Officially, the double-crested cormorant is a protected species, its safety guarded by federal law. But on the Lake Ontario shoreline west of Watertown, N.Y., the long-necked black birds have become a pest to anglers, who say the growing colonies of cormorants are devouring smallmouth bass and, along with them, the livelihood of people who sell bait and run charter fishing trips. This week, wildlife officials visiting an island nesting ground discovered an unusually shocking environmental crime: more than 800 cormorants slaughtered by shotgun fire. Although they have no suspects, officials say they believe the festering conflict between conservation and commerce is responsible for what they are calling one of the worst mass killings of a federally protected bird species in recent decades. State biologists said that when they went ashore on the uninhabited Little Galloo Island on Wednesday they encountered heaps of carcasses of fledgling cormorants, piles of shotgun shells and starving chicks squawking weakly among the carnage.

Clifford Schneider, who directs Lake Ontario projects for the New York state Department of Environmental Conservation, said “you see a young chick still laying there alive among all the others that had been wiped out, and you can’t help but be moved emotionally.” The mass shooting appeared to be the latest of several recent instances where a once rare species has recovered to the point where it comes into conflict with local interests. On July 23, the town of Carrollton, Texas, without a federal permit, bulldozed a rookery filled with nesting little blue herons, snowy egrets, and other species protected by federal law. The count of dead birds from that incident could be more than 1,000, said Pamela McCroskery, a spokesman for the Texas Audubon Society. Around eastern Lake Ontario, fish-eating cormorants have staged a dramatic recovery since the 1950s, when they were nearly wiped out by pesticides and shooting. In Henderson and other fishing towns near Little Galloo Island, owners of charter boats and other fishing related businesses, joined by some officials, have been pressing the government for several years to allow legalized hunting of cormorants, which they claim are responsible for a drop in populations of smallmouth bass and other popular gamefish.

With the decline in the sport fishing industry being blamed on the birds, there has been more and more talk along the shore lately of taking action, said Ron Ditch, a charter boat owner and guide for 43 years in Henderson Harbor. “I’ve been pretty instrumental in trying to do this in a proper and legal manner,” Ditch said Friday. “But everyone’s been hearing rumblings forever about how people are going to go out and take care of the situation. Apparently, someone finally wouldn’t be talked out of it anymore.” The controversy over the cormorants has centered on Henderson Harbor, a hamlet on a peninsula several miles from Little Galloo Island. The docks are a magnet for fishermen from across the country, some of whom spend $300 a day to charter boats and pursue smallmouth bass, salmon and other trophy fish. The hamlet has nine marinas and more than 60 professional captains, and for many years, fishing has been about the only source of jobs or revenue, said Grover Moore, captain of the Charter II.

“When I was growing up, there were signs at both ends of the harbor that said, ‘The Home of the Black Bass.”‘ But black bass, including smallmouths, have been hard to come by for several years, he said, and the fishermen say the birds are the only obvious culprit. He said anglers had shot videotape of cormorants devouring freshly stocked brown trout to persuade state officials to press for a hunting season. “You can see them eat so many that they couldn’t fly off the water,” Moore said. “But nobody wants to listen to the fishermen.” Growing threats against the birds first turned to action in April, when eight cormorants were killed, federal wildlife officials said. In June, about 100 cormorants were killed. But this week’s massacre, which left 840 birds dead and more than 100 others injured, transformed the local issue into an extraordinary environmental crime. Mitchell Snow, a spokesman for the Fish and Wildlife Service headquarters in Washington, said that a quick survey of officials there turned up no past mass killings of a protected species that compared with the cormorant shooting, except perhaps for the incident in Texas. “I’ve been with the department for almost 20 years and this is certainly the biggest in my memory,” he said. The long-necked diving birds have been protected for 25 years under the federal Migratory Bird Treaty Act, which prohibits the killing of ducks, geese, egrets, cormorants and other migrating birds without a permit. But as the colony on the island grew to upwards of 8,000 active nests in recent years, it was increasingly perceived as a threat to the local sportfishing industry.

The uninhabited island contains the largest rookery for the cormorants in eastern Lake Ontario, with as many as 8,400 active nests counted there in recent years. The island is owned by the Phillips Petroleum Co. but essentially is used only as a bird preserve, state officials said. Fishing guides and charter captains in the area have increasingly pressed members of Congress to write legislation authorizing controlled, legal hunting of the cormorants to reduce their numbers. Rep. John McHugh, a Republican who represents the lakeshore portion of upper New York state, complained last fall that the Fish and Wildlife Service was taking too much time to assess the impact of the birds on local fish stocks. Along with Rep. Colin Peterson, D-Minn., he introduced legislation last October that would authorize states to establish hunting seasons to control the cormorants. The birds can be legally hunted in only a few places where they pose a clear economic threat; for example, at catfish farms in Louisiana, federal wildlife officials said. But research on their impact, if any, on the fish in Lake Ontario is still in early stages, the officials said. Federal biologists have estimated that cormorants eat between 400,000 and 1.2 million smallmouth bass a year in the eastern part of the lake. But the significance of that number depends on the age of the bass, said James Farquhar, a biologist for the New York state Department of Environmental Conservation. “If those are newborn bass, that’s a drop in the bucket,” Farquhar said. “There are literally billions. But if those 1.2 million fish have already lived through several years, that is a significant number.” Friday, officials were continuing their investigation.

Conservation officers were interviewing anglers and others who might be able to pinpoint suspects in and around the fishing town of Henderson and other spots along the Lake Ontario shore. Offers of cash for information were being made, but no specific reward was posted. New York state Environmental Conservation Commissioner John Cahill said, “We’re making an all-out effort to find these people and prosecute them to the full extent of the law. “This was an act of savage brutality.” Killing a bird protected by the federal migratory bird act can bring a maximum penalty of a $5,000 fine and six months in prison for each count, said Adam O’Hara, the special agent in charge of law enforcement for the Fish and Wildlife Service in the Northeast. O’Hara said that evidence collected on the island, including more than 100 shell casings and some bird carcasses, was being sent to state pathology laboratories and a federal forensic laboratory for investigating wildlife crimes in Ashland, Ore. David J. Miller, the executive director of the National Audubon Society’s New York state chapter, said the shooting harked back to the turn of the century, when waterfowl and gulls were shot by the million for sport and to supply feathers to the hat industry. “This is a dark act that takes us back to that time,” he said. He called for a swift investigation and aggressive prosecution of the shooter or shooters. “The message has to be strong that people really can’t take the law into their own hands.”