Predicted Sex Ratios from the International Kemp's Ridley Sea Turtle Head Start Research Project
Wibbels T, Morris Y, Owens D, Dienberg G, Noell J, Leong J, King R, Millan R. 1989. Predicted Sex Ratios from the International Kemp's Ridley Sea Turtle Head Start Research Project. Pages 77 - 81. In Caillouet, Jr. C and Landry, Jr. A (ed): Proceedings of the First International Symposium on Kemp's Ridley Sea Turtle Biology, Conservation and Management. Galveston, TX. October 1-4, 1985
Sex ratios were determined for groups of turtles from six year-classes of Kemp's ridley sea turtles (Lepidochelys kempi) from the joint U.S.-Mexico Kemp's Ridley Sea Turtle Head Start Research Project. Gonadal histology, necropsy, laparoscopy, tail length evaluation and serum testosterone assays were used to determine sex. Turtles examined from the 1982 (n=92, 2.9M:1F) and 1984 (n=159, 25M:1F) year-classes were significantly male-dominated. The turtles examined from the 1978 (n=32, 1.9M:1F) and 1979 (n=2.2, 1.4M:1F) year-classes also were male-dominated, but not significantly so. Those examined from the 1983 (n=12, 1M:1F) year-class had equal representation of the sexes, and those from the 1981 (n=4, OM:1F) year-class were all females. Data from the 1984 year-class also indicated that sex ratios of clutches from a given year-class can differ significantly from one another. The significantly male-dominated groups of turtles from the 1982 and 1984 year-classes and the significant differences in sex ratios among clutches of the 1984 year-class are consistent with the hypothesis that the sex of Kemp's ridleys is determined environmentally. Because the number of turtles examined from most year-classes was small, our interpretations should be considered with caution. Conservatively, we concluded that relatively large numbers of both male and female Kemp's ridleys have been produced by the project in the past. However, a significant masculinization was evident in two of the year-classes. The implications of male-dominance in Kemp's ridley sex ratios are discussed.
- Type
- Conference Proceeding Paper
- Authors
- Wibbels, Thane; Morris, Yuki; Owens, David; Dienberg, Gayle; Noell, Julia; Leong, Jorge; King, Robert; Millan, Rene
- Units
- SFCN
- Keywords
- Breeding, Factors, female, Hatchlings, hormones, Male, Nesting, sex determination, Temperature