Development of Rainbow Trout Brood Stock by Selective Breeding

Management programs to maintain and increase the sports fishery require large numbers of strong, healthy, acclimatized fingerlings for restocking the lakes and streams. To produce the fingerling trout needed, stocks of fish are first developed and selected at fishery laboratories, then tested in the field. At the University of Washington over a period of 23 years of intensive selective breeding, rainbow trout (Salmo gairdnerii) stocks have shown increased growth rate, earlier maturity, increased tolerance to warm water temperatures, resistance to disease, and greatly increased egg production. The egg production has been most satisfactory, rising from an average of less than 1,000 eggs from 4-year-old spawners in 1932 to an average of 3,894 eggs for 2-year-old females, 5,029 for 3-year-old females, and 4,984 eggs for 4-year-old females in 1955.