ShareThisFor most fall-run chinook salmon in Central Valley rivers of California, youth is more akin to a factory assembly line than some aquatic nirvana.
Life begins in the concrete tanks of a hatchery on a four-month diet of manufactured food pellets. Teenage independence comes in the spring, with a tanker truck ride to Vallejo and a trip through a giant hose into San Pablo Bay.
Clean and programmed as this early life is, it hasn't worked too well. The fall-run chinook population set a historic low in 2009, after two years of fishing closures imposed to protect the species from extinction.
So officials are tweaking the formula this year. On Monday, the California Department of Fish and Game released 2 million baby salmon, raised at Nimbus Hatchery near Rancho Cordova, into the American River instead of trucking them to Vallejo.
"What we're trying to do is to get the fish to imprint on this river," said Joseph Johnson, a Fish and Game senior environmental scientist, as he watched thousands of 3-inch salmon smolts shoot from a chrome tanker truck into the American River beneath the Jibboom Street Bridge in Sacramento. "They look really good. I think this is going to work just fine."
The change is one of the first tangible results of a salmon-tagging program started in 2007. Before release, 25 percent of the young fish have their adipose fins clipped off their backs, then a tiny coded wire tag injected into their noses.
When the fish are caught as adults, the tags reveal where and when they were born.
Tags recovered from adults in 2009 show that too few American River salmon are finding their way home.
Nimbus Hatchery recovered enough adults to meet its annual target of 4 million smolts. But 72 percent of the salmon that returned to the American River were actually born in other rivers, mostly the Feather and Mokelumne.
The problem, called "straying," means these salmon have lost one of their most magnificent and defining traits: the ability to find their birth river after three years in the ocean.
It also means they are probably breeding with salmon from other rivers, which thins their genetic identity and may harm the smaller number of salmon that still manage to spawn naturally, outside the hatcheries.
In short, it means Central Valley salmon are becoming more like a domesticated animal, and less like the raised-on-nature delicacy that Californians like to catch and eat.
"Some are always going to stray, but this high percentage of straying is a great concern to all the fishery agencies," Johnson said as another chrome tanker backed to the river's edge. "We have enough information to say this is one of the best options. But to validate it, you're going to have to get those returning adults back in three or four years."
The practice of dumping young salmon into San Pablo Bay was started in 1995 to help young salmon avoid the perils of the Sacramento-San Joaquin Delta on their trip to the ocean. These threats include predators like the non-native striped bass, urban and farm pollution, and water-diversion pumps.
Johnson said the practice has helped boost the number of fish available to ocean fishermen. But he said it also probably contributes to straying, which threatens the species as a whole.
(E-mail reporter Matt Weiser at mweiser(at)sacbee.com. For other stories, visit www.scrippsnews.com.)
(Distributed by Scripps Howard News Service, www.scrippsnews.com.)
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