The 2000 Pacific West Coast upper continental slope trawl survey of groundfish resources off Washington, Oregon, and California: Estimates of distribution, abundance, and length composition

Abstract

The Alaska Fisheries Science Center's Resource Assessment and Conservation Engineering Division (RACE) conducted a groundfish bottom trawl survey of the West Coast upper continental slope (WCUCS) in 2000. The survey area stretched from the U.S.-Canada border (near Nitinat Canyon) to 34°30'N lat. (near Pt. Conception, CA) in waters ranging from 183 to 1,280 m deep. This was the twelfth survey in an ongoing series to monitor the long-term trends in the distribution and abundance of WCUCS groundfish populations. This was the third year that spatial coverage of the WCUCS groundfish trawl survey was expanded to include all of the International North Pacific Fisheries Commission (INPFC) statistical areas between Point Conception (34°30’N lat.) and the U.S./Canada border. Sampling was conducted aboard the NOAA ship Miller Freeman. We successfully sampled 207 of the 208 stations that we established during this and previous WCUCS surveys. Survey catches included 144 different species of fishes from 57 fish families and 252 different invertebrates representing 10 phyla and 23 classes. Only 159 of the invertebrates were identified to the species level. With all depth strata and INPFC areas combined, Pacific hake (Merluccius productus), Dover sole (Microstomus pacificus), and spiny dogfish (Squalus acanthias) had the highest catch rates. When all depths were combined, spiny dogfish were the most abundant in the U.S.-Vancouver INPFC area, and either Pacific hake or Dover sole had the highest catch rates in the Columbia, Eureka, Monterey, and Conception INPFC areas. The biomass estimates for Dover sole, sablefish (Anoplopoma fimbria), longspine thornyhead (Sebastolobus altivelis), and shortspine thornyhead (Sebastolobus alascanus) varied by depth stratum and INPFC area. The total biomass estimates for all INPFC areas and strata combined were 58,494 metric tons (t), 127,344 t, 97,552 t, and 31,898 t for sablefish, Dover sole, longspine thornyhead, and shortspine thornyhead, respectively.

The survey design and the methods used are described, the data collected are summarized, and the results of analyses of distribution, abundance, and biological parameters are presented. Data on water temperature, catch composition, relative abundance, and geographic distribution are reported. Estimates of biomass, population abundance, and length composition are also presented. Appendices include position and catch listings for each haul and catch rates of fish and invertebrates.