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New Lice Treatment Required

CANADA - Sea lice do not wait for fish farmers, pesticide companies, researchers and regulators to catch up, scientist Larry Hammell says. Which is why there is a need for another project to fend off the threat.

Last year, this bane to New Brunswick's salmon aquaculture showed resistance to emamectin benzoate, sold as SLICE, the industry's silver bullet since in 2000.

"SLICE was super-effective and no other product was coming into the market," Mr Hammell, director of the Centre for Aquatic Health Sciences at the Atlantic Veterinary College in Charlottetown told the Telegraph Journal. "We need another product."

The industry needs it before the warmer water causes the sea lice to grow in floating cages in the Bay of Fundy this summer, he said.

At a closed meeting in St. George recently aquaculture representatives discussed "well-boat" treatment for sea lice.

With this system, fish farmers pump salmon into a large boat with a waterproof hold or tank in which to treat the fish before returning them to their sea cages.

The New Brunswick Salmon Growers' Association expects a leased well-boat to arrive in the Bay of Fundy soon. "I hope (this) week," executive Pamela Parker said in an interview Friday.

The salmon growers still need approval from Canada's Pest Management Regulatory Agency for the pharmaceutical products they would use in the well-boat.

Ms Parker hopes for approval within two weeks to use the common disinfectant hydrogen peroxide in well-boats.

By the end of the summer, she hopes the agency will approve deltamethrin, sold as Alpha Max, for use in well-boats. The agency approved this product for use in a very limited area of Passamaquoddy Bay last year.

The growers also want the agency to approve azamethiphos, sold as Salmosan. The agency allows the aquaculture industry to use this product in sea cages but, so far, not in well-boats.

Hydrogen peroxide, Alpha Max and Salmosan kill sea lice in a "bath treatment" good at eliminating the pest in its adult phase, Ms Parker said.

The industry still needs an "in-feed" product like SLICE to kill juvenile lice, except that SLICE no longer works.

That leaves teflubenzuron, sold as Calicide, as the legal in-feed option for sea lice, Ms Parker said. "SLICE we would not like to use at all."

"Everybody used it for so long, and that is the only thing they used," Ms Parker said.

In some future year sea lice will lose their resistance to SLICE but, for now, the industry must look to something else, Mr Hammell said.

"If you use only one product there's always a probability you're going to develop some resistance to it," he said.

Aquaculture critics say it makes little sense to catch wild fish to feed to caged fish which people then eat.

Killing aquaculture would not decrease the amount of fish meal removed from the oceans each year, Mr Hammell said. This commodity would go to other uses, for example, chicken feed, he said.

Aquaculture already provides more than half the seafood protein that people eat across the world, Mr Hammell said. "There's still lots of future potential and it's going to grow."

A good integrated pest management system requires an arsenal of products, bath and in-feed, in a planned rotation attacking the sea lice at different stages of their life cycle, Mr Hammell said.

He began coming to St. George in 1990, making about 30 trips a year to visit sea cages, sharing laboratory space with the provincial Agriculture and Aquaculture Department.

The Atlantic Veterinary College, part of the University of Prince Edward Island, will soon welcome Ian Gardner from the University of California Davis, named to the Canada Excellence Research Chair in Aquatic Epidemiology.

Mr Gardner, too, will come to St. George to visit salmon cages, Mr Hammell said.

In the Bay of Fundy, fish farmers need something that kills sea lice but not other things.

Environment Canada identified the agricultural pesticide cypermethrin on the shells of lobster killed in the Bay of Fundy last fall.

New Brunswick farmers use this product to kill potato bugs, but Canada does not license it for use in a marine environment.

The salmon growers association denies that its members would use cypermethrin, but this chemical does kill sea lice. Environment Canada continues a criminal investigation into how this chemical got into the bay.

the Fish Site Editor

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