Metabolism in marine flatfish. VI. Effect of nutritional state on digestion in turbot, Scophthalmus maximus (L.)

1. A comparison has been made between the digestive systems in turbot maintained on a standard diet and turbot from the same stock which lacked food intake for 2 months. 2. The alimentary systems did not differ significantly between the two groups either in weight or in dimensions, although the average weight of the livers in the nutritionally deficient group was 25% lower than in the group fed the standard diet. 3. All digestive enzyme levels measured followed the same general pattern but were lower in the nutritionally deficient fish. 4. The enzymes responsible for digestion of the principle nutrients showed optimum activity in different zones of the alimentary canal. 5. The ratio of amylase to protease activity decreased with age of the turbot, possibly as a result of adaptation to dietary changes.