INTERINDIVIDUAL VARIATIONS IN FEEDING AND GROWTH IN RAINBOW-TROUT DURING RESTRICTED FEEDING AND IN A SUBSEQUENT PERIOD OF COMPENSATORY GROWTH

Compensatory growth responses of rainbow trout Oncorhynchus mykiss wer e studied by examining food intake and growth of individual fish held within groups that were switched between regimes that involved full an d restricted feeding. Restricted feeding led to marked interindividual variability in food intake, probably as a result of the establishment of feeding hierarchies. This disparity in food acquisition was reflec ted in highly heterogeneous growth amongst the fish fed low rations. W hen fish were transferred from restricted to full rations, they became hyperphagic and displayed high rates of growth. Growth compensation w as most marked amongst those fish which had shown the poorest growth d uring the period of feed restriction. These results suggest that the f eeding hierarchies established under feed restriction did not persist. but were rapidly broken down when food became increasingly available, enabling the previously suppressed fish to gain access to food and to display rapid growth. (C) 1996 The Fisheries Society of the British I sles