Determination of sex ratios and their relationship to nest temperature of loggerhead sea turtle (Caretta caretta, L.) hatchlings produced along the southeastern Atlantic coast of the United States

The sex ratios of hatchling loggerheads (Caretta caretta) were determined to provide robust assessments of regional and seasonal contributions of males and females to the population. Hatchlings from nests along the Atlantic coastline were raised to 120 g, sexed laparoscopically and verified histologically. Sex ratios differed at the beach, subseason, and subpopulation levels. There was no difference in overall sex ratios between the two study years. Average nest temperature and incubation durations were not accurate sex ratio correlates. Temperatures that produced female biased or male biased sex ratios overlapped in ranges with those producing a single sex. I found that the Transitional Range of Temperatures for loggerhead sea turtles is approximately 26.5°C--32°C, and the best correlation between average temperature and sex ratio occurred at 50--65% of incubation. Further studies are needed to define the roles of other environmental factors or the responses of tissues in loggerhead sex determination.