EFFECTS OF GROWTH-RATE, TEMPERATURE, SEASON, AND BODY SIZE ON GLYCOLYTIC ENZYME-ACTIVITIES IN THE WHITE MUSCLE OF ATLANTIC COD (GADUS-MORHUA)

In the fast-growing Atlantic cod (Gadus morhua), the specific activities of the glycolytic enzymes phosphofructokinase (PFK), pyruvate kinase (PK), and lactate dehydrogenase (LDH) in white muscle were positively correlated with growth rate. For PFK and PK, season modified the relationship between growth rate and enzyme activity. This effect may be due to differences in the initial condition of the fish used for the experiments in the different seasons. Acclimation temperature only affected the activity of LDH, but its effect was slight compared to that of growth rate and season. No relationship was found between glycolytic enzyme activities in white muscle and body size of wild cod ranging from 20 to 80 cm in length. These relationships suggest that in their natural habitat, cod are opportunistic feeders which increase the metabolic capacities of their muscles once food becomes available.