ENDERSON HARBOR, N.Y. -- When nearly 1,000 double-crested cormorants were found shot dead on an island in eastern Lake Ontario near here last week, federal wildlife officials labeled the incident "a brazen act of environmental terrorism." 

An animal rights group in California offered a $1,000 reward for the capture of those responsible for what it called "a brutal act of animal cruelty." 

But around this hamlet, where nearly everyone makes a living indirectly or directly from sport fishing, the incident was likened to the Boston Tea Party, and the as yet unidentified shooters were hailed as heroes. 

"I only wish they'd killed every last one," said Ronald Ditch, a longtime fishing guide. Ditch and many of his colleagues have spent a decade pressing federal and state wildlife officials to permit shooting of the rapidly multiplying fishing birds, which the guides blamed for a sharp decline in stocks of smallmouth bass, perch and other popular game fish. 

In the surrounding town of Henderson, where vacationing fishermen help swell the population from 1,200 to 10,000 every summer, anything that threatens the fish also threatens a way of life, said Frank Ross, the Town Supervisor and a mechanic at a local gas station. 

Just a few years ago, about 70 guides were kept busy all summer here taking fishermen from across the United States out into the eastern basin of the lake, which was renowned as one of the best bass-fishing spots in North America. Now there are about 20, marina owners say. 

The cormorants were nearly extinct on the Great Lakes in the 1950s, depleted by the combined effects of shooting, DDT and pollution. Although never protected by the Endangered Species Act, they have been covered since 1972 by a federal law governing migratory birds. 

But now their numbers have rebounded across North America, and every spring and summer thousands settle in to nest on Little Galloo Island, 10 miles west of Henderson Harbor. 

As the 52-acre island has grown to become the largest nursery for cormorants in the United States, it has also become a focus for the hatred of dozens of fishing guides and other business owners in Jefferson County, who have seen a decline in revenue as fishermen shift to waters with more fish and fewer birds. 

No conclusive link has been made between the return of the cormorants and the decline of bass and other fish here. Nevertheless, marina owners and fishing guides are losing patience with federal officials, who prohibit shooting the birds unless a clear economic loss is shown. 

The birds have so many enemies that the criminal investigation this week was taking on the appearance of an Agatha Christie mystery in which everyone is a suspect. Conservation officers were faced with half a dozen communities in which almost everyone, from fishing guides and gas station attendants to motel owners, had motive, opportunity and -- given the popularity of duck and deer hunting -- the necessary weaponry. 

The incident also had political overtones, since local residents say they resent what they regard as the intrusion of unreasonable regulations written far away and long ago. 

"You can only oppress people for so long and they're going to strike out," said David McCrea, a third-generation fishing guide, as he left four anglers and their catch of 20 bass and four walleyes at the Henchen Marina and Fishing Camp after a day on the lake. "If these birds did this in Washington or on some politician's golf course, they'd be gone in a minute." 

Federal and state wildlife officials, traditionally focused on saving endangered species, find themselves dealing increasingly with problems created by species that have recovered so well from past troubles that they have moved from rarities to nuisances. That is the case with the double-crested cormorant. 

The mass shooting was by far the most brutal of several recent incidents in which large numbers of birds protected under the 80-year-old Migratory Bird Treaty Act have been killed. That pact was worked out among the United States, Canada, Mexico and several other countries to protect hundreds of bird species that cross international boundaries. 

Before dawn on July 23, in Carrollton, Tex., city officials used bulldozers in a pre-dawn raid on a large rookery for several kinds of protected herons and egrets, killing hundreds of birds and injuring many more. They were responding to complaints about the squawking and odor from the colony. 

Around the same date, bulldozers clearing a road for a development in Conway, Ark., plowed through woodlands containing hundreds of egret nests, apparently killing many birds and sending orphaned baby egrets wandering around nearby streets and back yards. 

Across the country, protected birds have occasionally been shot in anger or hunters have exceeded permitted limits for protected waterfowl, federal and state wildlife officials said, but nothing in recent decades has come close to the systematic slaughter of the Little Galloo Island cormorants. 

The extreme nature of the incident most likely sprang from two factors, local residents and wildlife officials said: the exasperating nature of the cormorants, and the nature of the community here. 

