Relative abundance of Gulf of Alaska sablefish and other groundfish based on the domestic longline survey, 1989

Abstract

The Alaska Fisheries Science Center has conducted an annual longline survey of sablefish (Anoplopoma fimbria) and other groundfish in the Gulf of Alaska since 1987. This survey replicates as closely as practical the Gulf of Alaska portion of a Japan-U.S. cooperative longline survey conducted from 1979 to 1994 and also samples gullies not sampled during the cooperative longline survey. In 1989, 73 stations were sampled from 26 June to 12 September. Each day, 16 km of groundline containing 7,200 hooks baited with squid was set from the chartered fishing vessel Ocean Prowler.

Sablefish relative population numbers (RPN) on the upper continental slope decreased significantly: 18% from 1988 to 1989. Most of the decrease was observed in the western and central areas of the Gulf of Alaska; the RPN remained about the same in the eastern areas. The strong 1984 year class expected to recruit in 1989 was not apparent in the survey results, nor was there evidence for later strong year classes. The rougheye (Sebastes aleutianus) and shortraker (S. borealis) rockfish RPN increased 35% from 1988 to 1989; this increase was not statistically significant. The thornyhead (Sebastolobus alascanus) RPN increased significantly (77%).


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