In the late summer of 2011, hunters and biologists along Alaska’s northern and western coastlines began reporting highly disturbing sightings. Ice seals—specifically ringed, spotted, bearded, and ribbon seals—were stranding in abnormal numbers, showing severe physical distress.
The seals presented with a consistent, mystifying suite of clinical signs: severe hair loss (alopecia), delayed molting, ulcerative skin lesions around their eyes, nose, and flippers, and lethargy. Many were underweight with congested lungs. By December 2011, NOAA and the U.S. Department of Commerce declared an official Unusual Mortality Event (UME).
As the state’s premier marine veterinary diagnostic and rehabilitation center, the Alaska SeaLife Center (ASLC) was thrust into the frontlines of a massive, multi-agency epidemiological investigation.
+---------------------+ +--------------------+ +-------------------+
| Stranded Seals | --> | Diagnostic Triage | --> | Pathology Lab |
| (Alopecia/Lesions) | | (ASLC Seward) | | (Viral/Toxicology)|
+---------------------+ +--------------------+ +-------------------+
|
v
+------------------+
| Multi-Agency |
| Consensus & UME |
+------------------+The Triage and Diagnostic Challenge
Over the course of the UME (2011–2016), ASLC stabilized and triaged multiple affected seals, collecting hundreds of tissue, blood, and skin samples. The investigation required the collaboration of the North Slope Borough Department of Wildlife Management, NOAA, the U.S. Fish and Wildlife Service, and global pathology labs.
Veterinary pathologists at ASLC worked systematically to isolate the cause:
- Viral Pathology: Extensive screenings were conducted for known pinniped pathogens, including phocine distemper virus (PDV), influenza, caliciviruses, poxviruses, and herpesviruses. While some seals screened positive for endemic viruses, none accounted for the severe, widespread skin necrosis.
- Toxicology and Contaminants: Hypotheses regarding heavy metal poisoning or exposure to persistent organic pollutants (POPs) were investigated. Scientists scrutinized tissues for mercury, lead, and organic chemicals, but levels were largely consistent with baseline Arctic exposures.
- Harmful Algal Blooms (HABs): As warming Arctic waters trigger toxic algal blooms, biotoxins like domoic acid and saxitoxin were screened, but no direct epidemiological links were found.
- Radiation: Following the March 2011 Fukushima Daiichi nuclear accident, there was intense public concern about radioactive fallout. Tissues were tested for cesium-134 and cesium-137. The results showed radionuclide levels were within normal historical baselines and far below safety thresholds, completely ruling out radiation as a primary driver.
The Molting Connection
One of the most significant insights generated by ASLC’s study of the affected seals was the potential link to abnormal molting cycles.
Ice seals rely on stable sea ice to haul out and shed their old fur during the spring. When sea ice melts prematurely, seals are forced into the water before completing their molt. The cold water constricts peripheral blood vessels, starving the hair follicles of oxygen and nutrients, which can trigger severe alopecia, skin breakdown, and secondary opportunistic bacterial infections.
Legacy of the Investigation
The 2011–2016 Ice Seal UME officially closed in 2018. While a single “smoking gun” pathogen was never isolated, the cooperative research led by ASLC established invaluable baseline diagnostic metrics for Arctic pinniped health.
The event demonstrated the fragility of ice-dependent species and proved that marine mammals serve as critical bioindicators, reflecting the immediate, physical consequences of a warming subarctic marine ecosystem.