Metabolic Rates of Trout Fry from Swift and Slow-Running Waters

Recent studies on the respiration of fresh-water animals have shown that certain species of ephemerid nymphs and trichopterid larvae inhabiting swift streams have a higher oxygen consumption than other species, comparable in size, which live in still waters, the measurements being made under identical conditions (Fox, Simmonds and Washbourn, 1935). Moreover, within one species of crustacean, Asellus aquaticus, individuals from rapid water have a higher metabolic rate than those from slow water (Fox and Simmonds, 1933). The investigation reported below was undertaken to find out whether trout would show a similar phenomenon.