Species Profile

Westslope Cutthroat Trout Pacific populations

Scientific Name: Oncorhynchus clarkii lewisi
Other/Previous Names: Westslope Cutthroat Trout (British Columbia population)
Taxonomy Group: Fishes
Range: British Columbia
Last COSEWIC Assessment: November 2016
Last COSEWIC Designation: Special Concern
SARA Status: Schedule 1, Special Concern

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Quick Links: | Description | Habitat | Biology | Threats | Protection | National Recovery Program | Documents

Image of Westslope Cutthroat Trout


The Westslope Cutthroat Trout is one of two Cutthroat Trout sub-species occurring naturally in Canada. This relatively small (usually between 15 and 23 cm long) salmonid has small dark spots on a silver to yellowish-green body, and red coloration on the front and sides of the head. Spots below the lateral line are concentrated on the back half of the body, distinguishing British Columbian Westslope Cutthroat Trout from those in Alberta. A larger mouth and bright orange-red slashes beneath the lower jaw distinguish Westslope Cutthroat Trout from similar species. Bright red coloration all over the body may appear in spawning individuals.


Distribution and Population

In North America, Westslope Cutthroat Trout distribution straddles the Continental Divide. In British Columbia, the species occurs in hundreds of water bodies in the southeastern portion of the Province. Primary drainage basins include the Elk, Flathead, Upper Kootenay, West Kootenay, Columbia, Kettle and South Thompson. Population estimates for Westslope Cutthroat Trout in British Columbia are extremely limited, but the number of mature individuals is thought to be in the tens of thousands.



Westslope Cutthroat Trout inhabit rivers, lakes, or small mountain streams that are typically low in productivity and highly oxygenated. Cold, clean water and adequate cover, such as undercut banks, pool-riffle habitat, and riparian vegetation are also important. Spawning habitats require clean unsilted gravel, with pools usually formed by large woody debris, boulders, or bedrock. Rearing and overwintering habitats vary widely depending on life history form (see “Biology”). Fry generally make use of lateral habitats with adequate cover, while larger juveniles inhabit pools. Groundwater influx and the absence of anchor ice are both important to overwintering habitats. Resident forms may remain in natal streams for their entire lifespan, whereas fluvial and adfluvial forms migrate to larger systems with greater potential for growth.



Several life history forms exist for Westslope Cutthroat Trout: stream resident (the smallest in size, usually restricted by barriers to smaller streams), fluvial (medium sized, inhabiting both spawning/rearing tributaries and adult-rearing rivers), and adfluvial (the largest in size, inhabiting both spawning/rearing tributaries and adult-rearing lakes). Although age at maturity varies widely, most males are mature by four years, and most females by five years. Mature Cutthroat Trout return to their natal streams to spawn in May and August, and may reproduce several times during their lifespan. Females dig redds (gravel “nests”) usually in tailouts of deep pools where males compete for access to females. Once fertilized, eggs incubate for 6 to 7 weeks. Hatched alevins remain in their redds until their yolk sacs have absorbed, then emerge as fry in July and August. Westslope Cutthroat Trout are opportunistic feeders, preferring invertebrates (e.g. chironomid larvae, “true” flies, mayflies, caddisflies, zooplankton) over smaller fish. Predators include other fish, as well as raptors, and mustelids. Recreational fisheries are also a potential source of mortality.



Threats of the highest impact to this species are associated with water use, forest harvest, linear projects, mining, and aquaculture, hatcheries and stocking; however, threat impacts are variable across the species’ range.



Federal Protection

More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.

The Westslope Cutthroat Trout (British Columbia population) is listed as Special Concern under the federal Species at Risk Act (SARA). If a project is subject to an assessment under the Canadian Environmental Assessment Act, 2012 measures must be taken to avoid or lessen any adverse effects of the project on the species. Additionally, Fisheries Protection and Pollution Prevention provisions of the Fisheries Act provide protection to this species.

Provincial and Territorial Protection

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.


