When Captain John Smith first arrived in the Chesapeake Bay during the early 17th century, he noted such an abundance of oysters that it made it dangerous to navigate his ship. About 100 years later, Francis Louis Michel remarked, "The abundance of oysters is incredible. There are whole banks of them so that the ships must avoid them. They surpass those in England by far in size, indeed they are four times as large." But five centuries later, the oyster populations are but a fraction of those first seen by Captain Smith.

Called Chesapeake's "white gold," Crassostrea virginica - also known as the eastern, American or Atlantic oyster - is a tolerant organism able to withstand wide variations in temperature, salinity, suspended sediments, and dissolved oxygen. Found in estuaries, sounds and bays, the eastern oyster plays an important role in the health and survival of the Chesapeake Bay. Aside from the obvious economic role it has on Maryland's economy, the American oyster filters algae from the Bay improving water quality for all organisms that depend on the Bay. A paper by UMCES scientist Roger Newell in 1987 made the dramatic point that oyster populations at the beginning of the century could have filtered the entire Chesapeake in several days, while the populations remaining at the end of the 20th century would take more than a year.

Over the past few years, UMCES has worked to restore oyster populations in the Bay through its Horn Point Oyster Hatchery and the Maryland Sea Grant College. Oysters spawn when water temperatures become greater than 68°F (~20°C). They are broadcast spawners, releasing eggs and sperm into the water column. As seen in the video clip, the males will spray sperm from the side of their shells while females will slowly open their shells and give a short spurt of eggs. Fertilized eggs develop into a planktonic or swimming larval form. After about two weeks these larvae will "set", a process of cementing themselves to a hard substrate, and metamorphose. This newly attached oyster is known as a "spat." More than 50 million spat have been produced in Horn Point's hatchery and placed in the tributaries of the Chesapeake Bay.

Since native oyster populations are a mere fraction of its historic population, it has been proposed that the Suminoe oyster (Crassostrea ariakensis) be used in aquaculture facilities and even possible introduction into the Bay. Researchers in Virginia have begun growth and mortality trials with infertile specimens. To date the Suminoe oyster appears to be resistant to MSX and Dermo, two diseases that have decimated the native oyster. Any intentional introduction of a non-native species into the environment requires careful consideration due to possible unintended consequences. Scientists at UMCES have developed a position paper entitled "Resolving the Benefits and Risks of Crassostrea ariakensis in Chesapeake Bay and Atlantic Coast Estuaries."

The Maryland Sea Grant web site has additional resources regarding the complexities of oyster management in the Chesapeake Bay at its web site.

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