If you thought that salmon you ate was a natural organism, I hope you don't live in Canada. It turns out that GMO salmon have been on the market for more than a year in this country. Unlabeled. Untested by the government. Raised on who knows what hormones and feed stock. And that feed stock collected from places unknown - and with mysterious practices.
(FWIW, if I somehow caught the GMO fish appearing in the pic at the bottom of that second article, I think I'd throw it back. It looks .. wrong. Soft and bloated. Female steroids, perhaps?)