Diet and Size-at-Birth Affect Larval Rockfish Condition and Survival

Abstract

Feeding success and maternal effects on larval size have long been hypothesized as important contributors to interannual recruitment variability in marine fishes. This study examined the feeding ecology and influences of diet and size-at-birth on length and growth of larval rockfishes (Sebastes spp.). Prey carbon biomass and selection were calculated from gut contents, size-at-birth was estimated using otolith core size, and recent growth was derived from outer otolith increment widths. Biomass contributions of preferred prey and otolith data were integrated into Bayesian hierarchical models predicting length and growth. Larvae primarily fed on and selected for copepod nauplii and Calanoid copepodites, modulating feeding with ontogeny and in response to prey availability. Based on carbon weight, the relative contribution of Calanoid copepodites to the diet was more strongly and positively correlated with length and growth than that of nauplii. Younger larvae experienced faster growth in association with Calanoid copepodite consumption than older larvae. Positive effects of core radius suggest that initial larval size, believed to be mediated by maternal provisioning, increases the likelihood of survival, larger size and faster growth. These findings ultimately provide evidence that selective feeding and size-at-birth mediate rockfish survival in early life stages.