ISTS Symposium43 Program/Agenda

Recovery of imperiled species requires addressing conservation challenges within complex social-ecological systems (SES). Sea turtle bycatch in Florida’s trap fisheries exemplifies this challenge, combining ecological risks to turtles, economic impacts on fishers, and mistrust between fishers and regulatory authorities. We used a mixed-methods approach to explore stakeholder and fisher perspectives on sea turtle bycatch in trap fisheries and identify strategies to improve reporting and mitigation of bycatch events.

In Phase I, we conducted semi-structured interviews with 24 stakeholders representing diverse roles within the SES, including biologists/natural resource professionals, commercial fishers, wildlife law enforcement officers, and charter/tour boat operators. We aimed to examine the influence of diverse ways of knowing and lived experiences on attitudes and beliefs around sea turtle conservation, bycatch in trap fisheries, and potential mitigation strategies. Thematic analysis revealed key factors influencing fisher engagement in reporting and mitigation of turtle bycatch events, including trust in and perceived competence of institutions, social norms governing behavior within fishing communities, and concerns of legal consequences or overregulation. Stakeholder groups differed in their beliefs about the risks posed to turtles by the trap fisheries, with biologists describing an underreported and likely significant threat and fishers minimizing the threat in relation to other environmental challenges, such as poor water quality.

Insights from these interviews informed Phase II, a multimodal survey distributed to Florida’s commercial trap fishers (n=249; response rate: 18.2%). Survey responses quantified fishers’ knowledge of and salient beliefs about 1) reporting and mitigation behaviors and 2) preferences for conservation interventions. Significant barriers to reporting turtle bycatch include an aversion to interacting with authorities, inefficiency of filing reports, and not understanding the need or value of reporting. Fishers considered safe handling and release training to be the most acceptable mitigation strategy. There was not broad support for other interventions such as gear modifications, trap reduction programs, or time/area closures, despite those being the primary suggestions offered by biologists and managers during Phase I.

Optimization actions can include revising reporting protocols to ensure anonymity, incentivizing engagement through trusted messengers, and leveraging fishers’ operational concerns, such as trap damage caused by turtles, as a collaborative starting point for bycatch mitigation efforts. By integrating stakeholder perspectives with SES principles, this research offers actionable pathways for mitigating sea turtle bycatch and enhancing collaboration in conservation efforts.

Strandings of live and dead sea turtles occur frequently along the Iberia peninsula and its islands. The Andalusian coast, especially the Gulf of Cadiz, Strait of Gibraltar and Costa del Sol, is critical for sea turtles, representing migration and feeding grounds. Full necropsies on stranded animals are key, to diagnose the cause of death and to provide useful scientific data to support the development of mitigation measures. To date, there is none published information on the causes of strandings and/or mortality in sea turtles on Andalusian coast.

This study describes the pathological findings and causes of death (CD; grouped as ‘pathological entities’) of 43 sea turtles, representing 4 species, stranded in Andalusia between 2020 and 2024: 34 loggerhead (Caretta caretta), 5 leatherback (Dermochelys coriacea), 3 green (Chelonia mydas), and 1 Kemp’s ridley (Lepidochelys kempii) sea turtles. A CD was recognized in 36/43 (84%) studied individuals (whilst the cause of death in 7 could not be due to the state of the carcass).

Direct human activity is responsible for 79% (34/43) of sea turtles deaths, while ‘natural’ pathologies would account for 5% (2/43). Interaction with fishing activities encompassed 28 out of 34 while vessel strikes were responsible for 6 out of 34.

Regarding the interaction with fishing activities, the prevalence of the different findings was analyzed: 28 (100%) of the cases showed a good body condition; digestive content; cardiovascular presence of gas (embolism); subcutaneous, muscular and bronchoalveolar haemorrhages; bronchoalveolar edema; hepatic congestion; and multifocal scratches in carapace, head, or plastron. Additionally, 25 (89%) of the animals, showed multiple areas of skin abrasions, ulceration and necrosis in the plastron and/or carapace. These lesions are consistent with entanglement in fishing gear. Also, an increased serosanguineous free fluid in the coelomic cavity, were found. In 18 (64%) individuals, pulmonary emphysema was identified. At last, 5 showed mandibular fractures, 8 limbs fractures or amputation and 3 retraction of the limbs.

