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Endangered Species Research

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ESR 6:75-85 (2008)  -  DOI:

Comparing methods for the assessment of reproductive activity in adult male loggerhead sea turtles Caretta caretta at Cape Canaveral, Florida

Gaëlle Blanvillain1,*, Anthony P. Pease2, Al L. Segars3, David C. Rostal4, Adam J. Richards5, David W. Owens1

1College of Charleston, Grice Marine Laboratory, 205 Ft. Johnson Rd, Charleston, South Carolina 29412, USA
2North Carolina State University, 4700 Hillsborough Street, Raleigh, North Carolina 27606, USA
3South Carolina Department of Natural Resources (SCDNR), 32 Fiddler Drive, Beaufort, South Carolina 29902, USA
4Georgia Southern University, PO Box 8042, Statesboro, Georgia 30460, USA
5Medical University of South Carolina, Department of Bioinformatics and Epidemiology, 135 Cannon Street, Suite 303, Charleston, South Carolina 29425, USA

ABSTRACT: In an attempt to better understand the reproductive cycle of adult male loggerhead sea turtles, several techniques were used to assess their reproductive activity, including plastron-softness analysis, ultrasonography, laparoscopy, testicular biopsy samples, and measuring testosterone levels. Stress levels were evaluated on a subset of turtles by measuring testosterone and corticosterone concentrations after capture and before release. A total of 40 adult males were captured in the Port Canaveral shipping channel in April of 2006 and 2007. Four turtles were classified as reproductively inactive based on laparoscopic examination, histology of the testes, and testosterone levels. The relative area of plastron softness was significantly lower for the inactive males compared to the active males. Ultrasonography proved to be a promising tool, as we were able to visualize both the testes and epididymides on the turtles examined. Furthermore, we found no statistical difference in epididymal duct diameters measured by ultrasonography and during laparoscopy, suggesting that ultrasonography could be used successfully as a substitute for laparoscopic surgery. Finally, testosterone levels separated into 2 distinct groups, with concentrations of the inactive males below 5 ng ml–1, and concentrations of the active males reaching 188 ng ml–1. We conclude that in order to reduce stress levels due to capture and handling, especially during laparoscopy, ultrasonography and plastron analysis could be used together as a way to determine the reproductive activity of adult males in the field. The results from this study also suggest that not all adult males participate in mating activity each year.

KEY WORDS: Reptilia · Caretta caretta · Laparoscopy · Ultrasound · Histology · Plastron softness · Testosterone · Corticosterone

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Cite this article as: Blanvillain G, Pease AP, Segars AL, Rostal DC, Richards AJ, Owens DW (2008) Comparing methods for the assessment of reproductive activity in adult male loggerhead sea turtles Caretta caretta at Cape Canaveral, Florida. Endang Species Res 6:75-85.

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