Atlantic salmon: A polar and deep water explorer
Extra seminar by Audun Rikardsen
Through the SALMOTRACK-project (2008-2012), we have for the first time been able to describe oceanic migration routes and behavioral patterns of individual Atlantic salmon (Salmo salar) from different stocks in the open ocean. More than 170 pop-up satellite archival tags (PSATs) and 500 standard archival tags have been used to tag kelts (post-spawners) that departed from Norway (three areas), Ireland, Denmark, Iceland and Canada. In addition, we also tagged 1SW non-maturing salmon in the West-Greenland Sea with PSATS. The project has revealed unique and totally new information on salmon migration behaviour at sea, including new feeding areas, behavioural patterns and locations and reasons for mortality. Populations exhibited differing migratory routes, but individuals consistently used the polar fronts as primary foraging habitats and travelled with oceanic currents and gyres, some reaching latitudes almost up to 80° N west of Svalbard. Some populations mixed at the feeding areas while other did not. The salmon also regularly dived fast to depths between 400-900 m, a feat previously unknown. These data will have management implications and help explaining why survival and growth of salmon at sea often varies among stocks from different regions, as well as how environmental factors and changes in climate may influence salmon migration and feeding patterns in the oceans.
Audun Rikardsen, Prof.
University of Tromsø