Changes of gas concentrations in blood and water during moderate swimming activity in rainbow trout.

In a previous paper (Stevens & Randall, 1967) changes in blood pressure, heart rate and breathing rate during activity were reported. Interpretation of these results as to the physiological significance of such changes can be expanded with a knowledge of any concurrent changes in gas concentrations in blood and water afferent and efferent to the gills. Recent technical developments permitting gas analysis on small quantities of blood, associated with the development of suitable handling and cannulation techniques (Holeton & Randall, 1967 a, b), allow measurement of blood-gas concentrations in unanaesthetized, unrestrained, intact fish. The object of this study was to measure changes in gas concentrations in blood and water afferent and efferent to the gills of rainbow trout before, during, and after moderate swimming activity.