NOAA Technical Memorandum
NMFS-AFSC-121
Data report: 1999 Gulf of Alaska bottom trawl survey
Abstract
The sixth triennial (or first biennial) groundfish assessment survey of the Gulf of Alaska was conducted during the summer of 1999 by the Alaska Fisheries Science Center's Resource Assessment and Conservation Engineering (RACE) Division. The survey area covered the continental shelf and upper continental slope to 1000 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 trawlers, the F/V Dominator, F/V Morning Star, and F/V Vesteraalen. A total of 764 survey stations was successfully sampled using standard RACE Division polyNor'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 on 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.
At least 181 fish species and 271 invertebrate species were captured in survey tows (Appendix Q. In terms of total biomass, arrowtooth flounder (Atheresthes stomias), Pacific ocean perch (Sebastes alutus), walleye pollock (Theragra chalcogramma), Pacific halibut (Hippoglossus stenolepis) and giant grenadier (Albatrossia pectoralis) were the most abundant species within the survey area. Pacific cod (Gadus macrocephalus), northern rockfish (Sebastes polyspinus) and flathead sole (Hippoglossoides elassodon) were locally abundant in some areas. Survey results are presented including estimates of catch per unit effort and biomass, species distribution, length frequency distribution, and length-weight relationships for commercially important species encountered during the survey.
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