ISTS Symposium43 Program/Agenda

Diani Turtle Watch (DTW), a program under Local Ocean Conservation (LOC), is dedicated to safeguarding endangered sea turtles and their habitats along a 30-kilometre stretch within the Diani-Chale Marine National Reserve. Operating from The Sands at Nomad, DTW implements a range of conservation strategies that include nest protection, mortality responses, bycatch rescue, education, public awareness, and anti-poaching initiatives. The coastal stretch of Diani hosts five of the seven sea turtle species: leatherback, loggerhead, green, olive ridley, and hawksbill turtles. Among these, the green, olive ridley, and hawksbill turtles have been confirmed as nesting species. However, natural and human-induced barriers render only 24% of the beach suitable for nesting. To address threats such as illegal egg collection and the slaughter of nesting females, DTW collaborates with beachfront property owners to establish and manage nest relocation sites. Currently, seven such sites ensure that vulnerable nests are relocated to safer areas where they are monitored until hatching, with post-hatch excavations conducted to assess success rates. Beyond nest protection, DTW addresses sea turtle mortality by responding to reports of dead turtles. Freshly deceased turtles undergo necropsy to determine causes of death, while decomposed carcasses are buried for environmental safety. Insights from these assessments inform strategies to mitigate future risks. DTW also works closely with local fishermen to rescue sea turtles accidentally caught in fishing nets. Fishermen are compensated for any net damage, fostering goodwill and strengthening collaboration. Rescued turtles are examined before being released, significantly mitigating the threat of bycatch while promoting responsible fishing practices. Education and awareness are at the heart of DTW’s mission. Through school visits at the Marine Centre and community outreach programs, DTW fosters an understanding of marine conservation and promotes sustainable practices. These efforts extend to engaging tourists and locals, encouraging responsible human interactions with marine ecosystems. In collaboration with the Kenya Wildlife Service (KWS), DTW conducts regular anti-poaching patrols in identified hotspots. This partnership has significantly reduced poaching incidents, ensuring the protection of nesting females and their eggs. A critical element of DTW’s success lies in its partnership with the Turtleman Foundation. The Foundation has funded vital initiatives, including training for turtle monitors, student marine education programs, and the development of beach signage. Additionally, their provision of satellite trackers will facilitate the study of migratory patterns and reproductive behaviours, emphasising the value of collaborative efforts in achieving conservation milestones. DTW operates under Local Ocean Conservation (LOC), formerly known as Watamu Turtle Watch, established in 1997. LOC’s diverse conservation projects—ranging from nest protection to mangrove restoration—are driven by a commitment to community involvement and sustainable marine resource management across Kenya’s coastline. Community support remains a cornerstone of DTW’s efforts. Through initiatives like the Sea Turtle Nest Adoption Project, donation campaigns, and volunteering opportunities, DTW invites individuals to contribute to the protection of these endangered marine species and their habitats for future generations.

Email: dempsey@localocean.co
Phone: +254723153825
Facebook: @dianiturtlewatch
Instagram: @dianiturtlewatch

Emerging from a collaboration between organisations in India and Indonesia, the Eastern Indian Ocean Leatherback Alliance (EIOLA) was established to address knowledge gaps in the Northeast Indian Ocean leatherback subpopulation, currently classified as Data Deficient by the International Union for Conservation of Nature (IUCN). EIOLA currently comprises three organizations: Yayasan Penyu Indonesia (Indonesia) and Ecosystem Impact (Indonesia), which have been monitoring nesting sites across the Western Sumatra province in Indonesia, and Dakshin Foundation (India), which is involved in monitoring nesting sites in India’s Andaman and Nicobar Islands.

