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Scientists still unsure what's causing Arctic Alaska ringed seals to die

  • Author: Alex DeMarban
  • Updated: September 27, 2016
  • Published December 20, 2011

A federal agency said Tuesday that tests indicate a virus did not cause the deaths or illnesses of more than 100 Arctic Alaska ringed seals found with skin sores, ulcers on internal organs, patchy hair loss and other symptoms.

National Oceanic and Atmospheric Administration scientists announced via press release that despite numerous tests, it still does not know what's causing the illness.

Deaths in the Arctic and Bering Strait region of Alaska have been declared an unusual mortality event, a status that provides additional resources to investigate the cause, including access to more expertise and a contingency fund, the agency said.

The U.S. Fish and Wildlife Service is considering making a similar declaration for Pacific walrus in Alaska.

"Since mid-July, more than 60 dead and 75 diseased seals, most of them ringed seals, have been reported in Alaska, with reports continuing to come in," the NOAA press release said. "During their fall survey, scientists with the U.S. Fish and Wildlife Service also identified diseased and dead walruses at the annual mass haul-out at Point Lay (in Northwest Alaska)."

The disease has caused skin ulcers that usually appear on the animals' hind flippers or face. Some of the sick animals have had difficulty breathing and appear lethargic. Also, some necropsies have revealed "fluid in the lungs, white spots on the liver, and abnormal brain growths."

Scientists suspect that those internal wounds may be caused by bacteria entering the animals' bodies through the ulcers, said Stephen Raverty, a veterinary pathologist and working group member of the Provincial Veterinary Diagnostic Lab in British Columbia.

Testing continues for causes related to "immune system-related diseases, fungi, man-made and bio-toxins, radiation exposure, contaminants, and stressors related to sea ice change," the agency reported.

Scientists have tested for known viruses that could cause the symptoms but have come up empty, said Teri Rowles, national marine mammal health and stranding response program coordinator for NOAA.

Still, testing for viruses will continue, she said.

Here's a fact sheet from NOAA about the international effort to find answers. Here's the original news article on the outbreak among the ringed seals.

The press release said hunters continue to see numerous healthy animals. Humans who have been in contact with the animals have not reported similar symptoms.

"Still, it is not known whether the disease can be transmitted to humans, pets, or other animals," NOAA said. "Native subsistence hunters should use traditional and customary safe handling practices, and the Alaska Division of Public Health recommends fully cooking all meat and thoroughly washing hands and equipment with a water/bleach solution."

People who find the sick animals should not make contact with them. They can report animals to the:

  • North Slope area: North Slope Borough Department of Wildlife Management: 907-852-0350
  • Bering Strait region: Alaska Sea Grant Marine Advisory Program: 1-800-478-2202 or 907-443-2397
  • Elsewhere in Alaska: NOAA Fisheries Alaska marine mammal stranding hotline: 1-877-925-7773
  • Here is the rest of the release:

    "Walruses and ringed seals in Russia, and ringed seals in Canada, have reportedly suffered similar symptoms. While it is not clear if the disease events are related, the timing and location of the disease suggests the possibility of transmission between the populations, or shared exposure to an environmental cause.

    Since early November, federal agencies and partners have been consulting with the Working Group on Marine Mammal Unusual Mortality Events – a group of experts from scientific and academic institutions, conservation organizations, and state and federal agencies – to consider if the seal and walrus deaths met the criteria for an unusual mortality event. Late last week, the Working Group recommended NOAA and the Fish and Wildlife Service declare an unusual mortality event.

    The rigorous, collaborative investigation into these deaths has and will continue to involve the North Slope Borough, numerous organizations, local communities, tribal entities, and members of the Alaska Marine Mammal Stranding Network, including the Alaska SeaLife Center, Alaska Sea Grant Marine Advisory Program, and Alaska Department of Fish and Game. These investigations may require months or even years of data collection and analysis.

    NOAA's Alaska regional fisheries website has more in-depth information about this disease outbreak in ringed seals and walruses. NOAA will make any new information available to the public on this website and will work with local native organizations, including the Ice Seal Committee and the Eskimo Walrus Commission, to ensure that information is distributed to affected communities. Any findings of public health significance will be immediately released."

    Contact Alex DeMarban at alex(at)

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