Daylight responses to overhead cover in stream channels for fry of four salmonid species |
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| Authors: | Jan Heggenes Tor Traaen |
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| Institution: | Dept of Nature Conservation, Agricultural University of Norway, Box 39, 1432 Ås-NLH. Norway;Norwegian Institute of Water Research, Box 33, Blindern, 0313 Oslo 3, Norway |
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| Abstract: | Brown trout ( Salmo trutta ), Atlantic salmon ( Salmo salar ), brook trout ( Salvelinus fontinalis ) and lake trout ( Salvelinus namaycush ) fry entering the free-feeding stage, were tested for overhead cover preferences in stream channels at different temperatures and water velocities. Atlantic salmon showed strong preferences for overhead cover, brown trout moderate preferences, whereas lake trout had preferences only at high temperatures, i.e. 12.4–19.2°C. Brook trout showed no cover preferences. Temperature influenced cover preferences of Atlantic salmon and brown trout considerably. The fry tended to seek more cover at low temperatures, i.e. 6.0–8.3°C |
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