The Eastern oyster Crassostrea virginica was for three centuries the object of a major fishery in Chesapeake Bay. But in the latter half of the 20th century, over-harvesting, habitat degradation, and the  diseases MSX and Dermo devastated the Bay's oyster population. The diseases frustrated restoration and aquaculture efforts and brought the Bay oyster fishery to near ruin, especially in Virginia. The loss of oysters and their capacity for filtering algae also likely contributed to the decline of Bay water quality.

Evaluation of Non-Native Oysters

In response to the decline of the native oyster, the Virginia General Assembly in 1995 charged VIMS with developing a strategic plan for shellfish research, including testing of non-native oyster species. VIMS submitted the plan in 1996. Field studies began with Crassostrea gigas, an imported Japanese species that has long been the mainstay of oyster aquaculture on the U.S. West Coast. However, VIMS research showed that C. gigas in Chesapeake Bay exhibited unremarkable growth, disease tolerance, and taste compared to the native oyster. VIMS researchers then began investigating the Suminoe oyster C. ariakensis. Comparisons between infertile C. ariakensis and the native oyster showed that C. ariakensis was faster growing, better tolerated MSX and Dermo, and tasted just as good.

These findings suggested that hatchery-reared C. ariakensis held promise for rebuilding the commercial oyster industry in Virginia and Maryland through aquaculture. At the same time, there were strong concerns over using non-native species in light of past ecological impacts. In October 2001, VIMS hosted a symposium to inform stakeholders on issues related to use of C. ariakensis in Chesapeake Bay. In November 2001, VIMS issued a position statement on the commerical use of C. ariakensis in Bay waters. A web site provided data on VIMS' scientific monitoring of the 2003-05 Virginia Seafood Council trials of C. ariakensis.

National Research Council Report

In 2002, the National Academy of Science's National Research Council (NRC) was asked by several state and federal agencies to examine the ecological and socioeconomic risks and benefits of open-water aquaculture or direct introduction of C. ariakensis in Chesapeake Bay. Their report, published in 2003, offered a series of research recommendations to provide the information needed by  policymakers in order to weigh the potential risks and benefits associated with introducing a non-native species. Identified research areas include a better understanding of  C. ariakensis within its native range in Asia, the life history and ecology of the species, the effects of oyster diseases, human consumption risk, aquaculture feasibility, diploid or triploid C. ariakensis, and economics.

Environmental Impact Statement

Based in part on the recommendations of the NRC report,  the U.S. Army Corps of Engineers in 2004 initiated a "Programmatic Environmental Impact Statement" (PEIS) for a proposed introduction of C. ariakensis into the tidal waters of Maryland and Virginia. As part of the PEIS process, researchers around Chesapeake Bay  began to address the research questions that needed to be answered in order for regulatory agenicies to make informed decisions concerning the 8 policy options the PEIS presented. These options included native oyster restoration, non-native introduction, or a combination of these alternatives.


The Army Corps of Engineers in August 2009 issued their Record of Decision on the policy options offered in the PEIS, based on public input and research-based recommendations by officials in Virginia and Maryland:

After considering all available information and the input of all stakeholders, the lead agencies have concluded that Alternative 8a is the preferred approach for restoring the Chesapeake Bay oyster population, using a combination of alternatives that involves only the native Eastern oyster (Crassostrea virginica). The Preferred Alternative is also identified as the environmentally preferable alternative which is defined as "the alternative that will promote the national environmental policy as expressed in the National Environmental Policy Act's Section 101. Ordinarily, this means the alternative that causes the least damage to the biological and physical environment; it also means the alternative which best protects, preserves, and enhances historic, cultural, and natural resources" (Forty Most Asked Questions Concerning Council on Environmental Quality's National Environmental Policy Act Regulations, 1981). The Preferred Alternative 8a consists of the following elements:

  • Alternative 2 (Enhanced Native Oyster Restoration)
  • Alternative 3 (Harvest Moratorium)
  • Alternative 4 (Expansion of Native Oyster Aquaculture)

An unexpected benefit of the PEIS process was the discovery of enhanced growth among the spawnless oysters used to allow experimental comparisons between the native and non-native species in the field. Spawnless native oysters are at the heart of the recent rapid  growth of oyster aquaculture in lower Chesapeake Bay.