Juvenile current response, growth and maturity of above and below waterfall stocks of rainbow trout, Salmo gairdneri

摘要: Young rainbow trout were propagated from adults collected above and below a water-fall, impassable to upstream fish migration on Kokanee Creek, tributary Kootenay Lake, British Columbia. The two stocks of young (above waterfall) reared in hatchery under identical temperature, light food conditions. Their directional response water current was tested laboratory channel during their first summer autumn. as well the following spring. During tests light, both showed similar responses, but darkness falls stock much more downstream movement autumn than did stock. In addition, had higher growth rate. slightly heavier at same length matured earlier adaptive significance these differences are discussed relation maintenance populations waterfalls selective pressures faced by migratory waterfall populations.