Signs of asphyxia or water aspiration were detected in 16 individuals. Macroscopic evidence of drowning during the necropsy of a sea turtle can vary, is often nonspecific, and frequently altered by post-mortem changes, making the diagnosis difficult to establish and often reliant on the exclusion of other causes.

Boating and fishing can cause traumatic injuries to sea turtles. In our study we identified blunt force trauma as the cause of death in 6 out of 34 due to vessel strike. 6 showed fractures in the carapace, plastron or head, as well as muscular, subcutaneous and intracoelomic haemorrhages; 5 individuals presented damaged of the liver and alveolar edema.

Direct human activity is responsible for nearly 80% of the sea turtles in our study, primarily due to fishing gear interactions and vessel strikes, the leading causes of mortality along the Andalusian coast. The analysis highlights the significant impact of bycatch, with injuries such as abrasions, ulcerations, and haemorrhages commonly associated with entanglement in fishing gear. These findings stress the need for mitigation measures, including better protection in key areas and continued research to guide conservation actions.

The U.S. Virgin Islands (USVI) has a strong network of volunteers who respond to stranded sea turtles found in-water and washed ashore. The Territorial stranding network has operated under the non-profit Sea Turtle Assistance and Rescue (STAR) Network since 2019, but efforts made by local agencies, non-profits, and conservationists to find and document stranded turtles span decades. We conducted a 5-year review of the most recent strandings to identify current turtle strandings drivers. We created spatial hotspots of where these strandings occurred using kernel density estimation, with the goal of informing managers of transportation, port authority, and power utilities, as well as encouraging public and private entities to implement direct action to protect sea turtles. From 2018 to 2023, 165 sea turtle strandings were recorded around the USVI. Of these strandings, 120 were identified as green turtles (Chelonia mydas), 32 were hawksbill turtles (Eretmochelys imbricata), three were leatherback turtles (Dermochelys coriacea), two were loggerhead turtles (Caretta caretta), and nine were of undetermined species.vPreliminary comparison to other island groups shows that the USVI has a relatively high rate of turtle strandings for the size of our territory (Hawaiian Archipelago – 0.106 turtles/year/mile of shoreline vs. USVI – 0.282 turtles/year/mile of shoreline). The most common cause of strandings across the USVI was boat strikes (19.9%), followed by entrapment in vegetation (14.5%), fishing gear entanglement (13.9%), and entrapment in human-made structures (12%). As expected, boat strike injuries were highly correlated with areas of high boat traffic, such as inter-island routes, and fishing gear entanglements were correlated with popular on-land fishing locales, specifically on St. Croix. These results will be used to directly inform and advocate for no-wake zones and speed regulations in the boat strike hotspots outlined by this study. We hope to use this as evidence for increased support for all actions recommended by the STAR Network, like boating slowly, mitigation fencing and barrier removals around shorelines, and collecting monofilament during fishing activities. The evidence herein supports the advocacy of the volunteers and agencies that have been rescuing our sea turtle species since the inception of conservation efforts in the USVI.

Many marine species, including sea turtles, face threats due to pollution. In particular, heavy metals and plastic pollution in form of debris and microplastic are increasing rapidly in sea turtle’s habitats. These contaminants are known to have numerous detrimental physiological effects including sublethal effects such as endocrine disruption and hatchling deformities to lethal effects such as blockage of gut. Recent studies have highlighted the interactions between microplastics and heavy metals in small animal model systems. As of now, there are not many studies on the presence of these pollutants in sea turtles in the Indian Ocean, with a very small number of microplastic studies. The Bay of Bengal in the Indian Ocean is home to crucial nesting sites for olive ridley turtles. Among these are Rushikulya, an active mass nesting beach, and Devi, a historically significant nesting site which witnesses high mortality. However, this region is experiencing an alarming rise in pollution. Riverine influx and intensive fishing activities are contributing to high levels of pollutants, making these nesting beaches high-risk areas for plastic ingestion and heavy metal exposure in sea turtles.

