News from SeaSalar

Atlantic salmon juveniles start marine feeding soon after leaving the rivers

Published on: 27. February 2023

The diet of nearly six hundred salmon post-smolt caught in Norwegian fjords was analysed in a new study. Already at that early stage of the marine migration, it is important for the salmon to find fish larvae to feed on.  

Atlantic salmon juveniles start marine  feeding soon after leaving the rivers
Atlantic salmon smolt on the way from the River Etne immediately before entering the sea. Photo: Eva B. Thorstad


The diet of post-smolts caught in this study mainly consisted of fish larvae, krill, planktonic amphipods, and insects. However, diet varied among fjords and years. For example, post-smolts in Altafjord in northern Norway had a higher frequency of fish larvae in their diet compared to post-smolts from fjords in western Norway.

Post-smolts consuming fish larvae or krill had substantially higher feeding ratios, and these fish were on average 0.52 cm longer. Feeding on fish larvae did not influence condition factor. However, post-smolts sampled in this study had most likely been in the sea only for a few days, and dietary differences may therefore only have had a minor effect on energetic state in this short period.

There was no clear evidence of changes in the post-smolt diet in recent years (2018 and 2019) compared to samples nearly 20 years earlier in the same fjords. This indicates that the ecological regime shift in the Northeast Atlantic after year 2004 did not have a large impact of post-smolt feeding conditions within Norwegian fjords, at least in the years in which samples for the present study were collected.


Read more in the new publication:

Hellenbrecht, L.M., Utne, K.R., Karlsen, Ø., Glover, K.A. & Wennevik, V. 2023. Diet analysis of Atlantic salmon (Salmo salar) post-smolts after the ecological regime shift in the Northeast Atlantic. Fisheries Research 262: 106672. https://www.sciencedirect.com/science/article/pii/S0165783623000656