The U.S. Army Corps of Engineers has determined that it will require more stringent conditions on this summer’s planned deployment of 1 million sterile foreign oysters than are being required by Virginia officials.

While the action by the Corps’ Norfolk District is not expected to delay the project, set to begin in late June or early July, the Corps permit may end the experiment almost a year earlier than the one issued by the Virginia Marine Resources Commission.

The commission in February approved a plan from the Virginia Seafood Council, an industry trade group, to rear 1 million fast-growing, disease-resistant Crassostrea ariakensis oysters in the Bay and its tributaries to determine if they can be economically grown in aquaculture.

But the project also needs a permit from the Corps, which regulates the placement of any in-water structures.

After the VMRC decision, the EPA, National Marine Fisheries Service and the Fish and Wildlife Service urged the Corps to place more stringent requirements in its permit.

After a series of meetings, the Corps settled on a series of permit conditions, most of which will also be adopted by the VMRC, except for the end date of the project.

“There’s going to be a lot of controls to ensure we are proceeding as cautiously as possible while letting this proceed,” said Peter Kube, of the regulatory section of the Corps’ Norfolk District. “You have to take some risks.”

Besides the new permit requirements, the Corps also decided that after this year’s experiment, a full environmental impact statement would be required before any large-scale aquaculture project using C. ariakensis could be approved.

That is expected to take at least two years to complete, and would review a full range of potential risks and alternatives to C. ariakensis aquaculture.

“The environmental impact statement would have to consider alternatives like native oyster aquaculture for their feasibility,” said Carin Bisland, associate director for ecosystem management with the EPA’s Bay Program Office. “We feel that has not been given the same level of attention in this current debate as ariakensis aquaculture. If we are going to entertain introducing a risk into the Bay, we need to know that we’ve really focused on the alternatives.”

The potential use of the C. ariakensis, a native of Southeast Asia, has stirred huge interest among watermen and the seafood industry, who have seen populations of the native oyster plunge to all-time lows. Tests have shown that the foreign species is resistant to the diseases that kill the native C. virginica; it also grows faster and has a taste that appeals to consumers.

Based on that, the seafood council put forward a proposal to distribute 1 million oysters among 10 experienced aquaculture growers to see if it can be produced economically. The proposal, backed by a number of scientists and the Chesapeake Bay Foundation, won VMRC approval on a 5-1 vote.

But a number of other scientists, as well as federal and state agency officials, have worried that the VMRC initially failed to require adequate safeguards to reduce the chance of an accidental introduction of a reproducing nonnative population, which might cause problems in the Bay.

After a series of meetings, Kube said the Corps, VMRC and others agreed the permits will spell out in detail how the oysters are to be monitored both before, and after, they are placed in the water to minimize the risk of reproduction.

The sterile oysters are produced by mating chemically treated oysters that have four sets of chromosomes with normal oysters that have two sets of chromosomes. The result are oysters with three sets of chromosomes which cannot reproduce.

Statistically, however, 1 out of every 900 oysters may have two sets of chromosomes and therefore would be able to reproduce. That translates to 900 oysters for the whole project, or 90 for each of the 10 participants in the experiment.

Also, studies show that over time, some of the sterile “triploid” oyster begin to revert to normal oysters with two sets of chromosomes. That has raised concern that reverted oysters could begin to reproduce, although this has never been shown to happen. Under the permits, a batch of oysters would have to immediately be pulled from the water if 5 percent began to show signs of reversion.

Because oysters that remain in the water for two growing seasons are more likely to be able to reproduce, and because the potential for reversion increases over time, a team of scientists and agency officials who reviewed the project for the Bay Program recommended that the oysters not remain in the water beyond June 2004, considerably shorter than the April 2005 date allowed by the VMRC.

Kube said the Corps would include the June 2004 date in its permit. But if monitoring shows there is little risk of reproduction, the permit would be extended.

Also, the permit will contain specific guidance about how the bags of oysters are placed into the water. By separating bags of oysters, the likelihood of reproductive capable oysters being in close proximity will be reduced.

Another concern is that oysters could be released in the event of a storm and never recovered. When the VMRC approved the proposal, it required that each grower develop a plan for managing oysters in the event of severe weather such as hurricanes.

The permits will add more specifics, Kube said, such as requiring that emergency plans establish specific meteorological triggers that would result in the oysters being pulled from the water.

In addition, growers will need to post a bond to cover the cleanup and recovery costs if oysters escape.

Also, some wanted to postpone the project until after getting a report from a special panel created by the National Academy of Sciences, which is exploring the pros and cons of using C. ariakensis oysters in the Chesapeake. But the panel’s report is not expected until August, which the seafood council said would mean placing the oysters in the water too late in the growing season.

The permits will allow the project to begin as scheduled, but allows them to be altered to reflect any recommendations made by the NAS panel. “It’s like a midcourse correction,” Kube said. “The oysters will be out there, if there is something new that we haven’t considered in this report, we can revisit the issues and amend the permit.”

Kube said the provisions are aimed at reducing risks associated with the project, but ensuring that as much information as possible is gathered and shared during the experiment. That information will help in preparing any future environmental impact statement, he said.

“Under these permit conditions, we are going to learn more about the biology and how pure the batches of triploids are,” said Mike Fritz, living resources coordinator with the EPA’s Bay Program Office. “Because of the required monitoring, a year from now we will have more information on which to judge risk.”