ANNAPOLIS – Maryland’s oyster harvest could sink below historic lows this winter, scientists say, as the state continues to study solutions to a problem both economic and ecological.
“We’re anticipating an oyster harvest less than 50,000 bushels,” said Christopher Judy, shellfish division director for Maryland’s Department of Natural Resources. “This would be an all-time low.”
Chesapeake Bay watermen gathered more than 10 million bushels of oysters every year in the early 1900s, but drought and disease have brought the harvest as low as 80,000 bushels in 1994.
Rains in the mid-1990s reduced the impact of the two diseases, MSX and dermo, that are plaguing the Atlantic oyster, but drought conditions for the last three years have exacerbated the disease problem, Judy said.
Overfishing decimated the oyster population during the early part of the last century, said Judy, but for the last 15 years “the driving force behind the decline of oysters has been the diseases.”
Both MSX and dermo are microscopic parasites ultimately lethal to oysters. While MSX can kill oysters at any age, dermo takes some time to become lethal and tends to kill off entire populations growing into their third year.
“When you have both diseases active in the same area, you obviously have a very bad situation,” Judy said, “because at least dermo will allow you to have some chance of producing market oysters. When you have both . . . the oysters really don’t have much of a chance.”
The only solution under investigation is the introduction of a new oyster from Asia – Crassostrea ariakensis – which is similar to the native species, Crassostrea virginica, but appears to be more disease-resistant.
“That’s the only thing that’s going to help us,” said Michael Hayden, captain of the skipjack sailing dredge boat Nellie Byrd.
The newcomer can filter twice as much water and grows nearly three times as fast as the native species.
“They can get to market size in under two years, they are highly resistant to the diseases,” said Judy. “It survives very well. The meats are very plump. So far . . . it holds a lot of promise.”
But it isn’t ready to be spawned in the bay yet, he added. The benefits are clear, but the risks are not yet known.
Virginia has been experimenting with the oyster for a number of years, but it has not yet been introduced into the bay.
“It’s in the water; it’s in cages; it’s a sterilized oyster,” Judy said. “(Virginia researchers) have monitored their growth and their disease status.”
A group of state agencies is funding a study of the oyster by the National Academy of Sciences, to be completed by the summer of 2003, Judy said. The agencies have agreed to defer water trials of the oyster until the study is completed.
An oyster restoration experiment begun in 2000 has seen some success in quarantine, but has not yet had any impact on the bay population itself, he added.
Capt. Ed Farley, of the skipjack H.M. Krentz, said the state was approaching the problem correctly by studying the oyster thoroughly before considering introduction.
“There’s always a lot of concern about the concept of introducing a foreign species,” he said. “Like so many questions of science, the more information you have the better you can make the decisions.”
But, he added, the Asian oyster’s situation was different from previous non-native species introductions because it had already been quarantined and studied in Virginia.
“What we’re talking about here is introducing offspring for generations of hatchery-raised stock,” he said. “It’s a little bit more controlled.” From his perspective as a waterman whose livelihood depends on the oyster harvest, he said, “I have some strong sympathies for introducing the Crassostrea ariakensis oysters. I’ve tasted it, it’s very good.” – 30 – CNS-12-13-02