Canadian fish farms spread disease to wild salmon.

• Author: Ryan, John C.
• Position: Environmental Intelligence

On the west coast of Canada, aquaculture is big business--farmed salmon is the province of British Columbia's largest legal export crop. Back in 1995, British Columbia banned new fish farms because of concerns about their effects on the province's six species of wild salmon. But a newly elected pro business government lifted the ban in 2002 and began a push to quadruple the province s salmon-farm output in a decade.

In recent months, 90 new salmon farms have been proposed. But severe outbreaks of diseases and parasites--which can spread easily between caged and wild fish--have put a crimp in the government's big plan. Scientists suspect that sea lice infestations among farmed fish led to last year's unprecedented 98-percent decline in pink salmon populations in the Broughton Archipelago off Vancouver Island. Roughly 3 million wild fish failed to migrate home to the area, which has the province's densest concentration of salmon farms. A year earlier, biologists had found fatal loads of sea lice covering young pink salmon swimming out to sea past the fish...