On a fin and a prayer: Hundreds of tiny greenback cutthroat trout transplanted to their native habitat

Michel CooperLast Update : Tuesday 18 July 2017 - 1:30 PM
On a fin and a prayer: Hundreds of tiny greenback cutthroat trout transplanted to their native habitat

HERMAN GULCH — If Colorado’s imperiled state fish can still survive anywhere in its native South Platte River Basin, government wildlife biologists say, it would be here: isolated tundra headwaters 4 miles above traffic racing toward Eisenhower Tunnel on Interstate 70.

The biologists have purged this gulch of all other fish competitors.

But the first pure greenback cutthroat trout dropped into chilly streams Monday morning simply quivered at edges of eddies.

These captive-bred 1-year-olds — 960 of them — are thought to be hardier than the 4,000 hatchlings that Colorado Parks and Wildlife biologists put in Herman Gulch last year. State crews conducted a survey last week and found no evidence any of the hatchlings survived the hard winter.

A whole lot of people really want the greenback cutthroats to make it in their ancestral home.

So on Monday morning, an expanding cutthroats recovery team coordinated by CPW mobilized, with more than 50 volunteers from Trout Unlimited and other conservation groups hauling 20-pound bags of the 5-inch fish into the high-country basin.

“C’mon, sweetheart,”  said Tom Riegelman, 63, a Golden hotel industry consultant and lifelong Trout Unlimited member who carried his load of fish to a high spot beneath snow-splotched cliffs of Pettingell Peak.

He carefully lowered the fish into a protected, 3-foot-deep pool, leaving them in a plastic bag for about 15 minutes to minimize the shock of cooler water temperatures before slicing open the bag. He chose the spot for its ideal conditions, “with lots of insect life along the edges, lots to eat” and vegetation, and sunshine that lit up the cutthroats’ spots.

Most understood this is something of an ecological longshot because greenback cutthroats — listed as threatened on the nation’s endangered species roster — have all but disappeared. After all, evolution is all about change, and species come and go.

Greenback cutthroats originated in the South Platte River Basin headwaters. They disappeared as humans settled the region, mining for gold that turned water toxic, stocking streams with nonnative fish in hopes of promoting tourism.

State wildlife managers declared greenback cutthroats extinct in the 1930s. But they rediscovered them in 1953 and celebrated them in 1994 as Colorado’s official state fish. However, the fish that Colorado wildlife officials touted as the state fish was a different species of cutthroat trout.

In 2012, University of Colorado genetics scientists determined that only a few greenback cutthroats survived in the wild, by a fluke, southwest of Colorado Springs, in the Arkansas River Basin. Back in the 1870s, aspiring hotel resort operator Joseph Jones had captured some greenbacks from South Platte headwaters and plopped them into Bear Creek near his property. CU scientists verified that only the descendants of those fish carried the true greenback cutthroat genes.

CPW officials now are working intensely, gathering genetic material from Bear Creek fish and breeding tens of thousands of greenback cutthroats in hatcheries created to stock Colorado streams with trout that compete with native species.

CPW crews already have transplanted some greenback cutthroats successfully into Zimmerman Lake, west of Fort Collins.

“This would be the first steam,” CPW aquatic biologist Boyd Wright said Monday, directing the transplanting operation along 3 miles of streams. “And this is a fish that evolved in streams.”

“Ultimately,” he said, “streams are where we want to see them back.”

If this second attempt at getting greenback cutthroats to survive in Herman Gulch fails, CPW officials said they’ll try once more next year. State crews this year also are planning to drop cutthroats into Dry Gulch, to the west of this site, and into Rock Creek in South Park.

But much depends on how the fish respond in this ideal habitat, a basin considered ecologically healthy. Biologists used a rotenone poison to clear out nonnative trout that they say would have meant doom for the cutthroats. The poison targets just fish, preserving midges, flies and other insects that fish eat.

And around noon Monday, a slow situation turned for the better.

Volunteers noticed that after about 20 minutes in the water, the fish began twisting and turning their spotted flanks. A few darted into currents from calm eddies.

“This is perfect. Look, see, he just moved,” CPW technician Matt Guyerson, 25, said at the top of Herman Gulch, looking down on a fish that food designer Angela Hawkins, 39, of Arvada had just lovingly released from her pack.

“He’s happy — trying to find a good hole to hide in,” Guyerson said. “They’re starting to move, just like wild populations would.”

And a few of the introduced cutthroats began bolting up from muddy pools toward midges and flies dancing along surfaces of streams.

Trout Unlimited member Neil Fjeldheim, 61, smiled broadly,

“It tells me they’re acclimatizing fast. Almost all of the ones I introduced had their heads up, looking up at the surface. I saw six rises,” Fjeldheim said. “None died.”

Retired critical-care nurse Doug Smith, 67, spotted four fish cutting into currents and then flipping around robustly. One of them occasionally rose toward the surface.

“C’mon, guys, you’ve got to go to the surface and get the bugs,” Smith said.

Even if the greenback cutthroats don’t survive in their native habitat, the fish-saving effort is valuable, Riegelman said.

“You cannot change the direction of evolution,” he said. “I don’t think we can turn the clock back. But we can still preserve all kinds of wonderful things in the environment.”

And even if restoration proves impossible, he said, “we will learn to be better stewards.”

Source: denverpost

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Michel Cooper