of a GE animal, (2) the species transformed, and (3) stability and resiliency of receiving community. Inserting a transgene that increases fitness of a highly mobile species that becomes feral easily raises the greatest level of concern (e.g., a gene that increases salt tolerance in catfish). A transgene that increases fitness of a moderately mobile species that can become feral (e.g., the phytase gene in the pig) raises the next level of concern. Inserting a transgene that does not increase fitness in a low mobility species, which does not become feral easily (e.g. a gene for a protein of industrial value in cows), raises the least concern.

One case of immediate concern is the release of transgenic fish and shellfish. Production of some GE fish and shellfish might result in environmental benefits when compared to conventional aquacultural practices. For example, production of fish expressing a phytase transgene might allow use of less fishmeal in feeds while decreasing phosphorus in waste products from aquaculture operations. However, transgenic fish and shellfish might pose environmental hazards. Cultivated salmon have escaped into the wild from fish farms and these salmon already pose ecologic and genetic risks to native salmon stocks. In studies of transgenic salmon under laboratory conditions, some of these transgenic lines grew four to six times faster than nontransgenic salmon, with a 20 percent increase in feed conversion efficiency. In order to support their rapid growth, GH transgenic salmon consumed food at a more rapid rate than control salmon. In addition, their oxygen uptake is about 60 percent more than that of controls during routine activity and during sustained swimming. These findings suggest that the GE Atlantic salmon might show increased fitness, but gaps still exist in our understanding of the key net fitness parameters to allow an assessment of the impact of their entry into wild populations.

Possible environmental hazard pathways posed by escape or stocking of transgenic shellfish into natural ecosystems have not yet been thoroughly considered. Information is not yet available to assess ecologic risk posed by production of these organisms, but it is clear that confinement of these aquatic organisms will be difficult and they are likely to escape.

Animal Health and Welfare Concerns

The effects of genetic manipulation on animal health and welfare are of significant public concern. Animal welfare has proven difficult to assess because it is so multifaceted and involves professional and ethical judgments. The committee considered the following facets of animal welfare in discussing transgenic and cloning technologies: their potential to cause pain, distress (both physical and psychologic), behavioral abnormality, physiologic abnormality, and/or health problems; and, conversely, their potential to alleviate or to reduce

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