Project Title: Sex determination for Immature Kemp’s Ridley Turtle in the Ten Thousand Islands
Project Manager: Dr. Jeff Schmid
Organization: Conservancy of Southwest Florida (Non-Profit Organization)
Grant Amount: $22,035.00
Completion Date: 2019-07-15
Summary: This research project is to determine the sex of immature Kemp’s ridley turtles inhabiting the Ten Thousand Islands archipelago using testosterone radioimmnuoassay (RIA) and enzyme-linked immunosorbent assay (ELISA). In 2000-2001, a significantly female-biased sex ratio was predicted for Kemp’s ridleys in this region using RIA but the former study did not analyze the data for seasonal or size-specific differences. ELISA is relatively new technique with limited application for sexing marine turtles and testosterone concentrations obtained from ELISA need to be compared concurrently with those of RIA to determine the efficacy of the newer method. Blood samples will be collected from Kemp’s ridleys captured in the Ten Thousand Islands, plasma testosterone concentrations will be ascertained using RIA and ELISA, and sex of the turtles will be predicted using the established criteria for each method. The objectives of the proposed study are to predict the sex and estimate the sex ratio for Kemp’s ridleys using these complimentary techniques, to validate the sex determination data obtained from ELISA with that of RIA, to examine the sexing data for size-specific and seasonal variation, and to compare size-class and seasonal data with earlier sex determination studies in the Ten Thousand Islands and other regions of west Florida.
Results: A total of 62 Kemp’s ridley plasma samples (53 initial samples from turtles and 9 samples from recaptures of 5 turtles) were collected for RIA and ELISA sex determination analyses. Of this tot&. 43 plasma samples had been collected from previous efforts (Sep. 2014—May 2016) and 19 samples were collected during the contracted sampling trips (Sept. 2016— May 2017). Each plasma sample was divided into 3 aliquots; 2 for RIA and ELISA analyses in the current contract and I for ongoing stable isotope analyses. One set of samples was sent to Mr. Jeffrey Schwenter for RIA analyses. A portion of the other set was sent to Dr. Camiyn Allen and the remainder of the sample set was sent to Dr. Roldan Valverde for ELISA analysis. Results of the initial ELISA analyses were received January 2018, RIP. analyses were received April 2018, and ELISA analyses were completed July 2018. However, there was poor agreement between the latter ELISA results and the corresponding RIA data so the correction factor for the ELISA data had to be revised and revisions were received October 2018. Subsequent data analyses and report preparation were delayed owing to family emergency experienced by the project manager from Hurricane Michael.