Stream channel experiments on downstream movement of recently emerged trout, Salmo trutta L. and salmon, S. salar L.—I. Effect of four different water velocity treatments upon dispersal rate

Four experimental stream channels were used to study instantaneous downstream dispersal rates of young trout, Salmo trutta L., and salmon, S. salur L., relative to four different water velocities. Young salmon showed a high rate of dispersal at a low velocity of 7.5 cm s−1 and lower rates at higher velocities of 25 to 70cm s−1. Trout showed their lowest rate at 25cm s−1 with a slightly higher rate at 7.5 cm s−1 and increasingly higher rates at velocities in excess of 25 cm s−1. These results are consistent with field observations on the velocity preferences of young trout and salmon.