Leatherback turtles (Dermochelys coriacea) represent the oldest extant marine turtle lineage and one of the largest living reptile species. Leatherbacks have the most oceanic life history of the marine turtles and are capable of diving over 1,000 meters in search of their jellyfish prey. Their large size and counter-current heat exchangers permit foraging in cold Canadian waters that would be fatal to the hard-shelled marine turtles. Leatherbacks are listed as endangered globally by the Endangered Species Act and vulnerable by the IUCN. The Northwest Atlantic population is considered endangered by the IUCN, with incidental capture in fishing gear representing one of the primary threats.

Florida supports a small nesting population. Nest counts initially grew through the 1990s and 2000s but appear to have stabilized or declined since then. This recent reduction in nest counts has also been documented in other Northwest Atlantic rookeries. It’s not clear whether fewer nests equate to true declines in nesting female abundance or whether it is driven by reduced fecundity and/or breeding periodicity due to resource limitations. More complete demographic data are needed to test these scenarios.

Leatherbacks lay typical eggs but also deposit a large number of “spacers” or shelled albumin globs, often leaving a few at the surface following the nest camouflaging process. These spacers resemble small eggs but contain no yolks or embryos, and the shells of these provide a non-invasive and non-destructive means of collecting individual identity data. Dr. Stewart and I have validated this genetic tagging approach using freshly collected spacers.

We have established a Florida Leatherback Genetics Working Group to address the need for better demographic data and a statewide framework for consistent data collection. The first step of this process will be securing funding for genotyping of all archived skin samples collected from females tagged in northern Palm Beach County Juno Beach and Martin County between 2001 and 2021 to create a comprehensive population baseline. The ultimate goal will be future collection of spacers or dead hatchlings from all Florida nests with unknown mothers to assign each nest to an individual female. These data, combined with continued traditional tagging, will permit improved estimation of nesting female abundance, clutch frequency, remigration intervals, and annual survival.