Atlantic salmon growth in strongly food-limited environments: Effects of egg size and paternal phenotype?

I manipulated egg size and followed individual mass trajectories from the egg stage in Atlantic salmon to test for effects of size, and for interactions between size and paternal body mass, on offspring performance in strongly food-limited environments. Egg size had a strong effect on body mass at yolk absorption, causing juveniles originating from large eggs to outgrow their siblings from small eggs. This corroborates previous findings of egg size effects under more benign environments, and demonstrates that positive effects of egg size on offspring success are manifested even under strong food-limitation. Previously reported negative effects of being large during the critical period for survival in dense populations are thus likely related to social interactions, rather than to effects of density on total food abundance in the environment. The effect of egg size on offspring performance, and hence the optimal egg size, was independent of paternal body mass.