Juvenile coho salmon (101-400 mm) were sampled by purse seine off the Pacific Coast from Waatch Point, Washington to Four Mile Creek, Oregon, out to 30 mi offshore, during the months of May, June, and September in 1982 and 1983. Sea surface temperature, surface salinity, surface chlorophyll-a concentration, and Secchi depth were measured at each station. Sea surface temperatures were higher in 1983 than in 1982, while surface chlorophyll-a concentrations and surface salinities were lower. Catch data were not highly correlated with any of the four physical parameters measured. Strong northerly winds and strong upwelling tended to disperse juvenile coho offshore and south. Fish were found closer inshore during periods of weak winds and weak upwelling. In both years the center of distribution of the fish appeared to shift northward as the summer progressed. Larger fish, in general, were found farther north and offshore throughout the year. / Graduation date: 1985