No abstract

Age-0 juveniles may be the earliest, reliable indicators of recruitment into commercial marine fisheries, but independent fisheries assessments are usually conducted on older life stages in adult habitats. We used an 8 year juvenile gadid survey along the coast of Kodiak, Alaska to examine annual abundance, growth and mortality in age-0 Pacific cod (Gadus macrocephalus), with comparisons to saffron cod (Eleginus gracilis) and walleye pollock (Gadus chalcogrammus) where possible. Annual abundance of age-0 fish was positively correlated among all three species, suggesting Pacific gadids respond similarly to processes controlling pre-settlement survival and/or delivery to coastal nurseries. In Pacific cod, June temperature was positively correlated with size-at-settlement but post-settlement growth was density- rather than temperature-dependent. Age-0 abundance indices for Pacific and saffron cod predicted the number of age-1 fish the following year (i.e. positive “recruitment signals”), but only in the larger nursery (Anton Larsen Bay) where age-1 gadids were more likely to remain resident after their first year. Recruitment signals for Pacific cod improved with later estimates of age-0 abundance, likely because of high mortality following settlement in July. In contrast, very few age-0 and age-1 walleye pollock were caught across the entire time-series of the survey. Collectively, these data suggest that nearshore surveys may be a tractable means of examining early life history processes and assessing year-class strength in juvenile Pacific and saffron cod, but have relatively low value in understanding the population dynamics of walleye pollock.

Despite the ecological and economic importance of rockfish fisheries in Alaska waters, little information is available concerning the reproductive biology of the majority of federally managed rockfish species in the Gulf of Alaska. Pacific Ocean Perch Sebastes alutus are the most abundant and commercially important rockfish in this region. This study examines the reproductive biology of Pacific Ocean Perch within the Gulf of Alaska, utilizing histological techniques to microscopically examine ovarian tissue. Pacific Ocean Perch samples were obtained throughout the year during National Marine Fisheries Service and Alaska Department of Fish and Game scientific surveys, as well as scientific charters. Ovaries of Pacific Ocean Perch began to ripen during the month of August with yolk increasing until February. Embryos appeared within the ovaries during February and continued to grow and develop until parturition in May. Results from this study indicate the fork length at 50% maturity is 33.4 cm and the age at 50% maturity is 8.4 years. Both of these values are smaller than those currently utilized in the stock assessment of Gulf of Alaska Pacific Ocean Perch. Results from this study will improve the stock assessment of this species by providing more accurate estimates of reproductive parameters and reducing the uncertainty in estimates of length and age at maturity. Received July 30, 2012; accepted November 16, 2012