Redefining the oceanic distribution of Atlantic salmon

Determining the mechanisms driving range-wide reductions in Atlantic salmon marine survival is hindered by an insufficient understanding of their oceanic ecology and distribution. We attached 204 pop-up satellite archival tags to post-spawned salmon when they migrated to the ocean from seven European areas and maiden North American salmon captured at sea at West Greenland. Individuals migrated further north and east than previously reported and displayed increased diving activity near oceanographic fronts, emphasizing the importance of these regions as feeding areas. The oceanic distribution differed among individuals and populations, but overlapped more between geographically proximate than distant populations. Dissimilarities in distribution likely contribute to variation in growth and survival within and among populations due to spatio-temporal differences in environmental conditions. Climate-induced changes in oceanographic conditions will alter the location of frontal areas and may have stock-specific effects on Atlantic salmon population dynamics, likely having the largest impacts on southern populations.

Automated summary

The study found that the mechanisms driving range-wide reductions in Atlantic salmon marine survival are hindered by a lack of understanding of their oceanic ecology and distribution. The individual salmon migrated further and in different directions than previously reported, showing increased diving activity near oceanographic fronts, highlighting the importance of these regions as feeding areas. Differences in oceanic distribution among individuals and populations may contribute to variations in growth and survival due to environmental conditions.