Cooperative Development and Testing of Sink Gillnet Modifications for Reducing Atlantic Sturgeon Bycatch in the Monkfish Fishery

In 2012, five Distinct Population Segments of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) were listed under the Endangered Species Act. A preceding Status Review concluded that bycatch in sink-gillnets was a significant hurdle to Atlantic sturgeon recovery. Over three field seasons (2010-2012), we worked collaboratively with commercial harvesters to modify sink gillnet configurations to reduce Atlantic sturgeon bycatch while maintaining adequate catches of their target species, monkfish (Lophius americanus) and winter skate (Leucoraja ocellata). In 2010, we fished paired replicates of gillnets (standard 12 meshes x 12 inches (30.5cm) stretch) with and without tie-downs and although Atlantic sturgeon bycatch did not differ significantly, target species catches were reduced in nets without tie-downs. In 2011, we subjected two different tie-down configurations (standard 12 meshes tied-down to four) and low profile (six meshes tied-down to 24 inches) to the same experimental protocol. Bycatch of Atlantic sturgeon and landings of targeted species were both significantly reduced in the lower profile tie-down gillnets. During 2012 we compared another low profile net configuration (eight meshes tied-down to 24 inches) which reduced Atlantic sturgeon bycatch with little impact on the landings of targeted species. Although catches of sturgeon were low, generally, our findings suggest that the use of tie-downs is important for maintaining adequate catches of target species, and certain tie-down configurations can reduce Atlantic sturgeon bycatch. Additionally, experimental testing of gear developed by harvesters allows for the identification of gear configurations that both address conservation objectives and are realistic for commercial use. This model of collaborative research can prove useful in the recovery of other imperiled sturgeons.