Coppenrath, Christina

The migratory behavior of North Atlantic leatherback turtles (Dermochelys
coriacea) has been documented in the Wider Caribbean, but the migratory movements of
leatherbacks nesting in South Florida are relatively understudied. Our knowledge of their
migrations is currently limited to ten nesting females tracked from the east coast of
Florida that either moved north to the Northern Atlantic or east to the coast of Western
Africa. These results bring to light the need for further investigation and larger sample
sizes to identify and determine the relative importance of the different foraging areas for
the leatherbacks nesting in South Florida. Here, I analyzed stable carbon (δ13C) and stable
nitrogen (δ15N) values in whole blood and skin of leatherbacks nesting in South Florida
between 2014 and 2017 to estimate the putative foraging origins of these nesters prior to
coming to South Florida to nest. This study provides some of the first stable isotope
inferences and insights into the variable pre-nesting foraging habitat locations of
Florida’s leatherback population.

For highly migratory species, it is important to understand what habitats are used and what
requirements are essential for growth and development. These migrations often span different political
and regulatory boundaries, complicating conservation strategies. The hatchlings and post-hatchlings of
most sea turtle species migrate to oceanic habitats where they remain for several years before
returning to shallow developmental habitats. For critically endangered hawksbill turtle, Eretmochelys
imbricata, most research has concentrated on nesting ecology and very little is known about the posthatchling
migration. Many sea turtles then spend years in different foraging habitats before reaching
sexual maturity, and such foraging grounds typically represent a mixed stock of turtles from different
nesting beaches. Mitochondrial DNA analysis can be used to estimate genetic stock structure of mixedstock
foraging populations for sea turtles, and the duration of the post-hatchling oceanic stage can be
estimated using stable isotope analysis and satellite telemetry. Our objectives are to determine the
duration of the post-hatchling oceanic stage of development, to determine if the turtles sampled in a
particular foraging habitat represent a biased or unbiased assortment of matrilineages, and to infer
potential migratory pathways by investigating ocean currents between nesting beaches and the
foraging site. Here we discuss our methods, to determine the duration of the post-hatchling oceanic
stage and stock structure for immature hawksbills at a developmental foraging ground.