed in the hatchery at Rancho San Cristobal, located in Cabo San Lucas, Baja California Sur, Mexico. After collecting and buried the nests, the dome was placed over them during the entire incubation period (45 days).

The temperature inside the nests was lowered to 4°C, allowing the hatchlings to fully develop until hatching. It is worth mentioning that everything was done on an experimental basis, that is, obtaining empirical results, observing the number of live hatchlings and comparing with other turtle seasons. For the next turtle season that is about to begin, data loggers will be placed to have more precise data on the effectiveness of Nest Domes and to check if sex parity is achieved.

Novel miniaturized satellite tags reveal diving behaviors of early-life stage leatherback turtles.

Tony Candela1,2,3, Jeanette Wyneken4, Peter Leijen5, Emily Turla4, Philippe Gaspar2, George L. Shillinger1

1Upwell, Monterey, CA, USA; 2Mercator Ocean International, Toulouse, France; 3Aquarium La Rochelle, La Rochelle, France; 4Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL, USA; 5Lotek Wireless, Inc., Havelock North, New-Zealand

After hatching, sea turtles disappear into the ocean and are not seen until many years later when they return to nest at natal regions or occupy adjacent waters. Within the sea turtle community, this period is commonly referred to as the “Lost Years”. Until recently, the very small sizes and prolonged dispersal phases of juveniles posed many challenges for the development of satellite tracking studies. Recent advances in tag miniaturization technologies and data compression algorithms have enabled researchers to undertake groundbreaking studies on the movements and dispersal of early-stage turtles. Among others, new tags are now equipped with solar cells and pressure sensors, extending tag lifetime while providing first-ever dive data for extended movements (> 3 days) of very small early-stage turtles with Straight Carapace Lengths ranging from 7.4 to 9.7 centimeters and weights ranging from 75 to 146 grams.

This study harnesses an unprecedented dataset gathered since 2020 from 25 very young juvenile leatherback sea turtles released off eastern Florida. In addition to providing baseline data on dive behavior, the tags provide metrics such as the distribution of time spent at distinct depths, the daily maximum depth reached, and the temporal fraction of the day spent underwater. Tag-derived data present an opportunity to examine intricate relationships between diving behavior and other variables such as the time since the release, the carapace length of tracked individuals or physical variables of the dynamic marine environment of the Gulf Stream, using a suite of remotely sensed and modeled data (i.e., water temperature, significant wave heights).

The findings derived from this novel dataset offer new perspectives into the diving behavior of early-stage leatherback sea turtles and, relating dive behavior to environmental variables and others, provides an understanding of how oceanic conditions can affect dispersal during early life stages. Notions of adaptation to the open ocean, thermoregulation behavior or optimization of the swimming conditions are addressed in the present study, and some correlations are found. This study promises to offer new insights into the adaptation strategies, and survival mechanisms employed by early-life stage turtles, effectively demystifying the "Lost Years". This research informs sea turtle conservation and management by bolstering our understanding of the ecological dynamics governing the enigmatic and poorly understood early life stages.

Utilization of Artificial Intelligence (AI) to automate sea turtle identification in low water visibility in Uruguay, South Western Atlantic.

Rafael Rosa1,2,3, Natalia S. Teryda1,4, Gabriela M. Vélez-Rubio1,2,5

1Karumbé NGO, Av. Rivera 3245, Montevideo, 11600, Uruguay; 2Departamento MEDIA, Centro Universitario Regional del Este (CURE), Universidad de la República, Rocha, Uruguay.; 3Instituto de Computación (INCO), Facultad de Ingeniería, Universidad de la República, Montevideo, Uruguay; 4School of Natural Resources and Environment, University of Florida, USA.; 5Sección Oceanografía y Ecología Marina, Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias, Universidad de la República, Montevideo, 11400, Uruguay

Sea turtles are highly migratory and emblematic species that are threatened by multiple anthropogenic factors. To guarantee the sustainability of sea turtle populations, it is essential to have innovative tools and technologies that complement traditional research techniques. Recently, Artificial Intelligence (AI), built from neural networks, has emerged as a promising and revolutionary tool for the conservation and monitoring of species due to its efficiency and accuracy, processing speed and recognition of complex patterns in big databases. For this reason, AI promises to become an asset for the study of sea turtles. Consequently, our goal is to apply an AI-based tool to automate the recognition of sea turtles in population studies. Specifically, we aim to automate the sea turtle detection process from video images collected with unmanned aerial vehicles (UAVs or drones) in low water. For this, we used the Yolov7 model (convolutional neural networks) to analyze videos obtained with drones collected between December 2021 - May 2022 in Cerro Verde e Islas de La Coronilla Coastal-Marine Protected Area, Uruguay. The model analyzes the set of frames that make up each of the videos. The process requires two phases, first a training period with one set of images followed by validation with a different dataset. The second phase involves the application of the model to a third dataset which represents a testing process. Finally, we extracted the model metrics that were used to quantify the quality and accuracy of the model. Subsequently, we compared the results from the model to a manual count of turtles in the videos.

