Sea lice hurting B.C. salmon

Sea lice to a fish are like head lice to a child.

Lice are pests that can spread quickly within close quarters, but usually don't cause serious damage. This could be quickly changing though, at least for wild Pacific salmon along British Columbia’s coast.

Some research indicates that fish farming in B.C. is disturbing the life cycle of wild salmon and causing outbreaks of disease like sea lice.

Alexandra Morton, a biologist and director of the Salmon Coast Field Station in Simoom Sound, B.C., partnered with scientists across North America to study the impacts of fish farms on wild fish populations.

Sea lice eat away at the flesh of this juvenile salmon.

While researching killer whales, Morton was approached by local fishermen who told her they noticed more diseased fish, including flatfish and salmon, being caught around fish farms.

“Our local hatchery ran for ten years with a three per cent mortality rate," she says. "[Then] they started losing a quarter to half of the fish they brought in."

She brought her observations to the provincial government, but was told she didn’t have enough scientific evidence to support her findings.

Morton then partnered with scientists who had expertise in fishery science. They have since published research on the impacts of sea lice from fish farms on wild salmon. Morton has even published a report on the subject in Science, a world renowned peer-reviewed journal.

She says that fish farms interfere with the natural ability of wild salmon to fight disease.

“Because there are no predators in the fish farms to get rid of the sick fish, they act as incubators to the disease. It spreads like wild fire."

Lice hitch a ride inland

Wild adult fish bring sea lice from the ocean inland on their way back from migration. The lice is carried through the water on these wild salmon, infecting farmed fish.

In nature, the adult salmon die before their eggs hatch. The wild juvenile salmon then enter clean water without scales and without risk of infection when beginning their migration to the ocean.

But now, fish farms are keeping greater levels of sea lice in the water and the wild juveniles pick them up on their migration route to the ocean.

The lice create gaping holes in the fish, making it difficult to balance salt levels, as well as potentially creating a pathway for infection. Wild salmon populations are decreasing because the juveniles die prematurely due to complications caused from such diseases and predators can kill them more easily because of their weakened state.

However, despite all the evidence, Morton says the B.C. government hasn't listened. The fish farms around her community on Vancouver Island kept growing, and in resonse, she took legal action.

[DFO’s] research is deliberately misleading ... it’s a shameful episode in the history of science

Fish farms have been regulated by the provincial government since 1988, but they have no claim on wild fish. Meanwhile, the federal Department of Fisheries (DFO) is responsible for wild fish, but not farmed fish.

In 2009, there was a constitutional challenge in the B.C. Supreme Court over the regulation of the fish farms, and it was ruled that fish farms are in fact under the regulation of the federal government.

The DFO was supposed to take over this past February, but the federal government applied for an extension because they needed more time to create a replacement regime.

The deadline has been moved to December 18, 2010 but the B.C. government put a moratorium in place for handing out new aquaculture licenses for both finfish and shellfish.

In an email, DFO maintained wild and farm fish can co-exist under appropriate management. While they recognized sea lice have impacts on the health of farmed fish, they refrained from commenting on the impacts on the wild salmon.

The B.C. government says fish farms are not the reason for increased sea lice in these areas.

“It is generally accepted that this season's increase in abundance is a result of returning wild fish," says Patrick Vert, on behalf of the B.C. Ministry of Agriculture and Lands. "Other factors, such as ocean salinities, can also affect fluctuations in sea lice."

Treating the problem

Chemicals are often used to regulate sea lice on fish farms.

Vert says lice on farmed salmon in Canada are low when compared to other countries where farm lice have been exposed to anti-lice products repeatedly.

The underbelly of a sea louse.

He says there’s no evidence that sea lice in B.C. are resistant to the drugs used because drugs are only used once or twice per production cycle.

Nonetheless, Morton says the sea lice will inevitably become resistant and that managing the disease for farmed fish is not a long term solution.

“You can medicate your own fish in these farms, but you can’t medicate wild fish,” says Dr. Neil Frazer, a professor at the University of Hawaii, Manoa.

Frazer, who recently published a paper on sea-case aquaculture, sea lice, and declines of wild fish, is weary of DFO’s sea lice research. For example, he says, two DFO studies attempted to show wild juvenile salmon were being infected by sea lice from stickleback fish, instead of farmed fish.

“But what the DFO studies actually showed, if you read them carefully, is that the sticklebacks could not possibly be the source of the lice infecting wild juvenile salmon.

“[DFO’s] research is deliberately misleading ... it’s a shameful episode in the history of science."

It's not unknown, says Frazer, for industry scientists to try to deceive the public, as seen with some questionable reports about tobacco, lead and vinyl chloride. It is unusual though for government scientists in Canada to deceive the public deliberately, he says.

“I don’t think the people in Canada understand how badly they’re being robbed by the loss of the wild Pacific salmon. They are so iconic, and so important to the ecosystem,” Frazer says.

According to Morton, wild salmon are an integral part of the ocean ecosystem in Canada. They benefit both coastal and terrestrial ecosystems by feeding on the phytoplankton in the ocean and by being eaten by birds or bears.

“It’s tragic that society has gotten used to hearing that this is dying, and that is dying. They just assume everything is dying. I would really love people to know that the ocean is trying to produce life,” Morton says.

“We don’t want to wreck this.”

Breaking down the sea lice cycle

Find out more about the sea lice life cycle and how they infect salmon with the infographic below: