Westslope cutthroat trout are a species at risk. They now occupy less than 10% of their historic range in Alberta and are listed as Threatened under the federal Species at Risk Act. Without our help, wild stocks may completely disappear. 

Hidden Lake Westslope Cutthroat Trout Restoration Project

For decades, Hidden Lake and upper Corral Creek were home to westslope cutthroat trout. In the mid-1960s, brook trout – a fish native to eastern Canada – mysteriously appeared and quickly squeezed out the westslope cutthroat trout in the lake and upper streams. Now, the invading brook trout are spreading downstream.

Parks Canada is creating a long-term headwater refuge for westslope cutthroat trout in Hidden Lake and upper Corral Creek, made secure by a naturally-occurring waterfall barrier downstream. Brook trout will be removed from this refuge. Wild westslope cutthroat trout will then be translocated back into the lake and streams they once occupied in this valley.

The Hidden Lake westslope cutthroat trout restoration project began in 2011.

Update – August 2018


Despite six years of concentrated effort to remove brook trout by netting, electrofishing and angling, brook trout continue to populate Hidden Lake. The majority of the adult fish are gone. However, there has been an increase in the population of smaller fish which are more difficult to catch.

After consulting with fisheries experts from across Canada and the U.S.A., Parks Canada will begin using a compound called rotenone to remove the remaining brook trout. Rotenone occurs naturally in a number of tropical and subtropical plants. It has been used for centuries by Indigenous peoples in South America to capture fish for food. 

The heavily-researched compound is widely used by fisheries managers throughout North America. It will remove the brook trout efficiently and effectively with minimum impact to other wildlife. Treatment will be completed over a few days later this summer or early fall.


Update – December 2013


Work continued at Hidden Lake from July 2 - October 23, 2013. 5569 fish have now been removed from the lake and most adult fish are now gone. Over the last three years a total of 276 lbs or 125 kg of brook trout have been donated to a local veterinary hospital or the Alberta Birds of Prey Centre. 

This summer we placed extra effort on removing the smaller fish that were spawned during the first two years of the project. We did this by using custom small mesh gill nets and backpack electrofishing.

The Fairmont Chateau Lake Louise, Trout Unlimited Canada, Fisheries and Oceans Canada, Province of Alberta and the University of Calgary continue to support this project either financially, through in kind support or research. During the fall of 2013 the Fairmont Chateau Lake Louise obtained a substantial conservation grant to support this project. We will use this money during the summer of 2014 to fund an aquatic student to help work on this project and provide public presentations about fish conservation in Banff!

Sierra Sullivan (Parks Canada) and Teresa Holmes (Fairmont Chateau Lake Louise) dissect a brook trout Shelley Humphries accepts a cheque from the Fairmont Chateau Lake Louise
Left: Sierra Sullivan (Parks Canada) teaches Teresa Holmes (Fairmont Chateau Lake Louise) how to dissect a brook trout to determine sex and remove the ear bones (otoliths) that are used to age fish. Right: Shelley Humphries (Parks Canada) accepts a cheque from the Fairmont Chateau Lake Louise.

Update - October 2011

In October 2011, Parks Canada donated almost 40 kg of brook trout from the Hidden Lake Restoration Project to the Alberta Birds of Prey Foundation near Lethbridge. The fish averaged 100 grams each - too small for human consumption. They were loaded into soft coolers in the field, hauled to, aquatics specialist, Shelley Humphries' office in Yoho National Park, then frozen in single layers on trays in preparation for delivery.

The Birds of Prey Foundation was chosen to receive the fish because their mandate is similar to Parks Canada's, with a focus on conservation and public education. They accept injured birds of prey for recovery and rehabilitation. Many of them are released back to the wild, but some birds can never be released. Spirit is one such bird. Visit the Alberta Birds of Prey Foundation to learn more. 

(Left) Aquatics specialist Shelley Humphries meets Spirit, one of the rescued birds of prey that will benefit from non-native brook trout removed from Banff National Park and donated to the Alberta Birds of Prey Foundation.