California’s spring Chinook salmon population was already in collapse before the Park Fire spread across the state. Fourth largest wildfire in history. Biologists now fear the fires could scorch forests along creeks that provide critical spawning habitat, pushing the fish closer to extinction.
Wildfires have been burning in the upper Mill River and Deer Creek watersheds, threatening forested canyons that provide the last intact spawning habitat for spring Chinook salmon.
“The fact that this fire is entering an upper watershed where there is sensitive spawning and rearing habitat is concerning,” said Matt Johnson, senior environmental scientist for the California Department of Fish and Wildlife. “The timing of a wildfire is very concerning. “It’s highly inappropriate for the species, and the wildfires were caused by a hundred years of fire suppression and climate warming.”
The two creeks are considered critical for spring Chinook salmon, which are threatened by the federal government and whose populations have long declined due to water diversions, dams preventing them from reaching their spawning grounds and growing droughts exacerbated by climate change. .
Even before the fires, biologists were so alarmed by the recent collapse of spring salmon populations that last year they Start catching juvenile fish Coming from Deer Creek to raise them in captivity.
Fires burn near stream areas where adult fish often swim in deep pools for weeks before spawning in the fall. Young fish that hatched last winter also remain in the creek this time of year and could be at risk, Johnson said.
Population surveys along two tributaries of the Sacramento River have been delayed because of the fires.
a man has Charged with arson, Accused of starting a fire in Chico when he pushed a burning car into a ravine. crime suspect Deny the accusations.
California’s fire suppression over the past century has left a heavy fuel burden on forests.
Biologists worry that if the fires burn intensely in the watershed, exposed dirt and ash could fill creeks when rains come, severely damaging water quality and possibly killing fish.
“If we have a very hot fire that burns away the vegetation that holds the soil together, we could have increased sediment, debris and ash flow,” Johnson said.
While less intense flames are good for the ecosystem, destructive fires that destroy large trees can loosen soil, allowing it to wash into creeks and harm fish, he said.
Severely burned watersheds are also prone to landslides that can overwhelm streams.
“We’re still waiting to see how the fire evolves,” Johnson said. “We are all very anxious about the outcome.”
These creeks are sustained by springs and snowmelt from Mount Lassen and surrounding mountains.
Two small streams flow through a rocky canyon, shaded by pine and Douglas fir trees and with ferns growing on their banks.
In late September and October, salmon spawn in clear, cold waters, laying their eggs in the gravel.
Matt Johnson, a senior environmental scientist with the California Department of Fish and Wildlife, looks at an inflatable fish transport box containing spring run Chinook salmon caught in 2023 from Deer Creek.
(Peter Thiela/California Department of Fish and Wildlife)
For more than 20 years, Johnson regularly returned to the area to survey, walking miles along trails to spawning areas.
“This is one of the most beautiful salmon habitats left in the Central Valley,” Johnson said. “If it was badly damaged, it would be painful to see.”
Johnson said he expects the fires to have a variety of impacts — burning intensely in some areas but causing less damage in other areas. If the watershed is severely scorched, the habitat could be degraded in the coming years or decades, he said.
For state scientists who have been working to help salmon, the park fires could upend their long-term strategies.
“We’ve been treating this habitat as a safe bet,” Johnson said. “But now prime habitat is under threat.”
In 1999, the spring-running Chinook was listed as a threatened species under the federal Endangered Species Act.
“The level of harm to fish really depends on the specifics of the burn,” said Steve Lindley, director of fisheries ecology at NOAA’s Southwest Fisheries Science Center. “If it completely erodes the hillside and kills all the vegetation , that’s bad. It’s also bad if it burns directly into the water, which usually doesn’t happen. Riparian areas around streams are usually much wetter than upland vegetation.
After successive droughts, dwindling spring salmon populations now rely heavily on these two creeks as well as Boot Creek, another tributary of the Sacramento River.
If some habitats are lost, Lindley said, “there’s really not much you can do to save them elsewhere because other populations are so few and they’re all relatively small.”
“These populations really suffer during droughts,” Lindley said. “It was just one thing after another. Its numbers kept increasing to the point where they were really on the verge of extinction.
Scientists have warned for years that large, destructive wildfires could harm remaining salmon populations. Lindley and other scientists said in a report 2007 report Wildfires in Mill Creek, Deer Creek, and the headwaters of Butte Creek pose a significant threat to the Chinook River in the spring.
These fish were once abundant in rivers and streams throughout the Central Valley, but dams have prevented them from reaching many of their habitats in mountain streams.
While salmon are able to survive California’s natural fire cycle, their smaller numbers, combined with larger, more destructive fires, now create a potentially deadly combination.
“What we’re facing now are these mega wildfires that are exacerbated by climate change. We’re reducing fish populations because of all these other impacts — dams, water withdrawals, pollution,” said Professor of Fish Ecology and Watersheds at UC Davis said Science Center Director Andrew Rypel. “All these other effects have weakened them.”
Ripert said he fears this fire and others like it could “either wipe them out or make it worse.”
