GEIS, A.*; WIBBELS, T.; VEGA, L.; LIRA, D.; ACOSTA, R.; PENA, J.; BURCHFIELD, P.; SCHROEDER, B.; Univ. of Alabama at Birmingham; Univ. of Alabama at Birmingham; Gladys Porter Zoo, Brownsville, TX; Gladys Porter Zoo, Brownsville, TX; Gladys Porter Zoo, Brownsville, TX; Gladys Porter Zoo, Brownsville, TX; Gladys Porter Zoo, Brownsville, TX; National Marine Fisheries Service, MD: Estimation of hatchling sex ratios during the 2003 Kemp’s ridley nesting season

The Kemp’s ridley (Lepidochelys kempi) is an endangered sea turtle commonly found in the Gulf of Mexico and Atlantic coastal waters of the U.S. The Kemp’s ridley, like all species of sea turtle, possesses temperature-dependent sex determination (TSD). Under this sex determining system, there is the potential of producing a wide variety of sex ratios. As such, it is of ecological and conservational interest to monitor the hatchling sex ratios produced in nesting beach conservation programs. The Kemp’s ridley’s primary nesting beach is located in the western Gulf of Mexico, near Rancho Nuevo, Mexico. Virtually all nests on that beach are relocated to protected egg corrals. The current project monitored nest incubation temperatures within the egg corrals and additionally in nests that remained in situ on the natural nesting beach during the 2003 nesting season. Sex ratios were predicted based on the average incubation temperature during the middle third of incubation. In general, incubation temperatures were relatively warm in the majority of nests, suggesting the production of a female bias during the 2003 nesting season. Furthermore, the incubation temperatures of in situ nests were slightly cooler than those in egg corral nests. These findings suggest that thermal environments of both the natural nesting beach and the egg corrals result in the production of female biased hatchling sex ratios.