BIOCHEMICAL CORRELATES OF GROWTH AND CONDITION IN JUVENILE ATLANTIC COD (GADUS-MORHUA) FROM NEWFOUNDLAND

The aim of this study was to examine how the biochemical composition o f tissues varied with growth rate and condition in juvenile Atlantic c od (Gadus morhua) caught in the wild and kept in captivity. The hepato somatic index, brain water content, and muscle sarcoplasmic protein co ntent as well as the activities of phosphofructokinase, lactate dehydr ogenase, nucleoside diphosphate kinase, and citrate synthase in the mu scle, nucleoside diphosphate kinase and citrate synthase in the intest ine, and cytochrome c oxidase and citrate synthase in the brain increa sed with growth rate or condition factor. Conversely, liver and muscle water contents were lower in fish with a higher growth rate. A multip le regression model that included the hepatosomatic index, water conte nt of muscle and brain, and citrate synthase activity in the intestine explained 79.7% of the variability of growth in mass under our condit ions. A similar model, using liver water content instead of muscle wat er content, explained 82.5% of the variability of growth in length. Th ese easy to measure variables may be used in fisheries management to e stimate the growth rate of fish in the wild.