|
Stopping The Great Escapes
A continent away from their native waters, disoriented and out of captivity for the first time in their lives, 30,000-odd Atlantic salmon are roaming free off the British Columbia coast.
Their mass exodus from a pen at Marine Harvest Canada's Frederick Arm site on July 1 is B.C.'s largest farmed-salmon escape in eight years. It has spawned a government investigation, with Environment Ministry conservation officers combing the site to find out exactly what went wrong.
The company stopped trying to recapture the escaped fish Friday afternoon, leaving 29,616 fish missing.
“They're out, they're free, they'll be mingling,” said Raincoast Research biologist Alexandra Morton. And it doesn't bode well for wild Pacific salmon.
The Atlantic salmon are “big, silly animals” who lack much of the instinct driving wild salmon's life cycles, Ms. Morton said. “They do have instincts to feed, though, and that's what they're bred for, is to be voracious feeders.”
These appetites can take a bite out of wild salmon's precious food supply – or they can gobble up vulnerable young salmon. It's also possible the farmed salmon, although two years away from sexual maturity, will follow spawning Pacific salmon into rivers off the coast.
“[The rivers are] full of our little fry and smolts – they would simply start eating our young fish,” she said. “You don't know whether they're going to follow other spawning salmon into the rivers.
|
“Closed-containment, closed-containment, closed-containment. That solves everything.”
-- Morton on how to prevent an event like this from happening again
|
Early on Canada Day, unusually strong ocean currents shifted the 10-tonne concrete block anchoring Pen 11, one of the 12 pens at the Frederick Arms site. The anchor fell into a crevice, pulling the net down with it and allowing the salmon inside to escape through an opening about 4.6 metres underwater.
Workers on-site saw the escape as it happened but were powerless to do anything, said Marine Harvest communications manager Ian Roberts. The anchor could have pulled them down with it, or snapped and shot up in the air.
Mr. Roberts said the company checks its shallower anchors every 60 days, but the system anchors are too deep to check regularly.
Read the full article in Saturday's Globe and Mail.
|
