Tun Mustapha Park (TMP) is a marine protected area (MPA) in northern Sabah, Malaysia. It is known as foraging and nesting grounds for marine turtles; however, available data are scarce and have not been thoroughly analysed. Comprehensive information on foraging and nesting marine turtle within TMP remain largely unexplored, yet it is crucial for effective marine turtle conservation. In-water study spanning 23 days from 5 April 2019 to 16 August 2020 was conducted. Foraging grounds at Kudat Mainland and Balambangan Island were identified. We recorded 94 individual green turtles (Chelonia mydas) and one juvenile hawksbill turtle (Eretmochelys imbricata). These green turtles have curved carapace length (CCL) ranging from 36.0 to 105.5 cm (n = 94; mean 57.2 ± 13.0 cm). The captured turtles were categorized as juveniles (80.85%), subadults (14.9%), and adults (4.25%). Genetic analysis revealed 12 haplotypes from the green turtle samples, with both foraging aggregations exhibiting similar genetic compositions. Mixed-stock analysis (MSA) indicated the primary natal origin as the Sarawak and Sabah Turtle Islands Park nesting populations, underscoring TMP's importance as foraging grounds, especially for nearby rookeries. In addition, we analysed 12 years of nesting marine turtle data obtained from community-based beach monitoring and hatchery operations, covering the period from 2009 to 2020. This initiative, led by WWF-Malaysia in collaboration with government agencies, encompassed 11 nesting beaches. The beach monitoring surveys documented a total of 85 green, 23 hawksbill, and three olive ridley turtle (Lepidochelys olivacea) nests. The 12-year data analysis revealed TMP hosts a smaller nesting population compared to other Malaysian sites, an increasing nesting trend, and highlighted distinct nesting seasonality and hatching success patterns between green and hawksbill turtles. The nesting data analysis also demonstrates that community-based monitoring is essential for the conservation of marine turtle populations Malaysia. Both in-water and nesting beach surveys emphasizes the significance of northern Sabah, Malaysia, and the establishment of MPAs for the conservation of marine turtles in the Southeast Asian region.

Determining the population density of sea turtles in their foraging habitats is crucial for developing effective conservation tactics as these regions serve both as growth environments for young turtles and convergence zones for adults from various nesting sites. However, the remote nature of these habitats and the unique characteristics of the oceanic environment make research challenging. Although the use of drones for aerial surveys in sea turtle studies has seen an uptick recently, there is a notable lack of focus on distant offshore areas. Furthermore, aerial density assessments are intricate, particularly for species like sea turtles that are not always visible at the ocean's surface, necessitating a correction factor to account for their surface time. While satellite tracking offers a general idea of surfacing patterns, bio-logging devices yield more accurate data on the turtles' diving behaviour. This research seeks to calculate the fine-scale density of loggerhead turtles in the Tunisian shelf, a key feeding zone within the Central Mediterranean Sea, and explore spatial and temporal variations in density, developing a method transferable to other regions. Drone surveys were performed by DJI Phantom Pro 4 flying at 74 m, covered two 1 km² zones offshore in 2017 - 2018 and one 1 km² area nearshore in 2020 - 2023 and provided surface density estimates as turtle counts. A correction factor for density estimates was derived from a prototype bio-logging device equipped with cameras and sensors, which was attached to 22 turtles for a maximum of 12 h. The device's recordings provided the turtle surface time percentage (TAS), which was then used to adjust the surface density estimates to estimate the actual density. Annual trends in surface density of nearshore area were investigated. Turtle surface density in the Tunisian shelf resulted among the highest globally for loggerheads foraging grounds. In nearshore area, counts showed a negative relationship with years close to significance (est = -0.468; p=0.052). By focusing on delimited areas, the study highlighted as the confluence of these two innovative technologies offers a fresh methodology for gauging the density of sea turtles at sea, with implications for enhancing the conservation efforts of these endangered marine creatures.

As climate change and global warming continue to increase global average temperatures, species that exhibit temperature-dependent sex determination (TSD), like sea turtles, increasingly produce biased primary sex ratios. For leatherback sea turtles, incubation temperatures beyond the pivotal temperature (PT; where a 50:50 sex ratio is produced) produce substantially more females such that global warming may alter population demographics through limiting the number of males produced and genetic diversity within the population. However, understanding how primary sex ratios affect the breeding sex ratio and other demographic parameters has been complicated by only females coming ashore to nest with limited observations of males. One way to study the breeding sex ratio is through sequencing nesting female and hatchling deoxyribose nucleic acid (DNA) to construct paternal genotypes so that fathers can be assigned to each nest. By counting the number of different paternal genotypes constructed, the number of breeding males within the population can be determined and the breeding sex ratio estimated.Assessing population demographics and breeding sex ratio is critical for the accurate assessment of population viability of the critically endangered leatherback sea turtles in the Southwestern Indian Ocean (SWIO). It is therefore fundamental to quantify the ratio of breeding males to nesting females to understand population demographics. The overall aim of this project is therefore to determine the incidence of multiple paternity (MP) and breeding sex ratio of the critically endangered leatherback population in the SWIO. Through the use of genotyping-in-thousands by sequencing (GT-sequencing), paternal genotypes will be constructed from maternal and hatchling DNA sequences to estimate the number of males contributing to each nest (MP) and quantify the ratio of breeding males (number of male genotypes detected) to nesting females (number of unique nesting females identified through flipper tags throughout the study period).It is hypothesized that there will be no incidence of multiple paternity within the SWIO population of leatherbacks, since leatherbacks generally have low incidences of MP and that the breeding sex ratio will be balanced.The results of this project will contribute to the understanding of leatherback population demographics in the SWIO and can be used as a case study for other sea turtle populations around the world. Understanding male contribution to sea turtle populations will help gain insights into sea turtle mating systems, which is currently understudied due to data restrictions, but could assist in management of the species through fully understanding their structure, function, and behaviour.

