Oyster scientists say they remain more than two years away from answering key questions about the impact of introducing a nonnative oyster in the Chesapeake, and they caution that some important issues are getting little evaluation.

A survey of the more than three dozen scientists currently engaged in Crassostrea ariakensis research found that only one of 22 issues considered to be a “high” or “moderate” priority has been adequately addressed to date.

Some important studies will probably not be completed—and results analyzed—before the end of 2008, according to the survey, which was completed by the Bay Program’s Scientific and Technical Advisory Committee. That would keep pace with the time frame established when STAC outlined a five-year research program at a workshop in December 2003.

“The consensus was that at the end of the five-year research period, there would be a reasonable body of information from which to make a decision,” said Denise Breitburg, a scientist with the Smithsonian Environmental Research Center and vice-chair of STAC.

Since establishing research priorities, much of the work has been funded by the Maryland Department of Natural Resources and the National Oceanic and Atmospheric Administration’s Chesapeake Bay Office. Many of the projects, though, require multiple years of work, or results of previous studies, before they can be completed.

Jamie King, a biologist with NOAA’s Bay Office, said the projects that would be supported for the final year of the agency’s three-year C. ariakensis research program will be announced in September. Work on some of those projects probably won’t be completed until early 2008, she said. Analyses of the results could take several months or longer.

The time frame predicted by STAC is a year and a half later than the anticipated release of a draft environmental impact statement examining the risks and benefits of releasing nonnative oysters in the Bay. After a series of delays, the Army Corps of Engineers and the states of Maryland and Virginia in June said they anticipated releasing a draft EIS for public review next May.

In announcing the time frame in June, state officials said any work not completed by May could be used to update strategies later. C. ariakensis, a native of China, has been shown to be resistant to the diseases MSX and dermo, which plague native oysters, but little is known about the species and scientists say it is difficult to predict how it would perform in the Bay.

The EIS is examining the potential of an outright introduction of breeding C. ariakensis, as well as a variety of options, including limiting C. ariakensis to aquaculture, or enhancing restoration efforts with native oysters.

But the STAC survey, which was released in August, found that research on several key areas is still in the early stages. For example, questions remain about the timing and rate of reproduction by C. ariakensis and the native C. virginica under various conditions. If they reproduce at the same time, they may interfere with each other.

Another question of concern still in early research stages is understanding whether C. ariakensis—which accumulates but does not succumb to dermo—may increase the rate of disease transmission to the native species, which is highly susceptible to dermo infections.

Some issues identified by the scientists in 2003 have gotten little attention. For instance, little work has been done to understand how C. ariakensis may perform and what risks it might pose outside the Bay, even though scientists have said any introduction in the Chesapeake would ultimately lead to populations in other coastal areas.

In addition, few studies have examined genetic differences among C. ariakensis subpopulations in China. Although the states have proposed introducing the so-called “Oregon strain” oysters, which was accidently brought to the West Coast several decades ago, scientists say that group includes too few individuals from which to build a new Bay population.

They say those already here would need to be augmented with additional ones from China. But the oysters have genetic differences from place to place, and it’s not known if all would perform the same as those now being tested. “We have no idea whether the risks or benefits of other C. ariakensis would differ from the Oregon C. ariakensis currently under study,” Breitburg said

One of the reasons for past postponements of the EIS was a delay in completing several new computer models that will be used to evaluate oyster management alternatives. In June, state officials said significant progress had been made in model development.

But, Breitburg said, the information needed by the model won’t be available until the research is done. “Having the code and structure of the model completed is a completely different issue than whether or not there is sufficient data to put into the model,” she said. “The issue is whether the predictions of those models are going to be ready for use by management.”

The report is available on the Internet at www.chesapeake.org/stac/workshop.html#OY.