GEIS, A.*; BARICHIVICH, J.; WIBBELS, T.: Use of a testosterone RIA to estimate the sex ratio of juvenile Kemp’s ridleys at Cedar Key, Florida

The Kemp’s ridley (Lepidochelys kempi) is the most endangered sea turtle in the world. Like all species of sea turtles, the Kemp’s ridley possesses temperature-dependent sex determination (TSD) in which the incubation temperature of the egg determines the sex of the developing hatchling. Sex ratios produced under TSD have the potential of varying widely. As such, the sex ratios within the juvenile portion of the population are of a conservational, ecological, and evolutionary interest. The current study validated and utilized a testosterone radioimmunoassay (RIA) to examine the sex ratio of a population of juvenile Kemp’s ridleys inhabiting the waters near Cedar Key, Florida. Testosterone levels were measured in blood plasma samples collected from juvenile Kemp’s ridleys captured over a 3-year period. Results of this study indicated that a significant female bias (approximately 2:1) occurs in this population. It is plausible that this female-biased sex ratio may be beneficial to the recovery of this severely endangered species.