Marine resource surveys on the continental shelf and upper slope off Washington, 1975-76 : completion report July 1, 1975 to September 30, 1977

Groundfish surveys off the Washington coast were conducted in September of 1975\ud and 1976 between Cape Flattery and the Columbia River. The primary purposes of the surveys were to obtain estimates of biomass and further our knowledge on population parameters of important groundfish species, especially flatfish, occupying the continental shelf and upper continental slope.\ud \ud Survey design was based on a 5x6 N. mi grid with a random starting point. Samples were obtained for age, size and sex composition from important flatfish species. Weights were obtained from all species of fish.\ud \ud Estimates of biomass, all species, were 143,447 and 147,303 metric tons in 1975\ud and 1976, respectively. Pacific hake and English sole were the most abundant species. Estimates of biomass and potential yield were determined for six species of flatfish. Data indicate that most flatfish species are not fully exploited, but several species may be nearing full utilization. Increased yield could be obtained without increased fishing effort if market demand would increase on certain under-utilized species.\ud \ud Several population parameters were obtained. Age, length-weight constants, total annual and fishing mortality rates and exploitation rate were estimated for six species of flatfish. Distribution and abundance was depicted for major species by catch maps. Distribution of some species was closely correlated with depth and sediment type. Increase in mean weight was associated with increasing depth for many species, Strong year classes were indicated for several species. Data suggests that the Astoria Canyon may separate Dover sole and also arrowtooth flounder stocks