Westslope Cutthroat Trout (Alberta Population)

Oncorhynchus clarkii lewisi

SARA Status
No Status
NS
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

SARA Status

  • No Status NS
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX
COSEWIC Status
Not at Risk
NR
Special Concern
SC
Threatened
TH
Endangered
EN
Extirpated
EX

COSEWIC Status

  • Not at Risk NR
  • Special Concern SC
  • Threatened TH
  • Endangered EN
  • Extirpated EX

Description

The Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi) is a subspecies of the Cutthroat Trout (Oncorhynchus clarkii). This subspecies has been further divided into two populations, the Alberta and British Columbia populations. The Westslope Cutthroat Trout is a member of the Salmonidae family and has the following characteristics:

  • Streamlined body shape;
  • Generally trout-like in appearance with small, irregularly shaped dark spots, which form an arc from the anal fin to the pectoral fin;
  • Series of small basibranchial teeth at the back of the throat;
  • Colouration ranges from silver to yellow green with red on the front and sides of the head;
  • Spawning fish often develop a bright red colouration over the entire body; and
  • Typically small in size at 150 to 230 mm (28 to 142 g); larger individuals rarely exceed 460 mm (1400 g).

Habitat

The Westslope Cutthroat Trout has a disjunct distribution on both sides of the Rocky Mountains. In the United States, it occurs in drainages in Montana, Idaho, Washington, Oregon and Wyoming. In Canada, it is restricted to the upper Kootenay, upper Columbia and South Thompson drainages in British Columbia. The native Alberta population occurs in the Bow and Oldman drainages of the South Saskatchewan River. Although it has been recorded in the Milk River (upper Missouri River drainage), its current status there is unknown. The Westslope Cutthroat Trout has also been widely introduced in many naturally fishless lakes and rivers.

Westslope Cutthroat Trout are found in a wide range of habitats but do best in cold, clean, moving water with various forms of cover such as undercut banks, pool-riffle habitat and riparian vegetation. Spawning generally takes place in small natal streams in redds on bottoms of fine gravel. It occurs between May and August (depending on the location) at water depths of 20 to 50 cm and at 6° to 17ºC. Eggs incubate for six to seven weeks and once hatched, alevins remain in the gravel until their yolk sacs are absorbed. Young-of-the-year fry disperse to shallow riffles or backwater habitat. Juveniles may reside in natal streams from one to four years. Following spawning, older fish may or may not need to move to summer habitat for feeding. In late summer and early fall, fish migrate to suitable overwintering habitat.

Threats

The greatest threats to the Westslope Cutthroat Trout in Alberta include habitat loss, overharvesting and the introduction of non-native species. Habitat degradation and loss due to timber extraction, mining and hydroelectric developments have been directly responsible for loss of habitat and the decline of several populations. In addition, the resulting network of roads impacts remote, small streams and leads to greater off-road vehicular traffic. This further degrades sensitive habitat and increases angling pressure on this already popular sportfish. Stocking of non-native species may lead to displacement, replacement and/or hybridization of native Westslope Cutthroat Trout populations.

Further Information

A recovery strategy has been developed in collaboration with the recovery team, which includes representatives from Fisheries and Oceans Canada, Province of Alberta (Alberta Environment and Sustainable Resource Development, Public Lands, Fish and Wildlife and Alberta Tourism and Recreation), Environmental Non-Governmental Organization Coalition, Spray Lake Sawmills, TransAlta Corporation, Trout Unlimited Canada, University of Calgary and Canadian Association of Petroleum Producers. The Government of Alberta has completed the  Alberta Westslope Cutthroat Trout Recovery Plan 2012-2017 . The federal Minister of the Fisheries and Oceans and Minister of the Environment, as competent ministers under the Species at Risk Act, have adopted the Alberta recovery plan as part of the federal recovery strategy.

Several recovery measures have already been implemented. For example, the genetic integrity of Westslope Cutthroat Trout in the Cascade River watershed, Banff National Park, is being restored following their hybridization with Rainbow Trout. A multi-year project has begun to remove the Rainbow Trout and hybrids. A second location in Banff National Park is also be being restored. The creek contains exclusively Brook Trout, however, their removal and replacement with pure Westslope Cutthroat Trout will secure an additional population of Westslope Cutthroat Trout in Banff National Park.

For further information, visit the SARA Registry.

Westslope Cutthroat Trout (Alberta Population)

Image of a male Westslope Cutthroat Trout (© 	Joseph R. Tomelleri)

Macrhybopsis storeriana
© J. R. Tomelleri

Scientific name: Oncorhynchus clarkii lewisi
SARA Status: Threatened
COSEWIC Status: Threatened
Region: Alberta

Historical distribution of the Western Cutthroat Trout (Alberta population) as described in the following paragraphs

Map showing the distribution of the Western Cutthroat Trout (Alberta population).

Did You Know?

Cutthroat Trout generally tend to have a larger mouth than the Rainbow Trout (O. mykiss) with a longer maxillary. They are generally trout-like in appearance with small, irregularly shaped dark spots, which form an arc from the anal fin to the pectoral fin.

The Westslope Cutthroat Trout (Alberta Population)

The Westslope Cutthroat Trout (Alberta Population)

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