A multi‐population approach supports common patterns in marine growth and maturation decision in Atlantic salmon ( Salmo salar L.) from southern Europe

• Published in: Journal of Fish Biology
• Main Authors: Tréhin, Cécile, Rivot, Etienne, Santanbien, Valentin, Patin, Rémi, Gregory, Stephen, Lamireau, Ludivine, Marchand, Frédéric, Beaumont, William, Scott, Luke, Hillman, Robert, Besnard, Anne-Laure, Boisson, Pierre‐yves, Meslier, Lisa, King, Andrew, Stevens, Jamie, Nevoux, Marie
• Other Authors: Dynamique et durabilité des écosystèmes : de la source à l’océan (DECOD), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut Agro Rennes Angers, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Unité Expérimentale d'Ecologie et d'Ecotoxicologie Aquatique - U3E (Rennes, France) (U3E ), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Pôle OFB-INRAE-Institut Agro-UPPA pour la gestion des migrateurs amphihalins dans leur environnement (MIAME), Université de Pau et des Pays de l'Adour (UPPA)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Office français de la biodiversité (OFB)-Institut Agro Rennes Angers, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Université Grenoble Alpes (UGA), Centre for Environment, Fisheries and Aquaculture Science Weymouth (CEFAS), Salmon and Trout Research Centre, The Game and Wildlife Conservation Trust, Bournemouth University Poole (BU), UK Environmental Agency, Department of Biosciences, Faculty of Health and Life Sciences, Hatherly Laboratories, Exeter, UK
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: life-history traits;long-term monitoring;post-smolt growth;probabilistic maturation reaction norm;retrospective growth analysis;scale archive; [SDE]Environmental Sciences; Atlantic salmon; Salmo salar
• Online Access: https://hal.science/hal-04265790; https://doi.org/10.1111/jfb.15567

International audience Abstract This study provides a regional picture of long‐term changes in Atlantic salmon growth at the southern edge of their distribution, using a multi‐population approach spanning 49 years and five populations. We provide empirical evidence of salmon life history being influenced by a combination of common signals in the marine environment and population‐specific signals. We identified an abrupt decline in growth from 1976 and a more recent decline after 2005. As these declines have also been recorded in northern European populations, our study significantly expands a pattern of declining marine growth to include southern European populations, thereby revealing a large‐scale synchrony in marine growth patterns for almost five decades. Growth increments during their sea sojourn were characterized by distinct temporal dynamics. At a coarse temporal resolution, growth during the first winter at sea seemed to gradually improve over the study period. However, the analysis of finer seasonal growth patterns revealed ecological bottlenecks of salmon life histories at sea in time and space. Our study reinforces existing evidence of an impact of early marine growth on maturation decision, with small‐sized individuals at the end of the first summer at sea being more likely to delay maturation. However, each population was characterized by a specific probabilistic maturation reaction norm, and a local component of growth at sea in which some populations have better growth in some years might further amplify differences in maturation rate. Differences between populations were smaller than those between sexes, suggesting that the sex‐specific growth threshold for maturation is a well‐conserved evolutionary phenomenon in salmon. Finally, our results illustrate that although most of the gain in length occurs during the first summer at sea, the temporal variability in body length at return is buffered against the decrease in post‐smolt growth conditions. The intricate combination of growth over ...