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Resource Ecology & Ecosystem Modeling Program

Seabird Bycatch Estimates for Alaskan Federal Groundfish Fisheries

The AFSC is again producing annual estimates of seabird bycatch from the Alaskan groundfish fisheries monitored through the North Pacific Fishery Observer Program. Provisional estimates for 2007–10 are posted on the AFSC seabird web page. These estimates are of great interest to many scientists, managers, and stakeholders. This years’ estimates represent the third methodology employed since the start of our seabird bycatch monitoring in 1993 (Fig. 4). The first method was carried out by the U.S. Fish and Wildlife Service (USFWS) Migratory Bird Management Division in Anchorage, Alaska, following through on templates for collaboration done in the Dall’s Porpoise and High Seas Driftnet Programs of the 1980s and early ‘90s. The intent was to produce estimates of overall seabird mortality based on these data each year. However, given the complexity and scope of the data and the need of the USFWS to address Endangered Species Act issues at the time, this methodology proved unfeasible for the USFWS.

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Figure 4. Total seabird bycatch in the Alaskan demersal longline groundfish fishery as estimated by three overlapping methods during the period 1993 through 2010. FWS = U.S. Fish and Wildlife Service; NMML = Alaska Fisheries Science Center National Marine Mammal Lab; CAS = Catch Accounting System.

The AFSC then agreed to dedicate resources, with annual funding support from the Protected Resources Division of the NMFS Alaska Regional Office, to develop procedures to estimate annual seabird bycatch. Marine mammal take estimation was being completed by an analyst from the AFSC National Marine Mammal Laboratory (NMML). Because seabirds had similar estimation challenges (seabird bycatch is a relatively rare event) similar estimation procedures could be used. Estimates were produced for all years (1993 onward) through 2006 (Fig. 4) and made available on the AFSC website and through the Ecosystem Chapter of the annual Stock Assessment and Fisheries Evaluation Reports prepared for the North Pacific Fishery Management Council (available at

With retirement of the NMML analyst in 2007 and a new data platform launched in 2008, established procedures could no longer be used. Producing these annual estimates had also used resources that were now needed for other seabird projects. A workshop was held to address rare-event bycatch estimation in 2009 (reported in the April–May–June 2009 AFSC Quarterly Report). This workshop evaluated the stated needs of various end-users for these data. One result of the workshop was that the AFSC worked with the Sustainable Fisheries Division of the Alaska Regional Office, and the Catch Accounting System now produces seabird point-count estimates in a production mode that does not require as much staff resources as previous methods. The AFSC will use the results to again produce annual estimates of seabird bycatch in Alaskan fisheries.

By Shannon Fitzgerald

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