Drought-driven salmon deaths could have far-reaching impact
By Peter Fimrite SF Chronicle Updated 7:46 am, Thursday, October 29, 2015
One of the last wild runs of chinook salmon in California is sinking fast amid the four-year drought and now appears perilously close to oblivion after the federal agency in charge of protecting marine life documented the death of millions of young fish and eggs in the Sacramento River. The National Marine Fisheries Service reported Wednesday that 95 percent of the winter-run chinook eggs, hatchlings and juvenile salmon died this year in the river, which was too warm to support them despite conservation efforts. It was the second year in a row that most of the juvenile salmon died in the soupy water released from Shasta Dam, failing to make it to the ocean. The situation could have far-reaching effects, leading to cuts in water allotments to farmers next year if projected rains and a strong snowpack don’t erase drought deficits this winter. Commercial and recreational fishing limits could be imposed to protect the endangered chinook population, taking a toll on those industries. “Certainly there is cause for alarm when we are talking about 95 percent mortality,” said Garwin Yip, the branch chief for water operations and delta consultations for the fisheries service. “We think it is temperature-related.”
The problem was caused by a lack of snow this year on top of four years of drought. The U.S. Bureau of Reclamation, Yip said, was left without enough cold water behind Shasta Dam to release during spawning season. Chinook, also known as king salmon, are born in the Sacramento River and pass through San Francisco Bay. They roam the Pacific Ocean as far away as Alaska before returning three years later to spawn. There are three distinct runs of salmon — winter, spring and late fall, which is what West Coast fishers catch in the ocean. The winter and spring-run chinook salmon are listed under the state and federal endangered species acts. The winter run has been endangered since 1994. The fisheries service worked with two state agencies, the Department of Water Resources and the Department of Fish and Wildlife, to develop an elaborate plan this year to regulate cold-water releases from Shasta Dam.
Resource officials are required by law to release enough cold water to keep the Sacramento River at 56 degrees — the ideal temperature for fish. In a bid to meet that requirement, federal officials sharply limited flows and delayed water deliveries to hundreds of Central Valley farmers.
The problem, Yip said, was that “there wasn’t as much cold water as anticipated and the water wasn’t as cold as we thought it was going to be.” The lack of cold water forced regulators to come up with a new temperature management plan, this one allowing the water to warm up to 57 degrees. But it didn’t work, and water temperatures, at times, rose to 58 degrees, he said. As a result, the number of juvenile fish counted this month at the Red Bluff diversion dam, downstream of Shasta, was down 22 percent compared with last year, which was also a bad year. That’s despite the fact that there were 21 percent more adult fish laying eggs in the river, Yip said. Two months remain in this year’s run, but