Some high-country trout live in fragile habitats, and biologists and anglers alike are concerned that certain species may soon disappear. (Photo by Craig Springer/USFWS)
April 29, 2022
By Andrew McKean
Tim Brass looks across the horizontal landscape of northern New Mexico’s Rio Grande Plateau, peppered with juniper and mesquite shrubs. The river that named this place is well below us, in a water-scoured canyon, but Brass leads my eye to distant blue shapes out of focus in the shimmering heat.
He’s pointing out the island mountain ranges all around us, high mesas and alpine meadows that are defined by their abrupt rise out of the landscape and by the trees and even snow on their higher slopes.
They’re not part of the contiguous San Juan or Sangre de Cristo ranges with their long ridgelines stepping to crenelated peaks and manicured ski runs. Instead, these unattached ranges are much like islands in the ocean: small, distinct and swimming in a sea of sunbaked sagebrush and pinon.
That’s precisely their problem when considering the wild trout they hold, says Brass, at that time the Southern Rockies coordinator for Backcountry Hunters & Anglers (he’s now field operations director for the conservation group). We are gathered near Taos, N.M., mainly to fish the Rio Grande inside the Rio Grande del Norte National Monument, but it is hard to ignore those island ranges sailing across the pinon plateau all around us.
“Many of those ranges hold native trout,” notes Brass. “The Rio Grande cutthroat is the southernmost subspecies of cutthroats, and a number of streams have them in good numbers. Over in Colorado, native trout include the greenback cutthroat [federally listed as threatened] and the Colorado River cutt [considered a species of concern]. There used to be a yellowfin cutthroat, but it’s extinct.”
New Mexico has another native trout, the Gila trout, listed as an endangered species in 1973 but downlisted to threatened in 2006. It is similarly landlocked in the headwaters of southern New Mexico’s Gila River.
All these fish have a few shared attributes. First, they’re favorites of high-country anglers. Eager to take a drifted fly or a small spinner, they’re found in swift, high-gradient streams that are almost all on accessible public land.
Second, their habitat is getting smaller, warmer and dirtier by the year, and unlike rainbow or brown trout in a large river system, these tributary trout can’t move to more suitable water.
The Colorado River cutthroat (top), Gila trout (bottom right), and greenback cutthroat (bottom left) cutthroat are all species that exist in low numbers. As suitable high-country habitat is threatened, biologists and anglers worry that populations of these Western natives may soon be lost. Photos: Shutterstock (top), Craig Springer, USFWS (bottom right), Bruce Rosenlund, USFWS (bottom left) They can’t go downstream because their habitat literally ends after a few miles as water becomes too warm and lacking of enough oxygen to support them, or as flows are dewatered by diversions for irrigation or other uses. Upstream, the tributaries slow and flatten as they run into alpine meadows and beaver bogs. Because these native trout are so isolated in islands of habitat, they can’t utilize the main response of more mobile species to environmental change: migration.
HELP FOR HABITAT Conservationists are working on ways to insulate the cold-water habitat these native fish require. In some cases, that means timber management that reduces the risk of catastrophic wildfire. In 2012, some 300,000 acres of the Gila River’s headwaters were burned, eliminating the Gila trout from six of the species’ remaining eight streams. Adult fish were scooped out of rivers ahead of the fire by frantic volunteers in order to protect their genetic stock from loss.
Following the fire, ash and mud from the burned slopes slurried streams and further compromised trout habitat. Land managers are keen to avoid a repeat. But that’s hard as the continent’s climate warms, forest fire season is longer and more intense every year, and resources are often unavailable for either pre-fire mitigation or post-fire remediation.
Trout Unlimited (TU) announced last summer that its own studies of climate change indicate that the United States could lose as much as half of its viable trout and salmon habitat by the middle of this century. But TU says there’s some good news, too, and has put together a punchlist of measures that will help trout and salmon navigate a warming world.
The first is conserving the best remaining cold-water habitat, which TU’s president and CEO, Chris Wood, notes is “contained within large swaths of unmarred backcountry.” Ensuring that roadless areas remain undeveloped, and managing other disruptions in quality habitat are both readily achievable ways to conserve fish, says Wood.
Wildfires can raise water temperatures in tiny high-country streams and lead to excessive runoff, making the flows unfit for trout. (Photo by Craig Springer/USFWS) For example, TU advocates for “responsible logging” that keeps streamside buffers intact and ensures that trout and salmon streams have plenty of cooling shade. In addition, the group works with local communities, state and federal agencies and its volunteer base to decommission and remove outdated dams, and to fight “poorly conceived dam proposals” that would be harmful to trout and salmon.
Conserving water itself, which is available in limited quantities, is another organization objective. “TU works with farmers, ranchers and irrigators to make better use of water resources,” explains Wood. In some cases, that means retrofitting inefficient irrigation systems or paying water users to guarantee minimum pools for aquatic resources.
MORE CHALLENGES Compounding the problem of habitat decline is competition with invasive and non-native species, real threats that impair native fisheries. They come in all shapes and sizes, TU notes, from microscopic whirling disease spores to large mats of invasive rock snot. “These attackers either go directly after the fish themselves, such as non-native fish species that eat our native trout,” the group explains, “or they work to make habitat unsuitable.”
Further, TU says that “irresponsible” industrial development in trout and salmon country is another danger. The organization points to the impacts of fracking in the Marcellus Shale region of the East Coast and reports that about 40 percent of the West’s headwater streams are affected by abandoned mines and their toxic runoff. It also notes that “new mining proposals are often in places where the mere construction of a mine would trash irreplaceable trout and salmon habitat.”
Will mitigating these impacts, from development and strained water resources to non-native and invasive species, be enough to make the fragile high-country trout habitat of the island mountain ranges liveable for native fish? It’s hard to say. Some spots in the American Southwest are on pace to experience temperatures above 95 degrees for more than half the year by 2040 if current temperature trends continue.
Those temperatures will reduce snowpack in mountains, lead to wider and more intense drought conditions, and exacerbate forest fire intensity, according to climate authorities. For Brass and other advocates for native trout, that means we have little time to build resilience into what’s left of the cold-water habitat of the mountain ranges of the West.
“If you’ve ever fished for those little gems, then you know what it feels like to hold a native cutthroat in your hand, like a little piece of the sunset,” Brass relates. “We have to keep that as an essential experience for an American angler.”
Read more Conservation articles from Game & Fish
