An update on hatchery success of olive ridley turtles ( Lepidochelys olivacea ) at Playa San Miguel, Costa Rica

Abstract

Reducing threats to sea turtle eggs and hatchlings is critical for increasing hatching survival and recruitment, which supports the recovery of sea turtle populations. However, changes in temperature and rainfall from climate change have been identified as emergent risks to the nesting success of sea turtles globally. To reduce both of these threats and increase the nesting success of the beach, eggs are relocated to a protected area and covered in mesh (e.g., hatchery). However, the success rates of these nests in light of the changing climate are not fully understood, and must be continually assessed as climate change progresses. This study aims to elucidate and update the impacts of nest temperatures and rainfall on the San Miguel olive ridley hatchery success from 2019 to 2022 sea turtle seasons. Nest excavations were conducted inside the hatchery to determine emergence, hatching, and hatchery success (the proportion of viable relocated eggs that produce live emerging hatchlings under protected incubation conditions). We found mean nest sand temperature to be 29.63°C ranging from 28 to 31°C. Nest sand temperatures significantly affect nest failures (Estimate = 0.123 ± 0.059 SE, z  = 2.088, p  = .037) while nesting seasons also significantly affect nest failures with lower failure rates observed in 2021 (Estimate = −0.485 ± 0.171 SE, z  = −2.827, p  = .0047) and 2022 (Estimate = −0.398 ± 0.190 SE, z  = −2.094, p  = .036), but rainfall did not. Overall, hatchery success was 85% across the seasons, except in 2020 when success declined to 70%. These findings demonstrate that hatchery management at Playa San Miguel has been effective in maintaining high incubation success and suggest that adaptive management practices may help buffer nests from the effects of rising sand temperatures.