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Investigating the Interaction Between Terrapins and Crab Traps

ornate diamondback terrapins

Diamondback terrapins (Malaclemys terrapin) are found statewide in Florida’s coastal marshes, tidal creeks, mangroves and other brackish and estuarine habitats. They share these habitats with blue crabs (Callinectes sapidus) and are susceptible to drowning when trapped in crab fishing gear. Researchers at the Fish and Wildlife Research Institute designed a project to investigate the capture rates of ornate diamondback terrapins (Malaclemys terrapin macrospilota) in crab traps in Franklin County, Florida. This study will provide a basis for determining management actions regarding the deployment of crab traps where ornate diamondback terrapins are present.

Researchers modified crab traps so they would have an air pocket at the top of the trap to prevent terrapins from drowning. These terrapin-safe crab traps were then set at six distances from shore, allowing researchers to gather vital information about terrapin capture rates in blue crab traps without injuring the terrapins. They are also looking at how time of year and distance from shore affect terrapin capture rates.

In addition, researchers are using historic, current and ongoing scientific reports and population surveys to develop a statewide hot-spot map to gain a better understanding of diamondback terrapin distribution. Once the map is completed, staff will perform a population assessment on terrapin groups in the coastal areas of Florida’s Big Bend region – Franklin through Levy counties. Blue crab fishing efforts, summarized from Marine Fisheries-Dependent Monitoring trip ticket data, will then be incorporated into the hot-spot map to indicate specific areas of concern for diamondback terrapin bycatch.

Once the project is completed, the statewide hot-spot map and associated diamondback terrapin population estimates for the Big Bend region will be provided to fisheries managers, who can then determine potential areas of conflict and develop management actions accordingly. This pilot study aims to determine methods that can be applied to other parts of the state to prevent diamondback terrapins from being trapped in crab traps.