‘Near-complete loss’ of young salmon in Sacramento River possible, California officials say


The California Department of Fish and Wildlife staff on the ground is monitoring drought impact – and among the alarming results is the “possibility of a near-complete loss” of young, winter-run Chinook salmon on the Sacramento River this fall due to a water reduces supply and persistent dry, hot weather.

The waters of the Northern California River can become so hot that almost all the eggs and young in this endangered species, which migrated from the Golden Gate in winter and spawned just below the Shasta Dam in the Sacramento River in spring and summer, could die, according to California wildlife officials.

To cool the Sacramento River and protect the incubator and young eggs in summer and fall, the state releases water from Shasta Lake into the river. But after two consecutive dry winters, water in California’s largest reservoir is quickly disappearing. The lake was at 46% of its historical average as of Monday, the state done showed. There may not be enough water to release enough cold water to support fish survival.


“Patterns of monthly surgery predict high mortality levels for Chinook salmon during egg incubation in the Sacramento River due to limited cold water pools in Lake Shasta and upstream water delivery,” Fish and Wildlife said in a statement. “Unforeseen depletion has resulted in increased releases from many reservoirs in the Central Valley. The State Water Project and the Central Valley Water Project are trying to balance many beneficial uses, including municipal drinking water.


“Chinook salmon mortality during egg incubation could be higher than originally predicted. It is an extreme series of cascading climate events pushing us into this crisis situation.”


The Sacramento River supports one of the great southern runs of Chinook salmon in North America. There are four different salmon running on the river that flows for 400 miles from the Klamath Mountains to the Central Valley before reaching the Sacramento – San Joaquin River Delta and San Francisco Bay.

The winter-running salmon enters the Sacramento River system in late January through February, but runs may persist into June. The adult fish spawn, or lay their eggs, in the Sacramento River evolving into red bluff and spawn from late April through August.

Fish are conditioned to spawn in cold water, as the winter runs historically lay their eggs in the ice-cold rivers of the Sierra High fed by snowmelt, such as Little Sacramento, McCloud and the Pit Rivers.

“But they can’t stand up anymore,” said fish ecologist Andre Rypel, an associate professor at UC Davis and co-director of the Center for Watershed Science. “One of the big dams that gets in their way is Shasta. There are no fish passages around it. The dams have blocked them from their spawning historic habitat.”

The winter run now spawned in the Sacramento River, and the surroundings are controlled by cold water from Shasta Lake.

“This is a fish that is very vulnerable to climate change,” said Rypel. “Most of the management around the winter-running salmon is temperature management. Shasta Reservoir is a large deep lake … It all revolves around the cold water pool in Shasta. There is a certain finished volume of cold water. If drought “When you run out of cold water, when you run out of cold water, a large fraction of the juveniles will die.”

A view down the spill of the Shasta Dam into the Sacramento River in Shasta Lake, California, on Wednesday.  April.  4, 2018. The Trump administration and Republicans want to increase the height of Shasta’s dam.

A view down the spillway of the Shasta Dam into the Sacramento River in Shasta Lake, California, on Wednesday. April. 4, 2018. The Trump administration and Republicans want to increase the height of Shasta’s dam.

San Francisco Chronicle / Hearst N / San Francisco Chronicle via Gett

Chinook salmon in the Sacramento River winter have suffered severe declines in population size for decades and are federally listed as endangered. The fish population saw a long, slow decline after the construction of Shasta Dam between 1938 and 1945, and then a rapid decline during certain periods such as the late 1970s, Rypel said.

Data going back to 1967 show that the population of spawned hit a high of 117,800 in 1969 and went all the way down to only 200 fish in 1994, according to a 1998 paper published in the North American Journal of Fisheries Management.

Pacific United States Marine Fisheries Commission fishing technician Kaitlin Whittom pulled a dead salmon from the Sacramento River while working alongside U.S. Fish & Wildlife Spear biologist and surveyed the number of dead winter-run Chinook salmon due to low-level, heated water in the Sacramento River in Redding, California Wednesday, July 7, 2021.

Pacific United States Marine Fisheries Commission fishing technician Kaitlin Whittom pulled a dead salmon from the Sacramento River while working alongside U.S. Fish & Wildlife Spear biologist and surveyed the number of dead winter-run Chinook salmon due to low-level, heated water in the Sacramento River in Redding, California Wednesday, July 7, 2021.

San Francisco Chronicle / Hearst N / San Francisco Chronicle via Gett

The winter-run salmon saw significant compromise deaths in both 2014 and 2015 during the last major drought.

“It’s happened before, but the problem is if we start losing several years of grades in a row,” said Rypel. “This is an animal that spends a year in fresh water and two years in the sea. So every year class matters, and if you lose one you inch ever closer to the possibility of an extinction event. We are not far from extinction for the winter to run. “

While there’s talk of long-term solutions to help save the winter run, such as trapping the fish and hauling them to get colder and tributaries, this year it all comes down to the cold water pool at Shasta Lake.

“If they can maintain that fresh water pool in Shasta reservoir long enough to meet the demand, we can save them, but most experts think that will probably not happen,” Rypel said. “We are very worried about a major mortality event this year.”

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