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Colorado state fish, once believed to be extinct, is naturally reproducing in the wild once again

The species was thought to be extinct for decades.

COLORADO, USA — Greenback cutthroat trout, the state fish of Colorado, have naturally reproduced in their native waters for the first time since an intensive stocking program designed to bring the species back from extinction began six years ago.

Colorado Parks and Wildlife said they discovered adult fish and fry in Herman Gulch, which is part of the South Platte River drainage. Fry are young fish that have developed to the point of feeding themselves.

“Our team of field technicians literally high-fived right there in the stream when we captured that first fry that was spawned this year,” said Boyd Wright, an aquatic biologist out of Fort Collins. “When moments later we captured a one-year-old fish produced in 2021, we were truly beside ourselves.”

> The video above shows wildlife biologists stocking the trout in 2021.

Credit: Colorado Parks and Wildlife
A one-year-old greenback measuring three inches was found in a recent CPW survey of Herman Gulch. It is the first evidence of adult greenbacks naturally reproducing in the creek west of Denver.

In 1937, the greenback cutthroat was thought to be extinct due to the species being wiped out by pollution from mining, pressure from fishing and competition from other trout species.

Decades later, in 2012, Colorado Parks and Wildlife discovered a population of greenbacks in a small creek on the southwest edge of Colorado Springs. The trout species is not native to that area, so biologists think the fish were brought there in the late 1800s for a tourist fishing enterprise. 

RELATED: This type of trout was supposed to be extinct, but it was found in southwest Colorado

For years, the 3 1/2 mile stretch of Bear Creek was the only place known to have naturally reproducing greenback cutthroat trout.

Credit: Colorado Parks and Wildlife
This 12-inch greenback cutthroat trout was among those found in a recent survey of Herman Gulch by Colorado Parks and Wildlife aquatic biologists.

That led to a massive effort to protect the water that was holding these fish, as well as bring them back to their native water. CPW crews hiked into Bear Creek to capture the fish, fertilized greenback eggs in labs and hatcheries and stocked fry in water where biologists thought they might reproduce.

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The first greenback fry were brought to Herman Gulch in 2016, and this is the first time Colorado Parks and Wildlife has been able to confirm they are naturally reproducing in that area.

Other streams in the South Platte River drainage have also been stocked with greenback in the years since, but it has not been long enough for those fish to reach adulthood and start reproducing.

"While we will continue to stock greenback trout from our hatcheries, the fact that they are now successfully reproducing in the wild is exciting for the future of this species," Gov. Jared Polis said in a release. "CPW's staff and our partner agencies have worked for more than a decade to restore this beloved state fish, and [Friday]'s news truly highlights the success of the work."

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