DEVELOPMENT OF THE POPULATION BIOLOGY OF THE PACIFIC HAKE, MERLUCCIUS-PRODUCTUS

Pacific hake, Merluccius productus, population models have been assemb led and manipulated to use in determining research strategies and prio rities. Given the present preliminary estimates of life-table paramete rs, I estimate that the larval mortality rate is 0.135 instantaneous d aily mortality, which means that there are an average of 87 survivors for each 100 larvae present the previous day. Ninety-five percent of t he spawning takes place between December 19 and March 6 of each year. An equilibrium population requires 3.6 million eggs for each recruit a t age 2, and that 217 late larvae become juveniles in mid-June of the same year. Exceptionally high cohorts would have 2173 juveniles, and p oor cohorts would have 22 at this period, The fact that we have not ye t observed larger year classes in two adjacent years suggests that a h ighly successful year class may alter the narrow coastal brood habitat for ensuing cohorts, Mechanisms could include limited food, cannibali sm on the new cohort, or population growth of other predators in the b rood zone.