25 愿5 —Frethwater ATPase --------Seawater ATPase 20 15 10 Fish held reshwater past normal release 19 20 9 19 29 May June 1979 Fiqure 1.--Gill Na+-K+ATPase activity (means and standard deviations)of the Chelan Hatchery steelhead in fresh water and seawater. 11 Figure l.--Gill Na+-K+ ATPase activity (means and standard deviations) of the Chelan Hatchery steelhead in fresh water and seawater. 11