Bearded man standing beside boat with the words 'Vancouver Island University Centre for Shellfish Research' written on it.

Marine heatwaves a threat to B.C.’s shellfish industry says expert

Editor’s note: The shellfish industry is one of Cortes Island’s principle employers.

By Mick Sweetman,  CHLY 101.7 FM Nanaimo, through an LJI grant from

This summer was hot, not only for us, but also for the life in our oceans as marine heatwaves swamped B.C’s coastal waters. According to researchers, sea temperatures off northeastern Vancouver Island reached 21 degrees Celsius in July, boiling kelp alive.

In the first week of August the average global sea surface temperature reached a record-breaking 30 degrees Celsius.

Studies have found oceans have absorbed around 90 per cent of the heat from global warming.

Marine heatwaves may mean warmer swimming, but the warmer temperatures are a threat to B.C.’s $20 million shellfish industry with bacteria causing increased die offs.

Dr. Timothy Green is the Canada Research Chair in Shellfish Health and Genomics at Vancouver Island University (VIU) and an expert on how the shellfish industry is adapting to the increased frequency and intensity of marine heatwaves.

Green’s research focuses on the impacts of disease on farmed shellfish who started seeing a correlation between the outbreak of herpes in oysters, which he assures people is not the same as the one humans can get, and record breaking ocean temperatures.

“I started to see a recurring pattern that disease outbreaks were often occurring when we were having these atmospheric or marine heat waves,” he said.

He moved to Vancouver Island in 2018 and is the research director for VIU’s Deep Bay Marine Field Station where his primary research is to try and breed a strain of shellfish that is more resistant to ocean acidification, another effect of climate change.

“When I arrived about five years ago, most farmers were experiencing about half to four out of every five oysters dying before harvest,” he said. “That is a phenomenal number. To think 80 per cent of farmed shellfish die out just before they are ready to harvest.”

Green says that marine heatwaves are a major contributor to more shellfish dying off.

“If we look back in the 1970s, and 60s, a marine heatwave was really quite a rare event,” he said. “We were lucky to have one every couple of years. The difference is now we’re having about eight of these events every year in our local waters.”

While Green’s research focuses on shellfish, he’s also seeing fish change their behaviour.

“I’m an avid fly fisherman. Every morning, I get up at 4:30 a.m. I drive to the beach and I fly fish for salmon and this year, the salmon are just not behaving as they normally would,” he said. They’re not coming close to shore because all the black rocks are heating up during the day and the water’s too warm, it doesn’t carry enough oxygen and so they’re staying away in the deep, cold water.”

Green says that the impact of marine heatwaves is going to mean that shellfish farming could become more concentrated in large companies as smaller producers struggle to survive economically.

“Some of those bigger companies have the funds to weather the storms,” he said. “And some of these smaller producers are going to just realize it’s easier to exit the industry and make a living doing something else.”

Green says that while we are seeing the impact of climate change in our oceans, it’s not too late for people to act.

“My real big fear is that we’re just creating this environment that’s going to become dead and completely change,” he said. “So I really hope people take climate change seriously and try to help where they can.”

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Top image credit: Dr. Timothy Green, Canada Research Chair in Shellfish Health and Genomics at Vancouver Island University, says marine heatwaves are a threat to B.C’s $20 million shellfish industry. Photo courtesy of VIU.