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 commercial trawl fisheries. Because of good record keeping and the relatively brief history of fishing it is possible to reconstruct the spatial and temporal patterns of exploitation. Previously unfished (UF) areas can be identified and directly compared with heavily fished (HF) areas to investigate long-term consequences for the benthos. Using this approach, macrofauna populations in a shallow (48 m average) soft-bottom area were studied during 1996. 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 importance of life history characteristics, such as habitat requirements acid feeding 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 complex issue of bottorn-trawl disturbances. This begins with the identification of chronic and acute impacts, followed by focused investigations of ecological implications and, ultimately, cost-benefit analyses to evaluate specific resource-management options. (C) 2000 International Council for the Exploration of the Sea.