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Stock-specific variation of trophic position, diet and environmental stress markers in Atlantic salmon Salmo salar during feeding migrations in the Baltic Sea

Authors

  • K. Vuori,

    Corresponding author
    1. Centre of Excellence in Evolutionary Genetics and Physiology, Laboratory of Animal Physiology, Department of Biology, University of Turku, Turku, Finland
      Tel.: +358 23336263; email: kranvu@utu.fi
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  • M. Kiljunen,

    1. Department of Biological and Environmental Science, University of Jyväskylä, P. O. Box 35, Jyväskylä FIN-40014, Finland
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  • M. Kanerva,

    1. Centre of Excellence in Evolutionary Genetics and Physiology, Laboratory of Animal Physiology, Department of Biology, University of Turku, Turku, Finland
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  • M.-L. Koljonen,

    1. Finnish Game and Fisheries Research Institute, P. O. Box 2, FI-00791 Helsinki, Finland
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  • M. Nikinmaa

    1. Centre of Excellence in Evolutionary Genetics and Physiology, Laboratory of Animal Physiology, Department of Biology, University of Turku, Turku, Finland
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Tel.: +358 23336263; email: kranvu@utu.fi

Abstract

This study investigated stock-specific variation in selected ecophysiological variables during the feeding migrations of Atlantic salmon Salmo salar in the Baltic Sea. Oxidative stress biomarkers and EROD (ethoxyresorufin-O-deethylase, Cyp1A enzyme) activity were used as indicators of possible environmental stress and stable isotopes as determinants of diet and trophic position. Latvian S. salar stocks Daugava and Gauja had distinct stable-isotope signatures compared to the other stocks, indicating differences in migration patterns, residency or arrival times, or dietary specialization among stocks. Salmo salar originating from Daugava and Gauja also had lower catalase enzyme activity than the other stocks. Post-smolts originating from rivers of the Gulf of Finland had elevated EROD activities compared to fish of the same age from Bothnian Bay rivers, which could indicate exposure to organochlorine pollutants. No other stock-specific differences in oxidative stress biomarkers were found. The study demonstrates how genetic, oxidative stress biomarker, EROD and stable-isotope data may be combined to study trophic position, prey prevalence and environmental stress of mixed S. salar stocks foraging in the sea.

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