Urgent Action to Save Spring-run Chinook Salmon

October 11, 2023

The California Department of Fish and Wildlife (CDFW) and National Oceanic and Atmospheric Administration (NOAA) Fisheries biologists are pursuing urgent measures this fall to save some of the last remaining Central Valley spring-run Chinook salmon after the numbers returning from the ocean this year fell sharply toward extinction.

Biologists call this year’s sharp decline a “cohort collapse” because so few threatened adult spring-run Chinook salmon returned to the small streams still accessible to them. Mill and Deer Creek — two of the three streams that hold the remaining independent spring-run populations — each saw fewer than 25 returning adults this year. Returns to Butte Creek — the third independent population — were the lowest since 1991 and adults further suffered impacts of a canal failure in the watershed.

“We are running out of options,” said Cathy Marcinkevage, assistant regional administrator for NOAA Fisheries West Coast region. “We want this species to thrive in the wild, but right now we are worried about losing them.”

Central Valley spring-run Chinook salmon typically follow a 3- or 4-year life cycle, a strategy that provides some resilience to catastrophic events occurring to an individual year class. While other year-classes (or cohorts) will return in coming years, the 2019-2022 drought impacted multiple cohorts, increasing risks for extirpation.

Biologists will capture juvenile fish from Mill, Deer and Butte creeks to start a conservation hatchery program that will safeguard the genetic heritage of the species. UC Davis will house the captive broodstock at the University’s Center for Aquatic Biology and Aquaculture (CABA) for the next two years until a longer-term facility is identified.

“These drastically low returns come at a time when we’ve already been taking extreme measures to protect salmon strongholds and eliminate existing barriers keeping them from their historic habitat,” said CDFW Director Charlton H. Bonham. “We’ve got to continue to do everything we can to preserve these iconic fish.”

Conservation hatcheries are vital to the protection and recovery of other highly imperiled salmon stocks, including endangered Sacramento River winter-run Chinook and Central California Coast Coho salmon.

“It’s a privilege to work with this species, and I’m glad we have facilities and expertise that can help,” said Nann Fangue, UC Davis professor of fish physiological ecology and director of CABA. “My staff, the students and our partners are all really dedicated to this work and to the goal of conserving native species.”

The remaining populations of spring-run Chinook are declining more than 10% each year and face high risk of extinction, according to an updated viability analysis by NOAA Fisheries’ Southwest Fisheries Science Center. One population initially benefited from strong adult returns in 2021, but more than 90% of the fish died prior to spawning when high stream temperatures exacerbated by thiamine deficiency and wildfires fueled a disease outbreak in 2021.

Central Valley spring-run Chinook also face high risk from climate change, since dams have cut off much of the high-elevation habitat where they once spawned in cold mountain rivers. Their survival in lower elevation habitat often depends on releases of cold water from reservoirs that face competing demands for their limited volume of water.

“These cold water fish need cold water and that is going to become more limited in California’s climate future on the Valley floor,” said Dr. Rachel Johnson, research biologist at NOAA Fisheries’ Southwest Fisheries Science Center and lead author of the spring-run viability analysis. Their survival in the high temperatures of lower elevation habitat often depends on releases of cold water from reservoirs that already face competing demands.

Scientists will strive to maintain the genetic diversity of the species through the hatchery broodstock program. As the instream flow requirements and habitat restoration efforts improve the odds of the fishes’ survival in the wild, biologists could use hatchery offspring to restore genetically diverse and locally adapted populations of spring-run Chinook in California’s rivers.

From what I have read most put the blame on lack of water flow from dams, drought and other factors, however researchers are now identifying an ingredient in car tires that can kill up to 80% of newborn salmon. They gave the manufactures till next year to remove this ingredient. The manufactures say  at least up to now they have not found a replacement and are unable to make a switch or to remove the ingredient.

This ties with this and is revealing.  Also posted here on the Butte Creek thread.

http://www.norcalkayakanglers.com/index.php?topic=101216.msg1133562;topicseen#new

Fish & Game concerned about the shrinking Chinook salmon population while protecting the invasive striped bass population with a slot regulation.  Why protect one of the biggest threats to young salmon on their way to the ocean?  Doesn't make any sense to me. 

Fish & Game concerned about the shrinking Chinook salmon population while protecting the invasive striped bass population with a slot regulation.  Why protect one of the biggest threats to young salmon on their way to the ocean?  Doesn't make any sense to me.

Last time I checked there was a concern of some "unintended consequences" because striped bass had filled some ecological niche and who knows what might happen if their numbers declined. If it's broke, trying to fix it might make it worse, I guess?

I was part of snorkel surveys counting spring-run Chinook in Deer Creek from 2003-2016. We went from a high of over 2,800 fish in 2003, to a low of 140 in 2008. After 2008, numbers vacillated from 300-1,000 adults per year. A total of 22 fish is shocking.

That 2,800 fish year was pushing the carrying capacity for Deer Creek. There just isn't that much spawning gravel to accommodate that many springers in there. Deer and Mill creeks were never huge springer producers, but they're nearly all that's left of what you could call true "native" springers in the CV mostly free of hatchery genetics.

Stripers aren't the problem. It's all about the water. There were too many years where adult springers couldn't make it upstream out of the valley in time before they died from high water temperatures. We had mass adult die-offs in the valley, especially around water diversion structures that occasionally were blocked with debris, or low flows due to lack of snowmelt in May.

I know Deer Creek like the back of my hand. Every pool from Upper Falls down to the west end of the Ishi Wilderness. To see the numbers crash like this is like a stab in the heart.

I was part of snorkel surveys counting spring-run Chinook in Deer Creek from 2003-2016. We went from a high of over 2,800 fish in 2003, to a low of 140 in 2008. After 2008, numbers vacillated from 300-1,000 adults per year. A total of 22 fish is shocking.

That 2,800 fish year was pushing the carrying capacity for Deer Creek. There just isn't that much spawning gravel to accommodate that many springers in there. Deer and Mill creeks were never huge springer producers, but they're nearly all that's left of what you could call true "native" springers in the CV mostly free of hatchery genetics.

Stripers aren't the problem. It's all about the water. There were too many years where adult springers couldn't make it upstream out of the valley in time before they died from high water temperatures. We had mass adult die-offs in the valley, especially around water diversion structures that occasionally were blocked with debris, or low flows due to lack of snowmelt in May.

I know Deer Creek like the back of my hand. Every pool from Upper Falls down to the west end of the Ishi Wilderness. To see the numbers crash like this is like a stab in the heart.

When discussing salmon in Deer Creek, I must admit to being a hypocrite.  I used to catch some very nice brown trout (another invasive species) in the beaver ponds on Gurnsey Creek (aka North Fork Deer Creek).  The brown trout fishery died after the beaver dams were removed in what appeared to be an effort to convert Gurnsey Creek into gravel beds.

I'm too old to fish the section of Deer Creek above the lower Deer Creek bridge and Big Smokey Creek, but in my youth, fishing in that section was well worth the hike.     Those were the days!