Southwest Environment

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Department of Soil, Water and Environmental Science
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Gila trout return home to southeastern Arizona

By Brian Hickerson

Photo courtesy of Arizona Game and Fish Department
Gila trout are airlifted in 50-gallon drums to drop sites of Frye Creek.

High up the east side of southern Arizona’s Mount Graham, native Gila trout are thriving in a five-mile-stretch of Frye Creek decades after they had disappeared from the mountain stream. The reintroduced Gila trout in Frye Creek are some of the only members of this threatened species in the state of Arizona.

The Gila trout, native to a few river drainages of Arizona and New Mexico, was federally listed as endangered in 1967 under the predecessor to the Endangered Species Act. There were only five known populations of Gila trout in the world, all residing in small streams in the Gila Wilderness Area of New Mexico.

Forty-two years later, 500 Gila trout (Oncorhynchus gilae) were being airlifted via helicopter across the November sky for reintroduction into Frye Creek in 2009. Restoration efforts in New Mexico led to the species being downlisted to threatened status in 1988.

The reintroduction of Gila trout into Frye Creek was made possible by the cooperation of several federal agencies including: the U.S. Forest Service, the U.S. Fish and Wildlife Service, the New Mexico Department of Game and Fish, the Arizona Game and Fish Department, and volunteers. Collectively the government agencies working on the project are called the Gila Trout Recovery Team.

Gilas were eliminated from Arizona by a number of factors, said Jason Kline, a fisheries specialist with the Arizona Game and Fish Department. He explained that the main contributors were overfishing, impacts of overgrazing and wildfires, and cross-breeding with non-native trout species.    

A lack of fishing restrictions on Gila trout populations in the early 20th century led to creeks being depleted of these bronze-colored, coldwater fish, according to the Gila Trout Recovery Plan, a document prepared by the team of government agencies. For several decades after that, these empty creeks were restocked with a distant relative, the rainbow trout, so people could continue to fish. It turned out that some of the creeks stocked with the non-native rainbow trout in New Mexico and Arizona still had Gila trout populations, which muddled the genetic integrity of the species.

Little was known about native trout prior to federal listing of both species as endangered. The Gila trout was not even formally described until 1950, the recovery plan notes.

“Records for fish are kind of sketchy,” Kline said, due in part to the remote location and confusion regarding some of these fish populations. Early in the 20th century, officials believed that Apache and Gila trout, two different species, were one species, sometimes called Arizona trout, Kline explained.

To begin restoring populations of Gila trout in southeastern Arizona, the recovery team identified three creeks on Mount Graham’s east side for reintroduction efforts: Marijilda Creek, Ash Creek, and Frye Creek, Kline explained. The decision to stock Frye Creek first was made by nature. The ash flows following the Gibson Fire of 2004 killed all non-native fish species in Frye Creek, he said, which meant that the creek didn’t have to be renovated using chemicals to kill non-native species.  

Frye Creek was first stocked in 2009 with 500 fish and the help of the Gila Trout Recovery Team and volunteers. Mike Mehrer, president of the Old Pueblo chapter of Trout Unlimited and Clay Hernandez a member of the chapter, were some of the volunteers who helped carry the trout down to the creekGila trout Photo courtesy of Arizona Game and Fish Department
Gila trout are released from buckets into Frye Creek in November of 2009.

“There were four helicopter drop points for fifty-gallon drums of trout,” Mehrer said. “We then had to carry the trout in five gallon buckets to the deeper holes” of the stream.

The mission of Trout Unlimited is basically to maintain coldwater habitat for salmonids, Mehrer said. Salmonids are all the fish species in the trout and salmon family and include everything from Gila trout of the Southwest to Atlantic salmon of the Northeast. After members of the Tucson-based chapter spent years of volunteer work restoring Apache trout populations in Arizona’s White Mountains, Mehrer explained, “We began to look nearby Tucson for restoration work.” They heard about the Frye Creek project and joined on.

The group plans to help out on upcoming Gila trout restoration efforts in other creeks on Mount Graham in the Pinaleño Mountains near Safford as well, he said.

One creek there, Ash, has been chemically renovated and has received a small stocking of Gila trout from the Spruce Creek lineage, according to Jeremy Voeltz, a fisheries biologist with the U.S Fish and Wildlife Service.

Frye Creek was stocked a second time in a similar manner in February of 2011 to boost the existing population. This time 650 fish were added to the stream. Frye Creek was most recently stocked in mid-November of 2011 with a 100-fish load to the lower reaches of the stream, according to Voeltz.

“We were there the week before Thanksgiving and fish had already spread throughout the range and are reproducing," Voeltz said.

Kline explained that a successful reintroduction is measured by “fully occupied habitat” more than a set population number. Currently, successful reproduction and recruitment have been documented in the Gila trout population in Frye Creek, according to Kline.

“Reproduction means fish are having babies,” Voeltz explained. “Recruitment means that the babies grow to sexual maturity to reproduce.”

As Kline explained, the project is important because “it’s recovering a native species. Its part of our heritage here.”

There are also plans to open up Frye Creek to special regulation catch-and-release fishing in the near future, perhaps some time in 2012. Frye Mesa Reservoir, a small impoundment at the lower reaches of Frye Creek, was stocked in the spring of 2011with retired breeding fish from Mora National Fish Hatchery in New Mexico. This created an opportunity to fish for Gila trout in Arizona for the first time in decades.

“We had people come from as far away as British Columbia, Idaho, and Wyoming,” said Kline, “just to catch a Gila trout.”

Kline, Voeltz, and Mehrer are all optimistic about the future of the Gila trout and the opportunities for reintroduction in southern Arizona.

As Voeltz explained, individual species are like the rivets in an aircraft wing, and as you lose species, you lose those rivets. “Eventually that wing isn’t going to work anymore and you aren’t going to want to be on that plane.”

Brian Hickerson is a sophomore at the University of Arizona majoring in fisheries management. As an Arizona native, he has an appreciation of the native fishes of Arizona.


Related Story: Protecting diversity in Gila trout

Gila trout background

Endangered Species Act

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