Climate-fueled wildfires heighten danger to struggling fish

AMALIA, New Mexico — Biologist Bryan Bakevich unscrewed the top of a plastic bucket and pulled out a cutthroat trout from the Rio Grande that squirmed and dropped onto the grassy bank of Middle Ponil Creek.

“He wants to go home,” Bakevich said, leading the fish into the cold, narrow creek – the latest leg of a three-month, 750-mile (1,207 kilometer) odyssey for this cutthroat and 107 others picked. in June from another stream in the mountainous north of New Mexico.

The largest wildfire on record in the state had roared dangerously near their former home, scorching trees and underbrush on nearby slopes. The summer monsoon season was approaching and heavy rains could wash cindery mud into the stream, clogging fish gills and choking the gravel bottoms where they feed and spawn.

State and federal crews rushed to the rescue, using electrofishing gear to stun and capture as many cutthroats as possible. They were trucked south to Las Cruces and held in tanks at New Mexico State University until Middle Ponil Creek was ready to receive them.

Today, wildlife agencies in the Southwest United States consider missions like this essential as climate change drives more frequent and hotter wildfires, fueled by prolonged drought and infestations of tree-killing insects. Particularly vulnerable are Rio Grande cutthroat trout and gila trout, rare species found primarily in small streams at high elevations.

“With each fire, more of their populations are affected,” said Jill Wick, native fish program manager for the New Mexico Department of Game and Fish. “Their habitat has often disappeared, washed away by the stream. There is no place where they can hide and cool off. Their food is also decimated.

The danger rises elsewhere. Tens of thousands of salmon, trout and other fish perished in August when a flash flood swept through a scorched area in northern California, sending a plume of sludge into the Klamath River.

Trout numbers have dropped by up to 80% in sections of Colorado’s Cache la Poudre River after summer 2021 flooding and mudslides, a survey has found. The largest wildfire in state history had scorched 326 square miles (844 square kilometers) in this area the previous year.

LOCATION MATTERS

Fire is not always bad for fish. Many species have evolved to benefit from the “unevenness and diversity” that wildfires bring to landscapes and waterways, said Dan Isaak, a U.S. Forest Service fisheries scientist in Idaho.

Gunfire and torrential rains are less common in the northern regions. Ashes tend to stay in place in winter snowfalls and seep into the ground or run off into waterways during the spring thaw. It provides nutrients to algae eaten by insects which becomes food for fish. Burnt trees overturn into streams, creating pools and rapids for feeding and spawning.

But further south, growing fires are incinerating so much foliage holding the soil in place that heavy debris flows are causing oversized algal blooms that can suffocate fish.

Their health also depends on surrounding features such as steepness of slopes, plant life and soil types, said Christopher Clare, habitat protection biologist with the Oregon Department of Fish and Wildlife. . And, Clare said, climate change is warming waterways, a problem that gets worse when fire deprives banks of shade trees.

Rebecca Flitcroft, a U.S. Forest Service fish biologist in Corvallis, Oregon, modeled the danger that fire poses to chinook salmon and bull trout in Washington’s Wenatchee River system that feeds the Columbia River.

Although both species are at risk, the results suggest that trout are worse off because they occupy cold, isolated headwaters. Fire intensity is higher there than in lower reaches of river systems favored by Chinook for easier access to the Pacific, Flitcroft said.

Human-made changes to waterways and landscapes make it harder for fish to survive during and after fires, she said. Water diversions have reduced habitat. Low levels caused by drought, along with culverts, roads and dams, prevent fish from fleeing to cooler places.

“We’re in a critical spot right now with very intense fires, made worse by very disrupted systems that don’t allow for connectivity and movement,” Flitcroft said.

Cutthroats in trouble

The Rio Grande cutthroat, New Mexico’s state fish, has long been in decline. Drought and dams have disrupted its habitat. Non-native brown trout and speckled trout, stocked for sport fishing, compete for food. Introduced rainbow trout interbreed with cutthroat, diluting its genetics.

Named after the reddish slashes under its lower jaw, the colorful cutthroat occupies about 12% of its historic range in New Mexico and Colorado, according to a 2019 study that predicted continued decline.

New Mexico had 92 populations of Rio Grande cutthroats at the start of this year.

The US Fish and Wildlife Service in 2014 denied a motion to place the cutthroat on the federal endangered species list, but was denied by a federal judge and is reconsidering. The non-profit Center for Biological Diversity had sued for the designation, saying the trout were “barely hanging on”.

But a listing could result in land use restrictions that many would find unpopular, said Toner Mitchell, New Mexico water and habitat coordinator for Trout Unlimited.

“There is a risk of demonizing or vilifying the Rio Grande cutthroat,” Mitchell said. “It could result in anything from vandalism to outright efforts to exterminate the fish, when on the whole long-time residents appreciate them.”

Crews have rescued cutthroat and gila trout from New Mexico streams more than two dozen times since the late 1980s.

“Before these mega-fires, there could be one or two struggling populations at a time,” Wick said. “Now it’s two or three times more.”

Nine Cutthroat Creeks were in the Calf Canyon-Hermits Creek Fire this summer, which started with two fires to clear undergrowth but spiraled out of control, consuming more than 530 square miles (1,373 square kilometers).

Ash wiped out the cutthroats from at least one stream. Trout were recovered from three others. Among them was Rito Morphy, a winding, tree-lined cove in the Sangre de Cristo mountain range.

Not all of the 190 fish there survived the stress of two car trips and months in university tanks. But the effort remained most alive until new habitat could be prepared at Middle Ponil Creek, about 58 miles from Rito Morphy.

This required poisoning rainbow trout in the section of the stream where the fish would be placed. “We want to make sure the cutthroat stays genetically pure,” said Alyssa Radcliff, biologist with the US Forest Service.

It’s ecologically important to preserve a rare strain of fish, Radcliff said. Another goal is to make more available for anglers. “A lot of people were taken by their grandfathers and grandmothers to these streams to catch these fish,” she said.

FINALLY FREE

On a recent sunny, windswept afternoon, a pickup truck pulled up along a dirt road in the Carson National Forest. Workers dug cutthroats four to eight inches (10 to 20 centimeters) long from a large cooler into several five-gallon (19-liter) buckets, strapped them to backpacks, and dragged them to through a meadow to the stream bordered by brush and strewn with rocks. .

When the buckets were tilted in the stream, the released fish would dart into the clear water and wag their tails in the sandy bottom. Their new digs extended from the headwaters of the creek to a wire and rock barrier eight miles downstream to keep rainbow trout out.

It was a quick end to a mission that lasted all summer, said Bakevich, the state’s native fisheries supervisor.

“After doing all the hard work and coming here,” he said, “that’s the best part.”

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Flesher reported from Traverse City, Michigan.

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Follow John Flesher on Twitter: @JohnFlesher.

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