Abundance and mortality of Northeast Arctic cod and haddock during their first years of life

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For northeast Arctic cod and haddock, long time-series of year-class abundance are available at several stages before they recruit to the fishery (i.e. before they reach age 3). Several studies have already been made of the influence of various factors on the abundance and survival of these stocks during the first three years of life, in particular for cod. Revision of dataseries, however, as well as availability of longer dataseries makes a new analysis worthwhile. The analysis includes both virtual population analysis (VPA) estimates of abundance of spawning stock and recruitment, as well as estimates of total egg production and survey estimates from pelagic and bottom-trawl surveys. Information on cod predation on cod and haddock is also used. The mortality at various life stages is found to vary considerably between cohorts for both stocks. Although the mortality is highest during the first months of life, the year-class strength can be affected considerably by processes taking place between the 0-group stage (ca. six months) and age 3. The variation in mortality is related to density dependence, temperature, predator abundance, and other factors.