- The Washington Times - Sunday, December 7, 2003

The native oysters that once filtered the waters of Chesapeake Bay have mostly disappeared, devastated by overharvesting and disease.

Now some observers say oysters from Asia are the key to restoring oysters to the Bay. But scientists, public officials and environmentalists differ on the safest way to proceed.

While a Maryland state agency cautiously proposes the introduction of breeding oysters, university researchers are forging ahead with trials involving sterile oysters. A third project, involving the release of 1 million sterile Asian oysters, is already under way in Virginia.

All of the proposals generate concern. Some worry that the foreign oysters won’t thrive in local waters or that they will bring in new diseases, while others fear that the Asian mollusks could rapidly multiply, become invasive and crowd out what’s left of the local stock.

One proposal comes from the Maryland Department of Natural Resources (DNR), which hopes to scatter breeding oysters from Asia throughout the Bay. The agency is conducting studies on the environmental impact of the program.

If the scientists deem the breeding oysters safe, the oysters could be introduced next fall, said DNR Secretary Ron Franks.

Another experiment, devised by university researchers, involves placing 5,200 infertile, lab-bred Asian oysters in cages at several drop sites in the Bay, monitoring their growth and survival rates, then removing them. The cages would be placed in the Choptank, Patuxent and Severn rivers in Maryland, as well as in Virginia’s York River.

This experiment, developed by biologists at the University of Maryland’s Marine Estuarine Environmental Sciences program and a lab at the Virginia Institute of Marine Sciences, would help predict how the species would do if introduced permanently.

While there is no way to make oysters 100 percent sterile, these oysters were bred with an odd number of chromosomes to reduce their fertility. There is a small risk that they could become fertile as they age, but “there’s more risk in not knowing about a potential danger,” says Kennedy Paynter, who runs the experiments for the marine sciences program.

Mr. Paynter says the knowledge scientists will gain from monitoring the oysters is more important than the possibility that they might reproduce.

In addition, the infertile oysters, born and raised in a lab, are a generation removed from their progenitors, members of the Crassostrea ariakensis species native to China. Raising the oysters in a lab rather than harvesting them from the wild also reduces the likelihood they will introduce foreign diseases.

The state’s labyrinth of environmental regulations has slowed Mr. Paynter’s plan to introduce the infertile oysters. But his proposal is quietly winning permission from necessary agencies, and the mollusks are likely to be placed in the Bay this spring, months before the state introduces its stock of breeding oysters.

Meanwhile, Standish Allen, a scientist with the Virginia Institute of Marine Sciences, released 1 million lab-bred ariakensis oysters into state Bay waters in September. Virginia’s political climate, historically less environmentally conservative than Maryland’s, fostered the ariakensis research much earlier.

Officials in Anne Arundel County, which is home to the Severn River site where Mr. Paynter plans to drop some of his oysters, want Mr. Paynter’s project postponed until results are in from the Virginia experiment.

Anne Arundel officials fear the new oysters could become invasive, crowding out the native Crassostrea virginica species and dominating the Bay’s ecosystem.

“The county executive doesn’t want to take that risk,” said Bob Walker, the county’s land use and environment officer. “You just never know. What seems like a very worthwhile effort could turn into something unforeseen that could have devastating consequences.”

Anne Arundel officials cited the possibility of an “unforeseeable catastrophe” when it outlined its objections in a three-page letter to the state.

But Mr. Allen and Mr. Paynter advocate forging ahead.

“You can’t know the true impact of an introduction until you’ve actually made it,” Mr. Allen said. The Bay won’t see the benefits of a bolstered oyster population without taking some risks, he added.

“We’re basically applying every tool we have at our disposal to minimize these risks and still gain the information,” Mr. Allen told U.S. Rep. Wayne T. Gilchrest, Republican, at a hearing the Maryland congressman called in October to determine who has the authority to release oysters in the Bay.

Meanwhile, Mr. Paynter says that while Maryland researchers can use Mr. Allen’s findings from the Virginia project, they need to proceed with their own experiments.

“We need the information to be able to argue as a state whether ariakensis should be brought in,” he said. “What happens if we find out they don’t grow very well or there are other negatives?”

Mr. Paynter believes that diseases already present in the Bay make it impossible to restore the population of native oysters. In addition, he says, because the native virginica species has such a high mortality rate, it will never be able to accomplish its original “ecological job” of filtering Bay waters.


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