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Months later, Arctic ring seal deaths leave scientists flummoxed

Alex DeMarban
Photo courtesy North Slope Borough Department of Wildlife Management

Radiation does not appear to be causing the mysterious affliction that has sickened and killed scores of Arctic ringed seals.

Preliminary tests of a few tissue samples of healthy and sick seals show no evidence of radiation exposure, said the National Oceanographic and Atmospheric Administration in a press release issued Friday.

Walrus, some of which have been spotted with the unusual lesions on their skin, are also being tested.     

"At this point, scientists do not believe that radiation is a primary factor in this unusual mortality event or that radiation is causing the symptoms and deaths in pinnipeds," said the agency. Some have wondered whether radiation from the Fukushima power plant disaster in Japan last year caused the unusual affliction that has been most evident in the smaller ringed seals. Symptoms have included ulcers on organs, patchy hair loss, and open sores, especially around the rear flippers and eyes.   

"Marine animals and fish close to the accident site in Japan were impacted, but there is no evidence that supports any impacts to marine animals in Alaska," the agency said.

The agency has considered wind patterns and ocean currents in makings its determination, the release said.

Scientists have been searching for the cause since early last fall. NOAA declared the ringed seal deaths an unusual mortality event in December before ramping up a wide-ranging investigation. At the time, officials said a virus does not appear to be the cause and that some sort of bacteria was a more-likely culprit. But experts were still considering whether fungi, pollution or other factors had caused the illness.

Testing for radiation will continue, too.

Scientists with the University of Alaska Fairbanks and the Alaska Department of Environmental Conservation are leading the radiation assessment.

"Muscle tissues from sick and healthy pinnipeds will be measured for the presence of Cesium-134 and Cesium-137," the agency said.

"The results for each sample will go through quality assurance first and be provided to the UME working group followed by timely reporting to the public. 

If radiation levels are found that exceed human consumption guidelines, the news will be shared with state public health officials and residents immediately, the NOAA release said.

Contact Alex DeMarban at alex(at)alaskadispatch.com