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Oncorhynchus mykiss


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Steelhead trout (Oncorhynchus mykiss) is an anadromous species of fish, meaning that they migrate to the ocean and come back to freshwater to spawn. These fish can reach lengths of over 100 centimeters and 26 kilograms. They typically have a silver-colored body with black spots and a pink stripe that runs down their sides. The silver coloration is the feature that led to them being called the Steelhead. 


The anadromous steelhead trout typically begins life in fast flowing rivers and streams with gravel bottoms and high levels of oxygen. The fish then migrate to the ocean where they grow and mature. They then return to their freshwater habitats in order to spawn and restart the life cycle.

Community Relationships and Behavior

Steelhead, like other salmonid fishes, follow a “big bang” reproductive strategy in which vast numbers of eggs are produced which results in far more fry than can survive. These large numbers of eggs and fry provide prey for many small predators such as insects, crustaceans, small fishes, and birds. As the fish grow, they are consumed by other types of predators such as larger birds, larger fishes, and some mammals. They also become predators to a variety of invertebrates and smaller fishes. 


This species ranges throughout much of the United States as well as surrounding oceanic areas. It has also been introduced to all the continents with the exception of Antarctica.

(Photo by Zeynel Cebeci)


The anadromous lifestyle of the steelhead trout has been imperiled by human activity throughout much of its range. It is particularly vulnerable to dams and other types of water diversions which cut off their migratory paths. Most of the steelhead populations in California are considered threatened or endangered under the Federal Endangered Species Act. Management strategies have included hatchery propagation and release as well as habitat restoration.

Steelhead Trout at Stanford

The steelhead populations on Stanford lands are monitored annually. Habitat restoration plans are being developed which will hopefully bolster this population which has been impacted by damming and water diversion.