An Estimate of Energy Expenditure by Rainbow Trout (Salmo gairdneri) in a Small Mountain Stream

Abstract

A method is presented which estimates energy expended by rainbow trout (Salmo gairdneri) in a natural stream habitat. Swimming speeds were determined by counting caudal fin beat frequency in the field. Published data on metabolic rates estimated in a water tunnel respirometer were then used to calculate energy expenditure.Swimming speeds and hence energy expenditure did not vary statistically for time of day or night (overall means: swimming speed, 16.1 cm/sec; energy expenditure, 736.5 cal/kg per hour). Our calculations indicate that swimming at 16 cm/sec would cost a 100-g rainbow trout 53 cal/hr at 15 C, and about 0.48 g (live weight) of natural food per 6 hr would be needed to offset the cost of swimming.