The National Oceanographic and Atmospheric Administration, in a final decision in compliance with a court-ordered deadline, has listed two species of bearded seals and three subspecies of ringed seals as endangered.
Ringed and bearded seals both depend on sea ice and snow to survive.
"Our scientists undertook an extensive review of the best scientific and commercial data," Jon Kurland, protected resources director for NOAA Fisheries' Alaska region, said. "They concluded that a significant decrease in sea ice is probable later this century and that these changes will likely cause these seal populations to decline."
The species newly listed as endangered that occupy U.S. waters -- Arctic ringed seals and Beringia bearded seals -- are already protected under the Marine Mammal Protection Act, a NOAA release said.
The new listings were proposed by NOAA Fisheries in December 2010 and provided opportunities for public input through public comment periods and during public hearings held in Anchorage, Barrow, and Nome, the release said.