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Sea lice pesticide resistance 'inevitable'
Courier-Islander
Published: Friday, May 14, 2010
Despite all the recent objections and denials from BC fish farmers and their government regulators, it is almost inevitable that sea lice at B.C. salmon farms will become resistant to the chemical pesticide used to kill them, scientists at an international sea lice conference in Victoria said 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 department professor at the University of Victoria and a conference organizer.
"I think resistance on the West Coast is inevitable. It worries everybody, but because our ecosystems are different, I would expect a slow evolution to resistance," he said.
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Font:****The only universal treatment for sea lice at salmon farms is the product Slice, which uses the chemical emamectin benzoate to kill lice.
However, lice living in isolated communities, treated only with Slice, develop resistance.
In February, biologist Alexandra Morton warned sea lice at Greig Seafood farms in Nootka Sound appeared to have grown resistant to Slice treatments. She said the proof was that sea lice had reappeared too soon after farmed fish were fed Slice. The industry and the provincial Ministry of Agriculture and Lands responded that there was no evidence of Slice resistance.
Strangely, the saving grace for B.C. salmon farms might be lice on wild fish.
"The large wild salmon population brings wild sea lice back to the coast every year and that dilutes the population," said Simon Jones, Department of Fisheries and Oceans scientist. In B.C., there are between 50 and 100 wild fish for every farmed fish. That compares to one wild fish to every 100 to 200 farmed fish in Norway.
"In Chile, there are such vast numbers of farm fish that the sea lice have become devastating to the aquaculture industry," Koop said.
Crawford Revie, the Canada research chair at the University of Prince Edward Island, said lice in B.C. have not yet shown any tolerance for Slice, but research and more precise tests are essential.
"In B.C., we have to make sure we don't get caught on the hop with tolerance three, four or five years down the line," Revie said.
Currently, B.C. salmon farmers have no official access to alternate 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.
The aim of the conference, attended by 230 delegates from around the world, is to bring together experts to discuss the latest science and methods for studying sea lice and their effects on wild and farmed fish.
The tiny copepods, which have been co-evolving with salmon and other fish for up to 100 million years, arouse high emotions and conflicting claims about their effects on wild salmon runs. The conference comes just two days after Morton arrived in Victoria on her Get Out Migration, a two-week walk down Vancouver Island to sound the alarm that wild salmon stocks are being wiped out by sea lice from fish farms.
- with files from Canwest News Service
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Courier-Islander
Published: Friday, May 14, 2010
Despite all the recent objections and denials from BC fish farmers and their government regulators, it is almost inevitable that sea lice at B.C. salmon farms will become resistant to the chemical pesticide used to kill them, scientists at an international sea lice conference in Victoria said 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 department professor at the University of Victoria and a conference organizer.
"I think resistance on the West Coast is inevitable. It worries everybody, but because our ecosystems are different, I would expect a slow evolution to resistance," he said.
Email to a friend
Printer friendly
Font:****The only universal treatment for sea lice at salmon farms is the product Slice, which uses the chemical emamectin benzoate to kill lice.
However, lice living in isolated communities, treated only with Slice, develop resistance.
In February, biologist Alexandra Morton warned sea lice at Greig Seafood farms in Nootka Sound appeared to have grown resistant to Slice treatments. She said the proof was that sea lice had reappeared too soon after farmed fish were fed Slice. The industry and the provincial Ministry of Agriculture and Lands responded that there was no evidence of Slice resistance.
Strangely, the saving grace for B.C. salmon farms might be lice on wild fish.
"The large wild salmon population brings wild sea lice back to the coast every year and that dilutes the population," said Simon Jones, Department of Fisheries and Oceans scientist. In B.C., there are between 50 and 100 wild fish for every farmed fish. That compares to one wild fish to every 100 to 200 farmed fish in Norway.
"In Chile, there are such vast numbers of farm fish that the sea lice have become devastating to the aquaculture industry," Koop said.
Crawford Revie, the Canada research chair at the University of Prince Edward Island, said lice in B.C. have not yet shown any tolerance for Slice, but research and more precise tests are essential.
"In B.C., we have to make sure we don't get caught on the hop with tolerance three, four or five years down the line," Revie said.
Currently, B.C. salmon farmers have no official access to alternate 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.
The aim of the conference, attended by 230 delegates from around the world, is to bring together experts to discuss the latest science and methods for studying sea lice and their effects on wild and farmed fish.
The tiny copepods, which have been co-evolving with salmon and other fish for up to 100 million years, arouse high emotions and conflicting claims about their effects on wild salmon runs. The conference comes just two days after Morton arrived in Victoria on her Get Out Migration, a two-week walk down Vancouver Island to sound the alarm that wild salmon stocks are being wiped out by sea lice from fish farms.
- with files from Canwest News Service
20ft Alumaweld Intruder
