Assessing Benthic Impacts of Raised Groundgear for the Eastern Bering Sea Pollock Fishery

From the collaboration of Alaska Pacific University, Alaska Fisheries Science Center and the Alaska pollock fishing industry, six raised groundgear configurations were designed for a pelagic trawl. Reason being, the Alaska pollock fishery is facing a critical issue: to capture pollock near the seafloor while minimizing crab, halibut, and salmon bycatch, as well as avoiding habitat impacts. The groundgear configurations consist of various footrope materials, steel bobbins, and weight clusters. The components were all chosen based on their hydrodynamic qualities and ability to raise the footrope off of the seafloor. Each configuration was towed at sea, leaving track marks on the seafloor for our research purposes. We measured the performance, swept area, and impact to biological features using DIDSON sonar and video footage. The performance results are evaluated under the context of a fishery habitat impacts assessment that addresses concerns of the North Pacific Fishery Management Council. This quantitative evaluation provides evidence of decreased seafloor contact, seafloor clearance suitable for benthic habitat, and ultimately a smaller adverse impact than the nominal swept area might otherwise indicate. This research supports gear modifications, one of three primary tools outlined by the National Research Council for minimizing adverse effects from fishing.