LEWISTON – The Maine Department of Inland Fisheries and Wildlife has declared open season on northern pike in Sebago Lake as it warns that the invaders are threatening its famed landlocked salmon fishery.

The toothy and voracious pike arrived three years ago, and there is evidence the fish are reproducing, officials say.

“Catch and kill as many pike as you can,” said Mark Latti, a spokesman for the department.

Until April, it had been more than a year since a northern pike was hauled from Sebago’s depths. But then, Latti noted, three were caught. One of them was less than 3 years old, meaning the pike probably are reproducing.

Jim Pellerin, assistant regional biologist for the Sebago region, said the northern pike likely will establish a population.

Northern pike began showing up in Maine roughly two decades ago. They have become the principal game fish in some of the Belgrade Lakes, in Sabattus Pond and elsewhere.

Earlier this spring, pike were found in a small pond in Chesterville that stretches into the Sandy River watershed. The fish likely will migrate from there into the Kennebec River, a biologist said.

Despite the call for anglers to catch and keep pike, wildlife biologists say it’s probably impossible to eradicate pike altogether.

Pellerin blames people for introducing non-native species to Maine’s lakes, ponds and rivers. The illegal stocking of pike into Sebago’s watershed is “a senseless and selfish act by one or two people that will negatively change the history of the lake’s fisheries for all present and future anglers,” he said in a monthly report.