 Wild salmon in the Broughton Archipelago, off the west coast of Canada's British Columbia, will be extinct within 10 years due to parasite contamination from fish farms, according to a study published in the journal Science . 'The impact is so severe that the viability of the wild salmon populations is threatened,' said lead researcher Martin Krkosek, from the University of Alberta. 'The probability of extinction is 100 percent,' Krkosek said, 'and the only question is how long it is going to take.' Researchers compared the population numbers of different groups of salmon between 1970 and the present, depending on whether they had been exposed to aquaculture salmon farms or not. Using a computer model of population change over time, the researchers were able to show that exposure to fish farms was causing population growth of wild salmon to be 'severely depressed.' The effect comes from sea lice, a parasite that naturally infects adult salmon in the open ocean. The lice infest the skin and muscle of salmon, and adult fish can carry them without suffering serious harm. Juvenile fish, however, have little defense against such infection and often become seriously sick or die as a result. 'Salmon farming breaks a natural law' by massing adult salmon in large open nets just offshore, said study co-author Alexandra Morton, director of the Salmon Coast Field Station. 'In the natural system, the youngest salmon are not exposed to sea lice because the adult salmon that carry the parasite are offshore. But fish farms cause a deadly collision between the vulnerable young salmon and sea lice. They are not equipped to survive this, and they don't,' Morton said. Young wild salmon are exposed to sea lice when they swim past salmon farms on their way from rivers to the open sea. The researchers concluded that if measures are not taken to stop exposing young fish to sea lice, such as moving fish farms away from the paths of wild fish, wild salmon will be extinct in the archipelago within eight to 10 years. 