CBF's specialty fitted Patricia Campbell can distribute oysters on a reef with pinpoint accuracy.
A Homecoming for Oysters
By Cynthia Barry
Published in the Fall 2008 issue of Save The Bay magazine
Under a microscope, oyster "spat" resemble tiny brown spots. These infinitesimal specks, looking like freckles and about as active, represent the possible return one day of the great natural filter Crassostrea virginica, the Chesapeake's native oyster.
Karl Willey, operations manager at CBF's Maryland Oyster Restoration Center (ORC), explains, "Those are the babies—oyster spat-on-shell. They'll be going into the Bay in a couple of weeks." Spat are young oysters that have just attached to a smooth, hard surface—in this case, oyster shells.
Oysters are a keystone species, supporting and balancing many other forms of life by virtue of their amazing filtering prowess and reef architecture. An individual oyster can filter water at a rate of up to two gallons an hour.
About Eastern Oysters
HABITAT: Oysters usually live in three-dimensional reefs in water eight to 25 feet deep, but can tolerate tidal flows that expose them to air. They depend on the flow of food-laden water. Oyster reefs contain nooks and crannies that provide food and shelter for a constant play of predator-play relationships.
REPRODUCTION: A rise in water temperature prompts the male oyster to release sperm and the female to release millions of eggs in a spawn that clouds the water. The eggs are fertilized in the water and grow into free-swimming larvae.
GROWTH: The young oysters move with the current, eventually attaching to a hard surface—either oyster shell or another substance. Once anchored into place, the oysters grow about an inch a year, reaching market size (three inches in Maryland and Virginia) three to five years later. Their sexual development is complex: Oysters begin as males, then change to females. There is some evidence that they switch back later in life.
And a healthy oyster reef teems with life—grass shrimp, anemones, barnacles, oyster drills, hooked mussels, mud crabs, and red beard sponge, to name a few. These reef denizens in turn serve as food for larger creatures, including striped bass, sea trout, weakfish, black drum, croaker, and blue crabs.
"Oyster spat set naturally on other oyster shells," said Stephanie Reynolds, CBF
Maryland Oyster Restoration Scientist. "Today, underwater piles of shell have mostly disappeared, but we know from years of experience that a different hard surface, like a concrete ‘reef ball,' will give oysters the nooks and crannies they need to shelter and grow."
Reynolds and other CBF staffers not only wrestle millions of oysters physically back into the Bay by growing, transporting, and planting tons of oysters; they're active on many fronts, supporting research and advocating for funds, programs, and regulations to restore healthy oyster populations and a sustainable fishery.
When Europeans arrived in the Bay area in 1607, nature had been building up oyster reefs for 7,000 years and Capt. John Smith noted that they "lay thick as stones." But in the past two hundred years, humans have all but destroyed nature's work. Oysters could once filter a volume of water equal to that of the entire Bay (18 trillion gallons) within a week. Today, there are so few that it would take a year.
CBF believes oyster populations are now at approximately four percent of historic levels, hit hard by overharvesting, loss of habitat, pollution, and parasitic diseases.
Oystering, once a valuable commercial fishery that supported generations of Bay residents, has sunk to record lows. CBF's Oyster Restoration Center at Discovery Village in Shady Side, Maryland, is the home of Maryland's Oyster Gardening Program and headquarters for an educational outreach program on the value of Bay oyster reefs as water filters and fish habitats. It's also the homeport of the purpose-built, 60-foot oyster-restoration vessel, Patricia Campbell.
On a recent deployment, the state-of-the-art seeding vessel transferred 3.1 million oysters to a sanctuary reef north of Broomes Island in the Patuxent River. By the end of 2008, ORC aims to have helped restore 10 million oysters to sanctuary reefs.
"Oysters will not be restored to target levels overnight, but we have made progress," said Bill Goldsborough, Senior Scientist and Fisheries Program Director for CBF. "The scale of investment in the solution must be commensurate with the scale of the problem."
He points to the self-sustaining population established in Virginia's Lynnhaven River as a success model. Once almost completely closed to oyster harvest, the river today has approximately 30 percent of its water open to harvest of this prized shellfish.
At CBF's Virginia Oyster Restoration Center, successful aquaculture projects are gaining attention. CBF Senior Fisheries Scientist Tommy Leggett recently delivered 50,000 sterile (triploid) oysters grown at the center to a sustainable aquaculture program on Tangier Island. Sterile oysters grow faster because they do not put energy into reproduction and can use that energy for growth. "We hope to plant nearly three million triploid spat-on-shell in the summer of 2008 and harvest the oysters in December 2009. If we can demonstrate commercial feasibility, then watermen will be able to stay working on the water," explained Leggett.
Across the Bay, volunteers have pitched in to help with oyster restoration projects. "They're invaluable—we couldn't do it without them," says Reynolds. State and national agencies are involved as well. CBF has partnered with organizations such as the National Oceanic and
Atmospheric Administration, University of Maryland Center for Environmental Science Horn Point Laboratory, Virginia Marine Resources Commission, Virginia Institute of Marine Science, and U.S. Army Corps of Engineers to bring sound science and funding to the oyster restoration process.
Now, scientists face another question that could affect the Bay's native oyster: Because of the depredations of the past and the disease and pollution of the present, should a non-native species be introduced in hope of saving a fishery and an environment? Virginia and Maryland are evaluating the introduction of an Asian oyster, Crassostrea ariakensis. The U.S. Army Corps of Engineers is preparing an Environmental Impact Statement (EIS), and a draft document is expected to be issued by the end of the year.
"Native oyster restoration is clearly our preferred alternative," said Goldsborough. "It's simply a question of whether we have the political will to clean up our waters and invest substantially in the restoration of the iconic Chesapeake oyster."