Steelhead

Description

Steelhead trout (anadromous rainbow trout) typically range in weight from 5 to 10 pounds, but can get up to 45 inches in length and weigh up to 30 pounds. Steelhead in the ocean have metallic blueish-green backs and silver sides, especially below the lateral line. When sexually mature for spawning, males have a prominent pink to red band on the operculum (gill cover) and at and below the body’s lateral line; females less so. Males usually do not have the prominent hooked kype seen in male salmon when sexually mature.

In Whatcom County

Steelhead have two patterns for returning from the ocean to spawn in Whatcom County streams. Most local steelhead are winter-run fish, entering freshwater from October through February and spawning March through May (unlike salmon, which spawn in late summer to early winter). Winter-run fish are found in Dakota Creek, urban creeks in Bellingham, major tributaries such as Bertrand and Fishtrap Creeks, and the three forks of the Nooksack River. Summer-run steelhead spawn in the Nooksack South Fork, entering the river between June and September and holding in deep pools until spawning February through April.

Range

Major steelhead distribution is from northern California, Oregon, Washington and British Columbia to southeast Alaska, Alaska’s Copper River, and the easternmost Aleutian Islands. In Asia, significant numbers occur only on the western coast of the Kamchatka Peninsula.

Life History

Steelhead spend 1 to 3 years in fresh water and 1 to 4 years at sea; most common in Oregon and Washington is a 2 freshwater / 2 ocean life history. Steelhead juveniles behave much like resident trout. Because they can survive spawning (iteroparous), some return to the ocean to feed and may return to a stream after a year or more to spawn a second time.

Habitat Requirements

As for salmon, good steelhead habitat is found where water remains cool, clean and well-oxygenated and where aquatic and terrestrial insects are abundant. Because young steelhead spend up to 3 years in freshwater, high-quality stream habitat is essential. Steelhead spawn at sites similar to those used by coho and Chinook salmon; some evidence suggests competition for spawning habitat is minimized by spring spawning, after the salmon fry have emerged.

Did You Know

In 2007, Puget Sound steelhead, including those in Whatcom County, were listed as “threatened” under the federal Endangered Species Act. Until 1989, rainbow (and steelhead) and cutthroat (and sea-run) were in the trout genus Salmo. Steelhead exhibit reproductive “plasticity”: a female steelhead’s progeny may become anadromous steelhead or resident rainbow trout, and vice versa. Like Chinook and coho, the adipose fin of a hatchery steelhead is removed before release, so an adult lacking the adipose fin is hatchery-produced while one with an intact fin was naturally produced.

Illustrations: Pacific Salmon, Childerhose & Trim (Douglas & McIntyre, Vancouver/Toronto).