Oysters are the Chesapeake Bay's keystone species: they support and balance many other forms of life by filtering water and building habitat. A single oyster filters two gallons of water an hour. Oysters live by "setting," or attaching to, existing oysters or old oyster shells to build a reef. Oyster reefs, like coral reefs, provide a safe place for fish and other sea creatures to hide, eat, and raise young.
But native oysters have declined as reefs have disappeared.
History of Chesapeake Oysters
When Captain John Smith and the Virginia Company arrived in Virginia in 1607, oysters had been building reefs in the Chesapeake for 7,000 years. Early Chesapeake explorers said that the reefs were so large that they scraped the bottom of their boats. While the Chesapeake Bay's average depth is 20 feet, oyster reefs had grown to be eight to 25 feet tall. The oysters in these huge reefs fed on food in the water that they filtered as the Bay's tides rose and fell, moving across the reef with the current.
The first settlers also recorded that they saw huge refuse piles of oyster shells. The shells exposed the site of recent meals by Virginia Indians. Oysters were an important source of food for the native people and European settlers.
But in the last 200 years, the human appetite for oysters has led to the destruction of the natural reefs. While oysters were once able to filter a volume of water as large as the Bay in a week, the remaining population would need a year to do the same work.
Experts from the Chesapeake Bay Foundation believe that today's oyster population stands at four percent of pre-European settlement levels.
Can the Oysters and Their Reefs be Restored?
In the nineteenth century and through the early twentieth century, oystering was a valuable commercial fishery that supported watermen and their families. However mechanical harvesting methods allowed more oysters to be harvested and the ancient reefs were destroyed. As the oyster reefs necessary to support young oysters dwindled, it became harder for watermen to earn a living.
In addition, reduced numbers of oysters meant that the remaining mollusks were more susceptible to parasites and disease. The Chesapeake Bay region is attractive to people and more of them are moving into the region. Their waste and sediment pollution from construction and runoff from roofs and paved surfaces make the Bay murkier and less healthy.
In spite of this, the Chesapeake Bay Foundation has spearheaded aquaculture projects that are gaining attention. Senior Fisheries Scientist Tommy Leggett has encouraged sustainable aquaculture programs that use sterile oysters. The sterile oysters can grow faster because they don't use energy to reproduce. About 3 million spat or baby oysters have been deposited in the Bay in 2008. "If we can demonstrate commercial feasibility, then watermen will be able to stay working on the water," explained Leggett in a recent Foundation publication.
The rebuilding of stocks of the native oyster, Crassostrea virginica, is being helped by hundreds of volunteers who assist Leggett in the dirty work of collecting oyster shells and bagging them at his facility at the Virginia Institute of Marine Science in Gloucester Point, Virginia. There, the bagged oysters are held in water tanks where the spat are released and allowed to set on shells. The bags of shells with baby oysters are taken to reefs that are being rebuilt in healthy areas of the Bay. Once anchored, oyster spat grows at a rate of an inch a year and reach market size in three to five years.
Healthy Oyster Reefs Can Help Save the Bay
As the reefs grow, more oysters are not only rebuilding the industry, they are filtering the Bay's water. Bountiful reefs and less polluted water will mean that all Bay species will be more likely to thrive. A healthier ecosystem will improve the local economy and enjoyment of the Chesapeake Bay, a national treasure.
Read another article by the author about the objectives of oyster restoration.
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