Exploration of the N-Viro Dredge to Reduce Bycatch and Improve Fuel Efficiency in the Atlantic Sea Scallop (Placopecten magellanicus) Fishery

Atlantic sea scallop (Placopecten magellanicus) fishing vessels typically use New Bedford-style dredges for harvest, which are often criticized for high bycatch rates and impacts on benthic environments. The king (Pecten maximus) and queen (Aequipecten opercularis) scallop fisheries were criticized for similar impacts in the United Kingdom with New Haven dredges. Vessels in these U.K. fisheries have increasingly used the N-Viro dredge due to its improved fuel efficiency and reduced bycatch rates and habitat impacts. Through a two-phase pilot project, the Commercial Fisheries Research Foundation, Gulf of Maine, Inc., and Southern New England sea scallop fishermen conducted at-sea trials to determine the feasibility of the N-Viro dredge for use in the Atlantic sea scallop fishery. Through side-by-side comparisons of N-Viro and New Bedford-style dredges, the N-Viro dredge showed increased fuel efficiency, reduced habitat impacts, and decreased bycatch rates of at least 50% for nearly all bycatch species. The N-Viro dredge also had decreased catch rates of scallops, implying that bycatch reduction was a product of decreased overall effectiveness; however, the N-Viro dredge was more selective for the more valuable, larger-sized scallops, with catch rates near those of a New Bedford-style dredge. These results suggest that the N-Viro dredge has the potential to serve as a tool that Atlantic sea scallop vessels could use to access areas with mixes of juvenile and adult scallops, high bycatch species abundance, or areas of complex rocky bottom. Further gear improvement work to increase the overall scallop catch efficiency and provide additional support for size selectivity are important next steps for utility and overall industry acceptance.