Personality in hatchery Atlantic salmon (Salmo salar) is associated with growth but not metabolic rate or performance

The pace of life hypothesis (POLS) predicts that personality traits, like activity and boldness, are positively correlated with growth andmetabolism. Here, we assess whether personality could predict body mass, metabolic rate, and performance under stress for hatchery-raised Atlantic salmon (Salmo salar) 15months post fertilization. Personality was evaluated for individual fish using a series of repeated trials alongside two stressful events (PIT tagging, simulated transport), to determine performance under stress. Standard metabolic rate (SMR) was then assessed via intermittent flow respirometry, and the relationships between personality, body mass, performance, and SMR were evaluated. Fish displayed repeatable behaviours, but not in accordance with POLS hypothesis. Smaller fish were more active and responsive to stimuli, while personality was not associated with SMR. Although smaller fish and fish with higher SMR both performed better under stress, body mass was unrelated to SMR. We discuss the utility of supporting the occurrence of a wider range of growth rates and body sizes in hatchery environments, as a means of promoting greater stress tolerance as well as faster growth.