NOAA Fisheries News Releases
April 5, 2012
Julie Speegle, 907-586-7032 w., 907-321-7032 c.
Diseased seal found near Yakutat determined to be ribbon, not ringed seal
The ribbon seal skull is on the left and the ringed seal skull on the right. The ribbon seal has a shorter snout and larger, rounder eye orbits. The bridge of the nose is much broader in ribbon seals, and the cranium is very broad.. Photo: Alaska Department of Fish and Game
Juneau, AK — Marine mammal scientists say the diseased seal found near Yakutat last month has turned out to be a ribbon seal, not a ringed seal as originally thought.
Morphology—the study of form and structure—and genetics independently confirmed that the seal was a ribbon seal.
Genetic testing conducted at NOAA's Southwest Fisheries Science Center determined the gene sequence was a 93-percent match to a ribbon seal. An examination of the skull by Alaska Department of Fish and Game scientist Lori Quakenbush found the skull had a shorter snout, rounder eye orbits, a broad cranium, and broader nose bridge consistent with a ribbon seal's skull.
The yearling seal was discovered hauled out near Yakutat last month. It was reported to be fairly bald, sickly-looking, and lethargic. NOAA Fisheries scientists advised that the animal be captured and sent to Anchorage for examination by a pathologist and wildlife veterinarians.
When the seal pup arrived in Anchorage, it was found to be so ill it had to be euthanized.
Findings indicated that the seal had similar symptoms to those in the declared 2011 Northern Pinniped Unusual Mortality Event (UME), which has been affecting ice seals and Pacific walruses in the Arctic and Bering Strait regions of Alaska since last summer. The primary symptoms are hair loss, skin sores, and lethargic behavior.
Given the fact that sightings of ringed seals in the Gulf of Alaska are extremely rare and that most of the distinctly-patterned fur was missing from the seal found near Yakutat, a sample of its DNA was sent for analysis to determine species identity.
Since last July, nearly 150 seals have been reported in Alaska. Most of the seals were ringed seals. Scientists with the U.S. Fish and Wildlife Service have also discovered similar symptoms in Pacific walruses at the Point Lay haul-out.
Although scientists still don't know what is causing of the disease, they have ruled out numerous bacteria and viruses known to affect marine mammals. Advanced testing techniques (i.e. deep sequencing 4-5-4) for unidentified infectious agents is continuing as well as further testing for potential other causes including man-made and biotoxins, radiation, contaminants, auto-immune diseases, nutritional, hormonal and environmental factors. Recently, tests for domoic acid and PSP/saxitoxin were negative or of such low readings as to be clinically insignificant.
If you find a marine mammal which appears diseased or distressed, please call NOAA Fisheries Marine Mammal Stranding Hotline at 1-877-925-7773.
Information on the UME assessment progress and findings can be found at:
- Ice seals: http://alaskafisheries.noaa.gov/protectedresources/seals/ice/diseased/default.htm
- Walruses: http://alaska.fws.gov/fisheries/mmm/walrus/disease_investigation.htm
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