The Washington state fish farm that collapsed allowing many thousands of Atlantic salmon to escape into the Pacific showed signs of trouble last month, and was slated for upgrades.

In late July, the Cooke Aquaculture-owned operation near Cypress Island required emergency work to stabilize the net pens after crews saw them moving in currents.

Then last weekend, the same pens, containing 300,000 Atlantic salmon, began showing damage on Saturday before collapsing on Sunday, releasing an unknown number of fish.

While the incident happened in Washington state, it's reinvigorated the longstanding debate about fish farming on Canada's West Coast, including the controversial but common practice of farming Atlantic salmon in Pacific waters.

Atlantic salmon were caught in the Puget Sound after Cook Aquaculture's net pen was damaged. There is no way to confirm if the fish pictured here are the fish that escaped. (Beau Garreau)

In both cases, Cooke Aquaculture blamed high tides and currents, though tide tables show nothing unusual.

"The experience on the water from our farm crews found that they were seeing conditions that they had never seen before," vice-president of communications Nell Halse said on Wednesday, about this weekend's pen collapse.

"It was very very high current and unbelievable conditions — in fact so much so that they couldn't be on the farm during some of the tidal runs."

Terry Beech, parliamentary secretary to the minister of Fisheries, Oceans and the Canadian Coast Guard, said that although the incident happened in the United States the Canadian government will be monitoring B.C. waters for any escaped salmon.

"British Columbians can rest assured that Fisheries and Oceans Canada is taking this incident very seriously," Beech said in a statement.

"While our science shows that there is an extremely low likelihood of Atlantic salmon becoming established in B.C. waters, we are constantly monitoring to ensure the health of our marine ecosystems."

Currents very fast but 'not unusual'

The company said currents of up to 3.5 knots — or about two metres per second — were measured at the location last weekend, and has pointed to the tides "coinciding with this week's solar eclipse" as the reason.

The tides may have been a factor, but the eclipse was not, said Greg Dusek, senior scientist of the National Oceanic and Atmospheric Administration's tides and currents program.

If all it takes is a new moon to rip it apart ... perhaps having net pens of this type in the water is not a good idea. - John Volpe , University of Victoria ecologist

"The eclipse itself would have nothing to do with this," said Dusek in a statement.

"The predicted tides and currents were fairly high and fast on the 21st due to the new moon and [other factors] but definitely not unusual."

Preliminary NOAA measurements showed surface currents in the area of about three metres per second on Aug. 19, when the damage started. That's a "very fast current," but nothing stronger than what was observed multiple days in June and July, NOAA said.

In any case, industry observers note fish farms are sited to capitalize on currents, and should be built to withstand them.

"We have new moons regularly throughout the year," said University of Victoria ecologist John Volpe, who has studied farmed salmon escapes.

"If all it takes is a new moon to rip it apart ... perhaps having net pens of this type in the water is not a good idea."

A drone image of the collapsed Cooke Aquaculture salmon farm near Cypress Island in Washington state's Puget Sound. (Beau Garreau)

Escapes rare, say B.C. salmon farmers

Fish farm opponents say this collapse raises concerns about B.C.'s fish farms, which also grow predominantly Atlantic salmon and have long faced questions about whether escapees from those farms could be harming wild salmon.

On Wednesday, speakers at a rally outside Fisheries and Oceans Canada offices in downtown Vancouver repeated calls to end net pen farms in the open ocean.

"They don't belong here, and neither do any other Atlantic farmed salmon," said Eddie Gardner, president of Wild Salmon Defenders Alliance.

Opponents of salmon farming held a rally in front of Department of Fisheries and Oceans offices in downtown Vancouver on Wednesday, calling the pen collapse in Washington state 'disturbing.' (Farrah Merali/CBC)

But the B.C. Salmon Farmers Association said its members' farms use newer technology than the farm that collapsed in Washington state, designed for very high currents and turbulent water, making escapes rare.

"The structures in British Columbia are significantly more robust," said executive director Jeremy Dunn.

"Fifteen years ago escapees were relatively common.... Over the last three years we have had less than 50 individual fish escape from farms in British Columbia."

Dunn said the farms are monitored by staff and video cameras, and fish are counted at each step of the process.

Aerial image of a salmon farm near Tofino, B.C. Salmon farms in B.C. use newer technology to withstand strong currents and tides than the farm that collapsed in Washington State, according to the industry. (Courtesy of B.C. Salmon Farmers Association)

Site was slated for upgrades

In an interview, Cooke Aquaculture stressed it had only acquired the Cypress Island fish farm last year and had applied for permits to upgrade the pens.

The company said the 30-year-old farm was built to a different standard than it uses in its operations in Eastern Canada, and planned to install newer technology once these fish were harvested.

"Unfortunately this event occurred before we could do that," said Halse.

When asked whether it was wise to keep farming the 300,000 salmon in pens that were slated for upgrades and showed problems a month ago, Halse said permits take time.

"We did the best we could with what we had," she told CBC News. "At the time we believed we had the farm secure."

An early estimate, provided by the company to officials, suggested 4,000 to 5,000 Atlantic salmon escaped, but Halse said Wednesday the company now believes the number is "much higher."