The depleted population of beluga whales that swim off the coast of Alaska's largest city was listed as endangered on Friday by the US federal government.

Beluga whales are shown in the Chukchi Sea near Alaska in this July 1, 2008 publicity photo from the US National Oceanic and Atmospheric Administration National Marine Mammal Laboratory and released to Reuters October 17, 2008. The NOAA said it has determined that belugas in Cook Inlet, the channel that flows from the Anchorage area to the Gulf of Alaska, are at risk of extinction and deserving of strict protections under the Endangered Species Act. [Agencies]

Alaska Gov. Sarah Palin, the Republican vice-presidential candidate, called the listing "premature" after she had pressed for more time to make beluga population counts.

Environmentalists hailed the listing decision, but criticized the time it took to materialize.

"Hopefully the State of Alaska will now work toward protecting the beluga rather than, as with the polar bear, denying the science and suing to overturn the listing," Brendan Cummings, oceans program director for the Center for Biological Diversity said in a statement.

The National Oceanic and Atmospheric Administration said it has determined that belugas in Cook Inlet, the channel that flows from Anchorage to the Gulf of Alaska, are at risk of extinction and deserving of strict protections under the Endangered Species Act.

The population, which fell to a low of 278 in 2005 from 653 in 1994, has yet to rebound from a period of over-harvesting by the region's Native hunters, officials said.

Hunting of Cook Inlet belugas largely ceased in 1999, but the population continues to struggle, officials said.

"In spite of protections already in place, Cook Inlet beluga whales are not recovering," James Balsinger, acting assistant administrator for NOAA's Fisheries Service, said in a statement.