Effect of brown trout body size on post-stocking survival and pike predation |
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Authors: | P Hyvärinen T Vehanen |
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Institution: | Finnish Game and Fisheries Research Institute, Kainuu Fisheries Research and Aquaculture, Paltamo, Finland |
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Abstract: | Abstract – A total of 40 (20 age-3 + 20 age-4) radio-tagged hatchery-reared brown trout ( Salmo trutta L.) and 40 wild radio-tagged northern pike ( Esox lucius L.) were released into a regulated river. Age-3 brown trout were predicted and observed to be highly vulnerable to predation by pike (50% mortality), whereas age-4 brown trout were predicted and observed to enjoy an almost absolute size refuge from predation (5% mortality). Almost half of the fish from both age groups similarly emigrated and survived from the river within 3 days of the release. However, there was a considerable difference in survival between age groups for fish that remained in the river for a longer period. Of these, all except one age-3 brown trout were eaten by pike, whereas all but one age-4 fish survived predation. |
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Keywords: | Salmo trutta Esox lucius predation body size telemetry stocking |
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