Saturday, April 28, 2007

White sided dolphin dies in fishing net

The large nets that surround the West Coast's ubiquitous ocean fish farms are claiming an increasingly grim toll of marine mammals eager to gobble the farms' captive salmon.

The latest victims are a white-sided dolphin and a rare harbour porpoise, snared and drowned in the nets of a fish farm in the Broughton Archipelago off northern Vancouver Island.

Andrew Thomson, director of aquaculture management for the federal Department of Fisheries and Oceans, said yesterday that it was the first time he had heard of either animal dying from net entanglement at a B.C. fish farm.

The harbour porpoise is listed as a species of concern by the federal government because of its low numbers. The incident occurred at Mainstream Canada's operation on Wehlis Bay.

It follows news last week of 51 large California sea lions drowning in the nets of a fish farm near Tofino, a death toll that Mr. Thomson said was also unprecedented.

The DFO has launched investigations into the marine mammal deaths at both fish farms, he said. "It's a large number of animals and something the department views very seriously."

Mr. Thomson said the department also intends to send letters to all fish-farm operators in the province, reminding them of their obligation to report every incident in which a marine mammal drowns in their nets.

"We require this information for the proper management of the industry," he said, adding that he had no reason to believe fish farms are not complying.

However, Mr. Thomson refused to comment when asked if Mainstream Canada had reported the deaths of the dolphin and harbour porpoise.

"I really don't want to get into details until our investigation is complete."

Mainstream Canada did not immediately return calls.

Alexandra Morton, a prominent researcher into the problem of sea lice caused by ocean fish farms, said she passed the information on to the DFO, after receiving an anonymous e-mail about the dolphin and porpoise deaths.

When she went to investigate, there was no sign of their carcasses, although a diver did discover a dead Steller's sea lion in the nets.

"He was jammed in so tightly. That animal must have struggled so hard before he drowned," said Ms. Morton, a marine biologist with the Raincoast Research Society.

The spate of marine mammal deaths has fuelled calls for an end to the open-ocean net cages used by the scores of salmon fish farms on the West Coast in favour of a system with closed container tanks.

Environmentalists point to the dangers of farmed salmon escaping and mixing with wild salmon, the prodigious problem of waste from the salmon, the infestation of sea lice and now the growing mortality among marine mammals.

"The industry is going to have to face the fact that their nets are inappropriate on a coast so wild and vibrant," Ms. Morton said.

"They could get rid of all their problems if they stopped using nets in the open ocean."

Fish farmers argue that moving to closed containers would be too expensive to compete with farmed salmon from other countries, and the technology is unproven.

Once they smell the captive farmed salmon, marine mammals can become frenzied in their attempt to gorge on the fish, gnawing their way through several net layers to reach the prized prey.
But afterward, they are often disoriented and become trapped.

"It becomes a bit like a crab pot. Easy to get in, difficult to get out," said Andrew Trites, director of the Marine Mammal Unit at the University of British Columbia. "They become desperate looking for a way out and that's it. They drown.

"It's not a happy situation for anyone, for the fish farms and for people who value marine life."
Mr. Thomson of DFO said he is at a loss to know what has prompted the deaths of so many marine mammals.

"We certainly don't see this at all fish-farm sites in B.C. We want to find out why [these particular sites] have seen this type of incident. We've had these incidents before but never this serious."

Quick "Facts about Dolphins"