Rookery contributions, movements and conservation needs of hawksbill turtles at foraging grounds in the eastern Pacific Ocean

Understanding the spatial ecology of wide-ranging marine species is fundamental to advancing ecological research and species management. For marine turtles, genetic studies using mitochondrial DNA (mtDNA) markers have proven invaluable to characterize movement, particularly between rookeries (i.e. nesting sites) and foraging grounds. Hawksbill turtles Eretmochelys imbricata are a globally threatened species whose conservation status is particularly precarious in the eastern Pacific Ocean. Recent research in the region has identified unique life history characteristics, including highly restricted movements, the use of mangrove estuaries for foraging and nesting, as well as a regional pattern of natal foraging philopatry (NFP). For this study, we used mtDNA sequences and mixed-stock analysis of hawksbills from 8 designated foraging grounds and 5 primary rookeries to evaluate stock composition at each foraging ground, assess how stock contributions are affected by the NFP life history strategy, and search for evidence of unidentified rookeries. Although we found evidence supporting the NFP pattern at most foraging grounds, results indicated important site-specific variability at particular foraging grounds. We also found discrepancies among the haplotype frequencies of several foraging grounds and rookeries, as well as the presence of several orphan haplotypes, suggesting undiscovered hawksbill rookeries likely remain in the eastern Pacific. Our findings contextualize the prevalence and scale of the NFP life history strategy and provide insights that can be directly applied to future ecological research and species management and conservation.