WASHINGTON (AFP) - The US government has proposed listing six types of seals as threatened under the Endangered Species Act because they face hardships due to disappearing sea ice and melting snow packs. Four types of ringed seals that live in the Arctic basin and North Atlantic, as well as two populations of bearded seals in the Pacific Ocean, are among those put forward by the National Oceanic and Atmospheric Administration (NOAA). One of the five recognized subspecies of ringed seals, the Saimaa in Finland, is already listed as endangered. Under the proposed rules published today in the Federal Register, the remaining four subspecies of ringed seals - Arctic, Okhotsk, Baltic and Ladoga - would all be listed as threatened, NOAA said in a statement. Arctic ringed seals spend most of their lives on sea ice and they tend to give birth to one pup per year. Ringed seal pups are normally born in snow caves in the spring, and are vulnerable to freezing and predation without them, NOAA said. That the species produces only a single pup each year may limit the ringed seals ability to respond to environmental challenges, such as the diminishing ice and snow cover. NOAA said the bearded seals in the Pacific are closely associated with sea ice, particularly during the reproduction and molting stages. It noted forecasts predict the ice will decrease substantially this century, especially in the Sea of Okhotsk of the western Pacific Ocean. The Pacific subpopulation of bearded seals are at risk of becoming endangered species within the foreseeable future throughout all or a significant portion of their ranges, warranting a listing as threatened, NOAAs Fisheries Service said. The US government considers species to be threatened if they are likely to become endangered in the future. The bald eagle and the Arctic polar bear are among the animals on the threatened list.