Canadian experts from the Department of Fisheries and Oceans express concern that genetically engineered salmon, despite being deemed safe for both human consumption and the environment by the US Food and Drug Administration, could combine with conventional salmon and contaminate wild fish species.

http://www.vancouversun.com/technology
/Genetically+engineered+fish+could+pose+threat+wild+stocks+Documents/4328108/story.html , http://www.canada.com/technology/Genetically+engineered+fish+could+pose+threat+wild+stocks+scientists
/4328313/story.html#ixzz1EkZ8ZkzF