Ecology and Conservation of the Yellow-blotched Sawback, an Endemic River Turtle of the Pascagoula River System
The conservation of quality habitat worldwide is regarded as one of the most important aspects for species conservation. To this end, the Pascagoula River system of southeastern Mississippi is considered one of the most pristine and the least impacted major river system of the Lower 48 United States.
This river system is also the habitat for an endemic river turtle, the yellow-blotched sawback (Graptemys flavimaculata). Observed population declines in the 1980‚Äôs led this species to be listed as Federally Threatened in 1991 and Endangered in Mississippi. Following listing, populations within the Lower Pascagoula River were studied by Bob Jones (Mississippi Museum of Natural Science, MMNS) and by researchers out of Southeastern Louisiana, including the master‚Äôs thesis work of Brian Horne (TSA Advisory Committee). Studies found that turtles had complex seasonal movements and restricted home ranges, as well as extremely low reproductive output and high rates of nest predation/mortality. This species is threatened primarily by destruction/modification to riverine habitat, but other threats include humans shooting turtles as ‚Äòtarget practice,‚Äô collisions with boats, collection for the pet trade, by-catch by fishermen, and the destruction of nests on sandbars by recreational ATV riding.
Over the last 4 years, funding has been awarded to conduct research on Graptemys flavimaculata by the Mississippi Department of Wildlife, Fisheries, and Parks (MDWFP); U.S. Fish and Wildlife Service (USFWS); and the Chelonian Research Foundation‚Äôs Linnaeus Fund. This funding has gone to research a variety of topics of this imperiled turtle: assessing populations post-Hurricane Katrina, determining the impact of recreational boating on basking behavior and physiology, understanding the distribution/abundance throughout the Pascagoula River system, and conducting research on the conservation genetics of this species. Lower Pascagoula River populations were found to be negatively impacted following Hurricane Katrina (declines of ~50%), but no impact was observed with upstream populations. Distribution surveys indicated no range contraction and these surveys also documented populations in new river/creek systems. Results from other topics are forthcoming.
Currently, the TSA and the Batchelor Foundation have provided funding to continue the conservation genetics work and to establish a public outreach initiative for this species. This year, sampling for the conservation genetics project (i.e. tissue collection) was completed at multiple sites throughout the Pascagoula River system of southeastern Mississippi, including the Chickasawhay, Leaf, Pascagoula, and Escatawpa rivers. The latter site contains a geographically isolated population that was first documented in the 1990‚Äôs by Pete Floyd and Tom Mann (MMNS). Along with documenting the presence of this population, they reported unique pleural scute patterning with individuals exhibiting a high level of rings which is unusual for this species. Genetic analysis is ongoing and should be completed by the end of 2009. Another goal of this project is to design public outreach materials outlining turtle conservation in cooperation with MDWFP and USFWS. These materials will provide general information regarding turtle conservation, as well as outline proper recreational policies on protected nesting sandbars on Ward Bayou Wildlife Management Area (Jackson County, MS). The results from our work will add to the knowledge of this species, as well as provide informative material to educate the public. Hopefully this will ensure sound conservation decisions that will allow wild populations to persist within the Pascagoula River system.
- Will Selman, University of Southern Mississippi
The TSA provided partial support for this project with funds from the 2007 Batchelor Foundation grant.