Bycatch, Biodiversity and Understudied Species in the Northwest Atlantic

Recognition of bycatch impacts on sustainability of fisheries combined with an impetus for ecosystem approaches to management has created the need for improved understanding of traditionally understudied species. Bycatch events on unassessed species registered by the northeastern US observer program between 2003 and 2006 from bottom trawl, mid-water trawls, drift gillnet and sink gillnet fisheries were identified. National Marine Fisheries Service (NMFS) trawl data was analyzed to determine the geographic range of unassessed species in the last 10 years of the survey. Concentrations of capture events determined from observer data were compared to the NMFS survey generated distributions. We then focused on bottom trawls from both the observer and NMFS survey data for the Gulf of Maine, Georges Bank and the Mid-Atlantic regions, and species for which adequate data existed to determine a population trend. Trends in population decline from NMFS survey data were correlated to frequency of capture and total weight in the observer data. Spatial overlap in bycatch events and population abundance were determined, and locations of particularly high potential bycatch of unassessed species identified. Fish assemblage structure and migratory patterns were important in shaping results, as was observer coverage. The results will be placed into context by focusing on ecological approaches to fisheries, geographically-based management and protection of biodiversity.