Will It Float? Testing a New Technique for Reducing Loggerhead Sea Turtle Damage to Crab Pots

Abstract

Loggerhead sea turtles Caretta caretta have been found to damage crab pots and reduce catch of blue crabs Callinectes sapidus in North Carolina sounds. In response, crabbers have avoided fishing at locations and times of peak loggerhead sea turtle activity and have experimented with modifications to make their gear more robust. We field tested a new, lightweight, and inexpensive modification: self-righting floats tethered to the inside of the crab pots. Thirty pairs of regular and modified pots were fished between 16 June and 31 July 2006. Damage by loggerhead sea turtles was found in 38% of all replicates, and blue crab catch was 57% lower in crab pots that had been discovered by loggerhead sea turtles. The float modification effectively reduced damage, but stronger effects were found when using plastic bait-well covers that the crabbers had introduced. The modified pots were significantly less damaged (average damage index [ADI] = 1.38 with plastic covers and 2.01 with cardboard covers) than regular pots (ADI = 1.78 with plastic covers and 2.38 with cardboard covers). Average blue crab catch was significantly higher in pots with plastic bait-well covers (15 crabs/modified pot, 18 crabs/regular pot) than in pots with cardboard covers (13 crabs/modified pot, 11 crabs/regular pot). However, there was a significant interaction of pot type with bait-well cover type. When plastic covers were used, average blue crab catch was higher in regular pots (18 crabs/pot) than in modified pots (15 crabs/pot). The opposite case was observed when cardboard covers were used: catch was higher in modified pots (13 crabs/pot) than in regular pots (11 crabs/pot). A drawback to the float modification was a qualitative increase in pot drift and loss in high winds, resulting in the need for costly retrieval measures; crab pot loss may also jeopardize estuarine species that become trapped in derelict gear. Adopting these techniques, however, may help crabbers reduce gear damage, catch loss, and negative interactions with loggerhead sea turtles in this fishery.