High Country News: The long journey of the Gila trout
November 10, 2013
A caravan of mules and horses follows a stream-side trail lined with spring-green cottonwoods and alders through New Mexico's Gila National Forest. Some of the mules carry two metal boxes secured to their sides with thick purple webbing, and each box houses roughly 75 fish in water that sloshes throughout the 5-mile trek. One set of panniers weighs roughly 150 pounds and can throw off the mule's balance at the trail's river crossings. "If you're behind them, you can tell it's not easy," says Jill Wick, a trout biologist with the state's Department of Game and Fish.
While the experience is cumbersome for the mules, it's nothing short of bizarre for the threatened Gila trout, a small, freckled, golden fish that has been pushed to the brink by introduced game fish. Its existence now depends on a carefully orchestrated, human-assisted loop tacked onto its life cycle.
Each spring after the Gila trout spawn, members of the trout recovery team travel to the headwaters of the Gila River in the state's southwestern corner. Wearing waders and heavy backpacks with 24-volt battery systems, they shock the water and collect a variety of young and older stunned fish that rise to the surface to use for captive breeding.
This abduction is stressful for the fish, triggering an adrenaline rush and changes in blood chemistry. So the biologists doctor the panniers' water with medicine, aerate with oxygen and carefully regulate the temperature. At streams up to 5 miles from roads, the fish ride out on mules. Deeper into the wilderness, they fly out suspended from a helicopter's belly in a large metal box.
The final leg of this unusual journey is a 400-mile truck ride on Interstate 40 to a hatchery in Mora, N.M. The trout's offspring eventually help rebuild populations in new mountain streams, but after two years of well-fed life, the trophy-size adults are too big to return home. At 22 inches, they couldn't survive in the trickle that fills the headwaters, so they are returned to lower elevations near the river's main stem.
Gila trout first appeared in scientific literature in the late 1950s, when only five populations existed. By that time, says U.S. Fish and Wildlife Service biologist Jim Brooks, a member of the recovery team, "They were relegated to a few headwater streams" in the southern mountains of New Mexico. Brown trout were eating the young Gila trout, and rainbow trout diluted the gene pool by mating with them; the larger fish also outcompeted the Gila for food and space.
In 1966, the species was listed in the federal red book that pre-dated the Endangered Species Act, and in 1975 it was listed as endangered. With careful management, the fish rebounded enough that, in 2006, it was down-listed to threatened. But while managers have been able to use poison to cull brown and rainbow trout from some Gila streams, they can't introduce such chemicals to streams that pass through towns or over private property — one of many obstacles to further recovery efforts.
In May 2012, though, they received backhanded help when the Whitewater-Baldy Fire tore through 300,000 acres of the Gila National Forest. Officials feared that the impending monsoon season would sluice toxic ash and sediment into streams, killing all the fish. As soon as they received Forest Service approval, the recovery team raced to the most critical populations, rescuing all the Gila trout they could find. When they returned after the summer rain, many of the streams had indeed been scoured of life.
"It did damage to watersheds that will take decades to recover, and Gila trout will suffer because of it," Brooks says. But it also opened a new opportunity to restore some streams for Gila trout, especially those near towns. Once the habitat does recover enough to support the fish, the recovery team can begin reintroducing them with a clean slate, largely free from competition. In streams like Whitewater Creek, prime Gila trout habitat that trickles from the main fire scar area down into the town of Glenwood, Wick says that removing the exotic fish "couldn't have been done any other way."
This story was funded by a grant from the McCune Charitable Foundation.