Life history variation across four decades in a diverse population complex of Atlantic salmon in a large subarctic river

• Main Authors: Erkinaro, Jaakko, Czorlich, Yann, Orell, Panu, Kuusela, Jorma, Falkegård, Morten, Länsman, Maija, Pulkkinen, Henni, Primmer, Craig R, Niemelä, Eero
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NRC Research Press (a division of Canadian Science Publishing) 2018
• Subjects: Teno; Atlantic salmon; Subarctic
• Online Access: http://hdl.handle.net/1807/90374; http://www.nrcresearchpress.com/doi/abs/10.1139/cjfas-2017-0343

We used >154000 scale samples collected from salmon fisheries in the large River Teno system over a 40-year period to quantify life history diversity and long-term trends. We identified 120 different life history strategies including combinations of smolt (2-8) and sea ages (1-5) and previous spawning events. Most strategies were rare: 60% of individuals matured after one year at sea following 3-5 years in freshwater. Age at maturity has changed with an increase in two-sea-winter (2SW) salmon and previous spawners (PS), and a decline in 3SW fish. Smolt age distribution showed a decreasing proportion of age-3 smolts while that of age-5 increased. Fishing gear and fishing season times selected for fish differing in life-history strategies. Temporal variation in life histories reflects changes both in fisheries and the changing environment. There was an inverse relationship between years spent in freshwater and sea age. Biocomplexity was manifested by the multiple year classes (6-11) present in annual runs that increased with years, reflecting an increase both in PS and sampling effort. The high number of cohorts spawning simultaneously each year indicates strong generation overlap, which has been suggested to maintain genetic diversity and thereby resilience via the portfolio effect 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.