Competitive ability influences seaward migration age in Atlantic salmon

• Published in: Canadian Journal of Zoology
• Main Author: Metcalfe, Neil B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1991
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1139/z91-121; http://www.nrcresearchpress.com/doi/pdf/10.1139/z91-121

Juvenile Atlantic salmon (Salmo salar L.) reach a life-history decision in late summer as to whether they will migrate to sea the following spring or remain in fresh water for at least a further year. Here I show that the feeding efficiency of those fish that subsequently defer migration is significantly impaired by the presence of a size-matched competitor, whereas that of fish adopting the strategy of early migration is unaffected by a competitor's presence. This suggests that competitive ability influences the decision as to when to migrate, through its effect on food intake and growth rates, later migrating fish being the poorer competitors.