Variability in rockfish (Sebastes spp.) fecundity: species contrasts, maternal size effects, and spatial differences

Over 60 species of rockfish (Sebastes spp.) reside off the coast of California, many of which are economically important to both recreational and commercial fisheries. Rockfish are live-bearers with a diverse array of reproductive strategies. Understanding the reproductive potential of an exploited stock is critical to assessing the health and status of a fishery. We investigated the reproductive ecology of four rockfish species to examine species contrasts and to determine spatial and maternal-size effects on reproductive potential. Females were sampled during the winter parturition season (November through March) of 2009 through 2012. Maternal length and somatic weight were positively correlated with relative fecundity (larvae per g somatic weight) in all four species, indicating a disproportionately greater reproductive output by larger, older females. Fecundity estimates in Chilipepper, S. goodei, and Yellowtail rockfish, S. flavidus, varied regionally, but did not significantly differ over time within the years sampled (sample sizes for Speckled, S. ovalis, and Blackgill rockfish, S. melanostomus, were too small to allow spatiotemporal comparisons). Two reproductive strategies were evident as Yellowtail and Blackgill rockfish produced a relatively highly fecund, single brood of smaller-sized larvae annually, in contrast to Chilipepper and Speckled rockfish, which produced larger-sized larvae with lower fecundity. In some regions multiple broods were common, complicating estimates of annual fecundity for these two species. There was some evidence that egg production was positively correlated with female condition, indicating that environmental variability in oceanographic conditions and productivity may drive changes in fecundity and reproductive strategy (i.e., single versus multiple broods).