CS06 Benthos
Date: Friday, June 14, 2002
Time: 10:30:00 AM
Location: Colwood
 
BrownE, School of Fisheries and Ocean Sciences, University of Alaska, Fairbanks, USA, ftejb@uaf.edu
Dommisse, M, , Institute of Marine Science, University of Alaska, Fairbanks, USA, michaela.dommisse@arts.monash.edu
Finney, B, , Institute of Marine Science, University of Alaska, Fairbanks, USA, finney@ims.uaf.edu
Hills, S, , Institute of Marine Science, University of Alaska, Fairbanks, USA, shills@ims.uaf.edu
 
IMPACTS OF COMMERCIAL BOTTOM TRAWLING TO ESSENTIAL FISH HABITAT IN THE BERING SEA
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Evaluation of impacts to essential fish habitat by commercial bottom trawling is needed to ensure long-term sustainability of fisheries and the ecosystems that support them. We examined differences in sediment structure and benthic community composition resulting from bottom trawling in a shallow (26m), sandy substrate in the Bering Sea. Based on results from experimental trawling, we interpret differences between a long-term closure and adjacent fishery, and compare impacts of trawling to natural disturbance. Acoustic data, cores, grabs and video were randomly collected at 12 stations within a 2 km area immediately pre and post trawling by a commercial catcher-processor, and at 10 stations in the closure and fishery in 1999-2000. Wave and tide data from NDBC buoy 46035 were used to estimate near bottom current speeds and sediment resuspension. Significant increased variability of the sediment grain sizes at 2-4 cm depth correspond to increased variability in chlorophyll a at 2-3cm. This is evidence of a redistribution of sediments and downward mixing of surface organic matter. The implications of these changes will be evaluated relative to shifts in benthic and demersal fish populations.