FLAME University, Pune, India

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India’s coastal waters are home to five species of sea turtles, of which the olive ridley (Lepidochelys olivacea) arribada nesting population is of global significance. The species encounters numerous natural and anthropogenic threats during its life history, due to which it is accorded legal protection in India and is the focus of conservation efforts. The most public turtle conservation strategies in India are hatcheries that protect the egg/hatchling life stage. Hatcheries are protected enclosures on or close to the nesting beach, where threatened eggs are incubated to improve hatchling production. The majority of sea turtle eggs laid on nesting beaches in Gujarat, Maharashtra, Goa, Karnataka, and Tamil Nadu are relocated to hatcheries (Phillott & Kale, 2018). Their frequency of use is likely due to the ease of accessibility of this life stage compared to others, comparative cost, and potential for education and outreach benefits as well as conservation. Conceivably, hatcheries can have a significant impact on hatchling production and future sea turtle population dynamics in these states (Phillott et al., 2021).

However, not all hatcheries adhere to best practices, so hatching success may be comparable to or lesser than unprotected in situ nests (Phillott et al., 2021). Due to the risks (and financial and human resources) involved in ex situ conservation strategies like hatcheries, it is essential to examine whether they are achieving their intended objectives. This study is using population modelling to examine the implications of low hatchling numbers for local turtle populations in India and predict target hatchling production rates for population resilience and growth.

Stage-based Leslie matrix modelling is being used to obtain intrinsic growth rates of olive ridley sea turtle populations in the state of Maharashtra, 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. 

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. If the results show that increased survivorship in other life stages strongly reinforces the positive effect of increased hatchling production rates, then that might also lead to a recommendation for a combined conservation focus on multiple stages.

Literature cited:

Phillott, A.D. & N. Kale. 2018. The use of sea turtle hatcheries as an ex situ conservation strategy in India. Indian Ocean Turtle Newsletter 27: 31-34.

Phillott, A.D., N. Kale & A. Unhale. 2021. Are sea turtle hatcheries in India following best practices? Herpetological Conservation and Biology 16: 652-670.