Factors driving the density of derelict crab pots and their associated bycatch in North Carolina waters

Abstract

Abstract-Lost or derelict fishing gear can impair fisheries by contributing to the depletion of target species populations and can reduce nontarget fish and wildlife populations. We measured the density of derelict crab pot (DCPs) using side-scan sonar and examined bycatch associated with DCPs in nearshore waters (depths ≤4 m) of 6 waterbodies important to the North Carolina blue crab fishery, the state's most valued commercial fishery. Extrapolated mean DCP density was 105 DCP/km 2 of open water (range: 6-301). Densities of DCPs differed significantly among waterbodies but not among habitats (marsh creeks, estuarine edge ≤50 m from shore, and Atlantic Intracoastal Waterway margin). Extrapolated DCP densities were generally greater than those concurrently observed for actively fished crab pots within the 201 1-km 2 cells sampled during 23 survey days between April and November 2010. Of the DCPs examined, 41% contained bycatch (unintentional catch) and 37% remained capable of trapping organisms. Bycatch was dominated by blue crab (Callinectes sapidus) and Florida stone crab (Menippe mercenaria) and included 5 diamondback terrapin (Malaclemys terrapin) and 1 clapper rail (Rallus crepitans).

Examining derelict pot impacts on harvest in a commercial blue crab Callinectes sapidus fishery

“…Several past studies have identified the direct loss of biomass in the population of target species (e.g., blue crab, Dungeness crab Cancer magister) due to ghost fishing mortalities by derelict pots over time (Breen 1987, Guillory 1993, Havens et al 2008, Giordano et al 2010, Antonelis et al 2011, Anderson and Alford 2014, Bilkovic et al 2014, Voss et al 2015. For example, bycatch mortality of blue crabs in derelict pots is estimated at 20-26 crabs per pot per year (Guillory 1993, Giordano et al 2010.…”