Basin-scale phenology and effects of climate variability on global timing of initial seaward migration of Atlantic salmon (Salmo salar)
Jaime Otero
(1)
,
Jan Henning L'Abee-Lund
(2)
,
Ted Castro-Santos
(3)
,
Kjell Leonardsson
(4)
,
Geir O. Storvik
(1, 5)
,
Bror Jonsson
(6)
,
Brian Dempson
(7)
,
Ian C. Russell
(8)
,
Arne J. Jensen
(6)
,
Jean-Luc J.-L. Baglinière
(9)
,
Melanie Dionne
(10)
,
John D. Armstrong
(11)
,
Atso Romakkaniemi
(12)
,
Benjamin H. Letcher
(3)
,
John F. Kocik
(13)
,
Jaakko Erkinaro
(12)
,
Russell Poole
(14)
,
Ger Rogan
(15)
,
Hans Lundqvist
(4)
,
Julian C. Maclean
(16)
,
Erkki Jokikokko
(17)
,
Jo Vegar Arnekleiv
(18)
,
Richard J. Kennedy
(19)
,
Eero Niemela
(12)
,
Pablo Caballero
(20)
,
Paul A. Music
(13)
,
Thorolfur Antonsson
(21)
,
Sigurdur Gudjonsson
(21)
,
Alexey E. Veselov
(22)
,
Anders Lamberg
(23)
,
Steve Groom
(24)
,
Benjamin H. Taylor
(24)
,
Malcolm Taberner
(24)
,
Mary Dillane
(14)
,
Fridthjofur Arnason
(21)
,
Gregg Horton
(3)
,
Nils A. Hvidsten
(6)
,
Ingi R. Jonsson
(21)
,
Nina Jonsson
(6)
,
Simon Mckelvey
(25)
,
Tor F. Naesje
(6)
,
Oystein Skaala
(26)
,
Gordon W. Smith
(16)
,
Harald Saegrov
(27)
,
Nils C. Stenseth
(1, 28)
,
Leif Asbjorn Vollestad
(1)
1
CEES -
Centre for Ecological and Evolutionary Synthesis
2 NVE - Norwegian Water Resources and Energy Directorate
3 Silvio O. Conte Anadromous Fish Research Center
4 Department of Wildlife, Fish and Environmental Studies
5 Department of Mathematics [Oslo]
6 NINA - Norwegian Institute for Nature Research
7 DFO - Fisheries and Oceans Canada
8 CEFAS - Centre for Environment, Fisheries and Aquaculture Science [Lowestoft]
9 ESE - Écologie et santé des écosystèmes
10 Direction de la Faune Aquatique
11 Freshwater Laboratory Pitlochry
12 Finnish Game and Fisheries Research Institute
13 National Marine Fisheries Service
14 Fisheries Ecosystem Advisory Services
15 Fisheries Ecosystem Advisory Services
16 Freshwater Laboratory Field Station
17 Bothnian Bay Fisheries Research Station
18 Section of Natural History, Museum of Natural History and Archaeology
19 Agri Food and Biosciences Institute
20 Sección de Biodiversidade, Servizo de Conservación da Natureza de Pontevedra
21 Institute of Freshwater Fisheries
22 Institute of Biology
23 Vilt og fiskeinfo AS
24 Remote Sensing Group
25 Cromarty Firth Fisheries Trust
26 Institute of Marine Research
27 Radgivende Biologer AS
28 IMR - Flødevigen Research Station
2 NVE - Norwegian Water Resources and Energy Directorate
3 Silvio O. Conte Anadromous Fish Research Center
4 Department of Wildlife, Fish and Environmental Studies
5 Department of Mathematics [Oslo]
6 NINA - Norwegian Institute for Nature Research
7 DFO - Fisheries and Oceans Canada
8 CEFAS - Centre for Environment, Fisheries and Aquaculture Science [Lowestoft]
9 ESE - Écologie et santé des écosystèmes
10 Direction de la Faune Aquatique
11 Freshwater Laboratory Pitlochry
12 Finnish Game and Fisheries Research Institute
13 National Marine Fisheries Service
14 Fisheries Ecosystem Advisory Services
15 Fisheries Ecosystem Advisory Services
16 Freshwater Laboratory Field Station
17 Bothnian Bay Fisheries Research Station
18 Section of Natural History, Museum of Natural History and Archaeology
19 Agri Food and Biosciences Institute
20 Sección de Biodiversidade, Servizo de Conservación da Natureza de Pontevedra
21 Institute of Freshwater Fisheries
22 Institute of Biology
23 Vilt og fiskeinfo AS
24 Remote Sensing Group
25 Cromarty Firth Fisheries Trust
26 Institute of Marine Research
27 Radgivende Biologer AS
28 IMR - Flødevigen Research Station
Résumé
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 degrees 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 2.5days 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.