(Beyond Pesticides, October 25,2010) In an effort to control sea lice in farmed Atlantic salmon Health Canada has approved a request by the province of New Brunswick to use the pesticide Alphamax, whose active ingredient is deltamethrin. The high concentrations of salmon in aquaculture facilities has lead to major problems with sea lice, a type of parasitic crustacean that attaches to the fish. Health Canada has approved the use of the restricted pesticide deltamethrin through December of this year.
While many salmon farmers are pleased, the decision by Canada’s federal agency has many local fishermen concerned about the effects the pesticide will have on fish and shellfish populations. “Basically we are shocked in a nutshell,” said Grand Manan Fishermen’s Association project manager Melanie Sonnenberg, adding, “Dsappointed doesn’t cover it.”
The use of deltamethrin will be restricted to tarped cages or well boats, boats with large holds. Treatment would involve placing fish in the boats, bathing them in Alphamax and releasing them back into cages along with the treated water. The industry is ready to start using the treatment in the Bay of Fundy. Fish farmers have been challenged in controlling sea lice outbreaks this summer, particularly in the upper Passamaquoddy Bay area. They have been using other chemicals to control the outbreaks, including hydrogen peroxide, Salmosan (azamethiphos), SLICE (emamectin benzoate) and Calicide (teflubenzuron). Glenn Brown, owner of the Grand Manan Company Admiral Fish Farms Ltd. explained, “What we’d really like is a suite of tools we could use in a strategic way.” Unfortuantly pesticides that kill sea lice also kill lobster explained Ms. Sonnenberg.
Deltamethrin is a synthetic pyrethroid. Synthetic pyrethroids are synthesized deriviatives of naturally occurring pyrethrins produced by the chrysanthemum flower. They are designed to be more toxic and take longer to break down than natural pyrethrins. These types of pesticides are extremely toxic to aquatic organisms including fish. Lobster, shrimp, mayfly nymphs and zooplankton are the most susceptible non-target aquatic organisms.
Synthetic pyrethroids are also dangerous to human health. While not easily absorbed through the skin pyrethroids are absorbed through the gut and pulmonary membrane and can act as neurotoxins. Acute exposure can result in asthma like symptoms and irritation of the skin. Emerging evidence shows many pyrethroids are endocrine disruptors, interfering with sexual development and the immune system.
Environment Canada is currently investigating the illegal use of another synthetic pyrethroid cypermethrin. Cypermethrin is not permitted for use in Canada but is used to control sea lice in salmon farms in Maine. Cypermethrin has been linked to lobster deaths in waters around New England and Canada.
According to Matthew Abbot, coordinator of the Conservation Council of New Brunswick’s Fundy Baykeeper Project, putting anything into the water that kills sea creatures is a violation of Canada’s Fisheries Act. He suggests controlling sea lice simply by limiting the number of salmon in cages