Leatherback turtles nest in large numbers in India, with over 1,000 nests per season, and in smaller numbers in Sri Lanka, Thailand, and Indonesia. Nesting sites in the Andaman and Nicobar Islands have been surveyed sporadically since the 1970s, with focused, long-term monitoring at key sites on Little Andaman Island and Great Nicobar Island over the past 25 years. The long-term data from Little Andaman Island (2008-2023) indicate a stable nesting population with some inter-annual fluctuations, ranging from ~80-173 nests per year with an average hatching success of 60.5% (n=32).

In Indonesia, recent monitoring programs in Western Sumatra have recorded 250-300 nests per season, revealing more extensive leatherback nesting than previously documented, spanning beaches and islands from Aceh in the north to the Mentawai Islands in the south. In 2023, a leatherback turtle tagged on Great Nicobar Island was recorded nesting on Simeulue Island, Indonesia, indicating that these turtles use multiple nesting sites across the Northeast Indian Ocean. Satellite telemetry studies from India indicate that leatherbacks migrate and forage along Africa's eastern coast and Australia’s western coast, while individuals from Sumatra were observed migrating to Western Australia.

Leatherbacks have not faced significant direct threats in the Andaman and Nicobar Islands, resulting in only monitoring of nesting beaches with little intervention. However, in Western Sumatra, leatherback turtles are under pressure from egg and turtle poaching, leading to the initiation of hatchery programs at important rookeries. Since 2021, large infrastructure projects have been initiated to establish ports, greenfield airports, and townships in Great Nicobar and the Little Andaman Islands. These developments could significantly alter nesting habitats and disrupt nesting in the region. Consequently, the islands of Western Sumatra in Indonesia are likely to become increasingly critical for the survival of Northeast Indian Ocean leatherbacks.

In this study, we present findings from conservation and monitoring efforts in the Eastern Indian Ocean, highlighting the urgent need for collective action to protect the Northeast Indian Ocean leatherback population. We emphasize the importance of developing reliable datasets to assess the current status of this subpopulation and establishing conservation programs at key nesting sites to ensure safe nesting conditions.

Hawksbill turtles, Eretmochelys imbricata, are critically endangered by extinction and, besides some larger nesting aggregations in the Caribbean, tend to nest in smaller numbers on secluded beaches. Our study focuses on their reproductive biology at Gandoca Beach, a recently discovered critical nesting site on the Caribbean coast of Costa Rica. For five nesting seasons, from 2020 to 2024, we conducted a comprehensive investigation to understand nesting patterns and other parameters such as female size, clutch success, and hatching success.

Our research involved nightly beach patrols to record nesting events, tagging of nesting females for individual identification, and detailed data collection regarding female size, clutch size, incubation duration, and clutch success rate (percentage of nests documented that incubated for 55+ days) and hatching success rate (percentage of eggs within a nest that produced a live embryo, which hatched).

Our data revealed a mean of 115.6 clutches per season, 152.54 eggs per clutch and a mean incubation duration of 63.32 days. The mean clutch success was 83.24 %, and the hatching success rate was 67.48 %, reflecting favourable nesting conditions but also highlighting the loss from illegal egg collection, predation, and beach erosion, with averages of 8.6 %, 4.2 %, and 3 % respectively of all nests documented over the five seasons. The mean female size was 86.92 cm curved carapace length. Post-nesting migrations were monitored through satellite tracking (n=7) and in-situ tagging, revealing critical foraging grounds in Nicaragua and migratory routes essential for conservation policy developments.

Overall, our study found that Gandoca Beach is now the most important nesting ground for hawksbill turtles in Caribbean Costa Rica, and continued research and conservation initiatives are crucial to ensuring the survival of this nesting population. Future work will focus on the long-term monitoring of population trends, the genetic origins of our population, and the exploration of adaptive strategies to combat the evolving challenges posed by global environmental changes.

This study underscores the importance of long-term monitoring and our ongoing conservation efforts, including habitat protection and community engagement, to mitigate anthropogenic impacts such as illegal egg harvest and climate change effects on nesting habitats. Our findings contribute to a broader understanding of the reproductive biology of Caribbean hawksbill turtles and support the implementation of localized and international conservation strategies aimed at preserving these populations.

