Last summer, Berkeley fisherman Mike Hudson enjoyed some of the most profitable salmon fishing he had seen in a decade. Dense schools of big fish congregated along the Bay Area coast through the spring and summer, with numbers up from previous years, and for Hudson and other commercial trollers, fishing was fast and money easy as buyers offered sky-high wholesale prices. Recreational sport fishermen, too, had a memorable summer, and for thousands of people up and down the coast, from the boat dock to the barbecue, the summer of 2013 was one for celebration.
“We finally made some real money this year,” Hudson said. “We were getting $8.95 per pound. Every 12-pound fish meant $100 to the boat.”
But the drought has dampened the party. Central Valley river levels have dropped precipitously in the past months of dry weather, destroying thousands of nests, or redds, containing fertilized Chinook salmon eggs laid by spawning fish in the fall.
Hoping to prevent further damage to the Chinook’s population, environmental groups have called on the federal Fish and Wildlife Service to boost the survival rates of salmon born at one of the agency’s major fish hatcheries near Redding by trucking the finger-sized baby fish downstream and releasing them directly into San Francisco Bay. Most years, the Coleman National Fish Hatchery—located on Battle Creek, a tributary of the Sacramento River—releases millions of salmon smolts directly into the river.
Trucking the salmon, the hatchery’s critics say, would move them safely past the Delta, where powerful irrigation pumps kill countless small fish every year, and lead to greater numbers of adult fish in the ocean in coming seasons. It would also help the salmon smolts escape predators, like birds and nonnative black bass, which may take advantage of low river levels to prey on small fish.
“We need to get the salmon past these trouble zones,” said Dick Pool, a Concord fishery activist and the founder of Water4Fish. “Trucking them is critical in a drought year like this.”
Highway transport of baby hatchery salmon from their birth tanks to the sea is not a new concept. The state’s Department of Fish and Wildlife annually trucks about three fourths of the 16 million salmon it produces on four Central Valley hatcheries and releases them into San Pablo Bay, where the fish are held briefly in floating recuperation cages before being freed. These hatcheries use eggs of wild salmon that enter the facilities, where operators capture the fish by hand, combine their eggs and sperm and rear the young for several months.
But the Fish and Wildlife Service has never embraced the trucking system. The agency produces about 12 million baby fall-run Chinook salmon every winter and releases them onsite in April. Thousands of these fish survive to adulthood and return to the area to spawn—but Pool, Hudson and others in the fishing industry believe this is not enough. They say much greater numbers would survive each year—and contribute to the coastal fishing economy—if the agency assisted the young fish with a ride past the perilous Delta.
“Fishermen know, and we agree, that they’ll get a greater catch in the ocean if the salmon are transported [to the Bay],” said Dan Castleberry, an assistant regional director with the Fish and Wildlife Service.
But there’s a reason, Castleberry says, that his agency prefers not to truck its fish downstream: Baby salmon that do not migrate downriver on their own tend not to return to the same place when they spawn three years later.
That’s because they miss out on an important component of their development called “imprinting,” which entrains in a young salmon’s brain an olfactory recognition of the water it was born in. This scent memory is what allows salmon to make their legendary spawning migrations and even locate the precise tributary where its own parents spawned.
When such imprinting does not occur, salmon will spawn in almost any watershed they encounter, without preference for the one in which they were born. Scientists call this “straying,” and it’s bad for two main reasons, according to Scott Hamelberg, project director at the Coleman National Fish Hatchery.
First, the hatchery needs returning fish to remain operating; the more salmon born at Coleman that stray and spawn somewhere else, the fewer eggs the hatchery will have to work with.
Second, the genetic integrity of the Central Valley’s many native strains of Chinook is threatened when fish from one tributary stray and end up spawning in another stream.
“The Central Valley’s fall-run fish have become dramatically homogenized,” Hamelberg said. “We want to keep them coming back to the place where they were born in order to reassert the genetic distinctions that give them their adaptive evolutionary differences. You can’t get there if you keep mixing the gene pool.”
At Water4Fish, Pool feels the Fish and Wildlife Service is making a costly tradeoff.
“You get less straying but also less fish,” he said.
John McManus, executive director of the Golden Gate Salmon Association, points out that 2013’s fall salmon run has already taken a heavy hit due to the recent lowering of the river’s levels, which biologists estimated destroyed forty percent or more of the eggs laid and fertilized in the Sacramento River and at least eleven percent in the American.
Now, he says, a bumper fishing season is unlikely for 2016 unless Coleman hatchery’s fish are trucked to the Bay. He acknowledges that heavy rain just before the salmon are released could boost their odds at survival in the river by creating fast, turbulent, murky water—a smokescreen against predators.
“That could give those fish a big shot of water that would wash them down the river,” McManus said.
The Fish and Wildlife Service participated in the trucking program from 2009 to 2011, when the Coleman hatchery delivered ten percent of each year’s juvenile Chinook to the Bay for release. The action was an emergency measure intended to bolster fish numbers following the severe crash of the Central Valley’s Chinook runs, which bottomed out in 2009 at 39,000 spawning adults—about an eighth of the Sacramento’s historical average and the worst fall-run return ever recorded.
Many of those fish were marked with tiny coded wire tags, which biologists frequently use to track salmon. Subsequent recovery of these tags from adult salmon in the ocean indicated that the fish trucked to the Bay experienced far greater survival rates that their counterparts released into the river.
However, coded wire tags retrieved from adults that spawned in the Central Valley’s rivers proved what biologists predicted would happen:
“Ninety-five percent of the salmon we trucked down to the Bay went and spawned somewhere else,” Hamelberg said.
But El Cerrito resident Marc Gorelnik, with the sport fishermen’s group Coastside Fishing Club, feels that other factors that directly threaten Central Valley salmon populations—like pumping of Delta water for farmland irrigation—should be addressed before strident efforts are made to preserve the salmon’s genetic differentiations.
“If we don’t resolve the first- and second-order challenges that are threatening salmon in the rivers, what’s the point of addressing these third- and fourth-order challenges?” Gorelnik said.
He feels that the 12 million Coleman hatchery smolts will be wasted if they are released into Battle Creek.
“The river is low, warm and clear,” he said. “Those fish are going to be decimated.”
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