Scores of ringed seals along the coast of Alaska have fallen victim to a mysterious disease that has been afflicting the area since July.
Ailing seals have been beaching themselves in increasing numbers on the Arctic coastline. Close to 100 sick seals have been found near the northern city of Barrow, and half have already died. Other communities in the area have also reported sightings of afflicted seals.
Ringed seals live in the water and on floating ice, and they do not generally come ashore.
Biologists suspect a virus may be to blame. Stricken seals suffer from bleeding lesions on hind flippers, loss of fur, and skin irritation around the nose and eyes. But the exact pathogen remains unidentified. Bruce Woods, a spokesman for the U.S. Fish and Wildlife Service, told Reuters, “We’re kind of in the dark at this point.”
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The disease may not stop at ringed seals. Dead walruses and several bearded seals in the area were found with these symptoms as well, though it’s unclear if the cases are all linked by the same ailment. Wildlife officials in Russia and Canada have also reported similarly afflicted animals.
Veterinary care for the sick animals is limited by the remote locations they live in. Though scientists are collecting the dead seals for sampling and study, sick seals have to battle the illness on their own. Unfortunately, seals that are weakened are less able to fight off predators, such as polar bears.
Ringed seals are difficult to track because the live on the water in the summer, and under ice or snow in winter. An accurate count of seals in the area has not been made in decades, which complicates efforts to understand the scope of the disease.
For now, biologists are continuing to work to identify the elusive source of the seals’ affliction. Alaska’s seals face other challenges as well: global warming is threatening the floating sea ice and the snow cover that these animals depend on for living and breeding. The National Oceanic and Atmospheric Administration (NOAA) has proposed designating ringed seals as a threatened species.
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Allison Berry is a contributor at TIME. You can continue the discussion on TIME’s Facebook page and on Twitter at @TIME.