Rainbow trout with a cautery-induced 30% reduction in functional gill area showed significant proportional reductions in maximum oxygen consumption (Voo2max) in comparison to controls, but oxygen consumption at rest and at subcritical swimming speeds was not affected. This corroborates suggestions that total gill area is utilized for oxygen uptake only under conditions of maximum aerobic demand. During swimming trials, hyperoxia (POO2 300mmHg) neither increased VOO2max of control fish nor compensated for the reduced VOO2max apparent in fish with reduced gill area. Therefore a direct limitation on oxygen uptake at the gills is implied.

This content is only available via PDF.