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Alligator Snapping Turtles

Watch FWRI researchers as they trap and gather data on alligator snapping turtles in the Suwannee River.

Alligator Snapping Turtle Distributional Survey

Little is known about the status of alligator snapping turtles between the Ochlockonee and Suwannee rivers from Wakulla County to Dixie County. There are no museum specimens from any rivers in this part of the Florida, but there have been several unverified records. In July 2011, Fish and Wildlife Research Institute (FWRI) biologists began a one-year trapping study in seven rivers between the Ochlockonee and Suwannee rivers in Florida’s Big Bend region to determine whether the species is present in this apparent distributional gap. 

As of December 2012, trapping in the St. Marks, Aucilla and Econfina rivers yielded no alligator snappers, and severe drought conditions prevented biologists from trapping in the other rivers in the region. They decided to extend the study for another year to allow trapping during more favorable water levels.

In addition to answering questions about the distribution of the species, this project aims to determine the relationship between alligator snappers in this region and those in surrounding areas. Recent research indicates that the population in the Suwannee River drainage is genetically and physically distinct from populations in more westerly river drainages. In fact, FWRI biologists and other scientists have submitted a manuscript for publication that describes two new species of alligator snapping turtle – the Suwannee and the Apalachicola. If any turtles are trapped in this study, researchers will conduct genetic analyses to determine whether they are more closely related to Suwannee or Apalachicola river populations.  

Alligator Snapping Turtle Population Status and Distribution in the Suwannee River

FWRI biologists are conducting 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 are also tracking tagged turtles in three stretches of the river to determine their movements and habitat use. They use 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).