ABSTRACT:

The eggs and larvae of developing year-classes for cod Gadus morhua and haddock Melogrammus aeglefinus on Georges Bank were sampled during monthly surveys in the winter and spring of 1995 and 1996. The distribution and abundance ofthe age groups or cohorts within the egg and larval populations were estimated during each survey. The displacement of the cohorts between surveys was largely consistent with advection by the climatological circulation pattern. Egg mortality rates,calculated from the decrease in seasonal total abundance of early and later stage eggs, were 14 and 12% d^-1 for cod and 12 and 11% d^-1 for haddock in 1995 and 1996, respectively. Larval mortality rates, calculated from the decreasein the abundance of larval cohorts between surveys, ranged from 3 to 9% d^-1 for cod and 7 to 14% d^-1 for haddock, with no evident difference in the rate between the 2 yr. Variability in the larval mortality rate estimates did notexhibit a temporal pattern, suggesting that mortality was chronic and not dominated by events that caused particularly high or low mortality.