Hoping to keep non-native northern pike in Lake Davis from invading the Sacramento-San Joaquin river system, state wildlife managers have electroshocked, poisoned and netted thousands of the fish. Nonetheless, concludes a new UC Davis study, the pike are thriving.

Professor Ted Foin constructed a mathematical model that considered Lake Davis' fish habitat and pike population dynamics to estimate the impact of the removal program on estimated pike population for the next 10 to 100 years.

"The Lake Davis pike population is well-established and likely in the phase of explosive growth," said Foin, a systems ecologist and modeler in the Department of Agronomy and Range Science. "Methods currently in use are having no significant impact on pike population growth. Simply put, the pike population in Lake Davis has grown too large to be controlled by removal."

If the voracious pike (Esox lucius) were to escape over Grizzly Dam or were illegally transplanted by fishermen, they could devastate endangered fish in the Sacramento and San Joaquin rivers and delta, including salmon and the Sacramento splittail.

The California Department of Fish and Game and the Lake Davis Steering Committee are currently considering their next steps. One option is to try again to kill the fish using chemicals. In October 1997, the department put 76,000 gallons of rotenone into the lake to suffocate the pike. But in May 1999, pike were found in the lake again.

Foin said that while the new fish might have been illegally transplanted, they more likely were survivors of the 1997 treatment; some DNA evidence supports the survivor hypothesis.

The next public meeting to discuss the pike problem is Sept. 8 in Portola, in eastern Plumas County. More information: http://www.dfg.ca.gov/northernpike/index.html.