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Status of Stocks & Multispecies Assessment Program

Aleutian Islands Cooperative Acoustic Survey Study

Status of Stocks and Multispecies Assessment (SSMA) Program scientists Steve Barbeaux and Libby Logerwell conducted the Aleutian Islands Cooperative Acoustic Survey Study from 17 March to 20 April 2007. The purpose of the study was to assess walleye pollock abundance in the central Aleutian Islands and to test the feasibility of managing an Aleutian Islands pollock fishery at a finer temporal and spatial resolution using near real-time acoustic surveying.

To accomplish these objectives two acoustic surveys were conducted aboard a commercial fishing vessel equipped with a Simrad ES60 echosounder and a 38kHz split beam transducer. The vessel was also equipped for pelagic pollock fishing. The survey covered the area between Seguam Island and Amchitka Pass (long. 173°W to 179°W) on the north side of the Aleutian Islands archipelago.

To verify the acoustic data and to support the study, 1,300 metric tons (t) of walleye pollock were harvested within an area that included waters within 20 nmi of Steller sea lion haulouts and rookeries. This harvest was permitted under an experimental fishing permit (EFP) awarded to the Aleut Enterprise Corporation. The acoustic survey and fishing were conducted onboard the fishing vessel Muir Milach, skippered by Captain Dave Wilmore.

Conducting the project within Steller sea lion critical habitat was necessary because pollock aggregations had to be encountered to support the work, and historical information about the occurrence of pollock indicated that pollock aggregations were likely to occur inside critical habitat.

The acoustic and biological information from the project will be used to determine: 1) if it is feasible to conduct acoustic surveys in the Aleutian Islands subarea using commercial fishing vessels, 2) if the data collected in such a manner is of sufficient quality for management purposes, and 3) if the local aggregations of pollock are stable enough during spawning season to allow for fine-scale spatial and temporal management. Additionally, genetic samples were collected that will be used for stock structure analysis.

By Libby Logerwell

Flatfish Stock Assessment Review

On 11-14 June 2007, the SSMA Program hosted a review of the Gulf of Alaska and Bering Sea/Aleutian Islands flatfish stock assessments. An independent review of these ecologically and commercially important stocks was desired to assess the quality of the assessments and to ensure that the North Pacific Fishery Management Council (NPFMC) bases its harvest decisions on the best available information and science. The review was conducted by three scientists from the Center for Independent Experts who were contracted through the University of Miami.

In addition to detailed discussions of the flatfish stock assessments, presentations were made by various AFSC staff on age and growth, early life history studies, gear research experiments on catchability, the Groundfish Observer Program, and the role of flatfish in the ecosystem. A report outlining the strengths and weaknesses of the flatfish stock assessments will be made available in July 2007.

The SSMA Program looks forward to the reviewers’ comments which will improve the stock assessment advice.

By Tom Wilderbuer

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