Wild pink salmon on central coast may vanish

Groundbreaking report says sea lice from fish farms may cause extinction in four years

Wild pink salmon on the B.C. central coast will be extinct in as little as four years, due to sea-lice infestations touched off by salmon farms in that area, according to a groundbreaking study to be published in the journal Science today.

The report, in one of the world’s foremost scientific journals, has again put B.C. at the centre of a fierce international debate about salmon farming risks.

Hundreds of articles have been published over the past two decades in scientific journals, examining the decline of wild salmon and trout in the vicinity of sea-pen fish farming operations around the world.

But the Science article, based on 37 years worth of fish survival data collected by the Department of Fisheries and Oceans, takes the scientific debate to a new level by asserting that some wild pink salmon populations are in a mortal decline as a direct result of lice infestations from farms.

The article has already attracted international interest, particularly among nations with large-scale aquaculture operations.

B.C. fish farmers and government scientists were quick to dismiss the article’s findings—although one expert commentator said the conclusion is based on straightforward, uncomplicated calculations that can be quickly replicated by other researchers.

The industry is annually worth about $500 million to B.C. and employs 3,500 people, mainly in small coastal communities with few other opportunities for jobs—particularly with the collapse of the coastal forest industry.

The article’s authors, including University of Alberta researcher Martin Krkosek and B.C.‘s Alexandra Morton, looked at 37 years’ worth of DFO data for 71 central coast rivers and found that wild pink runs have comfortably withstood decades of commercial fishing—but cannot survive fish farms in the Broughton Archipelago.

They said lice infestation rates are 70 times higher among juvenile pink salmon from seven rivers in the vicinity of central coast fish farms, compared with fish whose natal streams are more remote, and that the mortality rate among infected fish is “commonly over 80 per cent.”

Sea lice hyper-concentrate around the farms and spread to wild salmon migrating in the vicinity of the farms.

“What we have seen is a very rapid four-year decline in the pink salmon populations in the Broughton,” Krkosek said in an interview. “Based on that measured rate of decline, which is real, we can expect that in another four years those fish will be all gone if the sea-lice infestations continue.”

The situation has become acute since 2000 as the industry has increased the volumes of fish it raises in its pens.

Krkosek said the situation has implications for adult salmon, grizzly bears, killer whales, eagles and other species that rely on pinks as a major food source.

“If outbreaks continue, then local extinction is certain, and a 99-per-cent collapse in pink salmon abundance is expected in four pink salmon generations,” the article says.

Only last summer, The Vancouver Sun reported that a B.C. government-financed fisheries research group suppressed a report reviewing threats to wild salmon from sea-lice infestations.

At the time, a senior federal fisheries scientist stated in the Sun story that there was no evidence that sea lice from fish farms are having population-level impacts on wild fish, although transfers of lice from farms to wild pinks may threaten individual fish.

In an interview Thursday, that same scientist, DFO division manager Brian Riddell, repeated that assertion.

He said the article’s warning of an extinction threat is “overstated and not consistent with the recent trends we’ve seen in salmon populations in the Broughton” where some individual populations showed nominal increase this past summer.

Mary Ellen Walling, executive director of the B.C. Salmon Farmers Association, suggested the research was driven by ongoing concern in the environmental community about fish farming.

The B.C. industry has been previously scrutinized in the mainstream scientific press. In 2004, an article suggesting farmed salmon contained potentially harmful concentrations of toxins caused sales to drop.

That article was subsequently discredited by federal heath agencies in Canada and the United States. Farm fish sales have not only recovered, they’ve expanded.

“It seems this sort of work is more interested in driving public opinion than contributing to this broader public understanding,” Walling said.

According to a University of Washington fisheries professor who reviewed the Science article prior to publication, the calculations linking salmon farms to wild salmon extinctions are simple and straightforward.

Professor Ray Hilborn predicted government will find the issue difficult to resolve, however, because the B.C. salmon farming industry is a big employment and revenue generator.

Article co-author Alexandra Morton said researchers have steadily answered all of the objections put forward by government and the aquaculture industry since she first raised the sea lice issue in 2001.

“We used DFO’s own data for a large part of the study. It’s not just a guess.”


© The Vancouver Sun 2007

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