Winter-run Chinook in the Sacramento seeing lowest survival rate ever
The U.S. Fish and Wildlife Service has counted 160,000 juvenile winter-run Chinook salmon in the Sacramento River this year, down from an average of 1.3 million.
That’s the lowest number ever recorded, about a quarter of last year’s count and 12 percent of the average. There are usually about 1.3 million juvenile salmon counted.
Michael Milstein, spokesperson for the National Oceanic and Atmospheric Administration’s Fisheries department, said one of the causes of this problem is increasing water temperatures due to climate change and drought.
"One of the biggest challenges of where they spawn now is keeping the temperatures low enough for the eggs to survive," he said.
Vitamin deficiencies have also played a role in the declining salmon numbers, particularly thiamin.
Winter-run Chinook in the Sacramento River are endangered and considered at-risk of extinction. With so few juveniles counted, Milstein worries about the number of adult salmon that will survive.
"So we’ll really see the consequences of this in two to three years when those adults come back. Because we’ve had now a couple years of low numbers overall, it becomes more and more difficult for the species to pull out of that," he said.
The U.S. Fish and Wildlife Service operates a salmon hatchery near Shasta Dam, where Milstein said the fish can easily be treated for vitamin deficiencies. He said the long-term goal is to move the salmon further up into the mountain streams in Northern California, where they can spawn in the colder water above the Shasta Reservoir. The salmon originally spawned there before the Shasta and Keswick Dams were built.
Milstein said a long-term solution is needed, as climate change will make survival even harder for these fish.
"We really feel it's essential to look at that longer term solution of getting the fish back up into their natural spawning area where the water is not only cold enough to be safe for the eggs to hatch, but now we're seeing may also be productive enough that the fish can do really well up there and have better odds of survival for the rest of their lifecycle," he said.