Eastern Bering Sea Pollock Trawl Fisheries: Variation in Salmon Bycatch over Time and Space
Diana L. Stram and James N. Ianelli
Abstract.—The Magnuson-Stevens Act emphasizes the importance of minimizing bycatch, to the extent practicable, as part of the goal to achieve sustainable fisheries. Measures to reduce Pacific salmon (Oncorhynchus spp.) bycatch for the eastern Bering Sea walleye pollock Theragra chalcogramma trawl fisheries have been developed and implemented, resulting in specific closed (no-fishing) areas when established bycatch limits for Pacific salmon are exceeded. These closure areas were designed based on analyses of groundfish observer data collected from 1990–1995, yet in recent years Pacific salmon bycatch in the pollock fishery has consistently exceeded the limits. As a result, large areas were closed to the fishery, and the spatial pattern of fishing by the pollock fleet was altered. An analysis of the effectiveness of the closed-area management system was reviewed by the North Pacific Fishery Management Council (Council) in 2005, and indicated that when areas were closed, salmon bycatch rates were often higher than observed earlier inside the closure areas. Thus, as an interim measure, the Council adopted a program in October 2005 to exempt vessels from the existing closed-area regulations so that near-real time inseason information could be used to establish dynamic closed areas where salmon bycatch levels are high. In this paper, we review information on the previous closed area management system and qualitatively characterize historical bycatch patterns using fishery observer data. Our results show that the spatial and temporal salmon bycatch patterns are highly variable between years. Variability in size and sex composition of the salmon bycatch adds to the complexity of developing effective management options aimed at minimizing the bycatch of the eastern Bering Sea pollock fishery. These results should assist managers in devising alternative approaches for managing salmon bycatch in the pollock trawl fisheries.