Industry-sourced approaches to diamond-backed terrapin bycatch reduction in the North Carolina commercial blue crab fishery

The commercial blue crab ( Callinectes sapidus ) harvest represents one of the most valuable fisheries in North Carolina and is a significant economic driver for coastal communities. The diamond-backed terrapin ( Malaclemys terrapin ), an estuarine Emydid turtle, is listed as a Species of Special Concern in North Carolina, where incidental bycatch in crab pots is a prominent threat. Efforts to reduce bycatch by installing bycatch reduction devices (BRDs) to funnel openings on crab pots have been met with resistance due to perceived negative impacts to blue crab catch. In 2020, the North Carolina Marine Fisheries Commission (NCMFC) designated Diamond-backed Terrapin Management Areas (DTMAs) in two waterbodies in North Carolina, within which North Carolina Division of Marine Fisheries (NCDMF) approved BRDs must be incorporated into all crab pots. While this regulatory measure was taken to mitigate fisheries impacts on diamond-backed terrapins, the NCDMF acknowledged the need to explore alternative gear modifications that exclude diamond-backed terrapins while minimizing impacts to target species catch. The primary goal of our study was to test the efficacy of industry-sourced gear modifications to crab pot funnel entries for diamond-backed terrapin exclusion and assess impacts of these modifications on blue crab catch. Results from fisheries-independent and fisheries-dependent testing show that narrow funnel designs (NFD) effectively exclude diamond-backed terrapins without significant reductions in catch or size of blue crabs. Our results highlight the effectiveness of collaboration between management agencies, researchers, and industry stakeholders to achieve broadly acceptable solutions to reduce diamond-backed terrapin bycatch in the commercial blue crab fishery.