Residents of Gibson Island, an exclusive, privately owned island just north of here, concluded a controversial two-day deer hunt tonight as a dozen animal-rights advocates held a lonely vigil nearby and opponents charged that they had been duped into believing the hunt was canceled.

The hunt was necessary to reduce an "excessive" deer population that had encroached upon the 1,000-acre-island's residential area to eat shrubbery. The hunt was conducted secretly to reduce the chance of injury to opponents who threatened to break it up, said Robert Scholz, attorney for the Gibson Island Corp., which manages the island.

In all, 10 deer were reported killed by islanders Thursday and today in comparison to the 16,000 that state officials estimate will be killed throughout the state during this week of deer season. The island has 80 to 100 deer, or double the number normally on 1,000 acres, according to unofficial estimates. State officials had recommended the hunt to thin the herd.

Nonetheless, Gibson Island has become a rallying cry for animal protectionists who say that hunting, a long-established means of wildlife population control in Maryland and elsewhere, is inhumane and inadequate in dealing with animals forced out of their habitat by encroaching civilization.

"We have to find a responsible, humane way to deal with the problem," said Jackie Cowan, director of the Anne Arundel County chapter of the Society for the Prevention of Cruelty to Animals.

Ingrid Newkirk, director of People for Ethical Treatment of Animals, said today that corporation officials violated a "gentleman's agreement" struck between her attorney and Scholz that the hunt would not proceed without notifying her. "They deceived everybody," she said.

Scholz said he made no such agreement.

Newkirk was tipped off to the hunt Thursday by outraged residents and members of the Gibson Island Club, a recreational club on the island that includes nonresidents, who saw deer carcasses. Several residents interviewed Thursday night said they had believed earlier that the hunt had been canceled entirely.

"It was all conducted basically in secret," said one observer who regularly visits the island and asked not to be identified. "They had to do it in secret because no one but the few who wanted to hunt wanted it."

At 7 a.m. this morning, as hunters took their places in deer stands along the island's forested southern shore, members of the People for Ethical Treatment of Animals stood solemnly at the guarded causeway leading to the island with handmade signs reading "Hunting is no sport" and "Savagery." But the group was helpless to stop today's killing.

Newkirk argued that hunting is a random and ineffective way to manage deer population. She likened it to "shooting fish in a barrel."

State Sen. Gerald Winegrad (D-Annapolis) said the answer to controlling the deer population is better development practices that will allow natural habitats to remain.

"What I'm saying is the deer population is threatened by the stripping of forest cover," he said. "Every week we lose thousands of acres of forest land in Maryland that is habitat for deer."

The six bucks and four does killed in the two-day hunt are not expected to sufficiently cut back the herd. A resident, who asked not to be named, said no decision has been made on how to further reduce the number of deer, but no more hunts are planned.