SEX RATIO PREDICTION OF JUVENILE HAWKSBILL SEA TURTLES (ERETMOCHELYS IMBRICATA) FROM SOUTH FLORIDA, USA

Abstract.—All sea turtles exhibit temperature-dependent sex determination, a process in which the incubation temperature of the nest determines the sex of the offspring. Given the potential effects of climate change worldwide, monitoring sea turtle population sex ratios has become a priority, especially for these threatened or endangered species. In this study, we examined the sex ratio of an aggregation of juvenile Hawksbill Turtles (Eretmochelys imbricata), a critically endangered species, at a coral reef in southern Florida, USA. This is the most northerly juvenile Hawksbill aggregation in the Atlantic Ocean for which this type of study has been completed, and the first one within the continental USA. We hand-captured turtles and collected blood samples from 69 individuals over a period of two years for sex determination using a testosterone radioimmunoassay (RIA). The RIA was calibrated with serum samples from juvenile Hawksbills whose sex was confirmed by laparoscopy, from Mona Island, Puerto Rico and Caribbean Panama. Our results indicate a significant female bias in this population (2.37:1), which has also been observed in several previous studies of juvenile Hawksbill turtle sex ratios