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Resource Assessment and
Conservation Engineering (RACE) Division

Annual Eastern Bering Sea Bottom Trawl Survey

The annual eastern Bering Sea bottom trawl survey of groundfish and crab began 29 May  2002.  The chartered fishing vessels Arcturus and Aldebaran have been chartered for 65 days each to conduct the survey.  Standard trawling operations began at the eastern end of Bristol Bay and will extend to cover the eastern Bering Sea continental shelf from inner Bristol Bay to the shelf break and between Unimak Pass to north of St. Matthew Island.  The primary objectives of the survey are to continue the annual series of assessment surveys of crab and groundfish to provide information for 1) the North Pacific Fishery Management Council on the distribution, abundance, and biological condition of important groundfish and crab resources; 2) the U.S. fishing industry on catch-per-unit of effort and size composition of important groundfish and crab species; and, 3) the support of ongoing studies on the biology, behavior, and population dynamics of key ecosystem components.  The survey consists of approximately 380 sampling stations positioned on a 20 nautical mile (nmi) by 20 nmi grid pattern.  The stations are at the center of the grids except where additional stations have been allocated to obtain more precise estimates of blue king crab abundance near the Pribilof Islands and St. Matthew Island.  The standard survey trawl, and 83-112 eastern bottom trawl, will be used to sample each station.  Catches will be completely sorted and identified to species level, weighed, and enumerated.  Biological information (length, maturity, age composition, weight, and stomach contents) will be collected for the primary species.  The survey will be completed on 1 August 2002.

By Russ Nelson.

Biennial Eastern Bering Sea Upper Continental Slope Bottom Trawl Survey

The chartered fishing vessel Morning Star began the 2002 biennial eastern Bering Sea upper continental slope bottom trawl survey of groundfish and invertebrates on 5 June 2002.  Survey station and research trawling will be conducted at predetermined stations between 200 and 1,200 m.  The slope regions have been divided into six geographical areas based on latitude and bathymetry.  The survey area is characterized by canyon areas, gentler sloping areas, and areas with very steep profiles.  The survey will employ a stratified random design which will divide approximately 200 predetermined trawl stations into the 6 area strata and the 5 depth strata within each of those areas.  A standard Poly Nor’eastern trawl equipped with 20-cm diameter rubber disc mudsweep roller gear will be used during the survey.  The primary objectives of the biennial survey are to 1) describe the composition, distribution, and relative abundance of groundfish and invertebrate resources of the upper continental slope; 2) collect biological samples from a variety of commercially and ecologically important species, including cods, flatfish, rockfish, grenadiers, sculpins, elasmobranchs, crabs, shrimps, and other invertebrates; and 3) collect temperature profiles from surface to bottom to relate changes in fish and invertebrate distribution among years to changes in oceanographic conditions.

By Russ Nelson.

Biennial Aleutian Islands Bottom Trawl Survey

Three chartered commercial fishing vessels, Vesteraalen, Morning Star, and Sea Storm will conduct the biennial bottom trawl survey of Aleutian Islands groundfish and invertebrates.  The 2002 survey began 27 May.  The primary objectives of the 2002 biennial survey are to 1) define the distribution and relative abundance of the principal groundfish and commercially important invertebrate species that inhabit the Aleutian archipelago; 2) obtain catch and effort data from which to estimate the abundance of the principal groundfish species; 3) collect data to define selected biological parameters of the principal groundfish species; 4) monitor and collect trawl performance data used in the estimation of catch-per-unit of effort; and, 5) complete special collections as requested by other researchers and research groups.  The survey design is a stratified random sampling scheme consisting of approximately 425 stations selected randomly from a combination of successful tows completed during previous surveys and sites not previously trawled.  The selected sampling sites are allocated to 45 sampling strata defined by geographical location and depth, ranging from shallow, near shore depths to 500 m on the continental slope.  Standard survey bottom trawling will be conducted with the polyethylene Nor’eastern bottom trawls equipped with rubber bobbin roller gear.  The survey will be completed on 15 August.

By Russ Nelson.


Scientists from the Midwater Assessment and Conservation Engineering (MACE) Program at the Alaska Fisheries Science Center completed Leg 1 of an echo integration-trawl (EIT) survey of walleye pollock on the eastern Bering Sea shelf aboard the NOAA ship Miller Freeman between 4 June and 3 July 2002.  Leg 1 of the cruise began in Kodiak, Alaska, and ended in Dutch Harbor, Alaska.  The first week of the cruise comprised acoustic system calibrations and transit to the Bering Sea.  The EIT survey transects began early in the second week north of Port Moller, Alaska, and ended 3 weeks later near St. Matthew Island.  Results from Leg 1 indicate that 2-year-old pollock were encountered frequently near the 100-m isobath.  Pollock size composition observed from 66 midwater and bottom trawl hauls was quite varied; pollock with 45- to 50-cm fork lengths were the most common, followed by those with 25- to 30-cm fork lengths.  In summer 2002, there appeared to be more pollock east of the Pribilof Islands than has been observed in the previous two summer EIT surveys of the Bering Sea shelf (1999 and 2000).  On 6 July, Leg 2 continued westward from St. Matthew Island to the U.S./Russia Convention Line and will end 2 August 2002 in Dutch Harbor.  Acoustic data as well as midwater and bottom trawl catch information collected during the survey will be used to determine the distribution, biomass, and biological composition of Bering Sea walleye pollock

By Taina Honkalehto.


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