Bye, bye bivalve

StoryImage( ‘/Images/Story//Auto-img-110615400030659.jpg’, ‘Photo by Dr. Robert A. Hedeen’, ‘An empty oyster shell now typifies the state of the once-abundant Chesapeake oyster.’);

When the first European settlers came to the Mid-Atlantic States of Maryland and Virginia, the oysters in the Chesapeake Bay and some of its tributaries were so numerous that they posed a threat to navigation. Some of those bivalved mollusks were so large, they had to be cut into three pieces before they could be swallowed. The settlers in early Jamestown were saved from starvation one brutal winter by subsisting almost entirely on oysters. Today, the oysters of the Chesapeake are almost on the verge of being classified as an endangered species.

This fact was driven home to me on a recent visit to Baltimore, where I attended a traditional bull roast and oyster community dinner. As is the usual case, a raw bar was available, and a large mound of oysters was piled up before two shuckers, who opened them with lightning speed and presented them on the half shell to the eager, queued-up aficionados.

As I waited in line for my first serving, an alarm was set off when I noticed that some of the oysters were less than 3 inches in length. It suddenly dawned on me that these were not Maryland, Chesapeake Bay oysters. A law was passed many years ago that prohibits the taking of oysters less than 3 inches in length, and this regulation is rigidly enforced by the marine police. The law was passed as a conservation measure. A newly hatched oyster grows about 1 inch a year, and three years are usually required for it to become sexually mature. The rationale behind the law is to give the oyster at least one chance to perpetuate the species.

I asked the individual in charge of the raw bar where these oysters were from, and, to my horror, he replied Mississippi and Alabama. I never thought I would see the day when Gulf Coast oysters would be offered to Marylanders. The man said he had provided about 3,000 of the bivalves for the some 300 guests. I guess I had more than my share when I polished off 24 of them.

I have not lived in Maryland for more than five years, but I was aware that the oyster populations in the Chesapeake were steadily declining from the days when I used to harvest all I could eat from right in front of my house on the Nanticoke River, a major tributary to the Bay. Figures from the Maryland Department of Natural resources verify this by listing the number of bushels of oysters brought to market: 1980-81, 2,532,321; 1990-1991, 418,393; 1993-1994, 79,618; est. for 1994-1995 164,641. The sad situation today is the waterman cannot make even a minimum wage harvesting them.

The reasons for the decline in this wonderful natural resource are twofold: over fishing and two diseases, MSX and Dermo. In 1957, MSX (multinucleated sphere unknown) appeared in Delaware Bay and wiped out 90 percent of the oysters. By 1960, it had made its way to the Chesapeake and quickly infiltrated the entire Bay. (In recent years, MSX has been identified as a one-celled protozoan and given a proper scientific name. Dermo is the nickname for a fungus, parasitic on oysters that was recognized at about the same time as MSX).

Overfishing is probably of more importance in the decline of Chesapeake oysters than the two diseases. Unfortunately, the attitude of generations of watermen was “Get ‘em today and to hell with tomorrow.” I once asked a waterman what he would do if there were only two oysters, a male and a female, remaining in the Bay, and he knew where they were. He replied, “I would go out and catch them and make a nice oyster stew. The Lord put them there in the first place, and he will give us more.”

As oysters are filter feeders, they are of great ecological importance to the health of the Chesapeake. Biologists have estimated that 100 years ago, all the trillions of gallons of water in the Chesapeake Bay would pass through the oysters in about three days. Now it is estimated that it would take five years to accomplish the same cleansing action. Unicellular algal blooms are now common as a result of fertilizer runoff, and whereas before the oysters would keep the algae under control, this is no longer possible.

If any of you had oysters over the holiday season, they undoubtedly came from the Gulf Coast or were non-native, Japanese oysters produced by aquaculture in the Pacific Northwest. Perhaps, through education and the natural selection of oysters resistant to the diseases, our grandchildren may again enjoy what has been termed the “Gem of the Chesapeake.”

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

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