EFFECTS OF TEMPERATURE ON ALLOCATION OF METABOLIC ENERGY IN PERCH (PERCA-FLUVIATILIS) FED SUBMAXIMAL RATIONS

Growth and long-term trends of oxygen consumption were monitored at 15 and 20 degrees C in spontaneously swimming juvenile perch fed a fixed daily submaximal ration. The average rate as well as the efficiency o f assimilation were the same at the two temperatures but a much higher proportion of food energy was allocated to activity and maintenance, and a correspondingly lower proportion to growth, at 20 than at 15 deg rees C. By computing average specific rates of oxygen consumption sepa rately for ah light and dark periods, it was found that at 20, but not at 15 degrees C, the 'scope for spontaneous activity' of two consecut ive (dark and light) phases of a diurnal cycle was indirectly proporti onal to the average rate of oxygen consumption in the dark phase. This indicates that at 20 degrees C the perch displayed partial compensati on for a high metabolic rate in the dark by reducing swimming activity in the following light phase. However, the overall effect of this beh aviour was probably too small to make a noticeable impact on the low c onversion efficiency in the juvenile perch at 20 as compared to 15 deg rees C.