I believe that to make the fish sterile they actually have to heat them when they are eggs, not that being genetically modified automatically makes them sterile. While I agree this is a benefit for AquaAdvtange salmon, as they would not compete with wild fish for more than one generation. However, this does bring up questions of how many salmon actually end up infertile? Is it a 100% guaranteed process, or is there an error rate? That would be my biggest worry, if there is still a possibility for fertile fish to exist.