SALMON MEETS JAMES BOND. HOW CAN WE HOPE TO SURVIVE?

A move by the USA has granted permission to begin the sale of genetically engineered fish that grow twice as fast in the same span of time. To prevent the specimens from escaping into the natural world, state of the art technology has been employed to folly the wayward imaginations of our aquatic friends. It strikes me odd that so much be invested to prevent the 'contamination' of the natural world by this seemingly harmless creature. What lurks beneath?
 http://www.newscientist.com/article/mg20727783.800-transgenic-fish-swimming-towards-a-plate-near-you.html