Vulnerability of larval northern anchovy (6-33 mm SL) to predation by adult northern anchovy and juvenile chub mackerel, Scomber japonicus, was estimated by measuring the response and escape probabilities of larvae. The proportion of larvae responding to the attacks of either predator increased with larval length and differed little between predator species. About 20% of 6 mm larvae responded to attacks of predators while 85-100% of 33 mm larvae responded. The proportion of larvae escaping attacks also increased with larval length, but more larvae of all sizes escaped the attacks of adult northern anchovy than those of juvenile chub mackerel. The rate of consumption of northern anchovy larvae by adult northern anchovy was highest when the larvae were 8.5-15 mm long, indicating that greater avoidance success of larvae in this size range relative to smaller ones may not completely compensate for their greater visibility to predators.

The events that cause variation in year-class strength in marine fish stocks occur during the first year of life, but no single life stage or period has been identified as being uniquely influential in the establishment of year classes. Mortality rates are size specific over this period with rates being the highest during the egg and yolk-sac stages and declining thereafter (Hunter 1984; Smith 1985). Variation in the relatively low mortality rates of older larval and juvenile stages may be more influential in year-class formation than the variation of the high mortality rates of eggs and first feeding larvae (Smith 1985). Thus all early life stages from egg through juvenile must be considered and knowledge of the size-or age-specific vulnerability of larvae to predation and starvation is central in any attempt at modeling the recruitment process. Starvation is probably a direct source of larval mortality for only a few weeks after the onset of feeding, and most losses in the first year of life may be attributed to predation. Predation is believed to be the major cause of mortality during the egg and yolk-sac stages (Hunter 1984), and incidence of starving jack mackerel, Trachurus symmetricus, and northern anchovy, Engraulis mordax, in the sea indicate that significant starvation mortality is