Over the last two decades, genetics has played a key role in the conservation and management of marine fauna such as whales, dolphins, and all sea turtle species. Assessing genetic variability is essential in effective conservation management, particularly for small populations that are disproportionately susceptible to extinction. The decrease in genetic variation not only limits the population's ability to adapt to changing environmental conditions but also heightens the risk of extirpation due to stochastic events. This situation often results in a positive feedback loop, where inbreeding depression exacerbates the reduction in genetic diversity. In the face of declining leatherback sea turtles (Dermochelys coriacea) globally, this study provides a critical examination of two contrasting groups: the Northwest Atlantic and the Southwest Indian Ocean (SWIO) populations. The Northwest Atlantic population, one of the largest in the world, has experienced a decline, with the Florida subgroup showing growth over the previous three generations. In contrast, the SWIO leatherback population is significantly smaller and has remained stable, despite significant conservation efforts over the last 50 years. These differences in population trend and size present a unique opportunity to understand the underlying genetic mechanisms that contribute to population resilience or vulnerability. Through restriction-site associated DNA sequencing, we evaluated the genetic makeup of the SWIO and Florida leatherback populations. We assess genetic diversity and inbreeding levels, crucial factors in understanding the adaptability and long-term viability. The genomic data can reveal patterns of genetic variation, offering insights into how these populations have adapted or struggled in response to environmental changes and human pressures. Furthermore, we aimed to determine population trends over recent (approximately 100 generations) and ancient (over 1,000 generations) timescales to ascertain if the current populations have maintained continuity throughout history. Our findings can offer pivotal insights into the genetic dynamics and resilience of marine fauna populations, particularly leatherback turtles. Understanding the genetic makeup and historical trends of populations is crucial for informed, tailored conservation strategies. This ensures the continued survival of these marine species, especially in the face of mounting environmental impacts.

Keywords: Restriction site-associated DNA, Bottleneck, Next-Gen sequencing, Nucleotide Diversity, Florida USA, South Africa

Sea turtle research has focused primarily on adult females and hatchlings due to the relative ease of accessibility to these life stages on nesting beaches, whereas male sea turtles have been extensively understudied as they spend the majority of their lives in neritic and pelagic habitats. Although often expensive and logistically complex, in-water studies are critical to address the knowledge gaps accompanying the life stages of free-swimming sea turtles, particularly for adult males. Inwater Research Group (IRG) has several long-standing in-water research projects in Florida, USA, the largest of which has captured and collected data from more than 20,000 sea turtles. In addition to the routine collection of morphometric data, captured turtles were outfitted with Inconel #681 flipper tags and Biomark passive integrated transponder (PIT) tags (beginning in July 2001) before their release. These tags allow for the long-term monitoring of individual animals through recapture and tag return data. We analyzed data from 735 male turtles captured from four research sites in Florida, USA. Males from six species of sea turtles were documented, with the vast majority comprised of loggerhead (Caretta caretta; N=521) and green (Chelonia mydas; N=204) sea turtles. There were 86 recapture events at the original tagging sites from 35 individuals. The mean number of captures for individuals was four (range 2-53), with a mean time of 1,919 days (range 1-12,539) between first and last capture. There were ten tag returns from researchers at other study sites; mean time between initial capture and subsequent tag return data was 1,050 days (range 52-2,916). Seven turtles were captured bearing tags from researchers at other study sites. The mean time between initial tagging and subsequent captures by IRG biologists was 3,717 days (range 312-5,988). Strange tag and tag return data show male turtles captured in southeast FL and the Florida Keys are utilizing waters far from their initial capture locations, including the nearshore waters of both the East and West coasts of Florida, Georgia, Virginia, and North Carolina. In addition to historical tag return data, satellite tags were deployed on four adult male green turtles in St. Lucie County, Florida towards the latter half of the 2023 nesting season. All four turtles made quick and directed migrations to waters in the Florida Keys, and in concert with tag return data, demonstrate the connectivity between our research sites. As climate change threatens to skew sex ratios even further, it is important to utilize in-water research projects to fill gaps in our knowledge and understanding of migratory pathways, habitat utilization, and mortality threats to male sea turtles over large temporal and geographic scales. These long-term study sites have provided continued access to male sea turtles and should be further utilized to collect additional data to help fill these identified knowledge gaps.