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May 29 2025
5In a startling discovery, scientists have found that coastal wolves in southeastern Alaska are accumulating unusually high levels of mercury, largely due to their consumption of sea otters. The findings come after the unexpected death of a four-year-old female wolf, identified as No. 202006, which had been part of a wildlife study.
Gretchen Roffler, a wildlife research biologist with the Alaska Department of Fish and Game, said the team initially struggled to determine the cause of the wolf’s death. “We spent quite a bit of time trying to figure out what happened, conducting a necropsy and analyzing her tissues,” she explained. “What we eventually found were unprecedented levels of mercury in her liver, kidneys, and other organs.”
Seeking expert insight, Roffler connected with Dr. Ben Barst, an ecotoxicologist and assistant professor at the University of Calgary, who was then at the University of Alaska Fairbanks. Barst and a team of researchers have now published their findings in the journal Science of The Total Environment, showing a clear correlation between the wolves' diet and mercury exposure.
According to Barst, mercury is a naturally occurring element released into the environment through human activities such as coal burning and small-scale gold mining. “It’s an unusual metal — liquid at room temperature and able to become vapor. Once it enters the atmosphere, it can travel great distances,” he said.
Once deposited into aquatic systems, mercury transforms into methyl mercury, a toxic organic compound that moves efficiently through food webs. “Predators linked to aquatic food chains, like these wolves, can accumulate high mercury levels,” Barst noted.
The study focused on wolves from Pleasant Island, west of Juneau, comparing them with wolves from adjacent mainland regions and interior Alaska. The results showed that Pleasant Island wolves had the highest mercury concentrations. Mainland wolves primarily feed on moose, occasionally consuming sea otters, while the island wolves rely heavily on them—up to 70% of their diet.
Barst emphasized that the wolves’ dependence on sea otters is likely contributing to their elevated mercury levels, although other contributing factors are still under investigation. “They’re eating so many sea otters that mercury is building up in their systems over time,” he said.
Roffler added that this behavior isn’t isolated. Other wolf populations in Alaska and British Columbia have also been observed preying on sea otters, hinting at a more widespread ecological pattern. However, the mercury levels in B.C.’s sea otters remain unknown.
The researchers also suspect a climate change connection. “Glaciers in Alaska are retreating rapidly, and these glaciers can release mercury contained in bedrock,” Barst explained. “As glaciers melt, the mercury could either settle harmlessly or enter aquatic systems and be converted into methyl mercury. That’s something we’re now trying to understand.”
Source:https://phys.org/news/2025-05-coastal-alaska-wolves-exposed-high.html
This is non-financial/medical advice and made using AI so could be wrong.
