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What We Do: Native Wildlife Recovery / Fish

The fishery resource of NE Oregon is an important part of a healthy and functioning ecosystem. The steelhead, Chinook salmon and bull trout are all on the threatened and endangered list. Restoration projects are underway to help return these great fish to abundant populations. Other fish species are native to the Hells Canyon/Blue Mountain area but there is little data or interest in most of these species. For more information go to:

http://www.fs.fed.us/r6/fishing/regional/fishresources/index.html

Steelhead trout are an important component of diverse wildlife heritage. They are a good indicator of the health of aquatic systems because they use all portions of a river system, and require cool, clean water.

Life Cycle

Steelhead trout (Oncorhynchus mykiss) belong to the family Salmonidae which includes all salmon, trout, and chars. Steelhead are the anadromous form of rainbow trout, a salmonid species native to western North America and the Pacific Coast of Asia. The term anadromous refers to fish species born in the stream that migrate to the ocean for their adult phase. Steelhead are similar to some Pacific salmon in their life cycle and ecological requirements. They are born in fresh water streams, where they spend their first 1-3 years of life. They then emigrate to the ocean where most of their growth occurs. After spending between one to four growing seasons in the ocean, steelhead return to their native fresh water stream to spawn. Unlike Pacific salmon, steelhead do not necessarily die after spawning and are able to spawn more than once.

Most steelhead spawn from December through April in small streams and tributaries where cool, well oxygenated water is available year round. The female selects a site with gravel substrate where there is good flow through the gravel. She then digs a nest, called a redd, and deposits eggs, which the male then fertilizes. The eggs are covered by gravels and cobbles when the female excavates another redd just upstream.

The length of time it takes for eggs to hatch is heavily dependent on water temperature. In hatcheries with carefully controlled conditions, steelhead eggs hatch after 30 days at a temperature of 51° F. The optimal temperature for egg incubation is between 44 and 50° F (7-10° C). Eggs hatch sooner in warmer water, but the young fish are smaller and generally have lower survival rates. If the temperature goes too high, eggs will not hatch at all. After hatching, the developing steelhead will remain in the gravel for another four to six weeks. During this time, they are called alevins and obtain nutrients from a yolk sack attached to their body. When they emerge from the gravel, they are called fry, and are able to catch their own food.

Newly emerged fry move to shallow, protected areas of the stream (usually in the stream margins). They establish feeding areas which they defend. Most juveniles can be found in riffles, although larger ones will move to pools or deep runs.

Source: Steelhead Restoration and Management Plan for California, by Dennis McEwan and Terry Jackson, CA Department of Fish and Game

Steelhead Habitat

Steelhead habitat requirements change as they go through different life phases. Adult steelhead need to have access to their natal streams. This means that streams must be free of barriers to migration, as the majority of spawning occurs in the upper reaches of tributaries. Adults also need access to spawning gravel in areas free of heavy sedimentation with adequate flow and cool, clear water. Steelhead utilize gravel that is between 0.5 to 6 inches in diameter, dominated by 2 to 3 inch gravel. Escape cover such as logs, undercut banks, and deep pools for spawning adults is also important.

For steelhead eggs and pre-emergent fry, the most important consideration in terms of habitat is cool water with adequate dissolved oxygen. Fine sediment will smother developing eggs, so the area must not have excessive fine silt or sand. During their first summer, juvenile steelhead are typically found in relatively shallow areas with cobble and boulder bottoms. They reside at the downstream end or in riffles less than two feet deep. Juvenile steelhead prefer areas including woody debris accumulation such as logs or tree roots. Cover structures such as boulder clusters and root wads provide both summer and winter rearing habit. Surface turbulence (or white water) provides another source of cover during the summer months. As juvenile steelhead grow, pools become an important habitat component. The best pools for habitat are those with abundant escape cover in the form of large woody debris, undercut banks, root masses, and large boulders.

Cool, clean water is essential for the survival of steelhead during all portions of their life cycle. Elevated water temperatures (>70° F) can greatly impair growth rates of juvenile steelhead if adequate food is not available. Warmer water also holds less dissolved oxygen and increases a fish´s susceptibility to disease.

Source: California Salmonid Stream Habitat Restoration Manual, by Gary Flosi et al., CA Department of Fish and Game, Inland Fisheries Division

Distribution

In North America, steelhead are found in Pacific Ocean drainages from southern California through Alaska. In Asia, they are found on the east and west coast of the Kamchatka Peninsula, with a few populations on the mainland. In the state of Oregon, known populations occur in coastal rivers and streams including the Snake, Grande Ronde and Imnaha Rivers in the Hells Canyon area.

Current Status

The major factor causing steelhead population decline is freshwater habitat loss and degradation. This has resulted from three main factors: inadequate stream flows, blocked access to historic spawning and rearing areas due to dams, and human activities that discharge sediment and debris into waterways.

Source: Steelhead Restoration and Management Plan for California, by Dennis McEwan and Terry Jackson, CA Department of Fish and Game, and The Napa Watershed Owner's Manual, Napa County RCD

For more information at:

http://www.nmfs.noaa.gov/pr/species/fish/steelheadtrout.htm

Read about Chinook Salmon at: http://www.nmfs.noaa.gov/pr/species/fish/chinooksalmon.htm

Read about Redband Trout at: http://www.fs.fed.us/r6/fishing/regional/fishresources/coldwater.html

541.963.3950PO Box 2768
La Grande, Oregon 97850