Variation in routine metabolism of juvenile muskellunge: evidence for seasonal metabolic compensation in fishes

Metabolic rate of age 0 muskellunge Esox masquinongy ranged from 0.10 at 5 degrees C to 0.24 mg O-2 g(-1) h(-1) at 25 degrees C and was significantly higher in spring and autumn than during winter months at comparable water t emperatures. Reduced metabolic rate in winter was consistent with the metab olic compensation hypothesis, implying that metabolism of muskellunge varie s independently of acclimation temperature and gonadogenesis. Moreover, sea sonal variation in metabolic rate has important implications for energy bud get studies. Single-season estimates of esocid metabolism may be inadequate to describe annual energy requirements; the magnitude of errors will depen d on the time of year metabolic rate was measured. As a result, it is sugge sted that seasonal variation in metabolic rate be incorporated into energy budget determinations for fishes. (C) 2000 The Fisheries Society of the Bri tish Isles.