formerly Salmo gairdneri
Steelhead trout, salmon trout, or coastal rainbow trout
In 1992 the steelhead trout, Salmo gairdneri (the species named in memory of Meredith Gairdner, a 19th-century naturalist) was reclassified in the genus Oncorhynchus ("hooked nose"), and mykiss (a Siberian word for the species). There are two races, both native to Western North America. The common name of the freshwater O.m. is rainbow trout, a colorful game fish that has been transplanted worldwide. The sea-run, or anadromous rainbow trout is called steelhead, a word that entered the common nomenclature in the early 1880s.
Unlike salmon, steelhead can spawn several times, although the hydropower dams on the Columbia River system have interfered with that pattern, and the species has been classed as threatened under the Endangered Species Act. On December 12, 2000, biologists for the Yakama Indian Nation released the first of 110 revived and rehabilitated kelts–as between-spawning steelhead are called–into the Yakama and Columbia Rivers. All were wearing identification tags, clipped fins, and inch-long cylindrical radio transmitters in their throats, for tracking, DNA testing, and genetic research.
Record-class steelhead can attain a length of up to 45 inches, and a weight of more than 40 pounds.
Meriwether Lewis described it on on March 13, 1806, while at Fort Clatsop:
At the Great Falls are met with this fish of a Silvery white colour on the belly and Sides, and a bluish light brown on the back and head. In this neighbourhood we have met with another Species which does not differ from the other in any particular except in point of Colour. This last is of a dark colour on the back, and its Sides and belly are yellow with transverse Stripes of dark brown. Sometimes a little red is intermixed with these Colours on the belly and Sides towards the head.
The flesh & roe is like those described of the Salmon.
The white Species which we found below the falls were in excellent order when the Salmon were entirely out of Season and not fit for use.
The Species which we found here early in November on our arrival in this quarter had declined considerably, reather more so than the Red charr with which we found them associated in the little riverlets and creeks. I think it may be Safely asserted that the Red Charr and both Species of the Salmon trout remain in Season longer in the fall of the year than the common Salmon. But I have my doubt whether of the Species of the Salmon trout ever pass the Great falls of the Columbia.
The Indians tell us that the Salmon begin to run early in the next month. It will be unfortunate for us if they do not, for they must form our principal dependence for food in assending the Columbia above the Falls and its S. E. branch, Lewis's river [the Snake River] to the Mountains.