NOAA releases results of 2011 Bering Sea Groundfish Survey
How much fish and crab can be sustainably caught by fishers in the Bering Sea next year?
The annual process to set total allowable catch levels for various groundfish and crab species in the Bering Sea took a big step forward this week, when NOAA scientists from the Alaska Fisheries Science Center completed calculating the initial biomass estimates from the 2011 eastern Bering Sea survey.
Groundfish and crab scientists from the AFSC completed the 30th in a series of standardized annual bottom trawl surveys of the eastern Bering Sea continental shelf this past summer aboard the chartered fishing vessels Aldebaran and Alaska Knight. The vessels bottom trawled at 376 stations over a survey area of 144,600 square nautical miles, finishing the survey August 4, 2011. The science crew processed and recorded the catch from each trawl catch by identifying, sorting, and weighing all the different crab and groundfish species and then measuring samples of each species.
At the conclusion of the survey, scientists carefully validated the data collected on fishing effort, catch rates, and biological characteristics of the fish populations (size distribution, age, growth rates, diet, etc.) in preparation to generate fishery-independent estimates of geographic and depth distribution, abundance, and population size and age composition of the various species. Supplementary biological and oceanographic data collected on the bottom trawl survey will improve understanding of life history of the groundfish and crab species and the ecological and physical factors affecting their distribution and abundance
Trends in the annual estimates of bottom trawl survey biomass for selected groundfish species on the eastern Bering Sea shelf from 1987 to 2011 are shown in Figure 1. The biomass estimates from the 2011 bottom trawl survey for these selected species are:
* Walleye pollock: 3.11 million metric tons
* Rock sole: 1.98 million metric tons
* Alaska plaice: 520 thousand metric tons
* Greenland turbot: 26.2 thousand metric tons
* Pacific cod: 911 thousand metric tons
* Yellowfin sole: 2.40 million metric tons
Compared to 2010, there were slight decreases in the survey biomass of walleye pollock and rock sole, and slight increases in the survey biomass for the other four species (Fig. 1).
Scientists also found that the mean bottom temperatures on the eastern Bering Sea shelf were generally higher in 2011 compared to 2010, and the cold pool (< 2°C) during the late spring and early summer sampling period was significantly reduced in size (Fig. 2)
The North Pacific Fishery Management Council's Groundfish Plan Team will begin their review and incorporation of the survey data in the scientific stock assessments at their November 14-18, 2001 meeting, and will provide reports to the Council’s Scientific and Statistical Committee. The SSC will recommend acceptable biological catch for the different species at the December Council meeting in Anchorage. The Council's Advisory Panel will then recommend a total allowable catch for each of the species. Following the committee reports, the Council will consider committee recommendations and public testimony before recommending a total allowable catch for the various groundfish species in 2012.
The 2011 eastern Bering Sea survey results for crab are currently being reviewed by the NPFMC Crab Plan Team at their meeting at the Alaska Fisheries Science Center, September 19-22 (http://www.fakr.noaa.gov/npfmc/public-meetings/committees-related-meetings.html ).
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