Comparing the Causes and Consequences of Larval Condition in Rockfishes (Sebastes spp.) With Alternative Life History Strategies

The early life stages of fishes are considered critical to population replenishment in marine fishes. Variation in maternal provisioning of offspring along with seasonal variation in upwelling-driven food availability may have strong effects on the condition and survival of larval fishes. Alternative life history strategies in rockfishes differ in larval provisioning, suggesting that there are investment trade-offs between offspring size and condition. To evaluate the drivers of larval condition and survival, we compared seasonal patterns in the growth and lipid content of recently settled rockfishes of winter (copper rockfish) and spring (gopher rockfish) spawning species. Recently settled rockfish were collected weekly in Bodega Harbor, CA. Otolith microstructure analysis was used to determine larval growth and age. Lipid extraction was used to determine relative condition. Older juvenile rockfish were collected and used to determine whether larval traits were disproportionally represented in surviving juveniles, thus identifying traits advantageous for survival. We found larval growth was driven primarily by seasonal patterns in food availability. Lipid content of recently settled fish was related to the seasonal timing of birth, with these relationships differing between years and species. Our results highlight the importance of accounting for variation in larval traits in population demographic models.