Appearance

Steelhead (Oncorhynchus mykiss) are the anadromous form of rainbow trout, meaning that they live in both freshwater and ocean ecosystems throughout their lifecycle, returning from the ocean to their natal streams to spawn. They are typically dark-olive on the back, shading to silvery-white on the sides and belly, with a pinkish-red stripe running along their lateral line when they are in freshwater. They have black spots on their back, dorsal fin, and tail. In the ocean, steelhead have a uniform silvery color that helps them blend into their marine environment. When returning to freshwater to spawn, they often regain their more vivid freshwater colors. Steelhead weigh between 8 and 11 pounds on average but can reach over 30 pounds.

Ecology

Steelhead are unique among salmon species for their variable life history strategies. Steelhead typically mature between the ages of 3 and 5. Unlike Pacific salmon, steelhead do not always die after spawning and may return to the ocean, known as “kelting,” to repeat the cycle and spawn multiple times.

In the Upper Columbia River Basin, steelhead spawn and rear in a variety of habitats, including small tributaries, larger rivers, and occasionally in lake outlets. They require clean, cold water with gravelly riverbeds for spawning. After hatching, juvenile steelhead, known as fry, inhabit freshwater for one to four years before migrating to the ocean. In the ocean, they spend another one to four years growing rapidly before returning to freshwater to spawn.

Juvenile steelhead primarily feed on aquatic insects and crustaceans in freshwater. In the ocean, they shift to a diet of smaller fish and other marine organisms. Predation is a significant factor affecting steelhead survival. Birds, larger fish, and mammals prey on juvenile steelhead in freshwater. In the ocean, they face predation from marine mammals and larger fish species.

Threats

Steelhead in the Upper Columbia face numerous anthropogenic, or human-caused threats. Habitat degradation from logging, mining, agriculture, and urban development reduces water quality and habitat availability. Dams and other barriers obstruct migration routes, alter river flow, and change water temperatures, making both upstream and downstream migrations challenging. Climate change exacerbates these issues by increasing water temperatures and altering flow regimes.

Upper Columbia River steelhead are classified as a “threatened” species under the Endangered Species Act.

Conservation

Conservation efforts for steelhead in the Upper Columbia are multi-faceted and include habitat restoration, improving fish passage, hatchery programs, and regulatory protections. Habitat restoration projects aim to enhance riparian areas and floodplains, remove barriers to migration, improve water quality, and increase habitat complexity. Fish passage improvements such as fish ladders and dam removals help facilitate steelhead migration. Hatchery programs support steelhead populations while carefully managing genetic diversity and wild population resilience. Regulatory measures that protect steelhead populations include fishing restrictions and water management policies.

Collaborative efforts among government agencies, non-profits, Tribes, and local communities are essential for the success of these conservation initiatives. The role of UCSRB is to develop and coordinate implementation of the Upper Columbia Spring Chinook and Steelhead Recovery Plan. Understanding the complex life history and ecological requirements of steelhead is crucial for developing effective conservation strategies. Ongoing research, monitoring, and adaptive management will ensure the long-term sustainability of steelhead populations in the Upper Columbia River Basin.