RESOURCE ECOLOGY & FISHERIES MANAGEMENT (REFM) DIVISION

Status of Stocks & Multispecies Assessment Program

Groundfish Stock Assessments for 2005 Fishery Quota Recommendations (part 1)

The Alaska groundfish management system is based on extensive data available from the NMFS Observer Program and dedicated research cruises. Catch of target and prohibited species (e.g., salmon, crab, herring, and Pacific halibut) are estimated at sea or in processing plants to provide real time information to ensure that fisheries do not exceed total allowable catches (TACs) or violate other fishery restrictions (e.g., time-area closures). Dedicated research cruises coupled with observer data make it possible to build detailed population dynamics models. Results of these modeling activities are used to determine the status of individual species.

Establishing TACs involves annual evaluation of the best available scientific information through a series of documents and public meetings. The first step begins with the preparation of stock assessment and fishery evaluation (SAFE) reports. These reports contain analyses summarizing the information about the individual stocks and groups, and include acceptable biological catch (ABC) and overfishing level (OFL) recommendations for future years. The authors of these reports, generally NMFS scientists, present their findings to the North Pacific Fishery Management Council’s (NPFMC) Groundfish Plan Teams in September and November.

At these meetings, the reports are reviewed, and recommendations for ABC levels are compiled into two SAFE report volumes (one each for the Bering Sea-Aleutian Islands (BSAI) and Gulf of Alaska (GOA) regions) along with Plan Team recommendations for ABC, which may differ from author recommendations. The compiled reports are then submitted to the NPFMC Scientific and Statistical Committee (SSC) for further review. The SSC makes the final ABC recommendation to the Council and the Council’s Advisory Panel of industry representatives makes TAC recommendations. Finally, the recommended TAC levels are adjusted (for some species) by the Council to ensure that other constraints (e.g., limiting the sum of all TACs in the BSAI to be less than 2 million t) are met. The following rule applies for all Federally managed groundfish species in a given year: Catch < TAC < ABC < OFL.

In practice, catch is often much less than TAC, and TAC is often much less than ABC. The multispecies management system is, therefore, based on the premise that no individual components are overfished or below stock sizes that are considered detrimental to the ecosystem. Stock assessments can be obtained at: www.afsc.noaa.gov/refm/stocks/assessments.htm.

A change in the timing requirements for conducting assessments was implemented in 2004. Based on an analysis conducted by scientists at the AFSC in coordination with the NMFS Alaska Regional Office, it was found that for longer-lived species, management advice on quotas could be based on biennial assessments. This cycle was designed to coincide with the current AFSC survey regularity (e.g., in the GOA the groundfish trawl survey is conducted in odd-numbered years). This meant that for a number of stocks in the GOA, ABC recommendations are based on analyses presented in 2003. Additionally, in order to extend the public review period for TAC specifications, ABC and OFL recommendations were provided for both 2005 and 2006 at the December 2004 Council meeting.

Figure 1 (above) and Figure 2 (below).  Relative 2005 spawning stock size compared to B_msy (taken to be B_35% for all species except EBS pollock) versus relative 2004 catch levels compared to 2004 maximum permissible ABC levels for BSAI stocks.
 

Presently, the main species of groundfish are all above their target stock size (B_msy), and 2004 catch levels were below maximum permissible ABC levels (Figs. 1 and 2 above). Fisheries for these groundfish species, during 2001-03, yielded 2.1 million metric tons (t) annually, valued at $615 million. Abundance of the major stocks of walleye pollock and Pacific cod are high, but subject to variability due to recruitment fluctuations. Virtually all flatfish resources (e.g., rock sole, yellowfin sole, Alaska plaice, and arrowtooth flounder) are at high and healthy levels. Atka mackerel abundance is increasing and above average levels. Rockfish species comprise 5%-8% of the groundfish complex biomass and are at healthy and stable levels.

For the main stocks with age-structured analyses, the biomass trends compared with the average levels since 1978 are shown in Figures 3 and 4 (below) for the GOA and BSAI, respectively. These figures suggest that stock conditions are fairly evenly split between those that are above average and below in the past few years.

Figure 3.  Biomass trends for Gulf of Alasaka (GOA) stocks relative to their mean level, 1978-2004.



Figure 4.  Biomass trends for Bering Sea and Aleutian Islands (BSAI) stocks relative to their mean level, 1978-2004.

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AFSC Quarterly Research Reports Oct-Dec 2004