US - A combination of overfishing, disease, pollution, silting and runoff has devastated oyster numbers in North America's biggest estuary. Harvests are at about 1 per cent of the records set in the 1880s, when 20 million bushels were pulled from the bay.
Now federal and state agencies are trying to reverse the trend with a $30-million dollar (S$37.9 million) oyster restoration experiment aimed at improving water quality, restoring habitat and stabilizing shorelines in the 3,200-square-mile (8,300-square km) estuary.
Two billion pinpoint-sized baby oysters are at the heart of the effort to restore the bay's oysters, one inlet at a time. The first testing ground: a narrow tributary of the Choptank River called Harris Creek, targeted as part of a 2009 executive order by President Barack Obama to protect the Chesapeake and its watershed.
Experts say it could take years before they know whether the creek's oysters can sustain themselves there.
"You want to get the snowball rolling downhill so that it can keep going by itself," said Mike Naylor, assistant director of the Maryland Department of Natural Resources' shellfish division. "It's going to be a really long time before we can say it worked, it's done."
If successful, the project could inspire similar efforts elsewhere. According to a 2011 Nature Conservancy Report, 85 per cent of oyster reefs-which provide habitat for sea life and feeding grounds for migratory birds--have been lost around the world.
Oysters also help maintain water quality by filtering water. An adult oyster can filter up to 50 gallons of water a day, and when numbers were at their peak oysters could strain the entire Chesapeake Bay in three days. Now, it takes a year.
The new project calls for the dumping of hundreds of thousands of tons of granite and old oyster shells on about 370 acres of the estuary bottom. The substrate then acts as a resting place for shells seeded with the speck-sized infant oysters called spat.
Hundreds of bushels of seeded shells at a time have been loaded onto the Robert Lee, a converted oyster boat, since the spring. The shells and their spat of native Eastern oysters are sprayed overboard into Harris Creek using a high-pressure hose attached to a boom.
So far, the shortage of oyster shells has proved the biggest impediment. Demand has skyrocketed with the expansion of aquaculture and the price of shells has gone from 50 cents to $2 a bushel, Naylor said.
Seeding the tributary is about half completed, according to a spokeswoman for the Oyster Recovery Partnership.
Harris Creek and other tributaries were declared off-limits to oyster fishing in 2010. The move angered commercial fishermen, who say their objections to the Harris Creek project were ignored.
Russell Dize, vice president of the Maryland Watermen's Association, said granite dumped on the bottom had hurt crabbing since it damaged fishermen's gear. The seeded oysters could have easily been deposited on existing beds in the inlet, he said.
"We've lost the creek for oysters. They took that away. Now they've screwed it up for crabbing. It just makes it harder to make a living," said Dize, who lives on Tilghman Island bordering Harris Creek.
The Harris Creek restoration is being overseen by the Army Corps of Engineers, the National Oceanic and Atmospheric Administration and Maryland's Department of Natural Resources.
Steven Allen, senior manager for aquatic restoration at the Oyster Recovery Partnership, a non-profit group helping on the project, said previous oyster efforts in the bay had been scattershot, with mixed results.
"This is the first actual project focused on tributary-wide restoration," he said.
The project is expected to be completed by early next year. After that, the wait to measure its success will begin.