Some of the consequences of varying flows on the downstream migration of salmon fry were investigated in five replicate streams adjacent to the lower Waitaki River, New Zealand. Fluctuating discharge appeared to increase the number of fry moving downstream, provided that mean water velocities at peak flows exceeded 25 cms−1’and that some fry were migrating out of the streams anyway. Salmonids appear to have a lengthier flow–sensitive period than has been proposed in the literature. Research is required to determine whether recently emerged fry that leave parental spawning streams in New Zealand disperse immediately to the ocean or develop and grow for extended periods en route. It may sometimes be feasible and worthwhile to minimize stream flow variations to encourage fry to remain longer in fresh