Currently all species of sea turtles are listed as threatened or endangered with extinction under the U.S. Endangered Species Act. Due to their status, sea turtle conservation is a high priority for the U.S. National Marine Fisheries Service and U.S. Fish and Wildlife Service. One major challenge conservationists face is the lack of a noninvasive, cost efficient method for determining the sex of hatchling sea turtles. Because secondary sex characteristics (i.e. males have longer tails) are not evident until turtles start to reach sexual maturity, the sex of hatchlings is not easily determined. The least invasive way to determine the sex is through hormone analysis of blood plasma. The testosterone enzyme-linked immunosorbent assay (ELISA) has been validated for use with all six sea turtle species plasma and has been shown to be an effective method of sex determination in juvenile sea turtles. We have validated two new high sensitivity ELISA’s (testosterone and estradiol) for use with loggerhead sea turtles (Caretta caretta) and will subsequently use these to explore whether sex can be assigned to live hatchlings. We will apply both ELISA’s to small plasma volumes from known-sex loggerhead hatchlings and examine the ratio of testosterone to estradiol to determine sex. If applied over multiple nesting seasons, this may facilitate subsequent studies to identify the degree to which climate change may impact sex ratios of annual hatchling cohorts at key beaches in the US and beyond
