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Status of Stocks & Multispecies Assessment Program

Rockfish Management and Research Presentation in Dutch Harbor

Paul Spencer gave a public presentation titled “Bering Sea/Aleutian Islands rockfish management and research” at the Forum of Alaska Marine Issues seminar series in Dutch Harbor, Alaska, on 23 February. The presentation covered a variety of topics, including the fundamentals of fishery assessments, unique aspects of rockfish biology including longevity and reproductive biology, historical rockfish management, and current rockfish research projects and management issues. About 20 people attended, including representatives of various community, fishing, and scientific organizations. The presentation was approximately 30 minutes, with a question and answer period of approximately 20 minutes that covered a variety of topics, including rockfish species ranges, habitat use, and management of non-target species.

By Paul Spencer


Chum Salmon Bycatch Analysis

Ecosystem fisheries management, as practiced by the North Pacific Fishery Management Council (NPFMC), involves many facets including measures to avoid exceeding prohibited species catch (PSC) limits. Likewise, another ecosystem principle ensures that catch limits remain below overfishing levels (typically set equal to maximum-sustainable yield levels), based on single-species assessment models for each stock or stock complex. This means that the management system is based explicitly on multispecies considerations. Salmon have been a prohibited species since the days of foreign and joint-venture trawl fishing in the eastern Bering Sea, and management has evolved after two decades of an extensive scientific observer data collection program. These data, supplemented with summer surveys and cooperative research programs, provide unique insights on the temporal and spatial structure of salmon stocks during their oceanic life stage. In particular, patterns of bycatch appear to be affected by season, location, and temperatures. However, year-effects appear to be the largest factor indicating that interannual variability in environmental conditions and run sizes likely play an important role in bycatch. For new, more optimal management measures (such as closure areas), the available data are limited due to the occurrence of past closures.

Presently, NPFMC and AFSC scientists are on track to present management alternatives to reduce chum salmon bycatch. Analyses of these alternatives are being conducted based on a variety of data sources. For example, chum salmon age data (based on examination of growth patterns on their scales), as compiled by colleagues at the Auke Bay Labs (ABL) with funds from the NPFMC, were used to estimate the proportion of bycatch that would have returned in the current or a future year. These estimates can then be combined with genetic analyses to estimate the origins of the chum salmon bycatch. The genetics work was completed by ABL scientists and is being applied to provide a rough idea of the historical impact the pollock groundfish fishery has had on western Alaska salmon returns. Another part of the analysis involves developing time-area closures that can be effective in reducing bycatch. The extensive quantification in space and time of chum salmon bycatch (1991-2010), based on observer data collection programs, provides critical information on the difficulty of the problem. Times and areas vary greatly between years, but they also reveal some consistent patterns that can be applied for management (and to assist industry in ways to avoid bycatch). The analysts note that new regulations designed to reduce bycatch of one species may result in higher bycatch of others. Such complications are highlighted so that the NPFMC will have the information needed to strike an appropriate balance of management measures.

By Jim Ianelli
 

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