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Basin‐scale phenology and effects of climate variability on global timing of initial seaward migration of Atlantic salmon ( Salmo salar )
Author(s) -
Otero Jaime,
L'AbéeLund Jan Henning,
CastroSantos Ted,
Leonardsson Kjell,
Storvik Geir O.,
Jonsson Bror,
Dempson Brian,
Russell Ian C.,
Jensen Arne J.,
Baglinière JeanLuc,
Dionne Mélanie,
Armstrong John D.,
Romakkaniemi Atso,
Letcher Benjamin H.,
Kocik John F.,
Erkinaro Jaakko,
Poole Russell,
Rogan Ger,
Lundqvist Hans,
MacLean Julian C.,
Jokikokko Erkki,
Arnekleiv Jo Vegar,
Kennedy Richard J.,
Niemelä Eero,
Caballero Pablo,
Music Paul A.,
Antonsson Thorolfur,
Gudjonsson Sigurdur,
Veselov Alexey E.,
Lamberg Anders,
Groom Steve,
Taylor Benjamin H.,
Taberner Malcolm,
Dillane Mary,
Arnason Fridthjofur,
Horton Gregg,
Hvidsten Nils A.,
Jonsson Ingi R.,
Jonsson Nina,
McKelvey Simon,
Næsje Tor F.,
Skaala Øystein,
Smith Gordon W.,
Sægrov Harald,
Stenseth Nils C.,
Vøllestad Leif Asbjørn
Publication year - 2014
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.12363
Subject(s) - salmo , fish migration , habitat , smoltification , fishery , ecology , climate change , phenology , streams , environmental change , environmental science , geography , oceanography , salmonidae , biology , geology , fish <actinopterygii> , computer network , computer science
Migrations between different habitats are key events in the lives of many organisms. Such movements involve annually recurring travel over long distances usually triggered by seasonal changes in the environment. Often, the migration is associated with travel to or from reproduction areas to regions of growth. Young anadromous Atlantic salmon ( Salmo salar ) emigrate from freshwater nursery areas during spring and early summer to feed and grow in the North Atlantic Ocean. The transition from the freshwater (‘parr’) stage to the migratory stage where they descend streams and enter salt water (‘smolt’) is characterized by morphological, physiological and behavioural changes where the timing of this parr‐smolt transition is cued by photoperiod and water temperature. Environmental conditions in the freshwater habitat control the downstream migration and contribute to within‐ and among‐river variation in migratory timing. Moreover, the timing of the freshwater emigration has likely evolved to meet environmental conditions in the ocean as these affect growth and survival of the post‐smolts. Using generalized additive mixed‐effects modelling, we analysed spatio‐temporal variations in the dates of downstream smolt migration in 67 rivers throughout the North Atlantic during the last five decades and found that migrations were earlier in populations in the east than the west. After accounting for this spatial effect, the initiation of the downstream migration among rivers was positively associated with freshwater temperatures, up to about 10 °C and levelling off at higher values, and with sea‐surface temperatures. Earlier migration occurred when river discharge levels were low but increasing. On average, the initiation of the smolt seaward migration has occurred 2.5 days earlier per decade throughout the basin of the North Atlantic. This shift in phenology matches changes in air, river, and ocean temperatures, suggesting that Atlantic salmon emigration is responding to the current global climate changes.