Wildlife experts are studying whether fur loss and open sores detected in nine polar bears in recent weeks is widespread and related to similar incidents among seals and walruses.
This polar bear was sedated to study its fur loss and oozing sores on the left side of its neck.
The bears were among 33 spotted near Barrow, Alaska, during routine survey work along the Arctic coastline. Tests showed they had "alopecia, or loss of fur, and other skin lesions," the U.S. Geological Survey said in a statement. "The animals were otherwise healthy in appearance and behavior."
Blood and tissue samples were collected from the sedated polar bears to see if the symptoms are related to those seen in ringed seals and walruses.
Patchy hair loss has been seen before in polar bears, but the high prevalence in those spotted recently and the earlier seal and walrus incidents raise a concern, Reuters quoted Tony DeGange, the chief biologist for the USGS in Alaska, as saying.
"There's a lot we don't know yet," he said, "whether we're dealing with something that's different or something that's the same."
"Observations last summer of unusual numbers of ringed seals hauled out on beaches along the Arctic coast of Alaska, and later on, of dead and dying seals with hair loss and skin sores, led to declaration of an Unusual Mortality Event by the National Oceanic and Atmospheric Administration on December 20, 2011," the USGS stated.
"Based on observations of Pacific walruses with similar skin lesions at a coastal haulout in the same region during fall, the U.S. Fish and Wildlife Service joined the UME investigation," it added.
Since then, it noted, "ice seals with similar symptoms have also been reported in adjacent regions of Canada and Russia and from the Bering Strait region."
While no dead polar bears have been found, 60 seals and several walruses were found dead. Many of the diseased seals and walruses were juveniles and had trouble breathing.
"Despite extensive testing for a wide variety of well known infectious agents, the cause(s) of the observed condition in walruses and ice seals remains unknown," the USGS stated. "Advanced testing techniques for unidentified infectious agents is continuing as well as further testing for potential causes including man-made and natural biotoxins, radiation, contaminants, auto-immune diseases, nutritional, hormonal and environmental factors."
Reuters noted that preliminary studies do not support a theory that the disease is due to contamination from the tsunami-wrecked Fukushima nuclear plant in Japan.
A nearly bald ribbon seal pup found a month ago near Yakutat was so sick it had to be euthanized.
Polar bears, ice seals and walruses have all seen a decline in the seasonal Arctic sea ice on which they depend.
Polar bears are listed as threatened under the Endangered Species Act. The Pacific walrus andringed, bearded and ribbon seals are being considered for ESA listing.
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