The effort to save #Colorado’s state fish — greenbacks

From The Denver Post (Bruce Finley):

Some slippery, spotted greenback cutthroat trout — Colorado’s long-lost and imperiled state fish — took a hit for their species Tuesday morning.

Not that the trout, lolling in a shady mountain creek southwest of Colorado Springs, had a choice.

They endured five Colorado Parks and Wildlife biologists sloshing into their already-degraded habitat to collect genetic material – eggs and milt – as part of an unprecedented ecological rescue. CPW’s Cory Noble lugged a 30-pound LR-24 Electrofisher strapped to his back, beeping like a backing-up beer truck, red light flashing, shooting electricity into the water. Cutthroats stunned by the electricity found themselves netted and then squeezed by CPW senior aquatic biologist Josh Nehring.

“It’s a female,” he said, grabbing one and massaging her pale-yellow belly with his thumb. “I got one egg out of her.”

The point?

“To improve their genetics. It is very important. This is our only known reproducing population of greenback cutthroat trout,” Nehring said, leading this mission in a three-week blitz that has collected up to 5,400 eggs in a day.

“These fish were here before man was here,” he said. “It is a unique species, a native fish. It fills a niche in the environment.”

CPW crews haul the harvested pink eggs and milky-white milt to the U.S. Fish and Wildlife Service’s National Fish Hatchery, atop the Arkansas River basin at Leadville. There, federal biologists running a captive-breeding program, using wild milt, artificially fertilized 73,000 greenback cutthroat eggs last year.

The greenback cutthroat rescue ramped up in 2012 when sleuthing by a University of Colorado team verified that the one true population of greenback cutthroat trout lives along a 3.5-mile stretch of Bear Creek southwest of Colorado Springs. While greenback cutthroats originated in the South Platte River basin, they vanished as humans settled the region. However, aspiring hotel resort operator Joseph Jones, owning property along Bear Creek in the 1870s, captured a few greenbacks and plopped them into Bear Creek hoping to draw tourists to his mountain retreat. And because of his actions, the species survived.

Greenback cutthroats were declared extinct in the 1930s, then rediscovered in 1953 and celebrated in 1994 as Colorado’s official state fish. For years, Colorado wildlife officials touting the state fish inadvertently pointed to other types of cutthroat trout. But the CU researchers determined that only the Bear Creek population carried the true genes — based on DNA analysis of cutthroats caught around Colorado compared with DNA from greenback cutthroat specimens preserved in East Coast museums. This revelation rankled some anglers who fished such Colorado high-country sweet spots as Rocky Mountain National Park and thought they caught the real thing…

CPW biologists on Tuesday said the Bear Creek habitat seems to be improving. Their latest greenback cutthroat population survey estimated 750 fish live along the 3.5-mile stretch, and they’re anticipating a new survey this fall will show a healthy increase. Greenback cutthroats are left to reproduce naturally along upper curves of the creek.

The rescue is gaining momentum. After collecting genetic material here to boost captive-breeding, CPW crews transplant thousands of greenbacks from the hatchery into native habitat in the South Platte River Basin — Zimmerman Lake west of Fort Collins, and several headwaters creeks, including Dry Gulch and Herman Gulch near the Eisenhower Tunnel, Rock Creek in South Park and Sand Creek west of Fort Collins.

Fishing for greenback cutthroats is illegal. Federal wildlife authorities have designated them officially “threatened” on the list of species protected under the Endangered Species Act, the nation’s system for preventing extinctions.

The state and federal biologists face challenges. Deformities are appearing in captive-bred greenbacks — distortions of the jaw and the gills that fish use to breathe underwater. More than 100 years of isolation in Bear Creek has rendered greenback cutthroats extra susceptible to sickness.

This compels the intense focus on improving fish genetic diversity by infusing fresh genetic material. The genetic diversity builds resilience.

“We have seen better survival in the hatchery using wild genetics,” Nehring said. “It is important to make sure that the populations we are putting out on the landscape are healthy.”

And the captive-bred greenback cutthroats released into the South Platte basin face threats from invasive nonnative fish competitors. Those creeks now are full of brook and rainbow trout introduced for sport fishing. In order to re-establish greenback cutthroats in the wild, CPW crews plan to clear creeks manually and by injecting Rotenone poison to wipe out the nonnative fish…

Eggs are fertilized along the creek, using mixing bowls and syringe-like injectors, because the eggs cannot survive longer than a day. Then crews move the fertilized eggs along with any extra milt in plastic coolers to the hatchery.

Before the biologists trudged up Bear Creek, the greenback cutthroats hung out placidly in pools, occasionally darting into faster currents to snap up flies.

CPW intern Katelyn Behounek brought up the rear gripping a large net as the collection crew worked their way up the creek, kicking through eddies and riffles, making sure zapped fish were caught.

“When you are protecting the species,” Behounek said, “it is not a disturbance.”

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