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A recent study has revealed that approximately 4 million common murres (Uria aalge) perished during a severe marine heatwave, known as “the Blob,” which disrupted the northeast Pacific, particularly Alaska, between 2014 and 2016.
Scientists report this event as the largest recorded mass mortality for a single bird species in modern history, signaling severe ecological instability in marine environments.
What did the Blob do in Alaska?
By late 2015, the blob and harmful algal blooms had crippled much of the Pacific fishing industry and disrupted the marine food chain. Dead fin whales and sea otters washed ashore along the Alaskan coast, while Chinook salmon populations in Washington and Oregon sharply declined.
As populations of forage fish, critical to murres’ diets, collapsed, the seabirds faced starvation. Carcasses of murres washed ashore in shocking numbers, littering coastlines across Alaska, Canada, and the western United States throughout 2015 and 2016. In many areas, researchers documented strandings at rates more than 1,000 times higher than average.
Around 62,000 common murres washed up on U.S. and Canadian Pacific coast beaches during the heat wave, including in Alaska’s Pigot Bay. New research estimates the total losses at 4 million birds. https://t.co/l180q4os2u
— Science News (@ScienceNews) December 13, 2024
What Do We Know Now?
Wildlife biologist Heather Renner of the U.S. Fish and Wildlife Service, who led the investigation, emphasized the scope of the crisis. Surveys covering decades of data revealed that the die-off claimed half of Alaska’s murre population, with many colonies shrinking to a fraction of their previous size. Some areas now report numbers as low as 25% of historical figures.
“We knew it was bad. What we’ve learned now is that it was so much worse than we thought.” – Heather Renner
This study draws attention to the consequences of marine heatwaves, which are becoming increasingly frequent due to climate change. Sudden disruptions to ocean temperatures reverberate throughout ecosystems, affecting wildlife at every level. The staggering loss of murres reflects broader challenges faced by seabirds and other species reliant on predictable food supplies in fragile ocean environments.
While some murre colonies have shown minor recovery, researchers stress that such catastrophic Alaska die-offs highlight ongoing threats posed by warming oceans. The future resilience of these ecosystems will depend on the ability to address rising global temperatures and protect the biodiversity that sustains marine life.
