Simulating Nest Census Data for the Endangered Species of Marine Turtle Caretta-caretta

摘要

In sea turtle studies, population trend assessments are primarily based on the number of recorded nesting females. However, it is often difficult to make a direct count of all nesting females, hence their abundance is often estimated by dividing the total number of nests laid during a season by the mean number of clutches deposited annually per individual, termed clutch frequency. In the present study, the potential effect of individual variability in clutch frequency has been investigated with respect to population trend predictions. We used two simulation models to perform our analysis: a stochastic model that simulates breeding performance as an individual based process, and a stochastic exponential growth model (Wiener - drift). Our analysis indicates that highly variable nesting performance strongly affected the model results regarding both population trends. Therefore, we conclude that population assessments based on annual censuses produced with respect to mean clutch frequencies should be viewed and used with increased caution.