ABSTRACT
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.
Thanks are due to Mr A. Severn for permitting the work to be done at Bibury, and for his expert knowledge and assistance throughout the investigation. to remove the largest fishes, as well as any others which were actually seen eating their fellows.
