Along the banks of Hunt Lake in the south of Whiteshell Provincial Park, the largemouth bass stalks in the water, threatening the survival of other fish in the ecosystem.

But this competitive, aggressive predator wasn’t always part of Hunt Lake. Anglers first spotted the freshwater fish there in 2023 — and unlike other species, the largemouth bass was neither native to the ecosystem nor brought to the lake through provincial fish farming programs.

Instead, it’s there because people have put it into the lake illegally, said Eric Mullen, a provincial regional fisheries manager responsible for eastern Manitoba.

Those kinds of illegally introduced species have had what Mullen calls an “adverse impact” on native fish populations, which have since declined in numbers and become less healthy.