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Steelhead, Central California Coast DPS

Oncorhynchus mykiss (Fishes)

Species Description

Steelhead are a unique type of salmonid. Unlike most other salmonids, Steelhead are iteroparous, which means they can spawn more than once during their lifetime. Furthermore, individuals develop differently depending on their environment. While all O. mykiss hatch in gravel-bottomed, fast-flowing, well-oxygenated rivers and streams, some stay in fresh water all their lives. These fish are called rainbow trout. The Steelhead that migrate to the ocean develop a much more pointed head, become more silvery in color, and typically grow much larger than the rainbow trout that remain in fresh water.

Steelhead can live for as long as 11 years and grow as large as 55 pounds. They may spend as long as seven years in fresh water before migrating downstream to the estuaries as smolts and then into the ocean to feed and mature. Their coloring is quite distinctive: from dark olive green on their backs shading to silvery-white underneath, they sport a pink racing stripe down the side. They are able to tolerate a greater range of water temperatures than other salmon, which may explain their longevity.

The Endangered Species Act permits the federal government to protect imperiled species, subspecies, and distinct population segments. The term “distinct population segment” is a term of art that allows the government to protect portions of an entire species before a particular threat or population decline becomes so severe that the entire species is placed in jeopardy. There are two federally protected distinct population segments of Steelhead in the GGNP: the California Central Valley Steelhead DPS and the Central California Coast DPS.

The Central California Coast Steelhead DPS includes all naturally spawned populations of Steelhead from the Russian River in Sonoma County through and including Soquel Creek in Santa Cruz County. This includes all Steelhead in San Pablo and San Francisco Bays. These Steelhead have several spawning streams in the GGNP, particularly in Marin County.


Click the image above for a larger range map of the Central California Coast Steelhead DPS.

The Russian River is the largest system in this DPS and probably contained the largest Steelhead population historically. Recent estimates indicate that the population in this river is only 15% of what it was 30 years ago. This may be indicative of the range-wide status of this Steelhead DPS. Although Steelhead remain fairly well distributed spatially throughout this DPS, impassible dams have cut off substantial portions of spawning habitat in some basins.

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Conservation Action Item

Restore Steelhead habitat:
Volunteer in the GGNP restoring riparian areas

Steelhead need cool, clean waters to reproduce successfully. Water diversions, dams, and water pollution are all lethal to their continued existence.

Help with SPAWN’s habitat restoration programs in Marin to keep the species’ habitat thriving.

Big Year Competitors have reported 11 sightings and taken 4 actions to help this species recover so far this year.

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