Stock Origins of Chinook Salmon in the Area of the Japanese Mothership Salmon Fishery

Abstract

Abstract 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 re...