Variation in growth and recruitment of Atlantic cod (Gadus morhua) off Greenland during the second half of the twentieth century

Abstract

The variation in length-at-ages 4 to 5 years for Atlantic cod (Gadus morhua) off Greenland was analysed based on a time series of samples taken from commercial catches comprising 190 000 individual age determinations. Multiple linear regressions revealed significant declines in size for age groups 4 and 5 since the mid-1950s, by 10 and 5 cm, respectively. Growth models accounting for temperature, fishing mortality and stock abundance effects were constructed. Positive temperature and negative fishing mortality effects were found to dominate the variation in length-at-age. The analyses did not indicate a negative effect of stock density on cod growth. During the period 1956-89, the number of recruits at age 3 years was significantly correlated with the spawning stock biomass and June water temperature on top of Fyllas Bank (West Greenland). Both factors positively affected the number of offspring and explained 51% of the observed variation in recruitment.