The Seaward Migration and Return of Hatchery-Reared Steelhead Trout, Salmo gairdneri Richardson, in the Alsea River, Oregon

A program was initiated in 1956 to evaluate current hatchery practices and to determine ways of improving the rearing and liberation of juvenile steelhead trout. The physiological changes which result in the seaward migration of wild juvenile steelhead appear to occur most frequently when the fish are in the 14- to 18-centimeter length range. These fish may be 1 to 3 years of age, but the majority are 2 years old. Hatchery-reared steelhead exhibited the highest survival as returning adults when liberated at a length of 16 centimeters or longer. Results indicate that the optimum release date for hatchery-reared steelhead coincides with the peak movement downstream of wild Steelhead smolts.