NPRB 1319 Assessment of the benthic impacts of raised groundgear for the Eastern Bering Sea pollock fishery.

The Alaska pollock fishing industry, in collaboration with scientists at Alaska Pacific University, the Alaska Fisheries Science Center, and members of the fishing gear design and fabrication industry are actively pursuing new trawl designs to address bycatch and seabed contact issues while maintaining a viable pollock capture efficiency. Adult Alaska pollock (Theragra chalcogramma) aggregate on or near the seafloor, particularly during the day (e.g. Mecklenburg, et al. 2002, Tsuji, S. 1989). Our research aimed to develop and test several trawl groundgear configurations to capture pollock aggregated near the seafloor while reducing bycatch and impacts to the benthic habitat.

In the US, federally managed fisheries need to minimize both by-catch and the adverse impacts of fishing on Essential Fish Habitat while maintaining commercially viable catch efficiencies of target species. Like many other large scale commercial fisheries, the Alaska pollock fishery operations are increasingly constrained by efforts to avoid bycatch (salmon, crab and halibut) and the rising cost of fuel. An inter-institutional, inter-disciplinary research team including scientists from NOAA Alaska Fisheries Science Center (AFSC) and Alaska Pacific University (APU), both major sectors of the Alaska pollock fishing industry, and members of the fishing gear design and fabrication industry is working programmatically to develop more optimal trawls for capturing pollock near the seafloor. This proposal addresses the seabed contact and benthic habitat impact aspects of several trawl groundgear configurations that are being considered within this program. Recent AFSC and industry cooperative work showed that raising trawl groundgear (sweeps and footrope) above the seabed via widely-spaced bobbins reduces the direct contact area of the gear, along with crab mortality and flatfish bycatch; while maintaining fishing performance for pollock. We propose fieldwork to compare bottom-contact characteristics and benthic impacts of raised groundgear by systematically varying bobbin weight, spacing and seafloor clearance. We aim to: 1) determine susceptibility of structure-forming geological and biological seabed features to these new groundgear to evaluate the potential for adverse habitat impacts; 2) quantify the component-specific (e.g. sweep, footrope) seabed contact for each groundgear configuration; and 3) compare the contact-adjusted swept areas of, and habitat-feature susceptibilities to, each configuration to support an evaluation of the new pollock trawl designs within the context of a fishery habitat impacts assessment. The proposed work directly addresses bycatch and essential fish habitat concerns of the North Pacific Fisheries Management Council.

Go to http://projects.nprb.org/#metadata/01f771ea-b802-41cb-b468-281ab28c8475/project and email rick.towler@noaa.gov

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Video and physical samples were viewed and assessed for degree of trawl interactions with benthos.