News of the Arroyo
Northern California salmon runs stronger than expected on many rivers despite drought
Salmon return to the Mokelumne River Fish Hatchery
|December 22, 2015 - On the Mokelumne River -- a central Sierra drinking water source to 1.4 million East Bay residents -- more than 12,000 adult chinook have returned for the fall run so far this year, exceeding a 17-year average of 8,000 fish.
|San Jose Mercury News|
|EAST OF LODI -- Long droughts like the one California is experiencing can be cruel to wild chinook salmon -- smothering, starving, overheating, disorienting and drying out the fish.|
But up and down Central Valley rivers, the story is surprisingly different this fall
On the Mokelumne River -- a central Sierra drinking water source to 1.4 million East Bay residents -- more than 12,000 adult chinook have returned for the fall run so far this year, exceeding a 17-year average of 8,000 fish.
They have come home to breed after a three-year struggle to survive migrations, predators, water-diversion pumps -- and drought.
|Chinook salmon are photographed at EBMUD's Mokelumne River Fish Hatchery on Monday, Nov. 30, 2015 near Lodi, Calif. (ARIC CRABB)|
The abundance is in sharp contrast to the meager returns for the coho salmon on many coastal creeks, and for the endangered winter-run chinook on the upper Sacramento River, where overheated water killed many young fish earlier this year.
Officials say the fall run on the Mokelumne and other Central Valley rivers -- the biggest such run in the state -- is doing better because of abundant food sources in the ocean the past three years and because of effective human intervention: operating hatcheries, trucking young hatchery fish out of shallow, drought-starved rivers, and delicately balancing the flow of water between people and fish.
The fall run is the main producer of salmon caught off the California coast and a foundation for the state's $1.4 billion annual commercial salmon industry.
"We are relieved to have these returns in a very challenging year," said Michelle Workman, supervising fisheries and wildlife biologist for the East Bay Municipal Utility District, which relies on the Mokelumne River as its main water source.
As Workman walked by the river recently, 2- and 3-foot-long salmon shot through the green, tree-lined waters below EBMUD's Camanche Reservoir some 35 miles east of Lodi.
Gravel beds used by spawning salmon in the Mokelumne River are photographed near EBMUD’s Mokelumne River Fish Hatchery on Monday, Nov. 30, 2015 near
|Gravel beds used by spawning salmon in the Mokelumne River are photographed near EBMUD's Mokelumne River Fish Hatchery on Monday, Nov. 30, 2015 near Lodi, Calif. (ARIC CRABB)|
Some salmon slapped the water with their tails and dug out gravel burrows to lay eggs. Others leapt out of the water in a flurry of spray before swimming into a channel leading to the hatchery, where they will be killed -- adult salmon die shortly after spawning in any case -- and their eggs harvested to rear baby fish.
The scene of plentiful salmon returning is playing out on several other rivers, including the American near Sacramento, where nearly 8,000 salmon -- more than average -- have swum into the federal Nimbus Hatchery.
More than 16,000 salmon, also above average, have traveled up the Feather River to a hatchery below Oroville Reservoir north of Sacramento.
"Our hatchery managers are pleasantly surprised by the returns," said Andrew Hughan, a spokesman for the California Department of Fish and Wildlife, which operates nine salmon hatcheries. "We are going to get as many fish as we need this year."
Dam and hatchery operators in California have taken unusual measures in the drought to protect salmon competing with 38 million state residents for limited water supplies.
Officials have installed water-chilling equipment at hatcheries, released pulses of cold water behind dams, and reared baby fish longer in hatcheries than before.
They also have stepped up efforts to truck young hatchery-reared salmon for release in the Sacramento-San Joaquin Delta or San Francisco Bay. The giant taxi service moves salmon past meager drought-stricken rivers and streams, where fish can be overheated to death or picked off by predators.
East Bay water officials, in particular, took trucking to new heights this year, garnering praise from commercial salmon fishermen.
"We want to boost salmons' natural production in the river," said Workman. "There is no doubt the drought has provided a learning experience for those of us trying to protect fish."
John McManus, the Golden Gate Salmon Association's executive director, praised EBMUD for giving a lift to the naturally spawned fish, even though he says it's too early to say what the long-term effect will be.
"They are regarded as the most progressive and most willing to experiment," McManus said.
EBMUD, as well as other California water suppliers, have practical reasons for acting to protect fish: Their water supplies can be slashed if salmon or other fish do poorly.
|A Chinook salmon jumps at a fish ladder along the Mokelumne River near EBMUD's Mokelumne River Fish Hatchery on Monday, Nov. 30, 2015 near Lodi, Calif. (ARIC CRABB)|
State and federal environmental regulators have broad authority to limit pumping water from rivers and the Delta, and have faced criticism from environmentalists who say too much water has been diverted to people and farms at the expense of fish.
"When you have many fall-run salmon returning, it masks the extent of the problem because most of the fish coming back are hatchery fish," said Jon Rosenfield, a scientist with the Bay Institute.
He contends drought is not the real problem but rather too much water being taken for farms and cities. "Salmon are amazingly resilient fish that can bounce back from extremes like drought, but the problem is our response to the drought."
Inadequate flows of cold enough water hurt survival of young winter-run salmon this spring on the Upper Sacramento River, with many of the endangered juveniles dying out, the National Marine Fisheries Service reported in October.
For their part, East Bay water officials said they made two big sacrifices this year to protect salmon.
The district dedicated some of its emergency purchase of Sacramento River water to river flows for fish.
Then, to save cold water in the lower depths of its Pardee Reservoir for salmon, the district this summer pumped poorer-tasting water with algae from the upper reservoir to people in the East Bay. Many customers complained about the taste, but district officials said they needed to save the cool water to be released in fall to attract the salmon.
Some customers say the East Bay district is aggravating water shortages for people by giving away so much to the fish.
EBMUD officials said their water supplies for homes and businesses could be slashed by state and federal environmental regulators unless adequate measures are taken to help the fish.
This year as before, the water district used a motion-activated camera to count and inspect every salmon on the run to gauge whether measures to help them are working.
"We have to protect the fish," said district spokeswoman Nelsey Rodriguez. "If the salmon on the Mokelumne River are not healthy, it jeopardizes our entire water supply."
Contact Denis Cuff at 925-943-8267. Follow him at Twitter.com/deniscuff