Aquaculture Environment Interactions
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DOI: https://doi.org/10.3354/aei00501
copiedEffects of salmon farming on Atlantic cod: insights from liver fatty acid composition in relation to biological and genetic variables
- Pablo Sanchez-Jerez
- Javier Atalah
- Ingeborg Mathisen Sætra
- Thomas Bøhn
- Bjørn-Steinar Sæther
- Torild Johansen
- Nigel Keeley
- Terje van der Meeren
- Pål Arne Bjørn
ABSTRACT:
The present study investigated the impact of salmon aquaculture on the fatty acid composition in the liver of Atlantic cod Gadus morhua L. in northern Norway, comparing Northeast Arctic cod (NEAC) and Norwegian coastal cod (NCC) ecotypes. Cod were sampled seasonally near salmon farms at 1 impact location (<5 km) and 3 control sites farther from farms (>10 km) from October 2019 to October 2020. Fatty acid profiles were analyzed after lipid extraction of liver samples and gas chromatography. Generalized linear mixed models and multivariate analyses were used to assess differences between treatments, ecotypes, and other biological factors. Results showed that cod caught near farms had distinct fatty acid compositions with higher concentrations of aquafeed-derived fatty acids (e.g. oleic, linoleic, α-linolenic acid), indicating direct and/or indirect consumption (e.g. prey fish, benthic invertebrates) of unconsumed aquafeed. These effects were independent of ecotype, age, and sex. No significant seasonal changes or accumulation of fatty acids over time were detected. Both NEAC and NCC exhibited similar fatty acid profiles, suggesting comparable residency rates around salmon cages. A measurement of energetic reserves, the hepatosomatic index, significantly influenced fatty acid concentrations, highlighting the importance of liver fat storage. While cod near farms maintained relatively high concentrations of marine-based essential fatty acids (e.g. docosahexaenoic acid), the potential long-term physiological impacts (e.g. growth, reproduction, recruitment) warrant further investigation. This study emphasizes the need for a precautionary approach in spatial planning of salmon aquaculture, considering its potential effects on wild cod populations and recovery.
KEYWORDS
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Pablo Sanchez-Jerez (Corresponding Author)
- Department of Marine Science and Applied Biology, University of Alicante, PO Box 99, 03008 Alicante, Spain
Javier Atalah (Co-author)
- Department of Marine Science and Applied Biology, University of Alicante, PO Box 99, 03008 Alicante, Spain
Ingeborg Sætra (Co-author)
- Institute of Marine Research, PO Box 6606, 9296 Tromsø, Norway
Thomas Bøhn (Co-author)
- Institute of Marine Research, PO Box 6606, 9296 Tromsø, Norway
Bjørn-Steinar Sæther (Co-author)
- The Arctic University of Norway, 9019 Tromsø, Norway
Torild Johansen (Co-author)
- Institute of Marine Research, PO Box 6606, 9296 Tromsø, Norway
Nigel Keeley (Co-author)
- Institute of Marine Research, PO Box 6606, 9296 Tromsø, Norway
Terje van der Meeren (Co-author)
- Institute of Marine Research, Austevoll Research Station, 5392 Storebø, Norway
Pål Arne Bjørn (Co-author)
- Institute of Marine Research, PO Box 6606, 9296 Tromsø, Norway
Handling Editor:
Bengt Finstad, Trondheim, Norway
Reviewers:
L. McAllister and 1 anonymous referee, and previous version reviewed in AEI by L. McAllister and 1 anonymous referee
Acknowledgements:
This study was funded by the Research Council of Norway (RCN), grant no. 294631 SALCOD and the Institute of Marine Research (IMR). J.A. was supported by a Maria Zambrano Grant, financed by the Spanish Government through the European Union NextGenerationEU fund. We thank Agneta Hansen and Alejandro Mateos Rivera for their technical assistance in the laboratory during the genetic analysis.