The current study aims to fill this knowledge gap by examining the extent of plastic ingestion, and bioaccumulation of microplastics and heavy metals in olive ridley turtles. On-field necropsies were conducted on 94 dead stranded turtles from the nesting beaches of Rushikulya (n = 51) and Devi (n = 43) in Odisha from November 2023 to February 2024, to collect scute, muscle, liver and whole gastrointestinal tract samples. The muscle and liver samples were analysed for microplastic presence. Alkaline digestion (10% KOH at 60 ºC) followed by vacuum filtration was performed to separate potential microplastics. Visual identification through stereomicroscope was done to categorise microplastic based on shape and colour. Ingested macro-plastics or plastic debris were found in 12.5% of the turtles. Microplastics were detected in liver and muscle tissue in all the samples (n = 38) analysed so far, with clear fibre being the most abundant microplastic type. The total microplastic load was significantly higher in Rushikulya than in Devi, and in liver than in muscle tissue. Based on microplastic type and colour, this study suggests that microplastics likely originate from fishing related activities. The microplastic aggregation around nesting beaches might be influenced by ocean currents and does not necessarily localize around the sources with higher pollutant influx. This research underscores the urgent need to better understand and mitigate plastic pollution in marine ecosystems. Furthermore, the ongoing analysis on heavy metals will shed light on the presence of other pollutants in sea turtles at this important nesting rookery.

Coastal development and artificial light are increasingly causing habitat degradation and impacting species such as sea turtles, with coastal squeeze limiting possible climate change adaptation. In highly developed coastal regions such as the Mediterranean this is a particular challenge. We used long term clutch counts and satellite imagery to investigate the impacts of specially protected areas (SPAs), coastal development, and artificial light at night (ALAN) on green (Chelonia mydas) and loggerhead turtles (Caretta caretta) nesting in Cyprus, where both populations appear to be recovering from historical population declines. Nearly all green turtle clutches were laid on beaches within SPAs, while just over half of loggerhead turtle clutches were laid in these areas. During three decades of monitoring, green turtle clutch counts increased significantly more than loggerhead turtles within SPAs. There was no significant difference between loggerhead turtle clutch count increases inside or outside SPAs, possibly due to poor management of certain important loggerhead beaches in key SPAs. Beaches used by green turtles had a significantly lower beach development score than those used by loggerhead turtles, but this was not the case for ALAN. There was no relationship between clutch count increase and beach development, or ALAN, regardless of sea turtle species. However, both the median development and ALAN scores were significantly greater for beaches used by loggerhead turtles located outside SPAs than those used by both species inside SPAs. Our study demonstrates that a) SPA management plans can be effective when they are applied, b) mitigation measures could benefit loggerhead turtles at some SPA beaches where management plans have not been adhered to, c) more SPAs are needed for loggerhead turtles and significantly more clutches could be protected by bringing a small number of beaches into the SPA network.

The Arabian Gulf, characterized by high salinity, shallow waters, and elevated temperatures, presents a unique and often harsh environment for marine life, including sea turtles. Despite these challenges, the Gulf also boasts extensive seagrass beds, coral reefs, and sandy beaches, providing an ideal habitat for sea turtles. This retrospective study examines sea turtle mortalities in Dubai, UAE, over a 15-year period from 2010 to 2024, aiming to identify primary causes of death, seasonal trends, and potential hotspots for turtle strandings. By analyzing data from local wildlife rehabilitation centers, stranding records, and environmental agencies, the study highlights various threats to turtle populations, such as entanglement in fishing gear, ingestion of marine debris, boat strikes, and habitat degradation. Findings show significant seasonal mortality patterns, particularly during the winter months when water temperatures drop. Anthropogenic threats are also a major contributor to sea turtle deaths. A major challenge in the study was the limited availability of data from government agencies, coupled with reluctance to release crucial information, hindering a full understanding of the scope of the problem. This study offers critical insights that can inform future conservation efforts and policy-making aimed at reducing mortality rates and ensuring the long-term survival of Dubai’s sea turtle populations.