Population Status and Distribution in the Suwannee River

FWRI biologists conducted a study to determine the population status and distribution of alligator snapping turtles in the Suwannee River. Beginning in July 2011, researchers set traps in 12 3-mile (5-kilometer) stretches of the river from White Springs in Hamilton County to the Gulf of Mexico. As of September 2013, researchers had caught 161 alligator snapping turtles, including 29 they had captured before.

Researchers captured turtles at 11 of the 12 trapping sites, and the only site at which turtles were not captured was within the tidal zone at the mouth of the river. Alligator snapping turtles may be less abundant is this area because there is less available habitat and the salt levels in the water are higher. The number of captures per site visit ranged from zero to 10 turtles. Male adults accounted for 61 percent of all captures, female adults 27 percent and subadults 12 percent. Thirty-three of 81 adult male turtles (41 percent) weighed more than 100 pounds (45 kilograms), with the heaviest weighing 126 pounds (57 kilograms).

A veterinarian accompanied researchers to conduct X-rays of captured turtles. One concern is bush hooks, which are unmanned fishing lines set on overhanging branches to catch catfish. They are fairly common in some parts of the river. Ingested hooks, particularly stainless steel ones, may pose health problems to turtles and eventually kill them. As of September 2013, four of 31 turtles X-rayed had ingested at least one hook, and one turtle contained three hooks. Another turtle had a hook embedded in its neck.

Researchers also tracked tagged turtles in three stretches of the river to determine their movements and habitat use. They used a manual tracking unit aboard a boat to locate tagged turtles. Most alligator snapping turtle maximum home ranges averaged between 2-5 kilometers (approximately 1-3 miles). Male and female movements appear to be equal; however, a few large male turtles were never relocated after being tagged and may have moved far outside of the study site (20 kilometers, or 12.4 miles).