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Effects of seawater‐acclimatization and release sites on survival of hatchery–reared brown trout Salmo trutta
Author(s) -
Jonsson N.,
Jonsson B.,
Hansen L. P.,
Aass P.
Publication year - 1994
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1994.tb01269.x
Subject(s) - salmo , fish migration , brown trout , biology , fjord , hatchery , fishery , acclimatization , seawater , salmonidae , fish measurement , zoology , ecology , fish <actinopterygii> , oceanography , geology
To test whether seawater–acclimatization of hatchery–reared anadromous and freshwater resident brown trout before release increased the survival of adults, smolts were retained 0, 2, 4 and 8 weeks in sea water before release. Total recapture rate increased for smolts retained 4 and 8 weeks in sea water before release relative to the controls. This trend was more pronounced for Freshwater resident than for anadromous stocks, Offspring of anadromous fish stayed longer at sea than offspring of freshwater resident fish. Recapture rates in fresh water were higher for brown trout released in the river than in the fjord in the R, Drammen area, but not in the R. Imsa. In both cases, most fish were recaptured in the sea. Moving into the R. Imsa (relative to other rivers) appeared higher for fish released at the mouth of the river (93%) than in the fjord (47%). Judged from the recapture rates, sea survival appeared to be the same whether released in the fjord or at the mouth of the river.