Bycatch reduction device conserves diamondback terrapin without affecting catch of blue crab

摘要

ABSTRACT: Bycatch mortality of non-target species in fisheries is a major threat to the conservation and restoration of marine and estuarine species. Attempts to reduce bycatch by fitting fishing gear with excluder devices have typically been met with resistance due to reductions in catch of target species. We examined the possibility that conservation and fishery goals could be met simultaneously. In lower Chesapeake Bay, we tested a mechanism for reducing bycatch of diamondback terrapin Malaclemys terrapin in blue-crab traps without affecting crab catch. Over 23 sampling dates during summer 2008, we compared terrapin captures at 2 shallow-water sites typical of recreational crabbing, using 10 paired sets of an un-baited trap fitted with bycatch reduction devices (BRDs) and a trap without BRDs at each site on each date. In a separate experiment, traps were baited and fished 4 times during the summer, when we recorded number, size, and condition of captured crabs. Of 48 terrapin captures in crab traps, only 2 were from traps fitted with BRDs. Crab catch (number, size, and biomass) was equivalent between traps with and without BRDs. Because BRDs are effective in excluding all but the smallest terrapins from entering crab traps and had no effect on crab catch, BRDs are recommended for all recreational crab traps at this time and should be seriously considered for commercial traps throughout shallow estuarine waters. Combined with bycatch reduction policies in other North American estuaries, a comprehensive and effective strategy for the conservation of diamondback terrapin threatened by fisheries is emerging.