A Maryland environmentalist alarmed by the steady decline of the Chesapeake Bay's native oyster population is trying to get it on the federal Endangered Species list -- a proposal that has sparked an uproar of opposition in the oyster industry from Maine to Louisiana.

Wolf-Dieter Busch, an environmental consultant, believes bay pollution and ineffective regulations could prove fatal to the eastern oyster. Ravaged in the past by overfishing, and now undermined by disease, 99 percent of the eastern oyster population in the bay has disappeared since the late 19th century, according to federal fisheries statistics.

In January, Busch petitioned the National Marine Fisheries Service to list the oyster on the Endangered Species list, despite the existence of millions of oysters living in the bay and thriving oyster populations elsewhere along the East Coast and in the Gulf states.

"It was the only thing I could see that would get people's attention," Busch said.

It certainly has. If the petition succeeds, those in the oyster industry say it could stop all harvesting of the species and render obsolete a large segment of the national seafood economy.

Richard Pelz, chief executive of the Circle C oyster ranch on St. Jerome Creek in St. Mary's County in Southern Maryland, is one who believes an endangered designation would destroy his business and also hamper attempts at oyster-recovery in the bay. Oysters behave as a natural filter for polluted waters, and Pelz markets his floating oyster reefs as a way for shoreline homeowners to clean up the bay while growing a delicacy. He estimates the brood line of oysters he's created, named the Lineback, alone is worth $1.5 million.

"They'd have to come up with that if they shut me down," Pelz said. "There will be lawsuits if they do this, I can guarantee you. Because I'll have nothing else to do."

The petition has made it past the first hurdle, a 90-day review by the National Marine Fisheries Service to assess whether there was a valid concern over the future of the species. The answer was yes, and the decision set off a more comprehensive investigation by a 12-member team of experts. This biological review team begins meeting Monday and Tuesday in Annapolis, and a final decision will be made by Jan. 11 by the head of the fisheries service, which is part of the National Oceanic and Atmospheric Administration.

"Oysters in the Chesapeake Bay are in serious, serious trouble. They've had such a drastic decline in the past century," said Jamie King, an oyster specialist in the National Oceanic and Atmospheric Administration's Chesapeake Bay office. "And things are not getting better under current management strategies."

While federal fisheries officials will not speculate on the chances of the petition's success, some at the state level view it with growing concern.

"We still have tens to hundreds of millions of animals in the Chesapeake Bay. It's pretty difficult to justify an endangered tag when you have so many of them and they continue to reproduce," said Michael E. Slattery, assistant secretary for the Maryland Department of Natural Resources, which does not support listing the oyster.

The main problem, Slattery said, is that 90 percent of Chesapeake oysters are killed off by diseases before they reach an age and size at which they can be commercially harvested. Some say the oyster industry in the Chesapeake is more endangered than the animal itself. Virginia had more than 400 shucking houses in the 1950s, and only about 15 remain, said James A. Wesson of the Virginia Marine Resources Commission in a congressional hearing last month.

At the hearing, a stream of marine biologists, members of the seafood industry and state officials testified to the House Resources Committee about the stable populations outside the Chesapeake and the economic importance of the oyster. In Louisiana alone, the 14 million pounds of oyster meat produced in 2003 provided more than 3,000 full-time jobs and generated $286 million in economic impact, said William S. Perret, marine fisheries director of the Mississippi Department of Marine Resources.

If the oyster were a vertebrate, it would be possible under the Endangered Species Act to protect it solely in the Chesapeake and leave it unrestricted elsewhere, as some biologists have suggested.

No such regional specificity is allowed for invertebrates. This summer, however, Rep. Bobby Jindal (R-La.) sponsored a bill that would amend the act to allow treating segments of the eastern oyster population as a separate species.

In the Chesapeake, the eastern oyster once was so bountiful that more than 100 million pounds a year were pulled from the bay in the late 19th century, a time when Baltimore was the world's largest supplier. That number had dropped to 236,512 pounds by 2003.

The attempts at rebuilding the oyster population have been manifold, from constructing oyster reefs to breeding disease-resistant oysters to establishing shellfish sanctuaries. In Virginia, $40 million in government money has been spent on reef projects alone, said Wesson. Little has worked.

In St. Mary's, the oyster once was central to the culture and economy; shucking houses dotted the shoreline, and oyster pirates sailed the Potomac River at night. Today, the industry has been reduced to little more than a relic.

Still, after hearing about the petition, the St. Mary's Board of County Commissioners wrote in protest to the National Oceanic and Atmospheric Administration, claiming that the listing "would have a devastating impact on local aquaculture operations and our local seafood industry."

The commisioners said the listing could shut down the annual St. Mary's County Oyster Festival, which brings in more than 15,000 tourists a year to watch the National Oyster Shucking Championship.

Richard Pelz of the Circle C oyster ranch on St. Jerome Creek in St. Mary's County says an endangered designation would destroy his business. A biological study of the status of eastern oysters begins Monday in Annapolis.Richard Pelz, left, chief executive of the Circle C oyster ranch, walks with employee Frank Taylor. Pelz says that if the eastern oyster is designated as endangered, "there will be lawsuits."