Steelhead - a River and Sea Rainbow Trout Species

Steelhead (Rainbow Trout)
Oncorhynchus mykiss

Other names: steelhead trout, sea-run rainbow trout
Average size: 8-11 lbs, up to 40 lbs

Steelhead and rainbow trout are the same species, but rainbow are freshwater only, and steelhead are anadromous, or go to sea. Unlike most salmon, steelhead can survive spawning, and can spawn in multiple years.

Spawning
Steelhead spawn in the spring. They generally prefer fast water in small-to-large mainstem rivers, and medium-to-large tributaries. In streams with steep gradient and large substrate, they spawn between these steep areas, where the water is flatter and the substrate is small enough to dig into. The steeper areas then make excellent rearing habitat for the juveniles.

Like chinook, steelhead have two runs, a summer run and a winter run. Most summer runs are east of the Cascades, and enter streams in summer to reach the spawning grounds by the following spring. A few western Washington rivers also have established runs of summer steelhead. Winter runs spawn closer to the ocean, and require less travel time.

Rearing
Steelhead fry emerge from the gravel in summer and generally rear for two or three years in freshwater, occasionally one or four years, depending on the productivity of the stream. Streams high in the mountains and those in northern climes are generally less productive. Due to their faster growth, hatchery steelhead smolt at one year of age.

Fry use areas of fast water and large substrate for rearing. They wait in the eddies behind large rocks, allowing the river to bring them food in the form of insects, salmon eggs, and smaller fish.