Species 'Extinct' for Nearly 100 Years Bought Back to Life in Colorado

Robyn White - 

A picture shows a greenback cutthroat trout, a species once thought extinct.© CPW

The Greenback cutthroat trout, Colorado's state fish, was thought to be extinct in the 1930s, when it had been decimated due to mining pollution, overfishing and competition from other species.

Biologists from Colorado Parks and Wildlife (CPW) said on Friday that the fish is naturally reproducing, marking the official recovery of the once-extinct species.

CPW said in a statement that "this is huge," after more than a decade of "intensive efforts" to rescue the species from the brink of extinction.

The naturally reproducing fish were found in Herman Gulch, in Clear Creek County, Colorado, one of the first places in which CPW stocked the fish.

"The long-term survival and natural reproduction of the greenbacks discovered is a major milestone for our recovery efforts and a huge win for conservation," the CPW statement read.

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Several endangered populations were found in 1957, 1965, and the 1970s, but it was discovered that they weren't pure-bred trout, but rather a type of subspecies, CPW said in a news release.

The only pure population of the species was discovered in 2012, near Bear Creek, central Colorado, and biologists began making the trek there every spring to collect sperm and egg samples from the population of fish in the region.

A small population of the species were kept in a hatchery to enable breeding and to establish new populations, the news release said.

Biologists then gradually implemented the species in several places, including the Herman Gulch in 2016.

Now, six years later, that population has been recorded thriving and populating without their help. There are other, fledgling populations in four other streams, but the Herman Gulch batch is the only one so far to reach adulthood and begin populating on its own.

CPW will continue to place the sperm and eggs in other areas to stabilize the species.

Josh Nehring, CPW's assistant aquatic section manager, said the reproduction of the species was "truly monumental."

"CPW aquatic biologists in the Southeast Region have worked incredibly hard to protect and preserve the only known population of greenbacks in Bear Creek," Nehring said in a news release.

"Our hatchery staff along with our federal hatchery partners overcame immense obstacles to be able to replicate the species in captivity. Now to see them on the landscape in their native habitat replicating on their own is a huge sense of accomplishment for everyone involved."