As I said at this time last year GMO fish are a disaster waiting to happen. This is the first hard science to prove that statement. Researchers have discovered a paradox that crops up when new genes are deliberately inserted into a fish's chromosomes to make the animal grow larger. While the genetically modified fish will be bigger and have more success at attracting mates, they may also produce offspring that are less likely to survive to adulthood. If this occurs, as generations pass a population could dwindle in size and, potentially, disappear entirely. This is the first demonstration that a genetically modified organism has a reproductive advantage over its natural counterpart.
With all the concern over whether transgenic food is safe for humans, the environment has been more or less left out of the picture. Plenty of laboratories are studying whether GMOs are safe for human consumption, but to my knowledge this is the first one that looks at whether they will be safe for the environment.
The most common question posed about genetically modified organisms--GMOs for short, and also called transgenics--is whether they are safe for people to eat. When GMOs were first made commercially available in 1996, many food crops, such as corn and soybeans, were altered to produce substantially more yield than they do in nature. The debate on GMOs in supermarkets has not yet been resolved, and it could be drawing attention from an equally important issue: whether GMOs are safe for the planet.
The researchers found that the larger transgenic males mated three times for every time the natural-bred males did--not surprising, considering the premium that female medakas place on male size. But though the transgenic males mated more often, fewer of their young survived to adulthood. Over time this effect could continue to multiply itself over generations, eventually decimating a population. For every 100 offspring sired by a natural male that survived to adulthood, only 70 of the young produced by a transgenic male survived.
Proceeds National Academy of Sciences February 19, 2004