The effectiveness of bycatch reduction devices on crab pots at reducing capture and mortality of diamondback terrapins (Malaclemys terrapin) in Florida

Abstract

Diamondback terrapins (Malaclemys terrapin) drown in blue crab (Callinectes sapidus) pots throughout their range. The objectives of this study were to test if bycatch mortality of diamondback terrapins in commercial crab pots is reduced by using bycatch reduction devices (BRDs) and to determine if BRDs affect crab catch in Florida by comparing sex, size, and number of blue crabs captured in standard crab pots with those captured in pots equipped with BRDs. We fished 15 standard crab pots (controls) and 15 crab pots with bycatch reduction devices (experimentals) for 10-d periods at two sites per year from 2002 through 2005. Study sites were located in eight Florida counties with one sample period per county. Pots were checked daily and baited on alternate days. We determined sex and size of captured terrapins and blue crabs to evaluate if BRDs affected the size of either species. Thirty-seven terrapins were caught in control pots and four in experimentals. Eleven terrapins were small enough that they would not have been prevented from entering either pot treatment, but we found that 73.2% of the terrapins in this study could have been prevented from entering crab pots with functional BRDs. There were no significant differences between the sex, measurements, or number of legal-sized crabs captured in control and experimental pots at any of the study sites. We recommend that the Florida Fish and Wildlife Conservation Commission devise and adopt regulations that require the use of 4.5×12 cm BRDs on all commercial and recreational crab pots in Florida without delay.