Testing Bioenergetics Models under Feeding Regimes that Elicit Compensatory Growth

We tested bioenergetics model predictions of fish growth and food consumption under feeding regimes that elicited compensatory growth (CG) responses and for control fish fed ad libitum daily. Three treatment groups of seven juvenile hybrid sunfish (F-1 hybrid of female green sunfish Lepomis cyanellus X male bluegill L. macrochirus) received repeating cycles of no feeding and refeeding; fixed no-feed periods of either 2, 4, or 14 d distinguished the treatment groups. The no-feed periods induced CG and were immediately followed by days of ad libitum refeeding. The refeeding periods for each treatment group were continued until the group's mean daily consumption no longer exceeded that of the controls, after which another no-feed period began. Bioenergetics model predictions of cumulative consumption and fish weight in 105-d experiments were not significantly different from observed values in the control group (2-3% model error). However, the model underestimated cumulative consumption (18-25%) and overestimated fish weight (24-37%) in each of the treatment groups. Compensatory growth has considerable potential in aquaculture, and our findings show that bioenergetics models will require modification to account for the effect of feeding history on fish growth and consumption before such models can be used to predict CG responses in aquaculture. The extent to which CG occurs in noncaptive fishes is uncertain, although developing evidence suggests that it may be common. The presence of CG in noncaptive fishes could result in significant errors in model estimates of their food consumption and growth.