The marine heatwave in northern Pacific waters known as the “Blob” is rearing its ugly head again.
First identified in 2013, the warm water mass kept Alaska water temperatures well above historical norms for nearly four years and was blamed for everything from plummeting numbers of Pacific cod and pink salmon to severe winters on the U.S. East Coast.
Observers breathed a sigh of relief last year when temperatures fell back to historical levels, but were set on edge again this fall as water temperatures in the Gulf of Alaska were over averages by four degrees Fahrenheit.
“Basically, in the Gulf (of Alaska), 2014, 2015, and 2016 were all warmer than what we’ve seen, at least in the last, say, 50 years. Then, 2017 it relaxed; it was what we would have used to call a very warm year, but it was within previous ranges. Then 2018 bounced back up into that never-seen-before range,” Mike Litzow, a researcher based out of Kodiak, Alaska who specializes in Gulf of Alaska cod stocks, told SeafoodSource.
University of Washington climatologist Nick Bond, who coined the term “Blob” back in 2013, explained that the warming is principally caused by calmer weather.
“Without winds to draw heat out of the ocean and to mix up colder water from below, the near-surface waters, again, got quite a bit warmer than normal,” Bond told Alaska Public Media’s KTOO.
Researchers still do not know what this might mean for fish stocks in the region. The crash in Pacific cod stocks in the Gulf of Alaska has prompted an 80 percent reduction in fishing quotas since 2016, and research indicates that the warmer waters are a main factor in the cod crash.
Counts on year-zero cod in 2018 had Litzow cautiously optimistic about a return to historical runs, but a resurgent Blob could hamper the chance of a rebound.
Decades-long periods of warmer and cooler weather in Pacific waters — known as Pacific decadal oscillation — are normal. Decadal warming events bumped up Alaska water temperatures in 1920s, 1940s, and again in the 1970s. And Litzow pointed out that a change in ocean temperatures of just one degree can provoke a massive shift in the food web and cause species to change location.
Before the 1970s warming, for example, Kodiak was a crab and shrimp town. Cod proliferated in the warmer waters and moved inshore and devoured the shrimp, and salmon populations thrived. However, man-made climate change makes this period of extended warm water temperatures more unpredictable.
“We sort of assume that these very extreme warm temperatures we’ve had since 2014 will relax back toward the normal, but then we understand that temperatures are being driven upward by human activities. Every year, the chance of increased warmth goes up,” said Litzow, who works for the University of Alaska Fairbanks but is based in Kodiak.
