Fresh Water Fish Identification
COMMON NAMES: Rainbow trout, Steelhead, Kamloops
SCIENTIFIC NAME: Oncorhynchus mykiss
IDENTIFICATION: Rainbow trout have the typical trout-shape with an adipose fin, and a squarish tail that has black spots throughout. The rainbow trout has 10-12 anal rays and a white mouth and gums and are generally bright silver with a bright pink band. Males develop a hooked jaw known as a "kype" during the spawning season.
RANGE AND HABITAT: Rainbow trout are native to the western coastal United States and Alaska, but this species has been introduced into cold water locations throughout North America. Rainbow trout prefer cold water streams with cobble, boulders, deep pools, and overhead cover.
LIFE HISTORY: Rainbow trout are a cold water species that in nature spawn in moving water over gravel or cobble substrate. The young trout live in these streams for one or two years before migrating out into the great lakes. They remain in the lake for several years before they return to the tributaries to run upstream and attempt to spawn.
ADULT SIZE: Rainbow trout average 20 to 23 inches in length.
FISHING METHODS: Steelhead can be caught on minnow-shaped crankbaits and spoons fished off downriggers or divers. In September, shore anglers catch steelhead off piers with spoons or jigs tipped with maggots. Once fish move into the rivers in the fall, anglers will catch steelhead with spawn bags, salmon eggs, flies, jigs tipped with maggots, minnows or worms. The best locations are pools or deep water (>2 feet) with some line of current flowing through it. During the spring, steelhead prefer flies, spinners, small minnow-shaped crankbaits, and jigs with maggots.
Rainbow trout and steelhead are the same species of fish. The two names reflect the different life history patterns. The name rainbow trout is typically used for the non-anadromous life history. Rainbow trout do not leave the stream to go to the ocean. They spend their entire life in the stream. The name steelhead refers to the anadromous life history described above.
Anadromous steelhead and resident rainbow trout did not arise from two distinct evolutionary lines. There is a close genetic and taxonomic relationship between these two forms. Anadromous forms of the trout can convert to resident populations when drought events or damming of rivers blocks their access to the ocean. Conversely, resident trout populations can become anadromous if ocean access becomes available. It is typical to have both life history patterns occurring in the same stream. In fact, resident and anadromous parents can produce offspring of both varieties. It has been speculated that there is a food availability related trigger which determines whether a particular fish emigrates to the ocean or remains in the stream. It may be that if there is abundant food in the stream and a fish is growing at a rapid rate, it will remain in the stream. If food is limited and growth is slow, the fish will have a tendency to emigrate.
This dual life history pattern of steelhead and rainbow trout makes the species more adaptable than some species of salmon. At the southern most limits of steelhead distribution this is particularly important due to unstable, variable climatic and hydrographic conditions.