ANCHORAGE — Federal, state and local wildlife scientists don’t know what’s sickening and killing ringed seals off the coast of Alaska and Canada but they will get more resources to find out.
The National Oceanic and Atmospheric Administration announced Tuesday it had declared the deaths of ringed seals an “unusual mortality event.” The declaration will provide additional expertise for the investigation and give researchers access to funds for more in-depth diagnosis, said Dr. Teri Rowles, a NOAA’s coordinator of national marine mammal health and stranding response.
“It’s additional work on top of all the excellent work that has been ongoing,” she said during a conference call for reporters.
Walrus off Alaska’s northwest coast have demonstrated some of the same symptoms and a declaration of unusual mortality may follow by the U.S. Fish and Wildlife Service, NOAA officials said.
Ringed seals are the smallest of Alaska’s ice seals and are the main prey of polar bears. NOAA is considering listing ringed seals as a threatened species because of projected loss of snow cover and sea ice from climate warming. Sea ice and snow are crucial for ringed seal breeding.
Starting in July, seals began showing up on the Beaufort Sea coast outside Barrow with lesions on hind flippers and inside their mouths, patchy hair loss, and skin irritation around the nose and eyes. Some were dead and others were unusually lethargic, allowing people to approach on foot instead of fleeing. Necropsies found fluid in lungs, white spots on livers and abnormal growth in brains.
More than 60 dead seals and 75 diseased seals — mostly ringed seals with some bearded seals — were confirmed.
Similar outbreaks have been reported in ringed seals in Canada and in ringed seals and walrus in Russia. Scientists have not confirmed that the diseases are related between the countries or even the species.
Tests to date have not linked the disease to a known virus. The scientists are looking for immune system-related diseases, fungi, man-made and bio-toxins, radiation exposure, contaminants, and stressors related to sea ice change, according to NOAA.
Dr. Stephen Raverty, a veterinary pathologist from the Provincial Veterinary Diagnostic Lab in British Columbia, said open sores on the skin may lead to liver damage and other symptoms.
“What we think is happening is these defects in this skin are allowing secondary bacteria to invade into the tissues,” he said. “The animals may have varying degrees of debilitation or possibly immune suppression.”
A virus on the skin, he said, may be present only for a short time.
“Often times with viral infections you may only have a very transient stage where the virus is present,” he said. “It incites that lesion, and then it is gone. Depending on the stage at which that animal succumbed and was sampled, we may very well have missed it.”
Scientists will try to sample the animals through the entire course of the disease from the initial outbreak on to develop a profile of lesions, he said.
Dr. Raphaela Stimmelmay, a wildlife veterinarian and research biologist for the North Slope Borough, said there was no indication of disease symptoms found in polar bears.