Georgia’s Giant Turtles

Alligator snapping turtles are the largest species of freshwater turtle in Georgia, reaching sizes of up to 200 pounds and carapace lengths in excess of 80 cm (over 30 inches).  Until recently, all alligator snapping turtles were classified as a single species: Macrochelys temminckii.  However, Thomas et al. (2014) split alligator snapping turtles into three species based on genetic analyses and scute morphology of turtle populations across the range of M. temminckii.  This split reduced the range for M. temminckii to include all populations west of the Choctawhatchee river drainage, while the eastern portion of the range was divided between two newly described species.  The Apalachicola Alligator Snapping Turtle (M. apalachicolae) occurs in river drainages bounded by the Choctawhatchee and Ochlockonee River in Georgia, Florida, and Alabama (although this species description is not without debate; Folt and Guyer 2015).  The Suwannee Alligator Snapping Turtle (M. suwanniensis) is found only in the Suwannee River Drainage in Georgia and Florida and is easily distinguishable from the other species via the size of the caudal notch.

Prior to being split into three species, there was already conservation concern surrounding alligator snapping turtles.  These turtles are long-lived but have low reproductive rates, making any decline in adult survival potentially threatening to long-term population persistence (Reed et al. 2002; Tucker and Sloan 1997).  Population declines from commercial overharvest during the 1970s and 1980s have already been documented (Pritchard 2006), and harvest is still legal in many places. Splitting M. temminckii into multiple species only heightens these conservation concerns.  All three species now have a more restricted range than M. temminckii had historically and states like Georgia and Florida now have to consider multiple species in their conservation planning.  Describing new species can also highlight data gaps where historic surveys may not have adequately inventoried for each species.

In Georgia, M. apalachicolae has been well-studied throughout the majority of its range (e.g., King et al. 2016).  However, there is little published data available for M. suwanniensis in Georgia river systems.  Jensen and Birkhead (2003) did do some sampling in the Suwannee River drainage, but their catch-per-unit effort (0.05 turtles/trap-night) from that drainage was extremely low in comparison to that found in Apalachicola drainages (0.45 turtles/trap-night).  Thus, an obvious need exists to determine the status of this species throughout its range in Georgia so that informed conservation and management decisions can be made.

Over the next two years, we will be performing surveys for M. suwanniensis at sites along the Suwannee River and its tributaries.  The standard method used to survey for alligator snapping turtles is to trap with large (4’ diameter) hoop-nets.  It is also possible to snorkel for this species in some places but only where visibility is high enough to detect turtles.  Working with alligator snapping turtles is not without peril. These large, powerful turtles possess strong jaws and have been reported to take a misplaced finger (Johnson and Nielsen 2016).  Other hazards of trapping with large hoop-nets include alligators and long days in the hot sun (particularly problematic for LSI Research Assistant Ben Stegenga). We are looking forward to spending some time on the water over the next two summers and will report back with survey results later this year.

Literature Cited

Folt, B., and C. Guyer. 2015. Evaluating recent taxonomic changes for alligator snapping turtles (Testudines: Chelydridae). Zootaxa 3947:447–450.

Jensen, J. B., and W. S. Birkhead. 2003. Status and distribution of the alligator snapping turtle (Macrochelys temminckii) in Georgia. Southeastern Naturalist 2:25–34.

Johnson, R. D., and C. L. Nielsen. 2016. Traumatic amputation of finger from an Alligator Snapping Turtle bite. Wilderness and Environmental Medicine 27:277–281.

King, R. L., B. P. Hepler, L. L. Smith, and J. B. Jensen. 2016. The status of Macrochelys temminckii (Alligator Snapping Turtle) in the Flint River, GA, 22 years after the close of commercial harvest. Southeastern Naturalist 15:575–585.

Pritchard, P. C.  2006. The Alligator Snapping Turtle: Biology and Conservation. Krieger Publishing, Malabar, Florida, USA, 140 pp.

Reed, R. N., J. D. Congdon, and J. W. Gibbons. 2002. The alligator snapping turtle [Macroclemys (Macrochelys) temminckii]: A review of ecology, life history, and conservation, with demographic analyses of the sustainability of take from wild populations. Report to Division of Scientific Authority, U.S. Fish and Wildlife Service. 20 p. Savannah River Ecology Laboratory, University of Georgia.

Thomas, T. M., M. C. Granatosky, J. R. Bourque, K. L. Krysko, P. E. Moler, T. Gamble, E. Suarez, E. Leone, K. M. Enge, and J. Roman. 2014. Taxonomic assessment of Alligator Snapping Turtles (Chelydridae:Macrochelys), with the description of two new species from the southeastern United States. Zootaxa 3786:141–165.

Tucker, A. D., and K. N. Sloan. 1997. Growth and reproductive estimates from alligator snapping turtles, Macroclemys temminckii, taken by commercial harvest in Louisiana. Chelonian Conservation and Biology 2:587–592.