An Annular Respirometer for Measuring Aerobic Metabolic Rates of Large, Schooling Fishes

Aerobic metabolic rates of fish at controlled levels of activity are usually measured with individual fish isolated in a flume-type respirometer, in which the fish must swim against a known water velocity (Brett, 1964; Beamish, 1978; Gehrke et al. 1990). Their use for large and fast- swimming fish is difficult owing to engineering problems and water turbulence and because swimming in the confined test section of the respirometer affects the performance of the fish. Some of these problems have been partially dealt with by applying corrections to compensate for the altered water flow around the body of the fish (Webb, 1971) and by developing highly sophisticated flume respirometers (Gehrke et al. 1990).