Female effects on offspring energetic status and consequences on early development in yolk feeding brown trout (Salmo...

Energetic status can be defined as the interaction between energy stores and metabolic rate. In salmonids, it is variable and influences the timing of emergence, and therefore may have strong effects on both juvenile and maternal fitness. The aim of this study is to (i) describe the ontogeny of energy use for different brown trout clutches to understand how such a variability of energetic status is developed at the end of incubation and (ii) to estimate maternal influences over offspring physiological processes. Using individual measures of total mass and metabolism throughout ontogeny combined with a hierarchical Bayesian modeling approach, we successfully described clutch-specific (i) metabolic trajectories, (ii) use of yolk resources and the building of new tissues throughout ontogeny. Our results show that females laying large eggs have offspring with lower metabolic costs and higher yolk conversion efficiencies. Females also influence within clutch variance of metabolic and yolk consumption rates leading to potential developmental variations. These results are discussed with regard to their consequences on early life history through the critical period of emergence.