populations that had been commercially harvested. Introductions of this same oyster to the U.S. West Coast and France filled voids created by previous overharvesting or diseases of native species and have become the basis of extensive aquaculture industries. It is impossible, given the present state of knowledge, to predict whether the Suminoe oyster will be a boon or an ecological disaster in this sense. The committee’s review of case studies clearly indicates that greater ecological or economic harm typically arises from organisms that are inadvertently introduced with the foreign oyster. With the exception of pathogens (including some viruses) that can be transmitted from adults to their progeny, unwelcome “hitchhiking” organisms can be avoided by strict adherence to the International Council for the Exploration of the Sea (ICES) protocols, which specify that only hatchery-reared nonnative oysters should be allowed in open waters. Current proposals to use the Suminoe oysters stipulate adherence to ICES protocols to minimize the risk of introducing a disease organism or other unwanted species. Although the nonnative oysters could become an unwelcome invasive species, this risk is probably lower than the risk of introducing a multitude of alien species incidental to an illegal rogue introduction. Consequently, regulatory and enforcement measures should be taken to reduce the risk of a rogue introduction.

Development of a quantitative risk assessment model for evaluating risks associated with the three management options would require a great deal of additional research that could take many years to complete. Moreover, while risk assessment is a tool for characterizing the likelihood of various outcomes, it does not provide a basis for determining whether an outcome or combination of outcomes is desirable or undesirable. That is, risk assessment may inform the decision-making process but cannot replace it. Nevertheless, a decision must be reached about whether or not to proceed with the use of the nonnative oyster despite uncertainty about the type and magnitude of the potential risks involved. Regulators and decision makers will need to consider all available information and weigh the often opposing interests of the various stakeholders to decide whether to allow introduction of the nonnative Suminoe oyster, C. ariakensis, into the Chesapeake Bay, either limited to aquaculture of the sterile triploid or as a deliberate inoculation of reproductive diploids. This is a particularly difficult circumstance because of the magnitude of uncertainty associated with each option and the perception, on all sides, that any decision will have lasting and serious consequences. Various decision analysis techniques have been used to clarify objectives and elucidate the effects of uncertainty on the possible outcomes of alternative management actions for similarly difficult decisions (e.g., Keeney and Raiffa, 1976; Hilborn and Walters, 1977; Walker et al., 1983; Bain, 1987; Saaty, 1990; Merritt and Criddle, 1993). The intention here is not to conduct a comprehensive deci-



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