UC San Diego

The hawksbill sea turtle (Eretmochelys imbricata) is an endangered species thought to spend their juvenile years in protected, nearshore areas before returning to their natal beaches to breed. We caught, measured, and sampled skin and anterior and posterior scutes from hawksbill turtles in a foraging ground around Isla San Jose, Gulf of California, Mexico. We analyzed the δ13C and δ15N values from tissues taken from mostly juvenile (96.4%) individuals, based upon morphometric measurements, as well as potential prey items to assess their foraging habits. A Bayesian mixing model analysis of the stable isotope values indicated hawksbills are consuming a primarily invertebrate-based diet supplemented by foraging on plant matter composed largely of seagrass and algae. The δ13C values from posterior scute samples increased with age, suggesting a potential location shift as younger turtles move from a more pelagic habitat to the nearshore foraging area at Isla San Jose.