Variability in Rockfish (Sebastes spp.) Fecundity: Environmental, Life History, and Maternal Effects

Over 60 species of rockfish (Sebastes spp.) reside off the coast of California.  All rockfish are live-bearers but they exhibit a diverse array of life histories and reproductive strategies.  For example, most species appear to produce only a single brood each year, whereas others produce multiple broods.  We are examining species contrasts in reproductive ecology and the factors underlying variability in fecundity.  In all species examined to date, maternal size was positively correlated with relative fecundity (larvae g^-1 female weight), indicating a disproportionately greater reproductive output by larger, older females.  The strength of this maternal effect varies widely among species.  Species that produce multiple broods appear to have a weaker maternal effect, lower brood fecundity, and larger larval size compared to species that produce a single annual brood.  In the highly dynamic oceanographic conditions of the California Current, rockfish fecundity appears to reflect productivity regimes.  We contend that foraging success of females in the months prior to parturition determines energetic allocation to fecundity of single brood species, and may determine the capability of multiple brooders to produce a second brood.  Thus, environmental conditions preceding parturition may be as influential as conditions during the subsequent larval period in determining cohort strength.