Poor feeding opportunities and reduced condition factor for salmon post-smolts in the Northeast Atlantic Ocean

K.R. Utne, B.D. Pauli, M. Haugland, J.A. Jacobsen, N. Maoileidigh, W. Melle, C.T. Broms, L. Nøttestad, M. Holm, K. Thomas, V. Wennevik

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15 Citations (Scopus)
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During the last few decades, many wild Atlantic salmon populations have declined dramatically. One possible contributing factor for the decline is reduced prey availability at sea. Here, we examine post-smolt diet and investigate if post-smolts show signs of selective feeding based on 2546 post-smolts sampled from west of Ireland to the northern Norwegian Sea over a 25-year period. We also test for changes over time in stomach fullness, diet, condition factor and body length. There was a clear reduction in condition factor for post-smolts sampled in the Norwegian Sea in the period 2003–2012. The post-smolt stomach fullness was also reduced in the same period. The reduction in condition factor is partly explained by reduced stomach fullness, including a reduction of highly energetic fish larvae and Amphipoda in the diet. Feeding on other prey, such as meso-zooplankton and insects, cannot substitute the high-quality fish larvae and Amphipoda in the post-smolt diet. This is the first study to document how salmon post-smolts feeding in the Norwegian Sea are affected by reduced feeding conditions. Possible causes for the observed changes in post-smolt feeding are ocean warming, decreased primary productivity, and reduced recruitment of important fish larvae
Original languageEnglish
Pages (from-to)2844-2857
Number of pages13
JournalICES Journal of Marine Science
Issue number8
Publication statusPublished - 2021


  • salmon
  • amphipoda
  • climate change
  • fish larvae
  • mackerel
  • Norwegian Sea


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