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Marine Vertical Distribution of Juvenile Chinook and Coho Salmon in Southeastern Alaska
Author(s) -
Orsi Joseph A.,
Wertheimer Alex C.
Publication year - 1995
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1995)124<0159:mvdojc>2.3.co;2
Subject(s) - chinook wind , oncorhynchus , fishery , fishing , juvenile , fish measurement , bycatch , oceanography , geography , fish <actinopterygii> , biology , geology , ecology
Vertical distributions of chinook salmon Oncorhynchus tshawytscha of marine ages x.0, x.1, and x.2 and coho salmon O. kisutch of age x.0 are reported for the marine waters of southeastern Alaska. (The number or letter preceding the decimal point indicates number of winters spent in freshwater, that following the decimal point indicates winters spent in salt water.) Understanding vertical distribution of prerecruit salmon may be useful in minimizing fishery bycatch. Salmon were caught to a depth of 36.6 m from chartered commercial power trollers fishing small hooks and lures. Sampling occurred throughout inside waters of the Alexander Archipelago and adjacent coastal waters during September 1986 and in inside waters near Ketchikan during February, May, and September 1987. Vertical distribution of salmon differed significantly by species and age‐group: in September, age‐x.0 coho salmon (mean fork length, 28.4 cm) were caught shallower than age‐x.0 chinook salmon (27.3 cm); age‐x.1 (44.2 cm) and age‐x.2 (60.4 cm) chinook salmon were deeper than age‐x.0 chinook salmon. Length of chinook salmon increased significantly with depth. Vertical distribution did not differ significantly between ocean‐type and stream‐type fish or between sexes. Chinook salmon were significantly deeper in February than in September or May and significantly deeper in September than in May. Our findings suggest that encounter rates of prerecruit chinook salmon and coho salmon in chinook salmon troll fisheries could be minimized by restricting fishing to depths of 30 m or more during selected periods.