Glacier National Park in Montana is a fisherman’s paradise. Hundreds of snow-fed lakes pepper the park, home to over 20 species of fish, including six kinds of trout.

And, because it’s federal land, no license is required to cast a reel.

And, because it’s federal land, no license is required to cast a reel.

But in a warming world, the National Park Service (NPS) is hoping to transform one of Glacier National Park’s coldest lakes into a refuge for a species of trout.

But it’s not as simple as translocating this species into the park. In order to create an environment for these fish, NPS first needs to get rid of the non-native trout that currently inhabit that lake.

The plan proposed by the park, which, if approved, would begin September 2023, recommends using a long-used pesticide and rat poison called rotenone.

Despite being a naturally derived compound, it has been banned for use on rodents since 2005.

While it is still a widely used fish toxin, or piscicide, as well as a widely used pesticide, researchers have unearthed strong epidemiological links with Parkinson’s Disease.

Like many lakes in the Western United States, Gunsight Lake was historically fishless.

Like many lakes in the Western United States, Gunsight Lake was historically fishless.