<img class="styles__noscript__2rw2y" src="https://s.w-x.co/util/image/w/beardedseal.jpg?v=at&w=485&h=273" srcset="https://s.w-x.co/util/image/w/beardedseal.jpg?v=at&w=485&h=273 400w, https://s.w-x.co/util/image/w/beardedseal.jpg?v=ap&w=980&h=551 800w" > A bearded seal is pictured here. The species is among those being found dead on Alaska shorelines. (NOAA Fisheries)

At a Glance At least 60 dead seals have been reported on the coast of the Bering and Chukchi seas.

Scientists do not know what is killing the seals.

The seas have lost ice cover earlier than normal.

Dozens of seals have been found dead recently on the coast of Alaska, and scientists don't yet know the reason.

At least 60 dead seals have been reported on the coast of the Bering and Chukchi seas, NOAA Fisheries said in a news release.

The first reports of dead ice seals came in early May when the carcasses of eight young bearded seals were found on St. Lawrence Island in the northern Bering Sea.

Multiple reports of dead bearded, ringed and spotted seals were made Monday. Many of them were in southwest Norton Sound, including 18 north of Kotlik, Alaska, and dozens on Stuart Island, north of Stebbins.

About 225 miles to the north, a National Park Service biologist reported six dead seals near Kotzebue, Alaska. Another 75 miles up the coast of the Chukchi Sea, as many as 30 dead seals were reported between Kivalina and Point Hope.

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Some of the seals showed signs of hair loss, a symptom that was seen during a rash of seal and walrus deaths from 2011 to 2016, NOAA Fisheries said. The agency estimated that 657 seals were affected over those six years, the Associated Press reported. Biologists confirmed 233 dead and stranded ringed, bearded, spotted and ribbon seals.

Bearded and ringed seals are listed as threatened or endangered under the Endangered Species Act. They and spotted seals all are protected under the Marine Mammal Protection Act.

Ice seals are a food source for Alaska Native communities, and there are some fears of contamination, the news release said.

Satellite images from the National Oceanic and Atmospheric Administration showed the Bering Sea largely ice-free on March 31 , weeks ahead of when the summer melt usually begins.

Sea-surface temperatures along the coasts of the Bering and southern Chukchi seas were as warm as 8.1 degrees Fahrenheit above normal last month and remained well above normal as of this week, Reuters reported, citing NOAA data.

The loss of sea ice could be a factor in the seal deaths. Seals use sea ice to rest and give birth. In spring, algae underneath the ice blooms dies and sinks, sending food to clams, snails and sea worms that become prey for gray whales, walruses and bearded seals, the AP reported.

The seal deaths coincide with an unusual increase in the number of dead gray whales found on West Coast beaches, the AP also said.

So far this year, about 70 gray whales have been found dead on the coasts of California, Oregon, Washington and Alaska.