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Juvenile current response, growth and maturity of above and below waterfall stocks of rainbow trout, Salmo gairdneri
Author(s) -
Northcote T. G.
Publication year - 1981
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.1095-8649.1981.tb03815.x
Subject(s) - rainbow trout , salmo , waterfall , smoltification , juvenile , biology , fishery , tributary , stock (firearms) , hatchery , trout , overwintering , darkness , ecology , salmonidae , fish <actinopterygii> , geography , cartography , archaeology , botany
Young rainbow trout were propagated from adults collected from above and below a water‐fall, impassable to upstream fish migration on Kokanee Creek, tributary to Kootenay Lake, British Columbia. The two stocks of young (above and below waterfall) were reared in a hatchery under identical temperature, light and food conditions. Their directional response to water current was tested in a laboratory migration channel during their first summer and autumn. as well as the following spring. During tests in light, both stocks of young trout showed similar current responses, but in darkness the below falls stock showed much more downstream movement in the autumn than than did the above falls stock. In addition, below falls trout had a higher growth rate. were slightly heavier at the same length and matured earlier than the above falls stock. The adaptive significance of these differences are discussed in relation to maintenance of trout populations above waterfalls and to selective pressures faced by migratory below waterfall populations.