Influence of Temperature Change on Spontaneous Locomotor Activity and Oxygen Consumption of Atlantic Salmon, Salmo salar, Acclimated to Two Temperatures

Abstract

Measurements of the effect of rapid change in temperature on the spontaneous activity and oxygen consumption were made on Atlantic salmon underyearlings acclimated to 6 or 18 C. The new levels of imposed temperature ranged from 6 to 30 C for both acclimations. At similar test temperatures the calculated standard metabolic rate of the fish acclimated to 6 C was higher than that of the fish acclimated to 18 C, up to about 23 C, where the two curves relating oxygen consumption and temperature intersect. Spontaneous activity could be separated into two phases, a transient phase occurring during the actual period of temperature change, and a stabilized phase. The transient phase was characterized by a peak in activity which was found to be correlated with the rate, rather than the amount, of the temperature change. In general, the peak was higher for fish acclimated to 18 C. The relation between activity in the stabilized phase and test temperature was characterized by a plateau or maximum in the general region of the previously determined selected temperature. Except at the coldest test temperature (6 C), the fish acclimated to 6 C were more active in the stabilized phase than were the fish acclimated to 18 C at similar test temperatures. Complete acclimation for both metabolism and activity, between 6 and 18 C, requires about 2 weeks, regardless of the direction of the temperature change.