Chan says that the Northwest has had an “hypoxia season” for the past 20 years. It typically begins in mid-summer, but climate change has been making the season worse. “When oxygen levels drop significantly, many marine organisms that are place-bound or cannot relocate quickly enough, such as Dungeness crabs, die of oxygen starvation,” he said.
According to Chan, 2021 has been “a really bad year” when it comes to oxygen levels in the ocean. “Oxygen levels got very low, very early, and the worst is not over. On Aug. 31, it was as close to zero as we’d seen this year,” he said. “Now we’re in September, at a time when we thought oxygen would have been rising for a while, and it’s just this endless summer, but in a bad way.”
“This year, these summertime north winds arrived earlier than at any time in 35 years and are still going strong,” said Jack Barth, an oceanographer from OSU’s College of Earth, Ocean, and Atmospheric Sciences. “Early and strong north winds supercharge the upwelling of low-oxygen waters and nutrients from depths that fuel an exceptionally productive food web.”
In July, the National Ocean and Atmospheric Administration published a research article on the significant risk of Oregon and Washington coasts becoming large “dead zones” following the discovery of a huge hypoxic area forming a mere 6 miles offshore. In the article, Richard Feely, an oceanographer with NOAA’s Seattle Based Pacific Marine Environmental Laboratory, said the measurements of dissolved oxygen and ocean acidity has the potential to create oxygen levels so low that crabs and other bottom-dwelling fish die.
Chan teamed up with Dungeness crab fishermen to help take measurements off the Oregon coast, using a sensor in crab pots. These sensors gather data to help study the ocean and help the fishermen learn more about the effects of hypoxia on their trade.
“Commercial fishermen have long been key to the study of hypoxia,” Chan said.
Oregon’s Dungeness fleet produces an average annual catch of 16.7 million pounds, according to the Oregon Dungeness Crab Commission. This year’s catch was about 12 million pounds, however, in recent years, the catch has ranged anywhere from 3 million pounds to 33 million pounds.
“But how are these hypoxia seasons going to be affecting the next two, three or four years?” said Tim Novotny, assistant administrator and communications manager for the commission. “How many females, who we do not harvest, are not making it through these zones?”
What is certain is this: ocean acidification, which exacerbates the effects of hypoxia and the formation of dead zones, is being driven — much like other climate-related phenomena — by rising levels of atmospheric carbon resulting from the burning of fossil fuels.