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NOAA Technical Memorandum NMFS-AFSC-349

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Data Report: 2016 Aleutian Islands bottom trawl survey

Abstract

The eighth biennial groundfish assessment survey of the Aleutian Islands region was conducted during the summer of 2016 by the Alaska Fisheries Science Center’s (AFSC) Resource Assessment and Conservation Engineering Division’s Groundfish Assessment Program (RACE-GAP). This effort constitutes the fourteenth in the full series dating from 1980. The survey area covered the continental shelf and upper continental slope to 500 m in the Aleutian Archipelago from Islands of Four Mountains (170° W long.) to Stalemate Bank (170° E long.), including Petrel Bank and Petrel Spur (180° long.), and the northern side of the Aleutian Islands between Unimak Pass (165° W long.) and the Islands of Four Mountains.

The survey was conducted aboard two chartered trawlers, the FV Alaska Provider and FV Sea Storm. Samples were collected successfully at 419 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 commercially or ecologically important principal groundfish and invertebrate species that inhabit the Aleutian marine habitat and to collect additional data to define biological parameters useful to fisheries researchers and managers such as growth rates; length-weight relationships; feeding habits; and size, sex, and age compositions.

Pacific ocean perch or POP (Sebastes alutus) was the most abundant species with an estimated biomass of 982,522 metric tons (t). Atka mackerel (Pleurogrammus monopterygius) and northern rockfish (Sebastes polyspinis) were also abundant with estimated biomasses of 447,976 and 253,215 t, respectively. Catches of POP were large throughout the survey area at intermediate depths. Arrowtooth flounder (Atheresthes stomias) was the most abundant flatfish species, having almost twice the biomass of second-place northern rock sole (Lepidopsetta polyxystra). The skate assemblage was primarily comprised of three skate species, whiteblotched (Bathyraja maculata), Aleutian (B. aleutica), and leopard (B. panthera) skates, with a wide diversity of species captured in the eastern portion of the survey area.

Survey results are presented as estimates of catch per unit of effort and biomass, species distribution and relative abundance, population size composition, and length-weight relationships for commercially important species and for others of biological interest.




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