In The NoCo

Scientists have a new strategy to eradicate an invasive fish species from Colorado streams

By In The NoCo,

Published June 24, 2026 at 5:35 AM MDT

Ways To Subscribe

A group of brown-spotted orange fish swim in a tank — Fingerling “Trojan” brook trout on April 23 receiving one in a series of treatments that genetically guarantee their eventual offspring will be male-only. The breeding stock is raised by Colorado Parks and Wildlife at the Bellvue State Trout Hatchery and Rearing Unit.

Scientists have a new tool in the fight to eradicate a fish that’s been causing havoc in some of Colorado’s mountain streams.

Brook trout are a nonnative species introduced in the state more than a century ago. They breed prolifically and edge out many native fish species for food and other resources. Over the decades, "brookies" have steadily pushed out Colorado's native cutthroat trout.

Now, scientists and wildlife officials are trying a new approach that involves altering the very biology of the brook trout.

Reporter Michael Booth covers the environment for the Colorado Sun. He joined Erin O’Toole to talk about this new strategy to restore some native ecosystems– and how it’s already shown promising results.

Tags

In The NoCo

KUNC's In The NoCo is a daily slice of stories, news, people and issues. It's a window to the communities along the Colorado Rocky Mountains. The show brings context and insight to the stories of the day, often elevating unheard voices in the process. And because life in Northern Colorado is a balance of work and play, we celebrate the lighter side of things here, too.

See stories by In The NoCo

Erin O'Toole

As the host of KUNC’s news program and podcast In The NoCo, I work closely with our producers and reporters to bring context and diverse perspectives to the important issues of the day. Northern Colorado is such a diverse and growing region, brimming with history, culture, music, education, civic engagement, and amazing outdoor recreation. I love finding the stories and voices that reflect what makes NoCo such an extraordinary place to live.

See stories by Erin O'Toole

Brad Turner

Brad Turner is an executive producer in KUNC's newsroom. He manages the podcast team that makes In The NoCo, which also airs weekdays in Morning Edition and All Things Considered. His work as a podcaster and journalist has appeared on NPR's Weekend Edition, NPR Music, the PBS Newshour, Colorado Public Radio, MTV Online, the Denver Post, Boulder's Daily Camera, and the Longmont Times-Call.

See stories by Brad Turner