The relation between early marine growth of pink salmon, Oncorhynchus gorbuscha, and marine water temperature, secondary production, and survival to adulthood

Juvenile pink salmon, Oncorhynchus gorbuscha, from four consecutive brood y ears were tagged as they emigrated to the estuarine waters of Auke Bay, and information was obtained on the relationships between early marine growth, environmental conditions, and survival to adulthood. Juveniles that emigra ted from Auke Creek later in the spring spent significantly less time in th e estuary. Individual growth rates of tagged fish recovered in Auke Bay ran ged from 3.1% to 7.1% per day. In all study years, juvenile pink salmon gre w more slowly in early April than in late April and early May. Water temper ature and growth were significantly correlated in all years, but growth did not consistently correlate with the biomass of epibenthic prey or zooplank ton available to the fish. Comparisons of expected and observed growth rate s suggested that low prey availability, as well as low temperatures, may ha ve limited growth for early spring emigrants. Although early emigrants enco untered poorer growth conditions, survivors were larger at a given date tha n later emigrants, their larger size possibly protecting them from size-sel ective predation. Early marine growth was significantly related to intra-an nual cohort survival to adults (r(2)=0.65, P<0.05). Larger fish consistentl y survived better than their smaller cohorts for all years. Although early marine growth was an important determinate of survival within a cohort of p ink salmon, other factors, such as predator abundance, contributed to the l arge interannual variability observed.