Rainbow trout are an anomaly within the animal kingdom. Many stay in freshwater streams and lakes all their lives, and these fish have a distinctive shape, size and coloration. However, rainbow trout can also exist as ocean-run fish and are known as steelhead. The fish that migrate to the ocean (steelhead) develop a slimmer profile, become more silvery in color and typically grow much larger than the rainbow trout that remain in fresh water. Rainbow trout—from here on, we’ll refer to the fish that stay in freshwater as 'rainbow trout' and those that migrate to the ocean as 'steelhead;' technically, they are all rainbow trout—rainbow trout are dark-olive in color, shading to silvery-white on the underside, with a heavily speckled body with a pink-red stripe along their sides. Steelhead retain some of these characteristics (e.g., a faint reddish stripe) but are much, much more silver in color and usually have fewer spots. Steelhead can grow up to 55 pounds and 45 inches in length, but are usually much smaller.
All Oncorhynchus mykiss hatch in gravel-bottomed, fast-flowing, well-oxygenated rivers and streams. Adult steelhead migrate from a marine environment into the freshwater streams and rivers of their birth in order to mate. (The process of migrating from saltwater to freshwater to spawn is called anadromy). Migrations can be hundreds of miles.
In the United States, steelhead trout are naturally found along the entire Pacific Coast. Worldwide, steelhead are naturally found in the Western Pacific south through the Kamchatka Peninsula. They have been introduced worldwide, e.g., into the Great Lakes.
Steelhead are capable of surviving in a wide range of temperature conditions. They do best where dissolved oxygen concentration is at least 7 parts per million. In streams, deep low-velocity pools are important wintering habitats. Spawning habitat consists of gravel substrates free of excessive silt. Steelhead can live up to 11 years and are sexually mature at 2-3 years. They feed on zooplankton while young; adults feed on aquatic and terrestrial insects, mollusks, crustaceans, fish eggs, minnows and other small fishes (including other trout).
Salmonid species on the west coast of the United States have experienced dramatic declines in abundance during the past several decades as a result of various human-induced and natural factors. However, given the complexity of the salmon species life history and the ecosystem in which they reside, there is no single factor solely responsible for this decline. A variety of conservation efforts have been undertaken, with some of the most common initiatives including captive-rearing in hatcheries, removal and modification of dams that obstruct salmon migration, restoration of degraded habitat, acquisition of key habitat, and improved water quality and instream flow. The Pacific Coast Salmon Recovery Fund was established by Congress in 2000 to support the restoration of salmon species. The fund is overseen by the National Oceanic and Atmospheric Administration-Fisheries and is carried out by state and tribal governments.
To learn more about steelhead spawning and Toppenish steelhead, read on.
Unlike other Pacific salmonids, steelhead can spawn more than one time (called iteroparity). When ready to spawn, steelhead will migrate from the ocean into the freshwater streams and rivers of their birth in order to mate. The females will prepare a "redd" (or nest) in a stream area with suitable gravel type composition, water depth and velocity and may deposit eggs in 4-5 "nesting pockets" within a redd. The eggs hatch in 3 to 4 weeks. Juvenile steelhead may spend up to 7 years in freshwater before migrating to estuarine areas as smolts and then into the ocean to feed and mature. They can then remain at sea for up to 3 years before returning to freshwater to spawn. Some populations actually return to freshwater after their first season in the ocean, but do not spawn and then return to the sea after one winter season in freshwater. The timing of return to the ocean can vary, and even within a stream system there can be different seasonal runs.
Steelhead can be divided into two basic reproductive types, based on the state of sexual maturity at the time of river entry and duration of spawning migration—stream-maturing and ocean-maturing. The stream-maturing type (summer-run steelhead in the Pacific Northwest and northern California) enters freshwater in a sexually immature condition between May and October and requires several months to mature and spawn. The ocean-maturing type (winter-run steelhead in the Pacific Northwest and northern California) enters freshwater between November and April, with well-developed gonads, and spawns shortly thereafter. Coastal streams are dominated by winter-run steelhead, whereas inland steelhead of the Columbia River basin are almost exclusively summer-run steelhead.
To learn about steelhead on Toppenish, read on.
Steelhead and other ocean-run salmonids are known by the area and season where/when they spawn. These seasonal/location distinctions are known as ‘runs.’ Toppenish Creek supports Columbia River summer-run steelhead (as well as resident rainbow trout), which are known as Mid-Columbia River steelhead. The Mid-Columbia River steelhead spawns and rears in tributaries to the Columbia River in central and eastern Washington and Oregon.
These steelhead spawn upstream of the refuge and use the segments of the stream that pass through the refuge for rearing and migration. Seasonally flooded areas adjacent to Toppenish Creek and fish-accessible tributaries may provide temporary rearing habitat, although use of this habitat by salmonids has not been investigated.
Spring-run Mid-Columbia River Chinook salmon and upper Columbia River coho are also present in the Marion Drain tributary to Toppenish Creek and in Toppenish Creek downstream of the refuge. Spring-run Mid-Columbia River Chinook are also present in this lower portion of Toppenish Creek and are considered to be potentially present in the segment of Toppenish Creek that runs through the refuge. Columbia River coho salmon spawn in the Marion Drain that runs along the northern edge of the Chambers Unit and may also be present in Toppenish Creek.
Historically, the Columbia Basin produced significant runs of anadromous fish, including coho, sockeye, steelhead and spring, summer and fall chinook. Currently, summer chinook and sockeye are extinct in the Columbia Basin, and greatly reduced runs of spring and fall chinook, coho and steelhead return each year, making even the few fish using Toppenish Creek of importance. The Mid-Columbia River steelhead were listed in 1999 as “threatened” under the Endangered Species Act by NOAA-Fisheries.
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Steelhead are part of the history and mystique of the Northwest. Immortalized in ink by Zane Grey, pursued by anglers from around the world, prized by chefs throughout the region, steelhead are a defining symbol of the West Coast. Steelhead fishing, especially by dry fly, is an almost mythical experience to its followers. Toppenish NWR is doing its part to ensure the long-term viability of steelhead populations.