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First came the fires. Then, the floods.
Now, wildlife agencies are concerned that ash-laden watersheds from this year’s wildfires have harmed at least two of New Mexico’s native trout species.
Crews this summer have rescued and relocated trout from burn scar areas. But ongoing flooding has complicated those efforts.
The Black Fire grew to more than 325,000 acres in southwest New Mexico.
Three Gila trout populations, including two genetically-pure “relic populations,” lived in the fire footprint.
Jerry Monzingo, wildlife and fish program manager for the Gila National Forest, said these fish “evolved with fire in the ecosystem.”
But historic drought has dried up much of the trout’s habitat.
“When all of these streams were connected, you could burn part of a watershed and it would impact one stream, but maybe not a tributary, so the fish could repopulate,” Monzingo said. “Now, the loss of connectivity prevents fish from moving from one stream to another, and naturally repopulating an area.”
Wildfires themselves may not harm the fish.
But ash, post-fire floods and debris can change the water chemistry in sensitive streams.
Monzingo said the floods can scour riverside plants and rearrange the stream habitat.
“Fire will also do that by burning the actual vegetation next to the stream system, and that increases the water temperature,” he said.
Warmer water is a threat to even the toughest trout species.
The Forest Service transported nearly 90 Gila trout from the burn scar to a Mora hatchery.
But severe burns and monsoon rains made one creek inaccessible.
“We feel pretty certain that we lost the population in South Diamond Creek,” Monzingo said. “We don’t know that for sure at this point, until perhaps this fall when we can get in and do some surveying to see if any fish survived.”
Rio Grande cutthroat trout
The Calf Canyon/Hermits Peak Fire burned across more than 340,000 acres in northern New Mexico this spring and summer.
Game and Fish spokesperson Ryan Darr said the fire impacted “high conservation value” Rio Grande cutthroat trout across the Canadian, Pecos and Rio Grande basins.
“We do not have any post-flooding sampling yet because flooding is ongoing, but we expect that some populations have been lost,” Darr said.
Game and Fish has rescued and relocated hundreds of fish this summer in the burn scar by working with the Forest Service, U.S. Fish and Wildlife Service and New Mexico State University.
Crews stun the fish with an electric shock device before transporting them by helicopter in oxygenated containers to a hatchery.
Biologists also add chemicals to the water that prevents infection by replacing fish slime that is lost with handling.
The team rescued genetically pure trout from the Rito Morphy southwest of Mora.
Those fish are at NMSU while the Forest Service removes non-native fish from a creek on the Valle Vidal.
Trout saved from Alamitos Creek near Holman were held at the state’s Seven Springs hatchery near Fenton Lake before being relocated into other waterways.
Seven Springs is housing a third trout population of about 180 fish rescued from the Valdez Creek.
“The Valdez Creek fish … will be used to establish a broodstock for eventual restocking of populations in the Pecos drainage,” Darr said.
Crews attempted a fourth rescue in the Rio Mora, a Pecos River headwater tributary, but Darr said the “fish had already perished.”
Fires can sometimes wipe out invasive fish species and open up habitat for native trout.
The 2012 Whitewater-Baldy Fire in the Gila eliminated non-native brown trout and rainbow trout from several streams.
The Forest Service was then able to restore Gila trout to those waterways over the ensuing few years.
But it can take a long time for streams to recover after catastrophic fires. Fish that are rescued from burn scar areas are more likely to spend the rest of their lives in a hatchery.
For trout that were already suffering from long-term drought and low water levels, the fires and floods could prove to be devastating.
“It could be years and years before that habitat supports the fish again,” Monzingo said.