Banff Trout Restoration Hits Milestone With 18,000 Eggs in Cascade Creek

A major fish restoration project in Banff National Park has reached a key milestone, with about 18,000 eggs from threatened Westslope Cutthroat Trout (WSCT) successfully placed into Cascade Creek last summer, achieving a hatch rate of more than 97%.

“These eggs were collected from adult WSCT in Marvel Lake, fertilized on-site, and initially incubated in a portable hatchery in Field, B.C. By early July, the fry hatched and dispersed into the creek, with a successful hatch rate of over 97%,” said Tomi Postma, Public Relations and Communications Officer with Parks Canada.

The reintroduction marks the start of a three-year plan, set to run through August 2026, aimed at establishing a self-sustaining population of the native trout.

The work is part of a wider effort to reverse decades of decline in WSCT, which have declined to less than 10% of their historic range due to habitat disruption, warming waters and the introduction of non-native fish species such as brook and rainbow trout.

Cascade Creek, located south of Lake Minnewanka in Banff National Park, was restored over several years and is now considered suitable habitat for reintroduction.

“Parks Canada and partners embarked on a comprehensive effort to rehabilitate Cascade Creek, a vital 9 km stretch of stream,” Postma said. “This initiative successfully restored the creek as a suitable habitat to reintroduce the genetically pure Westslope Cutthroat Trout.”

That rehabilitation included rebuilding the creek channel to restore natural features. These include riffles, shallow fast-moving sections, pools, which are deeper and slower, and runs, areas of moderate flow that fish rely on at different stages of their life cycle.

Water levels in Cascade Creek were increased by releasing more water from the Lake Minnewanka reservoir, helping keep the creek deep, cool and moving for fish. Non-native brook trout, a species that competes with native fish, were removed, and a barrier was installed to prevent their return. More than 6,000 plants were added along the banks to stabilize soil, provide shade and help regulate water temperature.

Scientists continue to monitor water quality, temperature and food supply to ensure conditions remain suitable. This includes tracking benthic invertebrates, small organisms that live on the creek bed and are a primary food source for fish.

A Restricted Activity Order prohibiting fishing in Cascade Creek has been in place since 2025 and is set to remain until August 2030.

“To ensure the best possible outcome for the newly introduced WSCT, Parks Canada implemented a no-angling Restricted Activity Order for Cascade Creek in 2025 to protect the juvenile reintroduced WSCT population,” Postma said.

The restriction applies only to Cascade Creek.

Parks Canada said the reintroduction follows extensive planning, including testing donor fish for disease, selecting genetically suitable populations and confirming the restored creek can support the species through all stages of its life cycle.

The agency also clarified that rotenone, a natural fish toxicant sometimes used in lake restoration projects to remove non-native species, was not used in Cascade Creek.

The effort is part of a broader push to rebuild native fish populations, including reintroductions in lakes such as Margaret Lake and habitat restoration in other waterways.

“By rehabilitating Cascade Creek and reintroducing WSCT, Parks Canada is helping to restore natural biodiversity, strengthen ecosystem resilience and support recovery of a species at risk,” Postma said.

WSCT depend on cold, clean and connected waterways, conditions that support a wide range of aquatic life. Their return is expected to benefit the broader ecosystem, including serving as a food source for birds and larger wildlife.