As the New Mexico Department of Game and Fish works to update its fisheries rule, a remote stream in the Gila wilderness could be opened for angling.

Fishing has not been allowed in McKenna Creek in Catron County in an effort to protect a small Gila trout population. For decades, this population was believed to be one of the few remaining pure Gila trout populations. But now biologists say the trout found in McKenna Creek have hybridized with rainbow trout. 

The New Mexico Department of Game and Fish is updating its fisheries rule, which expires on March 31, 2022. The updated rule will likely remove the prohibition on angling in McKenna Creek as it is no longer needed to protect the Gila trout.

Jill Wick, the native fish biologist for the New Mexico Department of Game and Fish, said regular testing is done to analyze the genetic makeup of the trout populations. Subsequent genetic testing confirmed that the Gila trout in McKenna Creek had indeed hybridized with rainbow trout.

“We had a waterfall at the base of the creek that we thought that rainbow trout wouldn’t be able to get up and over,” Wick said. 

The genetic evidence shows that the waterfall was not able to serve as a natural barrier to protect the Gila trout. 

“There is a specific genetic makeup that defines what a Gila trout is, so when they’re interbreeding…with another species then we no longer have Gila trout,” Wick said. “They’re not a pure Gila trout anymore.”

Wick said there are 15 populations of Gila trout in New Mexico. The Gila trout is also found in Arizona.

Rainbow trout hybridize with native species

The rainbow trout was introduced in New Mexico in 1896 for fishing and the New Mexico Department of Game and Fish continues to stock waters with rainbow trout. However, the rainbows being stocked today are triploid rainbow trout. That means they have three chromosomes rather than two, which prevents them from reproducing.

While the stocking of rainbow trout has changed, the non-native species established itself in some waterways prior to that change. In these areas, the rainbow trout continue to breed with native trout species like the Gila trout. This places the native species at the risk of extinction.

Related: Rainbow trout plays a complex role in cutthroat restoration efforts

The Gila trout was listed as endangered up until 2006. Efforts by agencies like the New Mexico Department of Game and Fish led to the Gila trout being classified as threatened rather than endangered. 

In 1975, a couple years after the fish were placed on the endangered species list, McKenna Creek was listed as one of five locations with relict Gila trout populations. At the time, biologists thought the Gila trout in McKenna Creek were pure and could be used to repopulate other areas of the state with the fish.

In addition to hybridization with the rainbow trout, the Gila trout face threats like warming waters caused by climate change, changes in land use, impacts from wildfire and competition and predation by non-native trout.

McKenna Creek is unlikely to become a popular fishing destination

The department is considering opening McKenna Creek up for fishing. Wick doesn’t anticipate it becoming a popular destination for anglers. 

“That creek is really far away from anything,” she said. “It’s kind of in the middle of the wilderness and you have to hike really far or ride a horse really far to get there.”

Wick said, however, those who do decide to make the trek out to McKenna Creek should it be opened to angling would find good fishing.

She said McKenna Creek is on the list of potential recovery waters where the Gila trout could be reintroduced in the future and the invasive trout could be removed. But she is not sure if that will happen.

The factors that make it unlikely to become a popular destination for fishing also mean that the department is less likely to try to recover the Gila trout population in the creek. In addition to its remote location, a barrier would have to be installed to prevent the rainbow trout from jumping over the waterfall and repeating the problem.

“Since we know that rainbows can make it over that waterfall, we wouldn’t put Gila trout back in there because we would expect the same thing to happen,” Wick said.

Pinelodge Creek may also open up for anglers

The proposed updates for the fisheries rule also include opening Pinelodge Creek up for fishing. This creek in the Capitan area was closed when the New Mexico Department of Game and Fish attempted to introduce Rio Grande cutthroat trout.

Like the Gila trout, the Rio Grande cutthroat has been exterminated from much of its historic range and often hybridizes with rainbow trout. In attempts to expand the cutthroat’s range, biologists release stocked cutthroat into new bodies of water within the historic range. But not all of these attempts are successful.

Wick said none of the cutthroat released into Pinelodge Creek survived.

Pinelodge Creek was chosen because of a wildfire that had previously swept through the area. These fires can destroy fish populations, providing a blank slate for introducing the native trout. 

However, when the biologists went to survey Pinelodge Creek following the attempted reintroduction, they did not find any fish. Biologists have now concluded that the water temperature is too warm for trout.

Wick said the people who live near Pinelodge Creek used to stock brook trout in the stream, but these fish also didn’t tend to survive.

While the creek cannot naturally support trout populations, it could be managed as a seasonal fishery. This would require stocking trout.

Although McKenna Creek no longer has pure Gila trout and Pinelodge Creek cannot support Rio Grande cutthroat, Wick said the department is continuing its efforts to increase the places where those species can be found and to increase the populations in those areas.