Some environmental factors that influence the growth of Arcto-Norwegian cod from the early juvenile to the adult stage

Abstract

A high growth rate for Arcto-Norwegian cod (Gadus morhua L.) in the Barents Sea and adjacent areas from the larval stage to the 0-group stage enhances survival and ultimately recruitment to the fishery. However, it appears that relatively high growth rates for a cohort through the 0-group stage are not continued as the cohort ages. Based on survey data, there is a negative, though not significant, correlation between a cohort’s average length at the 0-group stage and its average length as 1 year olds and a significant negative correlation between the average length at the 0-group stage and its average length at ages 2 through 9. It appears that the reason for this slowing of growth is that a strong inflow of warm, prey-rich Atlantic water into the Barents Sea from the Norwegian Sea provides favorable conditions for growth a”nl’d hence survival of the cod larvae and juveniles. But this same strong inflow cakes a proportion of the cohort farther to the east in the Barents Sea, where the bottom water is colder than in the west. Thus the young settled cod experience colder conditions, which slows their growth, than those cohorts that have a more westerly settlement, and this slow growth before age 2 appears to be the reason for the cohort’s relatively smaller mean length at older ages.