Metaboliс enzymes activity in smolts and parrs of Atlantic salmon (Salmo Salar L) grown under different light regimes

The activities of enzymes of energy and carbohydrate metabolism in the muscles and liver of smolts and pestlets of Atlantic salmon (Salmo Salar L), which were grown in the autumn period under the influence of two photoperiod modes (constant and natural) in combination with a different feeding regime and subsequent maintenance during the winter short photoperiod, were investigated. The dependence in the activity level of the studied enzymes was established both with the membership of the juvenile salmon to the experimental group, and between the parr and smolts selected at the end of the winter short photoperiod. The smolts, grown under conditions of constant lighting and round-the-clock feeding, differed from other groups by higher values of cytochrome c oxidase (COX) activity and low values of aldolase in muscles. The differences between parr and smolts in aerobic metabolism in muscles were found to be the same for all experimental groups, namely: relatively high activity of COX and aldolase in smolts. The pattern of changes in the activity of the studied enzymes in the liver of parrs and smolts differed in individuals from different experimental groups. The results of the study of the activity of energy metabolism enzymes in salmon juveniles grown under different photoperiod conditions suggest that the intensity and direction of the pathways of energy metabolism and glucose oxidation depend on the light regime used, which, cosequently, may affect the completeness of the smoltification process of the studied fish.