Aggressiveness can affect social hierarchies and result in the unequal distribution of resources, with aggressive individuals monopolizing access to food influencing growth. In Atlantic salmon, aggression has been found to have a genetic component, and growth also influences maturation timing. Maturation timing associates with a large-effect locus around vgll3, which is also linked to growth and condition, with vgll3*EE (early maturation) individuals having higher condition factor than vgll3*LL (late maturation). Here, we examine the possibility that aggressiveness may play a role in juvenile vgll3*EE individuals having higher condition factor by having increased food intake due to higher aggression promoting increased food access. This prediction was tested under a social context: aggressiveness and feeding activity in four size-matched individual salmon, two from each genotype, were observed over 95 trials. Contrary to our prediction, vgll3*LL individuals, not vgll3*EE, were more aggressive. Increased aggression of vgll3*LL individuals was independent of their sex and size, and genotypes did not differ in their condition factor nor feeding activity. These results imply that aggressiveness may have an energetic cost impairing growth and condition, especially when food cannot be monopolized. This may have critical implications for individual fitness and aquaculture practices.
Key Words: Aggressiveness, Atlantic salmon, Energy, Maturation, vgll3 genotype,