VANCOUVER, B.C. – Concerned about crashing salmon populations in an area with a number of fish farms, the Canadian government is boosting research into the impact of sea lice on wild salmon.
Brian Riddell, chief scientist in the Fisheries and Oceans Department’s sea lice program, said Tuesday it may take three to five years to determine conclusively how sea lice from fish farms affect native salmon mortality.
“At this point the information is actually equivocal,” Riddell said. “The salmon farms have demonstrated they can control lice on the farms.
“If they can control the lice and we do not see evidence of a negative effect on the natural dynamics of pink and chum, then we would have to say that they can coexist.”
The expanded research stems from concern about plummeting populations of native juvenile salmon in the Broughton Archipelago off northern Vancouver Island, where salmon-spawning streams empty into inlets where Atlantic salmon farms are located.
Environmentalists say the farms’ net pens are the main source of sea lice infesting young pink and chum salmon as they head out to sea, but operators of British Columbia’s growing multimillion-dollar aquaculture industry maintain they can control lice in the pens and note that the parasites also occur naturally.
The debate also has spilled south of the border into Washington state and Oregon, where fish farming is far less extensive.
Riddell said sustainable fish-farming is one of the Canadian government’s goals but added that his agency’s top priority remains conservation of wild stocks.
“There’s certainly no presumption that if aquaculture on the B.C. coast poses unreasonable risk to wild salmon that they have to maintain them (fish farms) anyhow,” he said. “What we are trying to work on now is a sustainable industry on the coast that has very low to no risk on the natural populations.”
Final results of sampling from 2004 won’t be released until mid-April, but the agency reported an increased prevalence of one kind of sea lice, a salmon-specific species, on young native fish. Chum salmon appeared harder hit than pinks, with an infection rate of 25 percent.
At the same time, scientists said they found no evidence that the parasite affected the physical condition of infected fish, casting doubt on whether sea lice caused higher mortality.
Whether sea lice come from the open environment or fish farms may be irrelevant if they have no impact on wild salmon, the researchers suggested.
This year, studies on the effects of sea lice infestation on salmon health and growth include laboratory work in Nanaimo; Halifax, Nova Scotia, and Washington state, expanded sampling in the Broughton Archipelago and closer assessment of lice numbers on wild and farm-reared salmon.
Fisheries scientist Richard Beamish said recent samples from area fish farms show the lowest sea lice levels in two years. Operators have been dosing the pens with Slice, a drug that critics say poses potential health and environmental risks.
Corey Peet of Saltspring Island, who has been conducting separate research with funding from the provincial government and Raincoast Conservation Society, said federal scientists should determine the relative involvement of each sea lice source in infestations before passing judgment on fish farms.
Fish farms have been recording infestation rates without passing on the raw data to scientists, Peet said.
“From the DFO research perspective I would say that’s their biggest failure,” he said. “They have not done the most basic approach to answer the fundamental question that’s being debated, which is: Are salmon farms transferring lice to salmon in the Broughton Archipelago?”
Peet said the farms’ data should be analyzed and that cages with captive juvenile wild salmon should be located at varying distances from fish farms to indicate how transmission rates vary.
He also said the federal agency had not collected baseline data on sea lice impact in areas without fish farms.