Some fish do the eating and others get eaten. That is the nature of nature.
But if man helps one voracious eater that doesn't belong, is that fair?
This is the essential question in a lawsuit over the striped bass, a non-native fish introduced to the Sacramento-San Joaquin Delta from the East Coast in 1879 to create a commercial fishery.
Today the striper is caught only for sport -- prized by anglers for its tasty flesh and hard fighting on the rod. But while the California Department of Fish and Game props it up as a sport fish, the striper has become the delta's top predator, feasting on delta smelt, juvenile salmon and steelhead. These are endangered species in California -- and the focus of Herculean conservation efforts.
The suit was brought by the Coalition for a Sustainable Delta, a nonprofit made up of San Joaquin Valley water agencies linked to Stewart Resnick, a billionaire with a huge Kern County farming operation.
Those farms require delta water diversions to grow crops including oranges, pistachios and pomegranates. Their water supply has been reduced by federal and state rules to protect smelt and salmon, because the giant pumps that funnel water out of the delta also kill large numbers of fish.
The lawsuit targets the Department of Fish and Game, alleging it has ignored harm to native fish and instead acted to bolster the striper population.
"This administration has a responsibility to fix this," said Michael Boccadoro, spokesman for the coalition. "They're going to be asking voters to pass $11 billion in [water] bonds in November. How can you do that when a state agency is knowingly worsening a situation in the Delta?"
Fish and Game has asked the court to dismiss the case, saying the plaintiffs lack standing because they don't engage in fishing in the delta.A trial date in the case is set for June 22 in federal district court in Fresno.
There is general agreement that striped bass eat endangered fish. But there is no scientific certainty about how many they eat.
A 1999 report by Fish and Game estimated stripers may eat as much as 6% of some salmon runs. Evidence uncovered by the lawsuit indicates state officials have known for years that it may be a bigger problem, according to documents the coalition obtained as part of the lawsuit.
"Last night a chill ran down my spine imagining that Delta smelt go extinct -- while we have done nothing proactive to address predation by striped bass," Marty Gingras, supervising biologist for Fish and Game's Bay Delta Region, wrote in a February 2007 e-mail. "I'm again thinking we should propose revising the striped bass policy to consider them a 'weed' like pigs or a similar pest."
The e-mail was labeled "Confidential" and sent to Gingras' boss, Chuck Armor, who replied, "I share your concern."
In a subsequent deposition, the coalition's attorney pressed Gingras to estimate how many juvenile salmon are eaten by striped bass. Because no one knows for sure, he gave a range of 5% to 25%. At the high end, that is four times the state's 1999 estimate.
The coalition wants Fish and Game to drop fishing restrictions that allow anglers to keep striped bass only within a certain size range, and only a certain number of them. This presumably would reduce the striper population and allow more native fish to live.
Angling groups are outraged, fearing a reduction in trophy-size stripers. They also dispute the significance of predation, arguing that other factors are bigger, such as water diversions that kill delta fish and alter the ecosystem.
"Striped bass is a high-value recreational fishery. A lot of people like them," said Bill Jennings, executive director of the California Sportfishing Protection Alliance, which intervened in the lawsuit on the state's behalf. "The lawsuit isn't so much against striped bass as it is an attempt to divert attention from the massacre at the pumps."
Scientists studying delta fish declines have been unable to find a single cause. Instead, they suspect multiple problems. One is the simple challenge of migration. Studies have hinted that young salmon migrating to the ocean die in much greater numbers if they spend too much time in the mazelike central delta. Often drawn there by water diversions, they face more threats from predators, pollution and the water pumps themselves.
Fish that stay in the main stem of the Sacramento River, on the other hand, encounter fewer threats.
A new study confirms these effects using the first available radio-tracking data. Tiny transmitters were implanted in juvenile salmon released in the Sacramento River in 2006 and 2007. The results: More salmon survived, and reached the ocean faster, if they stayed in the river.
Even so, there are doubts about whether unrestricted fishing for stripers will help smelt, salmon and steelhead.
"If you want to reduce predation problems like striped bass, you've got to go after them with nets and poison," said Peter Moyle, a University of California at Davis professor of fish biology. "Striped bass also feed on other predators. So if you reduce the striped bass population, quite likely other predators will just fill in the space."