Jack Moore remembers when the skies above the Chesapeake Bay grew dark and noisy with ducks every fall and the first day of hunting season was worth losing sleep over.

This week, when Maryland and Virginia allow duck hunters to take legal aim on the migratory waterfowl, Moore expects to see nothing but clouds.

"There are no more ducks down here," said Moore, 41, a professional hunting guide on Maryland's Eastern Shore. "When I was a kid, the ducks were so thick, if there were only 10,000 of them we'd say there weren't any. But I mean now there are just no ducks."

The decline in the black duck population has forged an unlikely alliance between hunters such as Moore and conservation groups such as the Humane Society of the United States and Maine's Audubon Society. The issue they are joined on: a ban on hunting what was once the East Coast's premier game bird.

In a suit filed against the U.S. Fish and Wildlife Service in U.S. District Court in Washington, lawyers for the conservationists argue overhunting, particularly in the bird's Maine nesting grounds, threatens to eliminate the species.

"The failure of the Fish and Wildlife Service to close the hunting season is irresponsible, and should be ruled illegal," said Dr. John W. Grandy, a wildlife biologist and vice president of the humane society. "If decisive action is not taken, the black duck will not survive as a species."

The wildlife service does not dispute that the black duck has had tough times. But officials say the cause of the decline is not necessarily the result of overhunting. In the last few decades, the black duck has suffered from a loss of habitat and competition for what remains from the larger and more aggressive mallard.

"Time is needed to evaluate the relative merits of several regulatory options and to determine which are most appropriate in various geographical areas in the eastern United States," reads the wildlife service's migratory bird-hunting regulations for this year. "Although a long-term decline is evident . . . it has been gradual and does not indicate an immediate crisis for the species' welfare."

Lawyers for the wildlife service and conservation groups are expected to begin arguments later this month. Although a request for a temporary restraining order to immediately halt the hunt already has been denied, a final decision could be reached in time to affect this year's duck season.

The debate over ducks involves a central issue in game conservation: money. Most state wildlife departments depend upon hunting fees for much of their budgets. The more hunting is limited, the less money to enforce those limits. Banning duck hunting entirely, even for just one season, could cause the loss of jobs and research.

"The trouble with fish and game departments these days is that they don't manage fish and game, they manage sportsmen," wrote one wildlife editor in a prestigious hunting magazine that was debating the duck-hunting issue in 1976.

Conservationists were delighted when Maine wildlife officials earlier this year recommended a closed duck-hunting season. Studies show that 65 percent of the Maine-bred ducks that are shot each year never make it past the state line. Pressure from local hunters, however, persuaded the state officials to compromise by reducing the length of the season and bag limits. The hunters argued it was unfair to impose a ban on them while hunters to the south were not restricted by their state agencies.

Much of the statistical evidence used by conservationists seeking a temporary hunting ban was gathered in Maine. Howard E. Spencer, the state's migratory bird expert, reported that in the last decade black duck brood production dropped by "as much as 75 percent." Spencer also reported that less than 45 percent of young black ducks survive long enough to breed.

Wildlife service officials insist, in characteristic bureaucratese, that their agency is "committed to a program to effect necessary hunting restrictions on black ducks." What they seek first is some agreement between state agencies and Canada, where most black ducks breed.

But conservationists like Grandy, who earned a Ph.D. in wildlife biology, studying black ducks, fear federal officials will do too little, too late.

"My wife was saying to me the other day, 'You may be able to tell your children that you did your doctoral dissertation on a species that is now extinct,' " said Grandy.