Field and laboratory experiments were conducted with the purpose of partitioning jack mackerel Trachurus symrnehicus larval mortality into portions due to starvation and to predation. Field collections were made to determine larval condition, growth, net retention and production; laboratory experiments were conducted to determine growth and body shrinkage due to preservation treatment. Age-specific starvation and total mortality rates were estimated and predation was inferred as the difference between the two. In the offshore oligotrophic part of the spawning habitat, larvae suffered a high rate of mortality which rapidly declined as they developed. Predation was the major source of mortality of yolk-sac larvae. As the yolks were absorbed and the larvae began to feed, starvation became a significant source of mortality. As the larvae further developed, starvation rapidly declined and predation again became the dominant source of mortality, although at a much lower rate.

There was a strong association among concentrations of microzooplankton prey sampled from the walleye pollock, Theragra chalcogramma, larval habitat, gut contents of larvae, and their nutritional condition. Subsequently, hypothesized survival potentials linked to food availability were validated by independently determined mortality rates. We present evidence that a significant number of walleye pollock larvae were starving in 1991 but that fewer were starving in 1992. At some stations where prey levels were anomalously low in 1991, up to 40% of the larvae were in poor condition. There appears to be a 2‐week period after first feeding when walleye pollock are vulnerable to starvation.

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