Temporal and Spatial Variation in Fecundity of Yellowtail Rockfish

Abstract

Fecundities of the commercially important yellowtail rockfish Sebastes flavidus were compared to determine interannual variability and geographic variation, which will assist in stock assessment, characterization, and management. Gravimetrically estimated fecundities were compared in 1985–1991 between California, the southern extent of the speciesˈ distribution, and coastal waters of Washington, near the center of the speciesˈ abundance, where yellowtail rockfish are most heavily fished. California yellowtail rockfish were older, smaller in weight and length, and had smaller mesenteric fat deposits and more extensive disease and parasite pathologies than Washington fish. Egg production of this comparatively fecund viviparous fish increased linearly and sigmoidally with body weight and length, and asymptotically with age. Significant interannual differences were found in fecundities of young fish (<age 15) from California while no differences were observed in older California fish (>age 14) or in young or old Washington fish. Washington yellowtail rockfish had higher group fecundities because they were larger at age. Rate-specific fecundities were significantly higher in young Washington fish. Predictive models of fecundity were highly correlated for young yellowtail rockfish, less so for old fish. Although fecundity of young fish depended on weight, length, and age, that of old fish was age-independent. Our findings show age-dependent interannual and geographic differences in reproductive effort, which suggest population-specific reproductive life histories.