Feeding interactions between Atlantic salmon (Salmo salar) postsmolts and other planktivorous fish in the Northeast Atlantic

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 78; no. 3; pp. 255 - 268
• Main Authors: Utne, Kjell Rong, Thomas, Katie, Jacobsen, Jan Arge, Fall, Johanna, Maoiléidigh, Niall Ó, Broms, Cecilie Thorsen, Melle, Webjørn
• Format: Journal Article
• Language: English
• Published: 1840 Woodward Drive, Suite 1, Ottawa, ON K2C 0P7 NRC Research Press 01.03.2021; Canadian Science Publishing NRC Research Press
• Subjects: Abundance; Analysis; Animal feeding behavior; Atlantic salmon; Biological competition; Biological sampling; Biomass; Climate change; Clupea harengus; Clupeidae; Ectoparasites; Environmental aspects; Feeding; Feeding habits; Fish; Fish larvae; Food and nutrition; Food supply; Geographical distribution; Growth; Hypotheses; Interspecific; Larvae; Lepeophtheirus salmonis; Mackerel; Marine; Marine environment; Methods; Modelling; Natural populations; Nutrient deficiency; Overwintering; Parasites; Prey selection; Salmo salar; Salmon; Salmoniformes; Scomber scombrus; Spawning stock biomass; Stomach content; Survival; Time series; Zooplankton; North Atlantic Ocean; ANE, Norwegian Sea; ANE, North Atlantic
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/cjfas-2020-0037

In recent decades, there has been a decline in the marine growth of Atlantic salmon (Salmo salar) over large parts of the distribution range. One hypothesis for this reduced growth is increased interspecific competition with other planktivorous pelagic fish in the ocean. Here, interactions between salmon postsmolts and other pelagic fish (mackerel (Scomber scombrus) and herring (Clupea harengus)) in the Northeast Atlantic were investigated. There was a low diet overlap between postsmolts and the two other planktivorous pelagic species. Both mackerel and herring were feeding predominantly on copepods and other small zooplankton, while salmon were feeding mostly on fish larvae. All three species feed on euphausiids and amphipods. Furthermore, postsmolts geographically overlapped with mackerel but had a low geographic overlap with herring. There was no correlation between the abundance or survival of salmon from key index rivers and the abundance of pelagic fish. This study did not find evidence to support the hypothesis that observed temporal changes in marine growth and survival of salmon can be explained by feeding interactions with pelagic fish.