Behavioural responses of hatchery-reared and wild cod Gadus morhua to mechano-acoustic predator signals

Authors

  • J. J. Meager,

    Corresponding author
    1. Department of Biology, University of Bergen, P. O. Box 7800, Bergen N-5020, Norway
      Author to whom correspondence should be addressed at present address: Faculty of Science, Health and Education, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia. Tel.: +61 4298 86459; email: Justin.Meager@gmail.com
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  • P. Rodewald,

    1. Department of Biology, University of Bergen, P. O. Box 7800, Bergen N-5020, Norway
    2. Department of Biosciences, P. O. Box 56, University of Helsinki, Helsinki FI-00014, Finland
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  • P. Domenici,

    1. CNR-IAMC Loc. Sa Mardini, Torregrande 09072, Oristano, Italy
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  • A. Fernö,

    1. Department of Biology, University of Bergen, P. O. Box 7800, Bergen N-5020, Norway
    2. Institute of Marine Research, Bergen N-5817, Norway
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  • T. Järvi,

    1. Swedish Board of Fisheries, Drottningholm S-178 93, Sweden
    2. Department of Zoology, Stockholm University, Stockholm S-106 91, Sweden
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  • J. E. Skjæraasen,

    1. Department of Biology, University of Bergen, P. O. Box 7800, Bergen N-5020, Norway
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  • G. K. Sverdrup

    1. Department of Biology, University of Bergen, P. O. Box 7800, Bergen N-5020, Norway
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Author to whom correspondence should be addressed at present address: Faculty of Science, Health and Education, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia. Tel.: +61 4298 86459; email: Justin.Meager@gmail.com

Abstract

The behavioural responses of wild (predator-experienced) and hatchery-reared (predator-naive) cod Gadus morhua to standardized mechano-acoustic (MA) stimuli were compared in the laboratory. Wild fish responded mainly with freezing and fast-start escapes away from the stimulus, whereas hatchery-reared fish often ignored or approached the stimulus. Wild fish also had stronger responses, turning faster during escapes and reducing activity immediately after the stimulus. Both fish types were less active on a ‘risky’ bare substratum after the stimulus. The antipredator responses of wild fish were consistent to repeated stimuli, whereas hatchery-reared fish that had generally only encountered harmless stimuli showed more variable responses with lower repeatability. This suggests that experience plays a role in shaping the behavioural response of fishes to MA stimuli.

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