Diets and Feeding Rates of Juvenile Pink, Chum, and Sockeye Salmon in Hecate Strait, British Columbia

Juvenile pink salmon Oncorhynchus gorbuscha , chum salmon O. keta , and sockeye salmon O. nerka were sampled in Hecate Strait, British Columbia, during July and August of 1986 and 1987. I described their seasonal and species‐specific patterns of feeding, and I tested assumptions and predictions of models relating feeding success of juvenile salmon during their first summer at sea to survival and recruitment. The three species consumed a wide variety of taxa, but a few taxa made up most of the daily food intake. Diet composition was more similar among species within sampling periods than within species among sampling periods, although there were some apparent species‐specific feeding preferences. Patterns of changing diet composition with increasing time and distance between samples were consistent with expected mesoscale patterns of plankton patchiness in coastal waters. Juvenile salmon fed selectively on larger‐sized taxa in the plankton community, and larger salmon fed on larger prey. Contrary to the assumption of one model, however, young salmon did not switch to larger prey later in the summer. Weights of stomach contents and estimated daily rations were small enough to limit growth rates for all three species, especially sockeye salmon, and the hypothesis that limitation of growth during early ocean life affects survival and recruitment could not be rejected.