Pike could devastate fisheries / Scientists say predator could devastate Delta
A predator fish that could endanger salmon and other fish populations throughout Northern California has survived efforts to poison it and has multiplied to alarming levels, according to the state Department of Fish and Game.
State biologists captured and killed 17,635 northern pike last year at Lake Davis near Portola (Plumas County), according to Fish and Game. That is up from 6,358 in 2001 and 600 in 2000.
Scientists fear that if this invasive, nonnative fish escapes downstream from Lake Davis, it could multiply further and take over the Sacramento-San Joaquin River Delta in similar fashion, threatening fisheries and endangered species.
"These new numbers are stunning to everybody who has monitored the situation," said Fish and Game official Patrick Foy.
The department poisoned the lake in 1997, at a cost of $10 million in fines and expenses, despite the opposition of local residents and some environmentalists. But the pike survived -- or, as many locals believe, were reintroduced.
Last summer, Foy called the pike a time bomb and said that "every day that goes by with pike in the lake, the Delta (and its migratory fisheries) is at risk."
The northern pike looks something like a set of crocodile jaws propelled by a powerful tail fin. With its ability to reproduce and its appetite for other fish, pike are dangerously well-equipped to take over ecosystems.
Despite efforts to kill as many pike as possible with netting, explosives, electro-shock and other methods, at a cost of $500,000 per year, there are more pike than ever at Lake Davis.
Earlier this month, Plumas County Supervisor B.J. Pearson even floated the idea of draining the lake, a major recreation destination in the region. Scientists believe that by itself wouldn't do the job and that the water that would remain below the outlet, and in the feeder streams, would need to be poisoned also.
"We believe it is not a simple solution," said Julie Cunningham, an environmental scientist for the Department of Fish and Game. "Draining would also require treatment (poison). There would be a standing pool of water at the dam and an existing stream in the valley (that would have to be poisoned). There is also the prospect of fish, larvae or eggs getting out during the draining."
DEVASTATING OTHER SPECIES
The results can be catastrophic when pike are mixed with trout, salmon and other species. In particular, the endangered winter-run salmon and Delta smelt could be wiped out if pike were able to populate the Sacramento-San Joaquin River Delta. That would also negate $250 million spent in efforts to restore the winter-run salmon.
Scientists have seen firsthand what can happen if pike escape into salmon waters.
Michael Meinz of the American Fisheries Society described a similar situation in Alaska, where pike that were introduced in a lake 20 years ago escaped downstream into the Susinta River drainage. The pike now inhabit 90 lakes and 44 river systems in the region and have destroyed runs of silver and sockeye salmon and 60 percent of the rainbow trout populations.
Lake Davis is about 50 miles northwest of Reno in southern Plumas County, set at 5,775 feet in the Sierra Nevada. Unlike most mountain lakes, Davis supports a rich aquatic biology, with an abundant food chain and weed growth. Yet it freezes over in winter, simulating conditions on lakes in Minnesota.
To keep pike from spreading downstream from Davis into Grizzly Creek, the state has installed a deep-water outlet where the water passes through grates and a fish grinder.
"The scientists are confident that will keep them in Davis," Foy said. "Anything bigger than four inches gets chopped up. Anything smaller is unlikely to be at the depth of the discharge."
GREATEST EVIL IS MAN
Yet Foy said the greatest fear is not juvenile pike slipping downstream through the fish grinder. "Our greatest fear is a malicious person who places them in some other lake," he said.
Many locals in Plumas County believe that northern pike were illegally planted at Davis by a homesick local trying to replicate fishing conditions in Minnesota or Wisconsin. In those states, pike co-exist with smallmouth bass, walleye and muskie and provide a popular fishery.
"You can spend millions again to get rid of the pike," said Al Bruzza, owner of the Sportsmen's Den in nearby Quincy, "and then the next year, somebody shows up and dumps in some more pike.
"Then you've gone to extraordinary lengths and cost to get rid of the pike, and you still have them anyway," Bruzza said.
But Foy said DNA evidence suggests a far more complex problem.
"What we've learned from DNA testing is that at least 50 pike had to be introduced to Davis in order to have the genetic diversity we're seeing," Foy said.