CaptionAfter four years at sea, massive wild Atlantic salmon return to one of the few remaining healthy rivers in Eastern Canada. As wild Atlantic salmon populations falter, salmon farming is on the increase globally, with over 274 million farmed fish present in the world's waters. Pound for pound, more pesticides and antibiotics are used than in any other livestock industry, having an impact on both human health and the environment. The waste from a large farm can be equivalent to a town with a population of 50,000 dumping sewage directly into the sea. Diseases and sea lice transfer quickly between fish packed tightly in pens, and many farmed salmon escape into the wild, spreading infection. It is estimated that over 500,000 farmed salmon escape each year in Norway alone. They breed in the wild, ultimately lowering the gene pool of wild salmon. In the US, Atlantic salmon is listed as critically endangered.