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Stock Origins of Chinook Salmon in the Area of the Japanese Mothership Salmon Fishery
Author(s) -
Myers Katherine W.,
Harris Colin K.,
Knudsen Curtis M.,
Walker Robert V.,
Davis Nancy D.,
Rogers Donald E.
Publication year - 1987
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8659(1987)7<459:soocsi>2.0.co;2
Subject(s) - chinook wind , oncorhynchus , bay , fishery , stock (firearms) , geography , stock assessment , pacific ocean , oceanography , biology , fish <actinopterygii> , archaeology , geology , fishing
The record catch of 704,000 chinook salmon Oncorhynchus tshawytscha by the Japanese mothership salmon fishery in 1980 intensified concern about the effect of high seas interceptions of salmon reared in North America. The goal of this study was to update and refine estimates of the relative proportions of Asian and North American chinook salmon stocks in the mothership fishery area in the Bering Sea and north Pacific Ocean. Linear discriminant analysis of scale pattern data was used to classify samples of immature chinook salmon aged 1.2 (one winter in fresh water, two winters at sea) from the area 46‐62°N, 160°E‐175°W in June and July 1975‐1981 to four regions: Asia, western Alaska, central Alaska, and southeastern Alaska‐British Columbia. Western Alaska, which included Canadian Yukon stocks, was further subdivided into three subregions: Yukon River, Kuskokwim district, and Bristol Bay. Overall classification accuracies averaged 74, 79, and 86%, respectively, in four‐, three‐, and two‐category regional models and 63, 66, 69, and 78%, respectively, in six‐, five‐, four‐, and three‐category subregional models. Estimated proportions of the regional stocks in the Bering Sea averaged 70% western Alaska, 18% Asia, 10% central Alaska, and 2% southeastern Alaska‐British Columbia; in the north Pacific Ocean, stock proportions were 54% central Alaska, 23% western Alaska, 19% Asia, and 4% southeastern Alaska‐British Columbia. For strata in which western Alaska was the predominant regional stock, estimated proportions of the subregional stocks averaged 48% Yukon River, 21% Kuskokwim district, and 14% Bristol Bay in the Bering Sea and 37% Yukon River, 20% Kuskokwim district, and 0% Bristol Bay in the north Pacific Ocean. Stock proportion estimates for the Bering Sea were similar to estimates from previous scale pattern analyses and are corroborated by scant information from tagging studies. Estimated proportions of North American chinook salmon in the north Pacific Ocean were much larger than estimated in previous scale pattern studies, and this disparity is attributed largely to differences in methodology. Additional improvements in scale pattern analysis techniques as well as in the quality and quantity of scale samples and of catch, escapement, and age composition data are needed.