Abstract
The relation of size (log weight, g) to metabolic rate (log O2-uptake, mg 02/hr) of sockeye salmon was found to have a continuous change in slope (0. 78-0. 97) with increasing activity at 15 C. The slope of the equation relating the 60-min sustained swimming speed (log speed, cm/sec) to length (cm) had a value of 0. 50, demonstrating a rapid decrease in relative performance with increasing size.