Waterfalls to the Rescue of Brook Trout

Learn about our efforts to protect the brook trout population in the Bouchard Lake watershed in La Mauricie National Park.

By Parks Canada

La Maurice National Park

Map, La Mauricie National Park (2022)Parks Canada

Protecting brook trout

Once again, La Mauricie National Park’s aquatic wildlife team has succeeded in protecting the brook trout population, a species native to the park, in the Bouchard Lake watershed as part of a project to restore aquatic ecosystems!

Preserving ecological integrity

Originally, brook trout were the only species found in most of the lakes and streams of La Mauricie National Park. By protecting these fish, Parks Canada is preserving the delicate balance known as ecological integrity.

Map, La Mauricie National Park (2022)Parks Canada

A threat to the ecological integrity of Bouchard Lake

Discovering invasive species

While conducting routine surveys, the aquatic wildlife team was unpleasantly surprised to discover invasive species at the Bouchard Lake outlet, in the creek where the lake water flows.

Creek Chub, La Mauricie National Park (2021) by Judith JacquesParks Canada

The creek chub and white sucker are considered invasive species because they were not originally found in this lake.

Explore Bouchard Lake in 360

A way had to be found to prevent these non-native species from invading Bouchard Lake and threatening its ecological integrity. Creek chub and white sucker compete with young brook trout for food.

Map, La Mauricie National Park (2022)Parks Canada

Invasive species from the Saint-Maurice River

A lack of natural obstacles

The few natural obstacles in the creek linking the Saint-Maurice River and Bouchard Lake allowed creek chub and white sucker to reach the lake outlet.

Map, La Mauricie National Park (2022)Parks Canada

The creek must be blocked to stop invasive species

Bouchard Creek, La Mauricie National Park (2021) by Judith JacquesParks Canada

Historically, there would have been more natural barriers along Bouchard Creek.

Log Driving Structure, La Mauricie National Park by Judith JacquesParks Canada

The history of the creek

However, the creek was modified in the days of log drivers to accommodate logs, and the water level rose after a dam was built downstream on the Saint-Maurice River. This would have allowed invasive species to cross some natural barriers.

Impassable Temporary Barrier, La Mauricie National Park, Judith Jacques, From the collection of: Parks Canada
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Impassable Permanent Barrier, La Mauricie National Park, Judith Jacques, 2021, From the collection of: Parks Canada
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The team therefore built two impassable barriers to prevent new fish not native to the lake from entering the creek and to block access to Bouchard Lake.

Map, La Mauricie National Park (2022)Parks Canada

Creating an impassable temporary barrier

A wooden structure was built in the creek to prevent the few invasive species that had entered the creek from reaching Bouchard Lake.

Map, La Mauricie National Park (2022)Parks Canada

Creating an impassable permanent barrier

Creek chub and white suckers are natural athletes! The team had to fracture the rock to make the waterfall impassable and thereby prevent invasive species from coming back up the waterfall.

We're monitoring fish

The team conducts frequent fish surveys to ensure that brook trout are the only fish living in Bouchard Lake, as was originally the case.

Fish Surveys, La Mauricie National Park (2021) by Judith JacquesParks Canada

“When I do surveys there and don’t find invasive species, it’s my greatest source of pride!” - Marc-André Lamothe, resource management technician at La Mauricie National Park.

Brook Trout, La Mauricie National Park (2021) by Judith JacquesParks Canada

Mission accomplished!

It can now be said that brook trout have avoided an invasion! They remain the only fish species in the Bouchard Lake watershed.

Impassable Temporary Barrier, La Mauricie National Park by Judith JacquesParks Canada

The temporary wooden barrier can therefore be removed. Only the permanent rock barrier will remain, which has proven its effectiveness!

Fish Surveys, La Mauricie National ParkParks Canada

We continue our efforts

The conservation team is working hard to improve the ecological integrity of La Mauricie National Park and keep its ecosystems intact. It protects native species and prevents the introduction of invasive species.

Boating at the Park, La Mauricie National Park (2019) by Judith JacquesParks Canada

You can help us!

Visitors also have an important role to play in preventing the introduction of invasive species to La Mauricie National Park. They must clean, drain and dry their boats before sailing on the park’s lakes.

Learn more

About invasive species in La Mauricie National Park

About ecological integrity monitoring at La Mauricie National Park

Credits: Story

Judith Jacques: designer, producer / external relations team of La Mauricie National Park
Marc-André Lamothe: idea man and top model
Benoit Grégoire: top model
Charles-René Bernier: creator of the map of La Mauricie National Park

Thank you to the conservation and external relations teams of La Mauricie National Park and to the new media team of Parks Canada.

"Waterfalls to the Rescue of Brook Trout" is a story produced by Parks Canada.

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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