It is ironic that the salmon may be the first approval as the ecological objections to such fish are well documented and more straightforward than for other animals. Broadly speaking, the potential ecological impact of an undesirable modification affecting the ecosystem is a function of a) the amount of ecological disruption caused by the modification and b) the reproductive success of the modified animal. It is standard for scientists to argue about the potential for disruption. However, if the animal doesn't reproduce, then the disruption will not spread. This is why it is so curious that salmon are likely to be the first approved, because the reproductive advantage of being larger quicker is very well documented. Simply put, if the genetically engineered fish get out into the wild, they will outcompete the wild fish for mates, giving them a higher reproduction rate, with the result that the genetic modification will rapidly spread throughout the population of wild fish.
To preclude this possibility, the industry claims that it will a) produce only sterile females that can't reproduce and b) sell the eggs only to fish farms that are contained units operating on-land such that the fish could not escape into the wild. However, there are questions about the effectiveness of the sterilization procedures and it is doubtful that a regulatory process (which won't even be able to require labeling) would be able to limit the sale of the eggs to land-based fish farms. As noted in the Times,
Under a policy announced in 2008, the F.D.A. is regulating genetically engineered animals as if they were veterinary drugs and using the rules for those drugs. And applications for approval of new drugs must be kept confidential by the agency.
Critics say the drug evaluation process does not allow full assessment of the possible environmental impacts of genetically altered animals and also blocks public input.
“There is no opportunity for anyone from the outside to see the data or criticize it,” said Margaret Mellon, director of the food and environment program at the Union of Concerned Scientists.