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Agencies aim to restore bay's depleted oysters, a creek at a time

RenovationCookingEnvironmental PollutionNational Oceanic and Atmospheric Administration

It's planting time in the Chesapeake Bay, just as it is on land for farmers and gardeners across Maryland.

Instead of seeds, though, hundreds of millions of speck-sized baby oysters — known as spat — are being planted this spring in Harris Creek, where it's hoped they'll grow and multiply. The Eastern Shore waterway is ground zero for an ambitious experiment — a multimillion-dollar gamble, actually — to see if the bay's depleted oyster population can be restored, one creek and river at a time. In the process, the effort just might help clean up and revitalize the bay.

"It's not the solution, but it can be a part of the solution, and potentially a pretty big part," said Michael D. Naylor, chief of shellfish programs for the Maryland Department of Natural Resources.

Once so chock-full that Native Americans called it "great shellfish bay," the Chesapeake has long since seen its oyster population decimated by overharvesting, pollution and disease. Annual harvests from Maryland waters that peaked at 15 million bushels in the late 1800s dwindled to fewer than 30,000 bushels a decade ago, idling watermen and shuttering shucking houses. Harvests rebounded some of late, but nowhere near the catch of old.

Ecologically, the decline has been devastating. The bivalves were once so abundant they filtered all the bay's water in a few days as they fed on algae. Though scientists estimate hundreds of millions of oysters survive throughout the estuary, the population is spread thin and remains just 1 percent what it was believed to be in the early 1800s.

State and federal officials are trying to turn that around in Harris Creek, an offshoot of the Choptank River near St. Michaels and the first of 20 bay tributaries in Maryland and Virginia to be targeted for large-scale restoration. Maryland and federal agencies have labored to restore oysters around the bay for more than a decade, with mixed results because of what Naylor called "scattershot" efforts. This time, he added, "we're putting all our eggs in one basket" before trying elsewhere.

Harris Creek is a good place to start, Naylor said, as surveys indicate it's already got one of the bay's healthier oyster populations. For years, it was a popular spot for watermen, but since 2010 has been off limits to commercial harvest, part of a large-scale expansion of sanctuaries in Maryland.

"If you can't restore Harris Creek," Naylor said, "you're going to have a very difficult time trying to restore an area that was worse to begin with."

Starting last year, the Army Corps of Engineers, the National Oceanic and Atmospheric Administration and Maryland's DNR teamed up to build 22 acres of underwater reefs in the creek, providing a plateau on which oysters can grow. They laid down a layer of granite rocks, topped with empty clam and oyster shells, to provide hard surfaces to which wild oyster larvae might attach.

Finally, to give nature a boost, the nonprofit Oyster Recovery Partnership "planted" more shells with an estimated 450 million spat already settled on them. A hatchery run by the University of Maryland at Horn Point in Dorchester County produced them.

Rebuilding the reefs is critical to ensuring the survival of all those new oysters. Newly spawned larvae need to attach themselves to a hard surface such as another shell or a rock. Between shore erosion and sediment runoff from building sites in the bay watershed, officials estimate that more than 80 percent of the bay's reefs have been lost in the past 25 years under a thick layer of silt and mud.

One day last week, 6,400 tons of clam shells barged down from New Jersey were spread on Harris Creek's bottom, using satellite navigation to pinpoint where the load would go.

Not far away, over one of the reefs built last year, the oyster partnership's vessel used a hose to spray 1,400 bushels of oyster shells overboard carrying an estimated 27 million spat to the bottom.

In all, the agencies and the partnership plan to deposit 390,000 tons of granite and old shells at various places on the creek bottom. When they're done, they hope to have 377 acres of thriving shellfish communities in waters they figure had just three acres' worth before they began.

The mammoth undertaking has a price tag to match. Officials estimated it would cost $31 million to complete, including paying the university's hatchery to produce up to 2 billion baby oysters for seeding the bars. But the new reefs received an unexpectedly healthy gift of spat from the creek's existing oysters last summer, which ought to save some on buying hatchery oysters, said Stephanie Westby, NOAA's oyster restoration coordinator.

"Nature smiled on us last year, we're not totally sure of the extent of it yet," she said.

Even in a time of tight budgets, state and federal agencies have made funding the project a priority. But it still faces challenges, including finding enough old shell to build the reefs. Shell has been trucked in from as far away as Louisiana, adding to the cost.

Officials also find they need to rebuild reefs closer to shore than originally planned, because there just aren't enough good spots in deeper water. But the change is meeting resistance from local watermen, Naylor said, who aren't happy with the project.

Jim Mullin, executive director of the Maryland Oystermen Association, said watermen are bothered by the "astronomical price," and because one of the state's more productive areas is off limits to harvesting.

Still, the state's battered oyster industry has benefited from the same favorable weather the past few years that has boosted restoration efforts. Watermen hauled in about 300,000 bushels during the last season, according to preliminary estimates, their biggest wild harvest in more than a decade.

While that may indicate the bay's oysters can rebound naturally, Naylor cautioned it's a fragile and limited recovery. Oysters aren't dying as much from Dermo and MSX, the two diseases that have devastated them since the 1980s. But prior infections that appeared in retreat have flared up again and undercut revivals, he noted.

Harris Creek faces the same threat, the DNR official said, which is why the restoration effort is a gamble. But if the project can establish a dense enough crop of oysters on its rebuilt reefs, officials hope that will provide some insurance against setbacks. And a University of Maryland study suggests the project could bear fruit elsewhere, with larvae spawned in the creek carried by currents to other areas of the bay.

"We know it works,'' Naylor said of planting oysters. "The question is, does it persist, and is the long-term population that results worth the significant amount of money we've invested?"

The bay stands to benefit in a number of ways. Oyster reefs serve as magnets for marine life, including rockfish and crabs. A study indicates restored reefs help clean up the bay's degraded water, too.

Researchers with the Virginia Institute of Marine Science and UM Center for Environmental Science found that oysters and the other creatures drawn to their reefs — mussels, barnacles and worms — remove significant amounts of nitrogen from the water, which otherwise might feed the algae blooms and oxygen-starved dead zone that form every summer in the bay.

Lisa Kellogg, an ecologist at VIMS and the study's lead author, cautioned that restoring oysters, even to unrealistic historic levels, would be no panacea for the bay's pollution woes. Cleanup is still needed of sewage disposal and farm and urban runoff, she said.

"This is not a substitute for all those other activities that are going on in the watershed, but it's a supplement," agreed co-author Jeff Cornwell, a biogeochemist at UM's Horn Point laboratory. "If we could get this to a viable, self-sustaining population, it could make a dent in water quality, there's no question."

tim.wheeler@baltsun.com

Copyright © 2014, The Baltimore Sun
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