By Judith Lavoie, Canwest News Service May 11, 2010



It is almost inevitable that sea lice in British Columbia salmon farms will become resistant to the chemical pesticide used to kill them, scientists at an international conference in Victoria said on Monday.

"One of the biggest issues is that in Norway and Chile there's a documented resistance to treatment -- and that is really huge," said Ben Koop, biology professor at the University of Victoria.

"I think resistance on the West Coast is inevitable. It worries everybody."

The only universal treatment for salmon farm sea lice is a product called SLICE, which uses the chemical emamectin benzoate. But lice living in isolated communities, treated only with SLICE, become immune to the chemical.

B.C. salmon farmers have no official access to alternative treatments, such as "bathing" the fish in chemicals, as was recently done as an urgent measure on the East Coast.

In Norway, various methods of lice control are being tried, said Tor Horsberg of the Norwegian School of Veterinary Science. "The signs are very clear in Norway, in Scotland and Ireland and on the East Coast of Canada pointing in one direction -- and that's the increasing tolerance of parasites to SLICE," Horsberg said.

Some fish farms have stopped using the pesticide except in emergencies. Instead, they have adopted a rotation of other chemicals, even though they do not work as well, he said.

About 230 delegates are attending the Sea Lice 2010 conference to discuss the latest science and methods for studying sea lice and their effects on fish. The conference follows biologist and fish farm opponent Alexandra Morton's two-week walk down Vancouver Island to warn that wild salmon stocks are being wiped out by sea lice from fish farms. Her walk culminated in a rally at the legislature on Saturday. Police estimated the crowd at up to 2,000 but rally organizers said it was about 5,000.
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