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Article
from The Seattle Times Monday,
October 2, 2006 - 12:00 AM Sea
lice from salmon farms killing wild salmon, study finds By
JEFF BARNARD
The Associated Press GRANTS
PASS, Ore. - A team of Canadian scientists has found the most direct evidence
yet that baby salmon pick up fatal infections of sea lice while swimming past
salmon farms in British Columbia's Broughton Archipelago, and that the more salmon
farms the more baby salmon die. "Before
we knew there were potential problems," said Martin Krkosek, a doctoral student
at the University of Alberta who was lead author of the study released Monday
by the American journal Proceedings of the National Academy of Sciences. "Now
it is very clear we have severe problems here." In
natural conditions, the adult salmon that carry the sea lice aren't in the migration
channels and rivers at the same time as young pink and chum salmon, so the little
fish are not infested, said Mark Lewis, University of Alberta senior Canada research
chair in mathematical biology, who oversaw the research. But
fish farms have changed that, raising hundreds of thousands of adults in floating
net pens anchored year round in the channels where the young fish migrate. The
young pink and chum salmon are only an inch long, and do not yet have scales to
protect them from parasites, he said. Ransom
Myers, a professor of biology at Dalhousie University in Nova Scotia, who was
not part of the study, said it was the most comprehensive to date on the issue
and hoped it would push the Canadian government to take action to protect wild
salmon. Andrew
Thomson, acting head of aquaculture for Fisheries and Oceans Canada's Pacific
region, said the agency had yet to review the study, but was monitoring sea lice
infestations of wild salmon, doing its own research, and was committed to protecting
wild salmon. "What
we're seeing is infection rates of sea lice vary year by year, and populations
of pink salmon show fluctuations year by year," he said. "It's a complex issue.
We need to do more research on it." Marine
Harvest, which owns many of the 30 salmon farms in the archipelago, did not return
a telephone call to its Campbell River, B.C. office for comment. When
West Coast salmon catches in the United States crashed in the 1990s, farmed salmon
filled the gap in supermarket coolers, and Canada now has about 280 salmon farms
that produce about 96,000 tons worth $387 million each year. About 70 percent
goes to the United States. British Columbia has about 100 salmon farms, and Broughton
Archipelago about 30. There
are nine salmon farms in the U.S. - six in Maine, two in Washington and one in
Tennessee. Concerned
about the impacts of hundreds of thousands of salmon crowded into net pens floating
in coastal fiords down which baby salmon migrate, environmental groups have campaigned
to convince consumers to boycott farmed fish. Alexandra
Morton, a biologist from Broughton Archipelago who took part in the study and
is founder of the Raincoast Research Society, said she started looking into the
issue in 2001 when a fisherman brought her a wild salmon covered with sea lice
and asked her whether salmon farms were the reason. "Every
time one of us publishes on this issue, the Canadian government finds a little
loophole and runs with it," she said. "First they said maybe it's not coming from
the farms. When we nailed that one down, they said maybe they don't kill the fish.
When we nailed that one down they said maybe they don't kill to affect the population.
"This
nails that final loophole down." The
study examined 17,000 fish, which were netted at regular intervals along three
different migration routes over the course of two years. Mortality rates at various
points in the migration season ranged from 9 percent to 95 percent. The
study found fish died after being infected with as few as one louse, that the
more louse on the fish the more likely it was to die, and that the more salmon
farms along the migration route, the more likely the fish were to die. The highest
mortality rate, 95 percent, came in the channel with three salmon farms at the
end of the migration season, when sea lice were most prevalent. The other two
channels had two farms. "The
basic physics says this result should not be surprising," said Neil Frazer, a
professor of physics at the University of Hawaii who worked on the mathematical
modeling that went into the study. "When you put a bunch of farmed fish into a
system of wild fish and parasites, you automatically are going to greatly increase
the number of parasites, because you now have a much better chance of finding
a host." Copyright
© 2006 The Seattle Times Company Used
with permission of The Associated Press Copyright © 2006. All rights reserved.
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