As crickets sing sunshine to sleep, it’s a wake-up call for alligator snapping turtles. They make a living by the dark of the night in big creeks, rivers, and marshes in the southern U.S. But in Oklahoma, where they form a special part of the state’s natural heritage, they’re not quite as abundant as they used to be. They once occupied much of the eastern third of the state, but habitat loss and over-harvest reduced this animal to living in only a few select sites.
The Tishomingo National Fish Hatchery, circa 1949.
That’s where the Tishomingo National Fish Hatchery stepped in with a captive-rearing program for an unarguably interesting animal. They grow big. They’re impressive to look at. What other animal has a piece of flesh on its tongue to wiggle and lure in unsuspecting fish, securing its prey with a forceful snap of its jaws? This one does.
Starting in 1999, scientists at the hatchery brought the animals on-station and developed captive-breeding and -rearing techniques, with great success. While they have not abandoned their work with paddlefish, catfish, and the endangered Arkansas River shiner, the alligator snapping turtle has risen in importance, if for nothing else but to stave off a potential listing under the Endangered Species Act. You might say they are getting out in front of the emerging conservation issue.
Alligator snapping turtles start out the size of turtles and end up the size of alligators.
To that end, turtle biologist Brian Fillmore recently co-authored research findings in the specialized scientific journal, Chelonian Conservation and Biology. Think of the journal as “all things turtle” for scientists. While it might be a specialized audience reading about Fillmore’s work, what is reported is of significance to conservation in East Oklahoma and beyond.
Kelly Graves holding an alligator snapping turtle at Tishomingo National Fish Hatchery.
Fillmore and his four co-authors examined how young turtles, raised and given a head start at the hatchery, survived the rigors of the wild. Captive rearing and releasing has worked for other animals in the past; you may not be aware that white-tailed deer and wild turkey were once a rarity. Now they’re quite common, thanks in part to “restocking” as a conservation measure. But will it work for alligator snapping turtles? The upshot: sure looks like it could.
“Think of the journal as ‘all things turtle’ for scientists. While it might be a specialized audience reading about Fillmore’s work, what is reported is of significance to conservation in East Oklahoma and beyond.”
Alligator snapping turtles from Tishomingo were tagged, stocked in the Caney River and Pond Creek in northeastern Oklahoma, and later recaptured. Some of the 246 tagged turtles were never seen again. Others were caught multiple times for several years in nets baited with dead fish and set out in the late afternoons. When those turtles were recaptured, scientists measured their size and weight. The data was compared to that of alligator snapping turtles of the same age that were kept at the Tishomingo National Fish Hatchery over the same period — revealing that the wild-raised turtles put on more mass and size than did those kept in captivity.
Tag & Bag: Researchers collect wild snapping turtles (left) when they’re relatively small; PIT tags (right) are used to collect data to compare to captive-raised animals.
That piece of information alone is encouraging. It may show that captive-bred alligator snapping turtles can quickly find the food and space that they need to survive in waters that provide required habitat. The ultimate sign of success will of course be a naturally breeding population, much like deer and turkey. But alligator snapping turtles are not deer; they aren’t quite so visible or as easily monitored. And that should be the next step in this turtle conservation endeavor, say Fillmore and his co-authors — to determine if repatriated turtles will naturally reproduce.
To learn more, visit www.fws.gov/southwest/.