Redefining the oceanic distribution of Atlantic salmon

Area of Science:

• Marine ecology
• Fish migration
• Conservation biology

Background:

• Atlantic salmon (Salmo salar) marine survival is declining, but oceanic ecology and distribution remain poorly understood.
• This knowledge gap hinders efforts to determine the mechanisms driving population reductions.

Purpose of the Study:

• To investigate the oceanic distribution and behavior of Atlantic salmon.
• To identify key oceanic feeding areas and understand factors influencing survival.

Main Methods:

• Pop-up satellite archival tags (PSATs) were deployed on 204 post-spawned European and North American Atlantic salmon.
• Tagging occurred during oceanic migration from European rivers and at West Greenland for North American salmon.

Main Results:

• Salmon migrated further north and east than previously documented.
• Increased diving activity was observed near oceanographic fronts, indicating their importance as feeding grounds.
• Oceanic distribution varied among individuals and populations, with greater overlap between proximate populations.

Conclusions:

• Oceanic distribution and feeding at frontal regions are critical for Atlantic salmon growth and survival.
• Climate-induced shifts in oceanographic conditions will impact salmon populations differently, with southern stocks potentially facing the greatest risks.