The birds are voracious predators, diving up to 60 feet to hunt fish, from minnows to 12-inch bass. Each one can consume a pound or more of fish a day. They brazenly dive under boats, swooping past anglers' lures. "They're an in-your-face kind of bird," explained Russell McCullough, a state fisheries biologist. 

Like the birds, most of the little towns along the shore are almost entirely focused on fish. "We've got no Kodak, no Du Pont," Ditch said. "You're either a fisherman or a farmer if you're going to live here." 

For 14 years, he and other guides said, the cormorant population has risen unchecked, until now tens of thousands of birds camp out each spring and summer on Little Galloo. The birds and people were bound to clash, everyone around here says. 

Tensions intensified with a recent unexplained crash of the population of smallmouth bass, which was the main species fished from Henderson Harbor for generations. Sampling by state biologists over the last 22 years has revealed a precipitous drop. 

Some people in the area say that some of the anger of the fishing community is misplaced, that the fishing guides should shift their business as the lake ecology shifts. 

"Everything here is a kind of weird balancing act between exotic species, native species, changes in the weather, changes in tourism patterns," said Stephen Fort, senior planner for Jefferson County. "The charter captains and the whole industry just has to adapt." 

But that view was nowhere to be seen at the Henchen Marina, where the docks were busy with the late afternoon rush of boats returning from a day on the water. 

Diane Gamble oversaw the pumping of gas, the sale of ice and the steady flow of fishermen sticking their catch on a board studded with pegs to pose for cameras. Her grandfather had built the marina 60 years ago, and the family had seen many ebbs and surges in fishing, but the drop in the bass these days -- and the related drop in business -- was like nothing in memory, she said. 

On top of the chest for bags of ice, white wooden placards painted with the names of three dozen fishing guides sat in stacks, but only a half dozen placards hung on hooks under a sign that read "Out." 

Mrs. Gamble said that just a few years ago, the numbers would have been reversed, and that most guides would be out on the water on a hot, sunny day like this one. 

If the cormorant population was kept in check, Mrs. Gamble said, she doubted that people would hate the birds as they do. But when fishermen have to pass through floating cordons of the birds hundreds of yards long, their frustration is hard to contain, she said. 

"Nature normally takes its course," Mrs. Gamble said. "But nature's out of balance right now." 

Lieut. Christopher Hanley, who is leading the criminal investigation for the state Department of Environmental Conservation, said that no matter what the fishing communities felt, there was no excuse for what took place on the island. 

"I've never seen anything like this," he said. "These were fledglings that could not fly away. This is a terrible crime." 

The attack was discovered on July 29, when a team of state wildlife biologists and technicians visited Little Galloo Island as part of a study of the bird's eating habits. The study is intended to determine, once and for all, whether the birds are responsible for the changes in fish stocks. 

This week, the same team returned to the island to resume the work, which involves picking up regurgitated balls of fish bones, then studying the material to determine the diet of the birds. 

But the biologist and two assistants also spent time picking up more 12-gauge shotgun shells, which could be distinguished from old shells left behind by duck hunters because the new brass still gleamed in the sun. 

They crossed a barren landscape of roughly heaped nests, weeds and dead birds. In the last 30 years, as the colony grew from a few nesting pairs to more than 8,000 at its peak in 1996. The birds have transformed the island from a grassy spot that once attracted picnickers into a place of yard-high dunes of guano that feel like a spongy mat under foot, a place where the few remaining trees stand like bleached skeletons, whitened by years of bird droppings. 

Brian Edmonds and Laura Brown, the assistants, circled the island as they had once a week since April. They reached the spot where they realized that something terrible had happened a week earlier. "I found seven freshly killed birds," Ms. Brown said. "Then seven led to 200, and 200 more." 

"Around here is where we stopped collecting pellets and started collecting evidence," Edmonds said. 

Just offshore, fleets of young cormorants bobbed in the chop. The biologists said the shooting happened at the tail end of the nesting season, so most of the birds escaped. 

But hundreds did not. The scientists passed spot after spot where dozens of birds were shot en masse, with the desiccated carcasses receding into the powdery soil, little more than black smudges of feathers and bones. 

Copyright 1998 The New York Times Company