Important open-ocean areas for northern Atlantic salmon (Salmo salar) — as estimated using a simple ambient-temperature approach

Tracking salmon migratory behaviour in the open ocean has been a challenge to researchers. As the marine phase essentially determines the size and survival of individuals and populations, it is arguably the most influential life cycle period for salmon population dynamics. Thus, methods providing an understanding of the spatial and temporal patterns of salmon marine migratory behaviour could improve the species' management and conservation. A model was developed that correlated temperature data from archival tags with sea-surface temperatures (SSTs) to identify the probable marine feeding areas of a northeastern Atlantic salmon (Salmo salar) population over 3 years. The marine distribution of the tagged population extended from the Greenland Sea, north to Svalbard, and into the eastern Barents Sea. Higher probability occupancy zones overlapped with the polar front area from September to April during all 3 years. While the migratory behaviour appeared similar between years and seasons, the fish were distributed farther south and west during the autumn of 2007 than during the autumns of 2006 and 2008. This may have been related to warmer summer SSTs and an earlier annual maximum SST. The ambient-temperature approach developed here is a cost-effective way to monitor the open-ocean migratory patterns of surface-oriented marine fishes.