We started by training the model to identify turtles in low water clarity. The model was trained with a set of images with 66% training images, 17% training validation images and 17% training testing images. Turtles were detected in validation videos with a confidence coefficient above C=0.60. Although these results are preliminary, they are a first step to continue training the model to detect individuals in different water conditions and indicate that it is possible to detect turtles from the rest of the image over the water.

The adoption of AI tools, particularly neural networks, have proven to be an effective strategy for identifying different taxa in optimal environmental and oceanographic conditions before. Here we showed that AI is also useful for areas with low water visibility, like the study region. Next steps include to use more images of estuarine or high turbidity areas in the South Western Atlantic Ocean.

Identification of sea turtle species using MALDI-TOF/MS

Rangsima Sujittosakul1, Sittiruk Roytrakul3, Siriwan Thaisakun3, Ekarit Duangmala4, Watchara Sakornwimon5, Kirsty Magson6, Patcharaporn Kaewmong7, Stephen Dunbar8, Thanida Haetrakul1,2

1Department of Veterinary Medicine, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand; 2Veterinary Medical Aquatic Animal Research Center of Excellence, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand; 3Functional Proteomics Technology Laboratory, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani 12120, Thailand; 4Ao-Siam National Park, Prachuab Khiri Khan 77140, Thailand; 5Marine and Coastal Resources Research Center (Central Gulf of Thailand), Chumphon 86000, Thailand; 6New Heaven Reef Conservation Program, Surat Thani 84360, Thailand; 7Phuket Marine Biological Center, Phuket 83000, Thailand; 8Loma Linda University, California 92350, United State

Sea turtles are reptiles belonging to the order Testudines and are among the most threatened groups of marine vertebrates. Sea turtles significantly contributions to the maintenance of both aquatic and terrestrial ecosystems by performing vital functions, such as facilitating nutrient cycling within and between ecosystems, and aiding the restoration of degraded environments. Populations of sea turtles continue to decline due to declines in prey, habitat loss, direct take of eggs and individuals for human consumption, traditional medicine, international pet trade, and illegal wildlife trafficking. Female sea turtles lay eggs that are in early embryo development. After incubation, young hatch from the eggs to the external environment. The eggshell serves a physicochemical function to protect the developing embryo from physical damage, defending against microbial invasion, facilitating gas exchange, and acting as a source of calcium for the embryo. Although the eggshell membrane provides a generalized foundation for calcification, differences in eggshell structure among sea turtle species may be based on compositional differences in membrane peptidome. Research on eggshell proteome and peptidome has focused mainly on avian eggshells, due to the poultry’s commercial priority and the availability of large numbers of samples. Since the methods used to identify animal species are mainly based on DNA analysis, DNA barcoding methods play a crucial role in species identification because of the advantages of specificity and sensitivity. However, this method is not always expedient for routine species identification due to the high costs and many steps involved in the working procedure. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) is a potential tool for species identification based on protein composition by generating peptide barcode signatures (spectra) from protein extracts of organisms. MALDI-TOF/MS is a reliable, efficient, and high-throughput technique useful for species identification in other taxa. Since studies using peptidome analyses of chelonians are extremely limited, we aimed to validate species differentiation and identification, and to present a spectra of peptide barcodes for sea turtle eggshell membranes.

A total of 105 post-hatching samples were obtained during the nesting season, consisting of 75 hawksbill (Eretmochelys imbricata), 15 green (Chelonia mydas), and 15 leatherback (Dermochelys coriacea) eggshells. MS spectra and peptide patterns were analyzed by using the Metaboanalyst software, respectively. Results differed in sea turtleeggshell membrane and peptide spectra demonstrating unique MS spectral peaks for hawksbill, green, and leatherback turtles.

The use of the MALDI-TOF/MS approach demonstrated effectiveness as a tool for developing nongenetic identification methods by using turtle eggshell membranes. This method can provide rapid, sensitive results for minimal costs, while increasing the ease of sample collection by utilizing eggshell membranes. However, the limitation of this study is that the current spectral database requires improvement in terms of both species coverage and intra-specific variation, thus enhancing analysis performance. Future studies may be focused on identifying peptide biomarkers from selected peaks for target species, and detecting the functionalities of identified peptides.

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