Prior residence, aggression and territory acquisition in hatchery-reared and wild brown trout |
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Authors: | J. I. Deverill,&Dagger ,C. E. Adams,&dagger C. W. Bean |
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Affiliation: | Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, U.K.;Fish Biology Group, University Field Station, University of Glasgow, Glasgow G63 0AW, U.K. |
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Abstract: | In an artificial stream environment, established wild brown trout initiated 44% of the mean aggressive acts whilst hatchery-reared trout initiated 34% and introduced wild trout initiated 22%. Established wild fish maintained home stations closer to a point source of feed than did both hatchery-reared and introduced wild conspecifics. Established wild fish were the only group to show a positive mean specific growth rate during the trials. Introduced wild fish showed a slightly negative mean specific growth rate, whilst introduced hatchery-reared fish exhibited a considerable negative mean specific growth rate. These results suggest that established wild brown trout in a semi-natural stream environment display a prior-resident effect over late introductions of hatchery-reared and wild conspecifics. Introduced hatcheryreared fish were more aggressive and exhibited a lower mean specific growth rate than simultaneously stocked wild fish, suggesting that excessive expenditure of energy for unnecessary aggression may contribute to the poor survival of hatchery-reared fish after they are stocked into streams. |
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Keywords: | behaviour dominance salmonid Salmo trutta L |
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