Posted by Josh Frazier: Agricultural Research Service scientist have created a technique to block reproduction in farm raised salmon and trout. This blockade of reproduction is ultimately due to an extra set of chromosomes which switches energy that was once utilized for reproduction to overall growth. Biologists have discovered that if they intrude in the early stages of development they can produced a fish displaying four sets of chromosomes. These four set chromosome fish are then crossed with a normal fish thus producing an offspring displaying three sets of chromosomes. These now sterile fish cannot reproduce with wild/native stock and with their fast growing capabilities are gaining attention in the sport fishing community.