The Effect Of Energetic Condition On Growth In Cod (Gadus Morhua)

No abstracts are to be cited without prior reference to the author.

Following periods of weight losses due to food shortages, refed fish experience a period of fast growth which may compensate for negative growth periods. Prolonged starvation was hypothesized to have a detrimental effect on the growth capacity of fish with sub-lethal condition factor values. Two experiments were conducted. The increased relative mass of the pyloric caeca and intestine relative to body mass following food deprivation in one of the experiments suggests that growth compensation is associated with an increased capacity of cod to produce digestive enzymes and to absorb nutrients across the gut wall. Cod were food deprived in the other experiment, so as to achieve a range of condition factors. Size was measured before refeeding and after 3, 6, 9 and 12 weeks of ad libitum feeding. Maximum growth occurred in the first 3 weeks in controls and declined after 6 weeks with very slow growth being observed in the last 3 weeks of the experiment. In contrast, cod with low condition factors experienced very slow growth in the first 3 weeks and maximum growth after 6 and 9 weeks of feeding. Weight gains over a period of 12 weeks were nearly identical in all groups. By the end of the experiment, condition factors were lower in fish with lower initial condition factors. These results suggest that compensatory growth would not allow cod with low condition factors to fully recover over a 3 month period of high food availability. The potential impact of partial recovery on survival is discussed.