controls under field conditions with natural predation levels. They concluded that GH-manipulated fish might compete successfully with wild fish despite behavioral differences observed in the laboratory for characteristics such as predator avoidance, foraging ability, and over-winter survival (Johnsson et al., 2000). These results emphasize the need to measure all components of fitness under conditions similar to those found in nature—a task that might not be possible for some species.
Possible environmental hazard pathways posed by the escape of transgenic crustaceans and mollusks into natural ecosystems have not yet been thoroughly considered. Research has not yet assessed ecologic risks posed by production of these organisms. Many freshwater crustaceans, such as crayfishes, are capable of overland dispersal; further, they are produced in extensive systems, where confinement is difficult. Many marine crustaceans have planktonic larvae, thus complicating confinement. Confinement of mollusks can prove difficult at the larval stage (USDA, 1995). Further, because the larval stages drift in the water column before settlement and metamorphosis to the sessile juvenile form, they have great dispersal capability.
The committee’s review of ecologic principles and empirical data suggests a considerable risk of ecologic hazards being realized should transgenic fish or shellfish enter natural ecosystems. In particular, greater empirical knowledge is needed to predict the outcome should transgenes become introgressed into natural populations of aquatic organisms.
Many critical unknowns complicate risk assessment and risk management of genetically engineered animals. Greater knowledge in these areas would support an informed judgment of whether and how to go forward with approval for marketing particular genetically engineered animals. For example, results of well-designed, interdisciplinary studies could prove useful for parameterizing net fitness-based models used for predicting whether transgenic genotypes would persist in natural populations. Should GE animals be approved, postcommercialization monitoring would provide a check on the utility of predictive models, suggest improved means of risk management, and support adaptive management of GE animals (Kapuscinski et al., 1999; Kapuscinski, 2002). More information supporting risk assessment and risk management also would support regulatory decision-making, and it would promote public confidence in the environmental safety of genetically engineered animals.