Data report: 2006 Aleutian Islands bottom trawl survey

Abstract

Tenth in a series dating from 1980, the fourth biennial groundfish assessment survey of the Aleutian Islands region was conducted during the summer of 2006 by the Alaska Fisheries Science Center’s (AFSC) Resource Assessment and Conservation Engineering (RACE) Division. 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 F/V Gladiator, and F/V Sea Storm. Samples were collected successfully at 358 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 principal groundfish and commercially or ecologically important invertebrate species that inhabit the Aleutian marine habitat and to collect 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. Atka mackerel (Pleurogrammus monopterygius) were the most abundant species in the survey area with an estimated biomass greater than 740,000 metric tons (t). Pacific ocean perch (Sebastes alutus; POP) were the most abundant species of rockfish; catches of POP were high throughout the survey area at intermediate depths. Arrowtooth flounder (Atheresthes stomias) were the dominant flatfish species and were ubiquitous. The skate assemblage was made up of predominantly two species, whiteblotched skate (Bathyraja maculata) and Alaska skate (B. parmifera), 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, length frequency distribution, and length-weight relationships for commercially important species and for others of biological interest.

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