Habitat utilization significantly influences the accumulation of chemical pollutants, including trace elements (TEs), in the tissues of large marine organisms. Previous research has demonstrated that sea turtles nesting in the same location may employ distinct foraging strategies. This study investigated the influence of habitat use strategies on the concentrations of 16 TEs in the eggs of green turtles (Chelonia mydas) nesting on the Xisha Islands. The analysis incorporated stable carbon (δ13C) and nitrogen (δ15N) isotopes, as well as characteristic elements. Additionally, inter-relationships between TEs were examined. The nesting female green turtles were categorized into two foraging groups based on isotopic signatures, namely oceanic (δ13C values: 21.5 to 17.0 ‰; δ15N values: 7.10 to 12.5 ‰) and neritic (δ13C values: 14.4 to 9.95 ‰ and δ15N values: 5.10 to 10.0 ‰). Different TE patterns were observed in the egg contents of these two groups. The neritic group exhibited elevated levels of V and Cu, which positively corrected with δ13C values. Conversely, the oceanic group displayed higher levels of Zn, Cd, Se, Sn, As and Hg, which positively associated with δ15N values. This distribution pattern is attributed to variations in background TE concentrations in the respective foraging habitats. Additionally, prey items and trophic levels of green turtles may contribute to the observed inter-group differences in TE concentrations (e.g. Zn, As, Se, Sn) found in their eggs, warranting further research. This study provides valuable in formation about habitat utilization patterns and TE distribution in green turtles nesting on the Xisha Islands. The findings enhance our understanding of TE accumulation mechanisms in turtle tissues and eggs, which is significant for the conservation of this endangered species, the green sea turtle.

The variability of nest count from one night to the next is well known to sea turtle biologists and conservationists. Indeed, the number of sea turtles that nest on a given beach can vary from the seasonal maximum to zero on consecutive nights. Such fluctuation poses obvious difficulties for those studying and protecting sea turtles.

For beaches that cannot achieve 100% monitoring coverage or that have significant ecotourism components reliant on observing nesting turtles, the capacity to anticipate nights with high nesting activity would be very helpful operationally and financially. An ideal predictor might answer the question: How many turtles are likely to nest tonight? Before approaching that (admittedly aspirational) outcome, we first need to better understand the factors influencing potential nesting synchronicity.

Existing studies on nest counts typically have the goal of estimating nesting numbers as a proxy for the total population. (See, for example: Whiting et al., 2014, doi: 10.3354/meps10832). When estimating total population, it is reasonable to smooth out the internight variability in nest counts, and those models perform their intended purpose. Precisely because of that smoothing, however, data simulated by such models do not exhibit the desired variability.

In this work we explore three novel, individual-based sea turtle nesting models: one that simulates nightly nest counts with only environmental factors, one that simulates nightly nest counts with network hypotheses allowing coordination between turtles, and a third combining both environmental and behavior cues to nest. We examine simulated internight nest count variability for three different species (leatherback Dermochelys coriacea, green Chelonia mydas, and loggerhead Caretta caretta).

Climate change and anthropogenic disturbance is driving the continual loss and degradation of critical breeding habitats of marine species. Species that exhibit natal philopatry, such as sea turtles, may be of particular concern given their reliance on specific nesting beaches. We explore how nest site fidelity of individual green turtles (Chelonia mydas) changes over time, using a 30-year data set of tagged females from our study population in North Cyprus. We investigate how fidelity changes within a season, using two measures of fidelity; overall proximity of clutches to each other, and distance between consecutive clutches. Second, we investigate how these measures change with subsequent breeding seasons and how the geographic location varies across time. We found that fidelity increases with experience, both within and across breeding seasons and discuss whether females are learning from their previous nesting experience or whether nest site location may be heritable.