An examination of chronic trawling effects on soft-bottom benthos of the eastern Bering Sea

The eastern Bering Sea has experienced rapid and intensive development of c ommercial trawl fisheries. Because of good record keeping and the relativel y brief history of fishing it is possible to reconstruct the spatial and te mporal patterns of exploitation. Previously unfished (UF) areas can be iden tified and directly compared with heavily fished (HF) areas to investigate long-term consequences for the benthos. Using this approach, macrofauna pop ulations in a shallow (48 m average) soft-bottom area were studied during 1 996. Samples of 92 taxa (reduced for analysis) were collected at 84-1 nm(2) sites straddling a closed-area boundary. Multi- and univariate statistical tests and raw patterns in the data support the Following generalizations: (1) sedentary macrofauna (e.g., anemones, soft corals, sponges, whelk eggs, bryozoans, ascidians), neptunid whelks and empty shells were more abundant in the UF area; (2) mixed responses were observed within motile groups (e. g. crabs, sea stars; whelks) and infaunal bivalves, suggesting the importan ce of life history characteristics, such as habitat requirements acid feedi ng mode; and (3) overall diversity and niche breadth of sedentary taxa were greater in the UF area. A systematic approach is required to address the c omplex issue of bottorn-trawl disturbances. This begins with the identifica tion of chronic and acute impacts, followed by focused investigations of ec ological implications and, ultimately, cost-benefit analyses to evaluate sp ecific resource-management options. (C) 2000 International Council for the Exploration of the Sea.