Academy report supports VIMS' stance on non-native oyster research

(August 14, 2003) A highly anticipated National Academy of Science report on the risks and benefits of introducing non-native oysters to Chesapeake Bay bolsters the long-term research strategy of oyster scientists at the Virginia Institute of Marine Science.

The Academy report asserts that carefully regulated aquaculture of sterile Asian oysters could help the oyster industry and generate needed risk-assessment data, whereas any introduction of a reproductive population of the non-native oysters should be delayed until more is known about potential environmental risks.

The report's recommendations mirror those expressed in a position statement released by VIMS scientists last fall, and add credence to their on-going strategy for oyster research. The VIMS statement notes that carefully designed and monitored commercial trials can provide data on both the aquaculture potential and the ecological impacts of the non-native oyster Crassostrea ariakensis, and agrees that introducing reproductively capable ariakensis into Chesapeake Bay would be imprudent at the present time.

The Academy report was written by an 11-member committee of oyster experts from around the U.S. Committee co-chair Dr. Dennis Hedgecock, a geneticist at the University of California, notes that "contained aquaculture of infertile non-native oysters on a small scale would provide more information for industry and policy-makers to make a sound decision on further use of non-native oysters."

At a press conference to announce the report's release, Hedgecock and fellow co-chair James Anderson of the University of Rhode Island endorsed last February's decision by the Virginia Marine Resources Commission to allow a commercial trial of sterile Asian oysters by 10 Virginia Seafood Council growers. That trial is scheduled to begin in September.

Frances W. Porter, the Virginia Seafood Council's Executive Director, says that the report validates the Council's project. "Our project has proceeded with caution and has observed all known protocols and regulations regarding non-native introduction," says Porter. "We're anxious for the return of a healthy oyster population in Chesapeake Bay, but realize the need for definitive answers to questions about possible risks."

Hedgecock and Anderson noted in the press conference that "the process used so far is a model program for the rest of the coast."

The sterile trial oysters are being provided to the growers by a team of researchers in VIMS' Aquaculture Genetics and Breeding Technology Center led by Dr. Stan Allen. Allen's team will also monitor the status of the oysters at each commercial grow-out site to ensure that the VSC test continues to meet the highest standards of science and biosecurity. In addition, they will conduct parallel experiments with a sterile, disease-resistant strain of the native oyster C. virginica to compare its performance to that of the non-native species.

VIMS began exploring the use of non-native oysters for Bay aquaculture in 1995 at the request of the Virginia General Assembly, and began field trials with sterile ariakensis oysters in 1998. Those trials showed that C. ariakensis was faster growing than the native virginica oyster, better tolerated the oyster diseases MSX and Dermo, and compared favorably in taste tests.

Allen's group renders oysters sterile using a state-of-the-art genetic technique that is more than 99% effective, giving growers and regulators the confidence to proceed with commercial trials under conditions of minimal risk. Allen and his colleagues are currently about halfway through the 6-8 week process of producing the 1-million oysters needed for the upcoming VSC test.

The Academy report also validates efforts at VIMS to investigate the potential effects of ariakensis on Bay ecology. The report lists several issues that require further research, including the potential introduction of a new disease, competition with native oysters, dispersal of non-native oysters outside Chesapeake Bay, and market demand for non-native oysters. This additional research, says the report, will be needed before scientists can reassess the environmental risks of wider aquaculture of sterile non-native oysters or the introduction of reproductive ones.

VIMS researchers are active in each of the research areas listed in the Academy report. Dr. Gene Burreson and colleagues in the VIMS Shellfish Disease Laboratory are studying potential pathogens of C. ariakensis in its native range in China. Dr. Mark Luckenbach of VIMS' Eastern Shore Laboratory is conducting competition studies between ariakensis and virginica. Early marketing studies of ariakensis were conducted by scientists in VIMS' Virginia Sea Grant Marine Advisory program.

To read a pre-publication copy of the Academy report on-line, visit www.nap.edu/catalog/10796.html?onpi_topnews_081403. To learn more about non-native oyster research at VIMS, visit www.vims.edu/abc.