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The Effect of Juvenile Length in Autumn on 2‐Year‐Old Male and Adult Coho Salmon Survival Rates at Three Washington Hatcheries
Author(s) -
Tipping Jack M.
Publication year - 2008
Publication title -
north american journal of aquaculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 41
eISSN - 1548-8454
pISSN - 1522-2055
DOI - 10.1577/a06-093.1
Subject(s) - juvenile , hatchery , biology , oncorhynchus , fish hatchery , fishery , fish measurement , fish <actinopterygii> , zoology , chinook wind , aquaculture , ecology , fish farming
During 3 years at three Washington State hatcheries, a total of six populations of juvenile coho salmon Oncorhynchus kisutch were length sorted and coded‐wire‐tagged in autumn using the AutoFish Tagging Trailer (Northwest Marine Technology, Shaw Island, Washington). After tagging, the length‐groups were combined at each respective hatchery and reared through spring release. Subsequent recoveries of tagged fish from two hatcheries indicated that juvenile fish with longer fork lengths (FLs) in autumn had a significantly higher incidence of mature 2‐year‐old males (jacks) than smaller juveniles, indicating that the physiological decision to become jacks was probably made by autumn; the third hatchery produced few jacks. Large autumn juveniles had significantly greater 3‐year‐old adult survival than small autumn juveniles at one hatchery (one release) and significantly lower survival at a second hatchery (two releases); at a third hatchery (three releases), the two length‐groups did not differ in adult survival. These variable results may reflect regional size optima. The proportion of adult males returning to the hatchery was generally not influenced by FL of autumn juveniles.