The 2001 Pacific west coast bottom trawl survey of groundfish resources: Estimates of distribution, abundance, and length and age composition

Abstract

The Alaska Fisheries Science Center’s 2001 West Coast triennial bottom trawl survey was conducted to assess stocks of groundfish inhabiting the continental shelf waters off the coasts of California, Oregon, Washington, and southern British Columbia. This was the ninth and final survey in a series spanning 25 years to monitor long-term trends in the distribution and abundance of these groundfish populations.

Although the objectives of the 2001 survey were similar to those of the previous surveys in the series, minor changes in the survey design have been made over the years. The five most recent surveys have shifted emphasis away from estimating rockfish abundance, as had been the case from 1977 through 1986, toward better assessing a broader range of groundfish species.

The current design also focuses upon more precisely estimating the near-bottom component of the Pacific hake (Merluccius productus) and juvenile (age 1+) sablefish (Anoplopoma fimbria) resources. The 2001 survey encompassed the coastal waters from Pt. Conception, California, to central Vancouver Island, British Columbia (34°30'-49°06'N). The depth range of the 2001 survey was 55 to 500 m, the same as it has been since 1995 when sampling was extended from the previous maximum depth of 366 m in order to cover the habitat of slope rockfish more completely. A total of 527 stations were occupied, of which 506 were successfully sampled. Catches included over 166 fish species representing more than 57 families.

This report documents the survey design and methods used in 2001, summarizes biological and environmental data collected, and presents the results of standard analyses of distribution, abundance, and biological parameters for the commercially important groundfish species in the region. Data on water temperature, catch composition, relative abundance, and geographic distribution are reported. Estimates of biomass, population abundance, length composition and age composition are also presented. Data appendices are located in a separate volume.


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