Other names—steelhead trout, steelie, sea-run rainbow.
There is a lot of confusion among the non-angling public about this fish. The term “steelhead” refers to the anadromous form of rainbow trout (see: trout, rainbow), and the fish known as steelhead bears the same scientific name as rainbow trout. Most scientific evaluations of rainbow trout list the steelhead as a form of rainbow trout. There are no major physical differences between a steelhead and rainbow trout, although the nature of their differing lifestyles results in subtle differences in shape and general appearance and a greater difference in color. Technically, the steelhead is a rainbow trout that migrates to sea as a juvenile and returns to freshwater as an adult to spawn, a process known as anadromy. Pacific salmon (see: salmon, Pacific) do this too, although steelhead (and rainbow trout) are positively separated from the various Pacific salmon species by having 8 to 12 rays in the **** fin.
“Anadromous” refers to fish that live a good portion of their lives in saltwater and spawn in freshwater; steelhead, which are endemic to the Pacific coasts of North America and Asia, have been successfully transplanted to inland environments, especially the Great Lakes. They live their entire lives in freshwater, residing in the lake but migrating up tributaries to spawn (which they accomplish more successfully than other introduced trout or salmon). Thus, steelhead may exist both in coastal environments and in large inland lake-river systems. The appearance and behavior of both forms of steelhead is largely the same.
The scientific classification of steelhead/rainbow trout, and the terminology that has been used for decades by the public, also led to confusion. Anglers view steelhead/rainbow trout as a type of “trout,” as that is how scientists viewed them for more than two centuries. Steelhead/rainbow trout were placed in the trout genus and called Salmo gairdneri until late in the twentieth century, when both were reclassified and incorporated into the genus of Pacific salmon. This change resulted in the current scientific name, Oncorhynchus mykiss. Unlike Pacific salmon, the steelhead/rainbow trout has 8 to 12 rays in the **** fin, does not always die following spawning, may spawn more than once, and returns to the sea after each spawning.
No matter what it is called or where it is found, the steelhead is one of the most coveted fish for anglers, both in freshwater lakes and in rivers or streams. It is frequently acrobatic, grows to large and challenging sizes, and is a strong battler. Some anglers consider it the best of all freshwater sportfish, and most would rank it among the top three or five.
The coastal steelhead is also a target of commercial fishing. Its flesh is bright orange or red, delicious, and marketed both fresh and frozen.
Identification
Generally speaking, steelhead are more slender and streamlined than rainbow trout. As with rainbow trout, the coloration on the back is basically a blue green shading to olive with black, regularly spaced spots. The black spots also cover both lobes of the tail. The black coloration fades over the lateral line to a silver white coloration that blends more toward white on the stomach. Steelhead fresh from the ocean or an inland lake are much more silvery than the resident rainbow. On steelhead, the typical colors and spots of the trout appear to be coming from beneath a dominant silvery sheen. This sheen gradually fades when the fish are in rivers, and steelhead become difficult to differentiate from resident rainbow trout as the spawning period approaches.
Steelhead and rainbow trout lack the red slash on the underjaw characteristic of cutthroat trout, but they do have white leading edges on the anal, pectoral, and pelvic fins. Spawning steelhead and rainbow develop a distinct pink to red striplike coloration that blends along the side, both above and below the lateral line. On steelhead, the rainbow trout coloration gradually fades following spawning to the more characteristic silvery color that the fish display during their ocean and lake journey. The distinct and beautiful coloration of steelhead during the spawning period is apparently important for mating and reproductive process. The silvery sheen and streamlined shape of ocean- or lake-bright steelhead is essential to survival in the large-water environment.
Juvenile steelhead trout are identical to rainbow trout until the period prior to their ocean migrations. Young trout and stunted adults have 8 to 13 parr marks on their sides. There are 5 to 10 parr marks between the head and dorsal fin. Prior to migrating to the sea, juvenile steelhead become very silvery and resemble miniature adults. They are called smolts during this life phase.
Size/Age
Steelhead grow much larger on average than rainbow trout and are capable of exceeding 40 pounds. The all-tackle world record is for a 42-pound, 2-ounce Alaskan fish caught in 1970. Steelhead are typically caught from 5 to 12 pounds, and fish exceeding 15 pounds are not uncommon in some waters. Most fish returning to rivers are five to six years old, and they can live for eight years.
Distribution
The original steelhead range in North America extended from Alaska’s Kenai Peninsula to the Baja Peninsula in Mexico, and far inland in coastal rivers. Northern California, Oregon, Washington, southern Alaska, and especially British Columbia have had significant steelhead populations. Overfishing, pollution, dams, other habitat alteration, and additional factors have adversely affected many native runs of steelhead, as they have impacted Pacific salmon stocks. Some coastal runs are depressed if not threatened. Steelhead are also native to the eastern Pacific and portions of Asia, and have been widely introduced throughout the Great Lakes in North America, where they are primarily supported through hatchery production, as well as to other waters in North America and on other continents.
Life history/Behavior
When compared to the mundane habits of rainbow trout that spend their entire lives in streams and lakes, steelhead lead a complicated and dangerous life. Each spring thousands of 6-inch steelhead smolts leave the streams to begin their ocean journeys. Few survive to return; in Alaska, for every 100 smolts that reach the sea, only 5 to 10 return as a first-spawning adult.
Over a period of one to three years, steelhead move hundreds of miles or more from their parent stream. Many steelhead from Washington and Oregon are known to migrate far at sea to areas off the Alaskan Peninsula. A steelhead tagged south of Kiska Island in the western Aleutians was recovered roughly six months and 2,200 miles later in the Wynoochee River, Washington. Some fish from Alaska migrate to areas west of the Aleutian Islands and are routinely caught in net fisheries off the coast of Japan. Large numbers are intercepted in high-seas fisheries.
Most populations of steelhead appear in rivers in the fall; called fall-run steelhead, they enter freshwater systems as adults from August into the winter. Some river systems have spring-run steelhead, which end their ocean journeys in mid-April, May, and June; bright, shiny spring-run fish may be mixed with well-marked resident rainbows that have spent the entire winter waiting for the spring spawning period. Still other populations return to their home stream in July and are known as summer steelhead. Spring and summer runs are much less common.
Spawning takes places in winter and spring. A male may spawn with several females, and more males than females die during the spawning period. Unlike salmon, steelhead commonly spawn more than once, and fish exceeding 28 inches are almost always repeat spawners. The ragged and spent spawners move slowly downstream to the sea, and their spawning, rainbow colors of spring return to a bright silvery hue. Lost fats are restored and adults again visit the feeding regions of their first ocean migration. On rare occasions, a fish will return to the stream within a few months, but most repeat spawners spend at least one winter in the sea between spawning migrations.
Generally, juvenile steelhead remain in the parent stream for roughly three years before migrating out to saltwater. If all steelhead left the stream at the same age, returned after the same length of time in the ocean, and died after spawning, the adults in a given stream would be of similar age. But they don’t. In some Pacific coast rivers, summer-run, spring-run, and fall-run fish appear at the same time, greatly complicating matters.
Steelhead of the Great Lakes and inland systems have a similar life history, although their appearance in or near tributaries varies depending on their origins. Most migrate into tributaries from late fall through early spring, spawning in late winter or early spring. Summer-run fish, called Skamania steelhead, appear near shore and in tributaries in summer months.
Food and feeding habits
Steelhead in the ocean consume squid, crustaceans, and small fish. In large lakes, they primarily consume pelagic baitfish such as alewives and smelt. When making spawning runs in rivers and streams, they do not feed.
