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Ontogenetic changes in temperature preference of Atlantic cod

Authors

  • P. Lafrance,

    1. Pêches et Océans Canada, Institut Maurice-Lamontagne, C.P. 1000, Mont-Joli, Québec, G5H 3Z4, Canada and
    2. Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec G5L 3A1, Canada
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    • Present address: Québec-Océan, Université Laval, Québec, Québec G1K 7P4, Canada.

  • M. Castonguay,

    Corresponding author
    1. Pêches et Océans Canada, Institut Maurice-Lamontagne, C.P. 1000, Mont-Joli, Québec, G5H 3Z4, Canada and
      §Tel.: +1 418 775 0634; fax: +1 418 775 0740; email: castonguaym@dfo-mpo.gc.ca
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  • D. Chabot,

    1. Pêches et Océans Canada, Institut Maurice-Lamontagne, C.P. 1000, Mont-Joli, Québec, G5H 3Z4, Canada and
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  • C. Audet

    1. Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, Québec G5L 3A1, Canada
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§Tel.: +1 418 775 0634; fax: +1 418 775 0740; email: castonguaym@dfo-mpo.gc.ca

Abstract

Final thermal preferendum (T) experiments were conducted in a horizontal thermal gradient tank from the beginning of August 2001 to mid-November 2001 using Atlantic cod Gadus morhua from 6·5 to 79·0 cm fork length (LF). The value of T varied significantly (P < 0·005) with LF(T = 7·23–0·054LF), with smaller (younger) fish choosing higher temperatures than larger (older) fish. The preferendum varied from 6·9° C for fish of 6·5 cm to 3·0° C for those of 79·0 cm. Experiments comparing fish positions in the gradient tank between thermal gradients of 0·5–11·0 and 4·5–14·5° C demonstrated that fish positions were determined by temperature selection instead of undesirable tank effects. This study is the first to demonstrate the effect of ontogeny on temperature preferences of a marine fish species.

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