Munya Olchowy, via Facebook asked:
What would happen if farmed salmon with a promoter modified growth hormone gene made it into the wild? Those things are big!! Would they be able to swim upstream to breed better than normal salmon?
Kenny - Well, if we do have them grown in open cages, and these fish have been developed - not in Europe but they have been developed. They do exist. If they did escape, unless we did something about it, in which I will talk about in a minute, there’ll be no real reason to suppose that they'd be any more benign than any other escaped fish. Escaped fish generally are bad news because they interbreed with wild populations to their detriment. If you've got a particular gene in there, it may have all sorts of consequences, people have talked about ecological and genetic consequences. One of the things you could do if you really wanted to do this which I don't think is a good idea anyway. There's no need to do it, but if you really wanted to do it, you could put in a suicide gene. You could put in a gene whereby, the animal has some dietary obligatory requirement so that when it went into the wild, it wouldn’t have that and it would die.