The westslope cutthroat trout (Oncorhynchus clarkii lewisi) is one of a handful of native trout species in British Columbia. Recognizable by the bright orange-red slashes beneath its jaw, this trout is well adapted to cold, clear mountain streams, rivers, and lakes.

With olive-green backs, yellowish sides dotted with black spots, and a streamlined body, these trout are built for life in flowing water. They spawn in spring in clean, gravel-bottomed streams with high oxygen levels and low sediment—conditions that make them excellent indicators of healthy aquatic environments.

Distribution

These trout are typically inhabit small, high-elevation streams with intact riparian zones that provide shade, shelter, and a consistent supply of aquatic insects, which form the bulk of their diet. In British Columbia, westslope cutthroat trout are native to the upper Columbia River system, including parts of the Kootenay, Kettle, and Columbia River watersheds. In the Thompson-Nicola region, they are found in tributaries of the South Thompson River (specifically the Shuswap system). These include Yard, Crazy and Frog creeks, which are tributaries of the Eagle River and Mabel Lake, and some small lakes on Mt. Griffin (all in the South Thompson system). Cold, clear water and relatively undisturbed habitat in these areas support some of the region’s remaining populations.

Threats

Westslope cutthroat trout are currently listed as Special Concern under Canada’s Species at Risk Act (SARA) and are blue-listed in British Columbia. Populations have declined across much of their range due to habitat degradation, hybridization with introduced rainbow trout, and the impacts of climate change.

One of the main conservation concerns in the Thompson-Nicola region is hybridization. Stocking of rainbow trout in past decades has led to interbreeding in many streams, resulting in the loss of genetically pure cutthroat populations. In some areas, only hybridized or fully introduced trout now remain.

Other threats include:

• Habitat alteration from forestry, roads, and livestock, which can increase sediment in streams and disrupt spawning areas.
• Barriers to fish movement, such as poorly designed culverts and stream crossings.
• Rising water temperatures and lower summer flows, which are being exacerbated by climate change and can limit suitable habitat.

Conservation

Conservation efforts for westslope cutthroat trout in B.C. focus on protecting genetically pure populations and improving habitat quality. This includes:

• Restoring and maintaining riparian buffers to protect water temperature and reduce erosion.
• Improving fish passage by modifying or replacing stream crossings and culverts.
• Preventing further introductions of non-native trout species.
• Monitoring genetic integrity to identify and protect remaining pure populations.

In the Thompson-Nicola, various government agencies, Indigenous communities, and stewardship groups are working to locate and protect remaining populations. Ongoing research and monitoring is helping to better understand their distribution and conservation needs.

Cultural Significance

For Indigenous Nations across the Interior of BC, including in the Thompson-Nicola, westslope cutthroat trout have long held cultural importance and served as a traditional food source. While salmon species remain central to many food systems and cultural practices, native trout such as cutthroat have also been traditionally harvested, particularly in higher elevation areas or smaller tributaries where salmon were less common. Fishing for trout contributed to seasonal food gathering, family livelihoods, and the intergenerational transfer of knowledge related to water, species behaviour, and local ecosystems.

Today, efforts to conserve native trout are deeply connected to broader Indigenous-led initiatives aimed at restoring watershed health, advancing food sovereignty, and honoring responsibilities to land and water. Indigenous governments and communities across the region are playing a central role in mapping, monitoring, and rehabilitating native trout habitats. These initiatives not only contribute to ecological resilience but also support the revitalization of Indigenous knowledge systems and stewardship traditions.

Learn More

•  COSEWIC: Westslope Cutthroat Trout Status Report
• BC Species and Ecosystems Explorer: Westslope Cutthroat Trout Reports and References
• Freshwater Conservation Canada: Westslope Cutthroat Trout

Feature photo: Forest Service – Northern Region, Public domain, via Wikimedia Commons