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NOAA Technical Memorandum NMFS-AFSC-208

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Data Report: 2009 Gulf of Alaska bottom trawl survey

Abstract

Scientists of the Groundfish Assessment Program of Alaska Fisheries Science Center's Resource Assessment and Conservation Engineering (RACE) Division conducted the sixth biennial groundfish assessment survey of the Gulf of Alaska during the summer of 2009.  These surveys extend the series of surveys, previously conducted every 3 years between 1984 and 1999, which constitute the time series used in stock assessments of Gulf of Alaska groundfish resources.  The survey area covered the continental shelf and upper continental slope to 1,000 m in the Gulf of Alaska from Islands of Four Mountains (170°W long.) to Dixon Entrance (132°40'W long.).  The survey was conducted aboard three chartered commercial trawlers, the FV Pacific Explorer, FV Sea Storm, and FV Vesteraalen.  Trawl haul samples were collected successfully at 823 survey stations using standard RACE Division Poly Nor'Eastern high-opening bottom trawl nets with rubber bobbin roller gear.

The primary survey objectives were to define the distribution and estimate the relative abundance of the principal groundfish within the survey area and to collect data to estimate biological parameters useful to groundfish researchers and managers including age, growth, length-weight relationships, feeding habits, and size, sex, and age composition.  The survey also collected ancillary data requested by other research groups.

A total of 185 fish and 393 invertebrate species were captured in survey tows.  Arrowtooth flounder (Atheresthes stomias), Pacific cod (Gadus macrocephalus), giant grenadier (Albatrossia pectoralis), walleye pollock (Theragra chalcogramma), Pacific ocean perch (Sebastes alutus), and Pacific halibut (Hippoglossus stenolepis) were, in descending order, the most abundant species within the survey area.  Atka mackerel (Pleurogrammus monopterygius), Pacific hake (Merluccius productus), southern rock sole (Lepidopsetta bilineata), flathead sole (Hippoglossoides elassodon), and spotted ratfish (Hydrolagus colliei) were locally abundant in some areas.   Survey results are presented including estimates of catch per unit of effort, biomass, population size composition, and length-weight relationships, as well as charts depicting the distribution of catch for commercially important species encountered during the survey.



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