Wild rainbow trout thrive in Gunnison as water managers forecast dry summer
The best and unexpected news coming from Thursday’s Aspinall Operations meeting, as compared to the challenging and not-unexpected news of continued drought, was notice of the return of wild rainbow trout to the Gunnison Gorge.
That news, conveyed by Colorado Parks and Wildlife aquatics biologist Dan Kowalski of Montrose, refutes fears that generations would be needed to recover the Gunnison’s once world-class rainbow trout fishery.
It’s accurate to say the fishery was decimated after the parasite conveying whirling disease was discovered at Ute Park in 1993.
The initial announcement was met with great concern, because at that time little was known about whirling disease except its devastating effect on trout, particularly rainbow trout.
The dire forecasts came true, the fishery crashed and the Gunnison’s future seemed bleak.
Incredibly, some great work by Parks and Wildlife biologists and researchers led to a long-term attempt at recovering the Gunnison and other Colorado fisheries hinging on a hybrid cross of wild Gunnison River rainbows with a hatchery raised whirling disease-resistant German rainbow trout.
As most long-time readers know, the eggs that originally stocked the German hatchery were harvested from the Gunnison River more than a century ago.
That century of living and reproducing in whirling disease-positive water gave the rainbow trout enough time to develop a resistance to the disease.
The Gunnison genes give the fish the ability to survive in a wild setting; the German parentage assures the young fish live long enough to survive infection.
Years of trial-and-error, indefatigable spirit and some masterful scientific endeavors have come to this: Once again there are wild rainbow trout living and reproducing in the Gunnison River.
“We’re not seeing whirling disease at the East Portal and now we have four to six year classes of wild rainbows in the Gunnison,” said Kowalski, one of the key people behind the rainbow trout revival. “Rainbow trout numbers at the East Portal are as high today as they were in the years prior to whirling disease.”
And on that high note, on to Thursday’s more challenging news: It’s going to be a dry summer.
Already water flows in many area rivers and streams are at levels usually not seen until late summer, and many water manager are forecasting this summer might be the driest since the severe drought of 2002.
That’s particularly true in southwest Colorado, where snowpacks are almost non-existent in a month when runoff should be dominating the news.
State conservationist Phyllis Ann Phillips of the Natural Resources Conservation Service said the snowpack hasn’t been this low since 2002, when the critical April reading also came in at 52 percent of average across all the state’s river basins.
That year, many anglers simply gave up fishing because of the physical toll the combination of warm water and the stress of angling was having on fish.
The Gunnison River below the East Portal already has been dropped to less than 400 cubic feet per second as the Bureau of Reclamation saves water in Blue Mesa Reservoir to meet summer demands.
At 400 cfs, anglers can walk across the Gunnison in a number (a high number) of places, meaning trout have fewer places to escape the relentless fishing pressure of a long summer.
“If it stays like this through the summer, you’ll really have to be careful about when you fish,” said Phil Trimm of Western Anglers Fly Shop in Grand Junction, noting that early morning flows offer the coolest water temperatures.
Some anglers have reported seeing stonefly nymphs in the Gunnison starting to move in pre-emergence style.
“I think the bugs are just like the fruit trees, everything is about two or three weeks early,” Trimm said.
In recent years, spring storms and high water have made fishing the stonefly hatch a test of the impossible, but this year the bugs, and the anglers, should be out in force.
“I expect the summer will be a really busy for us down in the Gorge,” said BLM river ranger Rooster Barnhart at the recent Bureau of Reclamation’s Aspinall Operations meeting. “Big water ruins the stonefly hatch but this year that’s not going to be a problem.”