Recovery Progress and Activities

The recreational fishery for Westslope Cutthroat Trout has seen increasingly strict regulations in response to declines in recent decades. The East Kootenay Angling Management Plan (EKAMP) completed by the British Columbia Ministry of Environment summarizes regulatory measures implemented to address angling use issues on selected water bodies. Seven streams in the East Kootenay Region were designated as Classified Waters in 2005–2006. A River Guardian Program, which entails fisheries data collection, compliance monitoring, and angler education as part of the Province’s Quality Waters Strategy, has also contributed valuable data for the management of this species. Fisheries and Oceans Canada in cooperation with the Province of British Columbia is currently developing a Management Plan for Westslope Cutthroat Trout (British Columbia population).


PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.

9 record(s) found.

COSEWIC Status Reports

COSEWIC Assessments

Response Statements

  • Response Statement - Westslope Cutthroat Trout, British Columbia population (2007)

    Populations are stressed by hybridization and competition with introduced species. Furthermore, expanding urban development, agricultural activities and resource-based industries are expected to lead to additional stresses associated with habitat loss and degradation, as well as increased exploitation. It should be noted that this assessment includes only genetically pure, native populations of the species occurring within their historical range. Any populations known to be hybridized significantly (i.e. >1%) with other trout species, or to have been introduced into a system previously free of native populations, were not assessed.

Management Plans

  • Management Plan for the Westslope Cutthroat Trout (Oncorhynchus Clarkii Lewisi), British Columbia Population, in Canada (2017)

    The Westslope Cutthroat Trout (Oncorhynchus Clarkii Lewisi) was designated as Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) due to concerns regarding introduced species (hybridization and competition), habitat loss and degradation, and increasing exploitation. It is listed as Special Concern in Canada on Schedule 1 of the Species at Risk Act (SARA). In British Columbia, the Westslope Cutthroat Trout is ranked S3 (vulnerable) by the Conservation Data Centre and is on the provincial Blue list. The B.C. Conservation Framework ranks the Westslope Cutthroat Trout as a priority 2 under goals 1 and 2 (contribute to global efforts for species and ecosystem conservation; and prevent species and ecosystems from becoming at risk).


  • Order Acknowledging Receipt of the Assessments Done Pursuant to Subsection 23(1) of the Act (2009)

    Her Excellency the Governor General in Council, on the recommendation of the Minister of the Environment, acknowledges receipt, on the making of this Order, of the assessments conducted pursuant to subsection 23(1) of the Species at Risk Act by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) with respect to the species set out in the annexed schedule.
  • Order Amending Schedule 1 to the Species at Risk Act [fish] (2010)

    Her Excellency the Governor General in Council, on the recommendation of the Minister of the Environment, pursuant to section 27(1) and (1.1) of the Species at Risk Act, hereby makes the annexed Order Amending Schedules 1 to 3 to the Species at Risk Act.

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2005 (2005)

    2005 Annual Report to the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
  • COSEWIC Annual Report - 2007 (2007)

    2007 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.

Recovery Document Posting Plans

  • Recovery Document Posting Plan - Fisheries and Oceans Canada - Fiscal Year 2016-2017 (2016)

    Under the Species at Risk Act (SARA), the competent Minister(s) must prepare a recovery strategy within one year of listing a species on Schedule 1 of SARA as endangered and within two years of listing a species as extirpated or threatened. A management plan must be prepared within three years for a species listed as special concern. Fisheries and Oceans Canada (DFO) is accountable for 111 of the 518 species listed under SARA. As of February 2016, proposed recovery strategies, management plans and action plans for 57 of those species have not yet been posted to the Species at Risk Public Registry. An additional 23 aquatic species have proposed management or action plans coming due in the future. The following outlines the Department’s plan for posting proposed documents for 64 species on the Species at Risk Public Registry. The Department has a plan to post recovery strategies for 9 species, management plans for 13 species, and action plans for 42 species over the next year.