ANCHORAGE, Alaska - Over 3,000 square miles (7,770 sq kms) in Alaska would be protected as critical habitat for the endangered Cook Inlet beluga whale, under a proposal issued on Tuesday by the U.S. National Oceanic and Atmospheric Administration.

The area would encompass more than a third of Cook Inlet, mostly the northern portion off Anchorage, including shallow areas where the whales spend summer days feasting on salmon and smelt and nursing their infants.

It also overlays areas heavily used for commerce, including oil and gas production, commercial shipping, fishing and municipal wastewater discharge.

Alaska Governor Sean Parnell said he would fight the designation.

"Listing more than 3,000 square miles of Cook Inlet as critical habitat would do little to help grow the beluga population, but it would devastate economic opportunities in the region," Parnell, a Republican, said in a statement.

A final ruling establishing critical habitat is expected in the spring after a public review period, NOAA said.

Under the designation, which is mandated by the Endangered Species Act, federal agencies may not allow activities that harm habitat considered critical to the listed species.

Cook Inlet belugas, known for their unique genetic make-up and behavior and their proximity to Alaska's urban core, have dwindled to a population of about 300 from as much 1,300 in the early 1980s.

A period of overharvesting by Native subsistence hunters in the early 1990s triggered a population tailspin, according to federal scientists, while pollution and other environmental factors have prevented a rebound.