Stream channel experiments on downstream movement of recently emerged trout, Salmo trutta L., and salmon, S. salar L.—11. Effects of constant and changing velocities and of day and night upon dispersal rate

Abstract

Four experimental stream channels were used to study instantaneous downstream dispersal rates of young trout and salmon relative to day and night, constant low and high water velocities and changes of velocity from high to low and vice versa.At high and low velocity for trout and at high velocity for salmon, the dispersal rate was higher by night than by day. Changes of velocity during daytime from high to low or low to high for trout and from high to low for salmon, were associated with much higher dispersal rates than were constant velocities.