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We examined spatial correlations for three coastal variables [upwelling index, sea surface temperature (SST), and sea surface salinity (SSS)] that might affect juvenile salmon (Oncorhynchus spp.) during their early marine life. Observed correlation patterns in environmental variables were compared with those in survival rates of pink (O. gorbuscha), chum (O. keta), and sockeye (O. nerka) salmon stocks to help identify appropriate variables to include in models of salmon productivity. Both the upwelling index and coastal SST were characterized by strong positive correlations at short distances, which declined slowly with distance in the winter months, but much more rapidly in the summer. The SSS had much weaker and more variable correlations at all distances throughout the year. The distance at which stations were no longer correlated (spatial decorrelation scale) was largest for the upwelling index (> 1000 km), intermediate for SST (400–800 km in summer), and shortest for SSS (

We compare alternative models of sockeye salmon, Oncorhynchus nerka, productivity (returns per spawner) using more than 30 years of catch and escapement data for Bristol Bay, Alaska, and the Fraser River, British Columbia. The models examined include several alternative forms of models that incorporate climatic influences as well as models not based on climate. For most stocks, a stationary stock-recruitment relationship explains very little of the interannual variation in productivity. In Bristol Bay, productivity covaries among stocks and appears to be strongly related to fluctuations in climate. The best model for Bristol Bay sockeye involved a change in the 1970s in the parameters of the Ricker stock-recruitment curve; the stocks generally became more productive. In contrast, none of the models of Fraser River stocks that we examined explained much of the variability in their productivity.

Previous research has documented two main migratory routes of juvenile sockeye salmon (Oncorhynchus nerka) through the Strait of Georgia, British Columbia, Canada, and large interannual variability in marine survival rates of the Chilko Lake stock. Simulation models were used to explore the influence of surface currents on the migratory route of juvenile sockeye salmon (smolts) through the Strait of Georgia. We used a model of downstream migration to generate daily numbers of Chilko Lake sockeye salmon smolts entering the Strait of Georgia, based on daily counts of smolts leaving the rearing lake. A numerical hydrodynamic model (driven by surface wind, tide, and Fraser River discharge) hindcasted surface currents in the Strait of Georgia on a 2 km × 2 km grid. A smolt migration model simulated fish moving through the Strait with different compass-oriented migratory behaviours (i.e. swimming speed and directional orientation) within the time-varying surface advection field. Results showed that surface currents within the Strait of Georgia can affect the migratory route of sockeye salmon smolts in spite of their large size (8 cm). Wind is the forcing mechanism primarily responsible for determining which migratory route would be used. Under prevailing wind conditions (i.e. toward the north-west), most sockeye salmon smolts would use the eastern migratory route; however, relatively brief south-eastward wind events (lasting about 2 days) would force most smolts into the western migratory route. Given the heterogeneity of food for salmon within the Strait, we hypothesize that wind-driven variability in the annual proportion of smolts that use the western and eastern migratory routes in the Strait of Georgia affects early marine survival rates of Fraser River sockeye salmon.