Fox Lab Behavioral and Evolutionary Ecology / Herpetology

Commercial harvest of most species of freshwater turtles had been allowed in Oklahoma before a temporary moratorium was put into effect in 2008, but the impacts of harvest and general status of freshwater turtles in Oklahoma are poorly understood. We conducted an intensive 2-year survey of the freshwater turtle species of eastern Oklahoma in 2009-2010, resampling 35 sites that were previously surveyed by D. Riedle in 1997-1999 (Riedle et al. 2005), and compared results between these two surveys. We compared catch per unit effort (CPUE), species richness, and species diversity separately for northeastern and southeastern Oklahoma. We found a significant decrease in CPUE compared to 1997-1999 across both the northeastern and the southeastern sites. We also saw significant declines in species richness and species diversity, but only for northeastern sites. The three most commercially harvested taxa (Trachemys scripta, Apalone spp., and Chelydra serpentina) showed significantly decreased CPUE compared to 1997-1999 at paired sites in the northeast, whereas only T. scripta showed significantly lower CPUE at paired sites in the southeast. Prevalence (number of sites occupied) of C. serpentina in the northeast declined, whereas prevalence of Apalone spp. in the southeast increased. We also compared carapace lengths in 2009-2010 between northeastern and southeastern sites for the three most harvested taxa. Individuals of two of the three species were significantly smaller in the northeast. Commercial turtle harvest in Oklahoma has been heavy. Records of the Oklahoma Department of Wildlife Conservation report that over 800,000 Oklahoma turtles were purchased from commercial collectors in 1994-2010. Overall, it appears that harvest played a role in the decline of aquatic turtle species across eastern Oklahoma since Riedle's surveys in 1997-1999. These declines have been more severe in northeastern than southeastern Oklahoma.