Oncorhynchus mykiss irideus
A chrome steelhead; the anadromous form of the coastal rainbow trout from Southeast Alaska
The coastal rainbow trout is a subspecies of rainbow trout that is native to the Pacific coast of North America from Alaska to southern California. Coastal rainbow trout are a highly sought after game fish and has been largely worked into the hatchery rainbow trout broodstock. The anadromous form of this fish is commonly called steelhead, due to their silvery appearance when fresh from the saltwater.
The coastal rainbow trout exhibits a wide range of life history strategies ranging from the extremes of stream resident populations to anadromous populations. Coastal rainbow trout spawn during the spring, but spawning runs of anadromous populations are generally broken up into summer and winter run fish. The summer-run fish arrive in late spring through summer and remain in the river till the following spring when the spawn. Winter-run fish generally arrive in late fall through mid-winter and spawn during the following spring. However these run times are not written in stone and across their native range there are populations of steelhead that return every month of the year. Depending on the temperature and location, steelhead may spawn anytime between January and June. Unlike the five species of Pacific salmon in North America, these fish do not die after spawning, and may return spawn several times although survival rates of repeat spawning fish are relatively low ranging from less than 10 percent to as high as 20 percent (Behnke 2002). However in populations of steelhead that have been introduced to the Great Lakes, repeat spawning rates may be quite high sometimes reaching 60 to 70 percent. While both Atlantic and Pacific salmon do not feed once entering freshwater, overwintering steelhead appear to feed to a limited degree as indicated by aquatic insects, eggs and other organisms found their stomachs.
Once coastal rainbow trout fry emerge and have absorbed their yolk sacs, they begin to actively feed on small invertebrates. Juvenile steelhead will generally spend two or three years in fresh water before undergoing the smolting process and migration to marine waters. Once in the salt water, steelhead move through the estuaries quickly than under take migrations that may bring them as far east as the Kamchatka Peninsula of Russia (Quinn 2005). Steelhead generally spend between one to three years on these marine odysseys feeding heavily on fish and squid (LeBrasseur 1966). In some rivers in southern Oregon and Northern California such as the Rogue and Klamath, there is an unusual life history form of coastal rainbow trout known as the half-pounder steelhead. These fish enter marine waters in late spring, but then return to their natal streams again in late summer at about 12 to 14 inches long to overwinter in the freshwater (Kesner and Barnhart 1972). The next spring these fish again set out on their oceanic migration to return as full fledged steelhead after two more years at sea.
Stream resident populations of coastal rainbow trout remain in their natal stream throughout their entire life. These fish establish territories and feed on a variety of aquatic insects and small fish. There are some populations of coastal rainbow trout have a lacustrine (lake dwelling) life history. A unique one of these populations is found in Crescent Lake in the Olympic Mountains of Washington and is commonly called the Beardslee trout. These fish lost access to the salt water when the lake's outlet was blocked by a landslide isolating them in the lake. These beardslee trout grow to large sizes deep waters of Crescent Lake and exhibit bright silvery sides and deep bodies. They were once considered to be a distinct subspecies of rainbow trout, but are now just recognized as a unique life history form.
Like many other salmonids, coastal rainbow trout have not escaped the influences of man and have suffered declines across much of their range. This has been especially true for their anadromous form (steelhead), which is facing declines due to a number of factors such as over-fishing, habitat destruction and competition with hatchery fish. Out of the twelve evolutionary significant units (ESU) identified NOAA fisheries in Washington, Oregon and California, only three a considered to be healthy. One population currently considered endangered, seven are considered to be threatened with extinction and one is listed as a species of concern (NOAA 2007). While the greatest declines have been suffered by anadromous populations, stream resident populations have also been impacted too. This has been especially true in the southern portion of their range in California, where stream alterations leading to high temperatures and unstable flows as well as the introduction of non-native fish have led to the loss of many populations.
Coastal rainbow trout have variable appearance, but generally have numerous irregularly shaped spots occurring both above and below the lateral line. Juvenile fish will often exhibit numerous oval parr marks that typically occur along the lateral line with smaller circular markings in between this spots above and below the lateral line. However in stream resident populations these parr marks often carry over into adulthood. The fins of coastal rainbow trout are generally gray to a peachy orange and the anal and pelvic fins are tipped with white. The dorsal and caudal fins are spotted and the dorsal may have an orange or white tip in some populations. The body coloration of these fish is usually olive on the back with silver or brassy sides. The steelhead form exhibits a bright silver color while in the marine but transitions to more typical rainbow trout colors after some time in freshwater. Like hatchery rainbow trout they have a pink to red color on their gill plate and across their lateral line.
Coastal rainbow trout are an extremely popular fish with recreational fisherman and can be readily taken fly fishing. Anadromous populations are generally best pursued swinging flies on sink tip lines or by nymphing, but can be taken on dry flies as well. Popular colors for swinging flies include black, purple, pink, blue and orange. The flies used range from standard streamers, such as wooly buggers and articulated leeches to more traditional attractor patterns. Nymphing is possibly more effective way to fish for steelhead and stonefly patterns, attractors and glo bugs take their share of fish.
Stream resident rainbow trout can often be readily taken on dry flies under the right conditions. These fish often fight very hard for their size, which has added to their popularity. Nymphing and fishing streamers is also very effective for these fish and will generally result in one catching larger fish than would be encountered using dry flies. When salmon are running the best way to catch these fish is generally by fishing egg patterns like glo bugs, but later in the season using flesh flies can be very effective as well.
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