They have been poisoned, stunned and scooped into nets. Soon, they may be blown up.
This spring, the state plans to launch a new line of attack on the thus-far-indomitable northern pike of Lake Davis. The Department of Fish and Game intends to explode detonation cord in pockets of the Plumas County reservoir to kill the unwanted pike, which prey on the lake's trout.
The process will not, the department says, be like setting off land mines. Rather, the small explosions will send pressure waves into the water, bursting the air bladders of any nearby fish. They will die, but most will stay relatively intact.
The planned assault is the latest strategy in state attempts to control the northern pike, a big, hungry fish that mysteriously made its way into the lake in the early 1990s and refused to leave.
The state dumped chemical poison into Lake Davis in 1997, wiping out its fish population. But some pike survived. They have since rapidly reproduced, and last summer, more than 6,300 pike were taken from the lake by fish and game personnel.
For now, the fish and game department seems to have given up hope of ridding Lake Davis of the pike. The goal instead is to control their numbers so they don't destroy the lake's prized trout fishery or spread downstream, where they could wreak havoc on valuable salmon fisheries.
Detonation cords have been used before in California to kill fish threatening salmon in the Eel River system on the North Coast, said fish and game senior biologist Ivan Paulsen. They have never been used in Lake Davis, which in the past has functioned as a drinking water source for local communities.
A recently released environmental report, now under public review, concluded that detonation would have no significant impact on the lake. Paulsen said experiments conducted for the study indicated that the detonations would leave some trace chemicals in the lake, but in quantities so minute they would be undetectable.
The detonations would kill any nearby fish and amphibians, including the lake's trout. Trout would be restocked, and some of the dead trout would be left onshore as food for bald eagles that nest nearby.
Fran Roudebush, chairwoman of the Lake Davis Steering Committee, said that once locals understand that the state is not going to blow up the lake, they are not objecting to the plan. A public hearing on the matter will be held Tuesday in Portola.
More controversial, she said, is talk about draining the lake to get rid of the pike. Fish and game officials have placed that option at the bottom of their list.
But Plumas County supervisors have expressed an interest in having the state drain the reservoir and store the water downstream, so the county could sell it and use the revenue to offset losses in tourism and sport fishing that the region would suffer until the lake refills. That would include buying any homes people wanted to sell when the lake was dry.
The supervisors have contacted the state about the proposal but have not received a response, said county Supervisor B.J. Pearson.
Residents have no particular objection to the detonation plan, he added. But, "at best, it's going to kill a few pike. It's not going to solve the problem."
Biologist Paulsen said the detonations should kill pike quite efficiently. A one-acre test detonation will be conducted in the reservoir in April. Water quality will be sampled as well as the intensity of the shock waves.
If all goes well, the state would use detonation cord in areas of up to 10 acres where pike are concentrated. In 2003 and 2004, areas of up to 20 acres would be treated.
Resembling clothesline, the cord would be run in lengths back and forth through the water. Any fish within 21 feet of a detonation would be killed.