A plan to kill sea lice on caged salmon with a powerful pesticide that will subsequently be flushed into several bays in southwest New Brunswick is generating concern among fishermen and environmentalists.
The New Brunswick Department of Agriculture and Aquaculture has secured an emergency authorization from Health Canada to conduct an experimental “bathing” of about two million market-ready caged salmon with an insecticide solution in three bays near Blacks Harbour.
Applications of the sea lice treatment deltamethrin in selected salmon test cages began on July 9 in Back Bay and will continue until sometime in mid to late August. Salmon cages will be “skirted” with tarpaulins and the fish they contain will swim in a dilute solution of the pesticide for 40 minutes.
After the fish have been treated the tarps will be removed and the pesticide solution will be released into the three bays. The provincial government and the aquaculture industry are counting on the Bay of Fundy’s strong tides to disperse the chemical rapidly to low concentrations so that it will not harm lobsters or other marine life.
Sea lice (Lepeophtheirus salmonis), tiny parasitic crabs that attach themselves to salmon and other fish and eat their skin, flesh and other tissues, are normally found in New Brunswick’s marine waters.
When present in large numbers, sea lice can kill adult and juvenile salmon directly. But the small parasites pose at least an equal danger to their hosts because their bites create openings for bacterial and viral diseases including infectious salmon anemia (ISA), the highly contagious virus that has killed or required the destruction of millions of farmed salmon in New Brunswick, Maine and other areas where salmon are raised in ocean cages.
“Right now there is no emergency, no big infestation, ” says New Brunswick’s chief aquaculture veterinarian Dr. Michael Beattie. “We have seen indications in a few cage sites that our present way of controlling sea lice is not working as effectively as it should be. With this experiment we’re trying to address the sea lice problem proactively, before we’re faced with a major infestation.”
Currently salmon farms in Atlantic Canada and Maine control sea lice by feeding affected salmon a medicated feed that contains a pesticide called emamectin benzoate (or EB, marketed as “Slice”). Slice is toxic to crustaceans, bivalves and other animals native to Maine and New Brunswick waters. But exposure to Slice from salmon farms is indirect, a result of Slice residues that are excreted in salmon feces.
The research New Brunswick is doing this summer is designed to test the safety and effectiveness of deltamethrin, a synthetic pyrethroid insecticide that is registered for use on some livestock and field crops in the U.S. and Canada. Although deltamethrin has been used to treat sea lice on farmed fish in Norway, Chile, the United Kingdom and Australia, the chemical is not registered for use in salmon farming or for any other aquatic use in Canada or the U.S.
The $700,000 research project is being funded by the Canadian and New Brunswick governments, the New Brunswick Salmon Growers Association and PharmaQ, the Norwegian manufacturer of deltamethrin.
Marketed as AlphaMax., deltamethrin concentrate is highly toxic to crustaceans (including lobsters, shrimp and crabs), amphibians, and fish, and also to the microscopic animals known as plankton that sustain the entire marine food chain. The dilute solution of deltamethrin that will be used in New Brunswick’s experiment is expected to be harmless to the market-ready salmon that will be treated. Veterinarian Beattie says the fish can be harvested, processed for market and will be safe for human consumption within just a few days after they are treated with deltamethrin.
Controversy about deltamethrin and the way the fish will be dosed with it in this summer’s experiment heated up shortly after June 8 when Cooke Aquaculture (which owns the most of the cage sites that will be treated with the insecticide) announced that it has received “Certified Quality Salmon Eco-Certification” from Seafood Trust for the salmon that its True North marketing division sells in Canada. Seafood Trust uses International Food Quality Certification (IFQC) standards to assess companies that apply for its certification.
Environmentalists, consumers and fishermen have raised questions about how Cooke’s salmon can meet IFQC’s key standard which requires “maintenance of a pristine quality marine environment” if its salmon and the bays in which they are raised are dosed with deltamethrin.
Dale Mitchell of Deer Island fishes lobster and scallops, operates herring weirs and serves on the board of directors of the Fundy North Fisherman’s Association as well as that of the Fundy Weir Fishermen Association. “A lot of us who fish,” Mitchell says, “just don’t think the aquaculture industry should be using these chemicals in the water where we’re fishing. We don’t necessarily believe they’re safe, and even if they are, we don’t think the aquaculture people can be trusted to use them safely.”
Reid Brown of Deer Island, who also serves on the Fundy Weir Fishermen Association board, says he is “very concerned about this experiment. We can’t understand why they have to do this in so many cages. Well, we do, really-it’s because they have the lice getting out of control in those cages, but they don’t want people to know too much about that.”
Dr. Vladimir Zitko, a chemist and former head of toxicology at the Fisheries and Oceans Canada biological station in St. Andrews, New Brunswick, now retired, is concerned about the planned release of deltamethrin into marine waters. “Deltamethrin is a very toxic insecticide,” Zitko says, “very similar to cypermethrin, the chemical that killed the lobsters in Back Bay in 1996. It’s extremely toxic to aquatic animals and I’d be very hesitant to use it this way in the ocean. It’s strongly acid and I think it should at least be treated with something alkaline to help neutralize it and then disposed of in a toxic waste facility.”
Fundy Baykeeper Thompson, a career fisherman and former federal fisheries officer, says “It would be foolhardy and dangerous to do this regardless of the time of year, but it’s especially dangerous and irresponsible in the summer when the young larval lobsters, which are much more susceptible to pesticides than the adults, are congregated close to shore and in the sheltered bays. If those young lobsters are poisoned by this pesticide it could be a long time before the damage shows up in reduced lobster numbers, and by then it would probably be impossible to prove what caused the problem.”
David Coon directs the Fundy Baykeeper’s parent organization, the Conservation Council of New Brunswick (CCNB). The province-wide environmental organization is asking for reductions in the number of salmon kept in each cage and also in the number and density of salmon aquaculture sites.
Dr. Fred Whoriskey ,vice president for Research and Environment at the Atlantic Salmon Federation (ASF), an international organization dedicated to the protection and restoration of wild Atlantic salmon, says his organization’s research tends to support David Coon’s opinion. Whoriskey points out that “wild salmon in our region have very low levels of infestation with sea lice. Salmon entering the Magaguadavic River, which is near the bays where they will be using this pesticide are examined every year, and it’s unusual to find a sea louse on those fish. A survey of sea lice populations on salmon taken at sea in the Gulf of Maine near the mouth of Fundy Bay about five years ago examined 330 fish and only one sea louse was found on all those fish. So this would indicate that if the lice are moving from fish to fish, it’s happening within the caged populations, not from wild salmon to caged fish.”
Contacted for its point of view on the July sea lice control experiment, the New Brunswick Salmon Growers’ Association sent a copy of a background paper on “AlphaMax (deltamethrin) Trials for Sea Lice Control on Salmon Farms” prepared by the New Brunswick Department of Agriculture and Aquaculture. Cooke Aquaculture spokeswoman Nel Halse did not respond to a request for comments on the deltamethrin experiment.
Philippe Laroche, a media relations officer with Health Canada says the Pest Management Regulatory Agency (PMRA), a division of Health Canada, gave the New Brunswick Ministry of Agriculture and Aquaculture emergency approval to use deltamethrin in marine waters for the July sea lice experiment. Laroche says anyone with questions or comments can write PMRA at 2250 Riverside Drive, Ottawa, Ontario K1A 0K9 Canada, or phone, in Canada only, 1-800-267-6315.