Toxic contamination will linger at Island salmon farm site, government finds
The Vancouver Sun, 25th August 2009, By Scott Simpson
An August 2009 Environment Ministry study estimates that Centre Cove salmon farm will degrade seabed marine life as much as 100 metres from the site of the farm for 15 years dating from the farm’s 2004 shutdown.
VANCOUVER — Toxic contaminants from a “notorious” Kyuquot Sound salmon farm
are having a lasting, negative effect on the seabed in the farm’s vicinity,
according to a new provincial government report.
An August 2009 Environment Ministry study estimates that Centre Cove salmon
farm will degrade seabed marine life as much as 100 metres from the site of
the farm for 15 years dating from the farm’s 2004 shutdown.
The report warns that the toxic effects from metals released from the farm,
notably zinc and copper, could last significantly longer.
“It is notoriously one of the worst fish farms on the coast,” David Suzuki
Foundation fisheries biologist John Werring said in an interview, adding
that an unspecified number of other salmon farms along the B.C. coast are
believed to be causing similar effects — “but we just don’t know how many.”
Werring said the province is considering regulatory changes that would
actually make it easier for farms to discharge waste into the ocean.
Copper is part of an “anti-fouling” agent used to deter growth of algae and
barnacles on sea pen nets, while zinc is present in fish food and
subsequently defecated.
The report said that while oxygen-deficient organic material, notably fish
waste, will eventually be flushed away, “metal toxicity” at Centre Cove is a
persistent concern for so-called benthic organisms, including oysters and
clams.
The west coast Vancouver Island salmon farm dates back to the 1980s, and was
owned and operated by Marine Harvest from 1998 to 2004, when the company
shut it down because low ocean-current speeds were not effective in
dispersing contaminants escaping from the farm.
The environment ministry report said the seabed in the vicinity of most
farms recovers in four to six months, but described the Centre Cove’s seabed
impact as “more severe.”
The report also suggests that a few month’s fallowing may not be long enough
to allow the seabed to recover from metal contamination, in areas without
strong currents to disperse farm waste.
Bernie Taekema, a senior aquaculture biologist with the environment
ministry, said in an interview that Centre Cove has been studied annually
since 2000 and that despite the persistence of contaminants, sea worms have
colonized the area and appear to be contributing to its recovery.
Sharon Dedominicis, environmental sustainability manager for Marine Harvest
Canada, described Centre Cove as a “non-typical” site compared to an ideal
farming venue with good tidal flows and high oxygen levels.
“It’s certainly not a place we’d choose ever again,” Dedominicis said,
adding that a typical Marine Harvest farm remediates in one to three months.
“Essentially, about 40 per cent of the company has been modified over the
last five years or so, looking at improving benthic performance,” she said.
She added that a conventional fallow period has been proven sufficient for
seabed recovery at a typical fish farm,
“I would have to assume there are other farms in this sort of situation,”
said Stan Proboszcz, fisheries biologist for Watershed Watch Salmon Society.
“According to the province’s Waste Management Act, this farm would be
considered a contaminated site.”
ssimpson@vancouversun.com