Climate-driven bio-physical changes in feeding and breeding environments explain the decline of southernmost European Atlantic salmon populations

• Main Authors: Almodóvar, Ana, Ayllón, Daniel, Nicola, Graciela G., Jonsson, Bror, Elvira, Benigno
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NRC Research Press (a division of Canadian Science Publishing) 2018
• Subjects: Atlantic salmon; North Atlantic; Salmo salar
• Online Access: http://hdl.handle.net/1807/94875; http://www.nrcresearchpress.com/doi/abs/10.1139/cjfas-2018-0297

The consistency of the global declining trend of Atlantic salmon Salmo salar populations suggests that climate-driven reduced survival and growth at sea are the main driving factors. The southernmost populations have experienced the greatest declines, consistent with harsher conditions in natal freshwaters. We analyzed temporal trends in Spanish Atlantic salmon, important food organisms at sea, and climatic variables in the breeding (freshwater) and feeding (marine) salmon areas from 1950 onwards, to elucidate drivers of declining patterns. Salmon abundance dropped abruptly in 1970-1971, plausibly linked to widespread overfishing coincident with incipient changes in the marine food-webs and freshwater hydrology. A major regime shift in bio-physical conditions throughout the North Atlantic salmon feeding grounds occurred in 1986-1987, driven by the concurrence of an abrupt acceleration in the anthropogenic warming trend and the warm phase of the Atlantic Multidecadal Oscillation. This regime shift may be the proximate cause of the collapse of Spanish salmon observed in 1988-1989, which kept declining in parallel to trends of ever-increasing ocean and freshwater temperatures, decreasing river flows, and poorer marine trophic conditions. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.