Cortes Island shellfish deaths

Roy L Hales/ CKTZ News - In the midst of a heat wave that may have left as many as a billion dead marine creatures along the West Coast, there were also an abnormally high number of shellfish deaths reported at two Cortes Island sites.

Daily temperature highs of between 35°C and 40°C were recorded, at the Cortes Island School, during the last five days of June.

Mike Manson reported a extraordinary high number of dead cockles, in southern Cortes Island, on June 27th.

“On a low tide of 2 feet or less, I would typically expect to find maybe half a dozen live ones partially exposed in the sand, and maybe a few more dead ones that sharp–eyed gulls had spotted and turned into a meal. To see several hundred half shells littered across the beach was a shock,” he wrote.

Manson returned the following day to take the picture accompanying the written version of this article, which he wrote, “was taken on a 2 ft tide, following 5-6 days of very low tides, one of which was a negative tide ( the 25th ), and that is a rare event.”

Cortes Island biologist Sabina Leader-Mense added that, “the cockle die off Mike Manson observed is classic, as cockles have the shortest siphons, sitting at shallow depths, where they are vulnerable to the heat.”

A Squirrel Cove resident who did not wish to be identified said there was a persistent stench coming from the beach beside his home as long as the high temperatures persisted. He suggested there may have been a ‘partial die off’ of the oysters.

Curt Cunningham, owner/manager of the Squirrel Cove, and his sister Lynne Cunningham, also noticed the unusual odour. They said some of the store’s customers complained about the smell.

A week after the return to normal temperatures, Michele Douglas from the Friends of Cortes Island (FOCI), carried out a quick survey of the area.

“The first thing is I actually smelled a bit of a different beach odour than I would normally have smelled. Sometimes low tide can small a bit sulphury, but this just kind of smelled dead one would say. It was definitely an unpleasant odour,” she said.

Douglas found ‘quite a few live oysters’ and ‘quite a few that looked like they had died recently’ between the boat launch and dock.

She believed that the death was recent, “If the shell was open a little bit and you could pry it open and there was also still some organic material in there. I also sniffed them, If it smelled pretty fresh, then I presumed it had died in the last week or so.”

Douglas counted 10-12 dead oysters. Not having carried out any previous examinations in Squirrel Cove, she did have a base line to compare her findings with.

There was a questioning tone in her voice, “It is hard to say if there are always dead oysters on the beach? Or maybe it is totally related to this heat wave?”

The temperatures at Squirrel Cove Store – courtesy Mike Manson
The odour at Mansons Lagoon
Douglas and Max Thaysen, FOCI’s Acting Executive Director, also investigated a report that there were die offs in Mansons Lagoon. They did not find any dead oysters or clams.

“We dug into the surface and pulled out a couple of clams. They looked pretty happy and the oysters looked okay, but there was a little bit of the decaying sea-life smell that I would not attribute as normal thing to smell at those beaches, she said.

Douglas added, “It was a lot more apparent at Squirrel Cove.”

Leader-Mense added, “These temperature related die offs are not new; the extent, possibly yes, but not the occurrence of… We have witnessed them in Manson’s Lagoon over the years when the hottest days of the year correspond with the lowest tides of the year.”

“The blue mussels that once lined the edges of the channel into manson’s lagoon have never returned after being cooked in their shells one summer afternoon at low tide (about 1998); We were there to witness… unbelievable.”

Image credit: Cortes Island tides - courtesy Mike Manson