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Presented at the NABS Annual meeting, Vancouver, British Columbia, 2004
in Fish Ecology 2
Effect of food abundance on habitat selection, growth, and habitat suitability curves for juvenile coho salmon
JS Rosenfeld1, T Leiter2, G Lindner2, and L Rothman3. 1Aquatic Ecosystem Science Section, Province of British Columbia, 2204 Main Mall, Vancouver, B.C., CANADA, V6T 1Z4, 2University of Agricultural Sciences, Gregor Mendel Strasse 33, 1180-Vienna, Austria , 3SAS Institute, 181 Bay St., Toronto, Ontario, CANADA, M5J 2T3
To understand how fish density and food availability affect habitat selection and growth rates of juvenile coho salmon, we manipulated fish density (2-12 fish∙m-2) and natural invertebrate drift (0.047-0.99 mg ∙m-3) in 12 experimental stream channels in a side-channel of Chapman Creek, British Columbia. Elevated food increased growth of both dominant and subdominant fish, and caused a shift to higher average focal velocities (6.3 to 8.2 cm∙s-1) with maximum growth in the range of 10-12 cm∙s-1. Increased food appears to permit juvenile coho to exploit faster microhabitats that might otherwise be bioenergeticly unsuitable at lower food levels. Increased fish density resulted in a general displacement of fish to both higher and lower focal velocities and caused decreased growth of subdominant fish. The shape of habitat suitability curves was sensitive to food abundance, implying that differences in food availability may affect transferability of habitat suitability curves between streams of different productivity. While the habitat suitability curve at high food accurately represented the change in extent of available habitat following prey enrichment, actual increases in growth rate with enrichment (i.e. changes in habitat quality) were poorly represented by habitat suitability values and better represented by bioenergetic model predictions.
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