Species: Rainbow trout
Scientific name: Oncorhynchus mykiss
Claim to fame: Rainbow trout are a popular sportfish in Missouri. Studies have shown trout fishing in the state provides a multi-million dollar benefit to the state’s economy each year. Missouri’s current trout program consists of Lake Taneycomo, four trout parks, 20 trout management areas and winter trout fisheries in 20 urban lakes in St. Louis and Kansas City. Virtually all of these areas and opportunities are sustained by stockings from Missouri Department of Conservation hatcheries. The Department stocks more than 1.5 million trout annually in the state.
Species status: Rainbow trout are not native to Missouri, but were first imported here in the 1800s. The rainbow trout’s native range stretches along the Pacific Coast from Alaska to northern Mexico.
First discovered: The first scientific description of the fish was written by Russian naturalist Johann Julius Walbaum in the 18th century.
Family matters: Rainbow trout belong to the salmonidae family of fish. This family includes several species high in angling popularity such as brown trout, salmon, char and whitefish.
Length: The average length is 10 to 15 inches, but longer lengths have been reported.
Diet: Aquatic insects, terrestrial insects, snails and small fish make up the bulk of a rainbow trout’s diet. There is some variance based upon local availability of food.
Weight: Most adult rainbows caught in Missouri range in weight from under one pound to one-and-one-half pounds, but they can grow larger.
Distinguishing characteristics: The upper parts of a rainbow’s body are dark olive and thickly speckled with black spots. Of course, the tell-tale sign of a rainbow is the pinkish to pinkish-red stripe that runs the length of the body on both sides.
Life span: Rainbow trout have been reported to live up to 11 years in some parts of the country.
Habitat: Within their natural range, rainbow trout inhabit streams, naturally occurring lakes and reservoirs. Trout do best in waters that generally remain below 70 degrees F. In Missouri, suitable trout habitat is limited to approximately 170 miles of Ozarks spring branches and spring-fed streams and the 2,080-acre coldwater reservoir of Lake Taneycomo.
Life cycle: Most of the trout in Missouri waters come from hatchery-raised brood-stock, with the few exceptions of some areas where conditions are suitable for some trout spawning to occur. In parts of the continent where trout reproduce in the wild, spawning occurs from early winter to late spring, depending on local conditions. Eggs are laid by the female in a shallow pit dug by the female on clean, gravelly riffles. The female resumes digging upstream and the eggs are covered by gravel carried down by the current. No parental care is provided to the eggs, which are dependent on oxygen present in the water percolating through the gravel. Eggs hatch in about 21 days and the fry remain in the gravel until the yolk sac is absorbed.