MONTPELIER, Vt. (AP) – State wildlife biologists shot or trapped 208 cormorants on Lake Champlain this summer in their latest attempt to slow a population explosion of the fish-eating, tree-damaging bird.

The killings put the Fish and Wildlife Department at odds with environmental groups that support efforts to control cormorants but oppose the shooting because they say it could drive the birds elsewhere to nest.

“We cannot leave this situation alone. We are not going to let all the islands in Lake Champlain be denuded,” said John Gobeille, a state wildlife biologist, of the decision to kill some of the birds.

Cormorants are large, crested migratory birds that have turned state-owned Young Island into a wasteland of dead trees and guano-covered ground.

Their numbers have exploded in the Northeast in recent years, in part because they are able to spend winters poaching fish from the big fish farms in the southeastern United States.

Cormorants feed on yellow perch and other fish in Lake Champlain. While Gobeille gets frequent complaints from anglers who blame the birds when the fishermen don’t catch fish, he said there is no evidence, yet, that the birds are damaging the lake’s stock of fish.

The Fish and Wildlife Department is more worried about the land impacts of the birds — that the Young Island colony will spread and establish new nesting sites on other islands or in the Missisquoi Bay wildlife refuge.

Already the birds have established a colony of more than 5,000 birds on the Four Brothers Islands on the New York side of the lake.

The state obtained a federal permit this summer to kill up to 10 percent of the breeding population on Young Island.

Audubon Vermont’s executive director, Jim Shallow, said the danger is that disrupting the cormorant colony on Young Island will only drive the birds to establish colonies elsewhere. “Our concern with shooting the adults is that it encourages them to go elsewhere to nest, which is just going to make the problem worse,” he said.

Audubon has endorsed oiling the cormorants’ eggs to prevent reproduction. That technique tricks the birds into staying on their nests rather than moving elsewhere to lay a new clutch.

Gobeille acknowledged there is a risk in disrupting the birds, but said he has tried to minimize that risk.

After days on which the birds were shot or trapped, he said, “the following day we’re out checking other islands, watching for movement, hazing them off other islands. We did that all summer.”

Gobeille said the state probably will continue “lethal control” next summer, but will wait to see first how many birds return.