They want the public's help quashing the quagga mussel, discovered in far southeast California for the first time earlier this year after likely hitching a ride there on the bottom of someone's boat.
Millions of dollars are being spent to at least slow the advance of the striped quagga, named after an extinct relative of the zebra.
"It could very well spread from the south," said Gary Adams, a Delta fisherman and president of the California Striped Bass Association. "That could really compound the damage that we're experiencing within the Delta."
Divers have scoured Southern California channels for signs of the mussel. Officials have boosted inspections of vehicle-towed boats entering the state.
"This is an extremely high-profile situation and one in which we can't take any chances," said Carrie Wilson, a spokeswoman for the state Department of Fish and Game.
What can some obscure mollusks accomplish in the massive Delta? Their tiny, hair-like cilia draw water into their shells - perhaps a quart per day - gorging on plankton, algae and even other baby mussels. Millions of quagga mean substantially less plankton for ecologically valuable species like smelt and striped bass.
Quagga also are known to clog intake pipes, cutting off supplies for cities and farms. And they colonize any hard surface they can find: Docks, buoys, boats and beaches, potentially a pain for anyone who recreates on the Delta.
Quagga come from the Ukraine and weren't spotted in the United States until 1989 in the Great Lakes. Their sudden presence on the California/Arizona border marks an "extremely large leap in their range and cause for much concern," says one report by the U.S. Geological Survey.
Quagga would be just the latest in a number of exotic animals threatening San Joaquin-area waterways. Asian clams compete with smelt in the Delta, while New Zealand mud snails carpet the beds of rivers, gobbling up food needed by trout.
"Our system is under such pressure now," Adams said. "It's just too many issues."
Timing isn't ideal for a mussel invasion. Budget cuts in 2003 forced state officials to limit inspections of private boats at California's 16 agricultural inspection stations on highways.
The quagga's close cousin, the zebra mussel, has been found on boats 18 times since the inspection slowdown. Which raises the question: How many mussels, zebra or quagga, have slipped through?
No one knows.
A recent state report on the problems facing smelt and other native species called for hiring 60 inspectors to staff all of these stations, at a cost of up to $4 million a year.
"Inaction will be disastrous," the report warns, saying a mussel infestation could cost billions annually.
On the lookout
Boaters can help prevent the spread of the quagga mussel:
• Wash the hull of each watercraft once it leaves the water.
• Drain any water through the vessel's plug.
• Make sure the lower outboard unit is drained and dry.
• Any boat coming from Lake Mead should remain dry and out of the water for five days.
Among other problems, mussels:
• Ruin a boat's engine by blocking the cooling system, causing overheating.
• Create drag on the bottom of a boat, reducing speed and wasting fuel.
• Require scraping and repainting of boat bottoms.
• Colonize on boat ramps and docks, requiring constant cleaning.
To report mussels or for more information, call the quagga hot line (866) 440-9530.
Contact reporter Alex Breitler at (209) 546-8295 or abreitler@recordnet.com.
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