A global assessment of the potential for ocean-driven transport in hatchling sea turtles

Abstract

Ocean circulation models are an essential tool for use in estimating the movements of drifting marine species. Across the world, hatchling sea turtle transport to the pelagic ocean is facilitated by the local currents off their natal beaches. It is difficult, if not impossible, to observe this transport reliably for any lengthy period, and, as such, ocean circulation models are an essential tool for studying sea turtles during this vulnerable time. Here, we use the ocean circulation model HYCOM and the particle simulator Ichthyop to model the first month of hatchling transport across all sea turtle species from nesting sites across the world from 25 cohorts of hatchlings at 67 nesting sites. We evaluated transport as a function of spatiotemporal factors that could influence turtle movement, using generalized linear models and the information theoretic approach to model selection. We found that multiple physical factors influence transport across the first month of movement and that annual variability is an important factor in hatchling transport. Our findings suggest that the beaches turtles hatch from and the year in which they hatch may shape their early life and the speed of transport into the relative safety of the open ocean. An increased understanding of the likely survival of a cohort may aid in designating funds and planning conservation strategies for individual beaches to either compensate for or take advantage of the local currents.