Fish may fight rather than feed in a novel environment: metabolic rate and feeding motivation in juvenile Atlantic salmon

This study tested the hypothesis that juvenile Atlantic salmon Salmo salar with a high resting metabolic rate and probability of dominance will also have a correspondingly higher feeding motivation in a novel environment to offset their greater costs of maintenance. The opposite was found to be the case: Atlantic salmon with a high standard metabolic rate had a slightly but significantly lower feeding motivation. It is hypothesized that Atlantic salmon with higher maintenance costs opt to be more aggressive at the expense of the costly activities associated with feeding, since elevated aggression in a new habitat is a more successful strategy for acquiring a feeding territory (and hence sustaining food intake in the long-term) than a high feeding motivation alone.