Friday, October 10, 2008

BALTIMORE (AP) - Introducing disease-resistant Asian oysters into the Chesapeake Bay could supplement the shellfish’s dwindling population but could hurt native oysters and threaten other ecosystems along the East Coast, according to a federal study.

The draft environmental impact statement by the U.S. Army Corps of Engineers presents pros and cons of the proposal but makes no recommendations. The $17 million four-year study was aimed at settling the debate over introducing nonnative oysters in the Bay, where the native population has been severely damaged by parasitic diseases and overharvesting.

A copy of the document was obtained by the Baltimore Sun.

“I think there’s some serious promise” with the Asian oyster, said Kennedy Paynter, a University of Maryland oyster biologist who has worked with both species. “But I think that the potential for serious negative impact that we don’t understand yet is still quite high.”

The study examined introducing billions of Asian oysters, growing sterilized ones in the Bay for commercial use and native restoration efforts, including a Bay-wide harvesting moratorium.

Introducing sterile and reproducing Asian oysters and restoring native species held the most promise for rebuilding the Bay’s population, the study said. But it warned that the approach is the riskiest environmentally and may not restore oysters to levels seen until about 40 years ago.

Asian oysters are fast-growing and resistant to the two parasitic diseases killing native ones, but research has shown they are more vulnerable to predators and poor water quality than native oysters. Other research suggests they may also be vulnerable to another parasite not seen now in the Bay but capable of surviving in its saltier waters.

There are also concerns that the Asian oysters could crowd out native ones since research has shown they may compete for food and habitat.

“If the Asian oyster is introduced successfully to Chesapeake Bay, that’s an irreversible decision … that still has very uncertain consequences, in terms of risk and benefits,” said Denise Breitburg, senior scientist at the Smithsonian Environmental Research Center in Edgewater.

“Given that,” she said, “we should exhaust all possibilities for native oyster restoration before we do what I consider a drastic step.”

Maryland, Virginia and the Army Corps hope to agree next year on whether to introduce Asian oysters, continue native restoration efforts, or both. Six public meetings on the subject are planned in the next two months.

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