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The effect of temperature on growth and early maturation in a wild population of Atlantic salmon parr

Authors

  • D. Baum,

    1. Fish Biology Group, Division of Environmental and Evolutionary Biology, Graham Kerr Building, Institute of Biomedical & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, U.K.,
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  • R. Laughton,

    1. Spey Fishery Board Research Office, 1 Nether Borlum Cottage, Knockando, Morayshire, AB38 7SD, U.K. and
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  • J. D. Armstrong,

    1. Fisheries Research Service Freshwater Laboratory, Faskally, Pitlochry, Perthshire, PH16 5LB, U.K.
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  • N. B. Metcalfe

    Corresponding author
    1. Fish Biology Group, Division of Environmental and Evolutionary Biology, Graham Kerr Building, Institute of Biomedical & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, U.K.,
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§Tel.: +44 (0)141 3305968; fax: +44 (0)141 3305971; email: n.metcalfe@bio.gla.ac.uk

Abstract

Atlantic salmon Salmo salar parr exposed to heated water effluent were larger than parr living upstream of the discharge. There was no effect, however, of temperature on the incidence of male parr maturation, despite the link between growth and maturation found in other studies. Mature parr upstream of the effluent were smaller than mature parr downstream of it, suggesting a higher size threshold for maturation in those parr exposed to the heated water. The small distance between upstream and downstream sampling sites probably precluded genetic differences between the parr, thus implying an environmental influence on the threshold size above which male parr matured.

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