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Delta Eludes Duck-eating Fish

Despite one unconfirmed sighting of a northern pike at the John F. Skinner fish screen, Cal Fish & Game officials say they are confident that the predator has not yet escaped from Lake Davis, where it was illegally stocked during the mid-1990s. That's good news for the Delta's native fish and other species, which would likely face one of their biggest challenges yet if the pike did make their way into the Delta.

The fish are voracious eaters, capable of consuming other fish up to one-half their own length. "A 30-inch pike can eat a 15-inch trout, and will do so readily," says Cal Fish & Game's Patrick Foy. Pike pose a threat not only to fish such as salmon, smelt and trout but also to frogs, snakes and virtually anything else they can sink their very sharp teeth into. According to Foy, one Michigan study found that pike consumed 1.5 million ducks in a single year.

Pike, which are native to the Great Lakes region, are popular with sport fishermen because they grow quickly to 10 pounds or more and are ferocious strikers. Pike prefer weedy, slow moving water and would find the Delta an extremely congenial home. The fish are much more prolific than native trout-a mature female can lay up to 100,000 eggs at a time; by contrast, trout lay only 1,000 to 2,000 eggs at a time.

Pike represent such a threat to the Delta that Fish & Game is preparing to take drastic measures to eradicate the intruders. The agency plans to lower Lake Davis and treat it with rotenone in the fall, which will kill all the fish in the lake. Following the treatment, Fish & Game will restock the lake with one million fingerling trout, and plant the lake with catchable trout next spring.

The pike eradication plan was delayed by protests from residents of nearby towns, which use Lake Davis as asupplemental drinking water source. Earlier this summer a judge issued a temporary restraining order requiring the agency to complete a well and construct a 500,000 gallon tank to hold an alternate drinking water supply before proceeding with the lake drainage. The Department plans to have the alternate drinking water supply on line by late August.

The Lake Davis pike represent at least the second illegal attempt to establish a pike fishery in California. In the early 1990s, Fish & Game used rotenone to kill pike that had been stocked in Frenchman Lake, but apparently not before some of the fish had been moved to nearby Lake Davis. To prevent any further efforts by pike fans, Foy says the department is relying on stepped up law enforcement and will strive to "educate people on the ecological consequences of bringing in non-native fish."

Contact: Patrick Foy (916) 358-2938

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