The Obama administration is setting aside 187,000 square miles off Alaska as a "critical habitat" for polar bears, which could add restrictions to future offshore drilling for oil and gas.
The total, which includes areas of sea ice off the Alaska coast, is about 13,000 square miles less than was included in a preliminary plan released last year.
Tom Strickland, assistant Interior secretary for fish, wildlife and parks, said the designation would help polar bears stave off extinction, recognizing that the greatest threat is the melting of Arctic sea ice caused by climate change.
"This critical habitat designation enables us to work with federal partners to ensure their actions within its boundaries do not harm polar bear populations," Strickland said. "We will continue to work toward comprehensive strategies for the long-term survival of this iconic species."
Designation of critical habitat does not in itself block economic activity or other development but requires federal officials to consider whether a proposed action would affect adversely the polar bear's habitat and interfere with its recovery.
Nearly 95 percent of the designated habitat is sea ice in the Beaufort and Chukchi seas off Alaska's northern coast. Polar bears spend most of their lives on frozen ocean and use it to hunt seals, breed and travel.
Alaska Gov. Sean Parnell and the state's oil and gas industry had complained that the preliminary plan released last year was too large and dramatically underestimated the potential economic impact. The designation could result in hundreds of millions of dollars in lost economic activity and tax revenue, they said.
The U.S. Fish and Wildlife Service said reductions included in the final rule were mostly due to corrections that more accurately reflect the U.S. border in the Arctic Ocean. Five U.S. Air Force radar sites were exempted from the final rule, as were Native Alaskan communities in Barrow and Kaktovik, Alaska.
The Interior Department has declared polar bears "threatened," or likely to become endangered, citing a dramatic loss of sea ice. Officials face a Dec. 23 deadline to explain why the bears were listed as threatened instead of the more protective "endangered."
Kassie Siegel, a lawyer for the Center for Biological Diversity, an environmental group that has filed a lawsuit to increase protections for the polar bear, praised the designation of critical habitat.
"Now we need the Obama administration to actually make it mean something so we can write the bear's recovery plan, not its obituary," she said.
Siegel called for the administration to impose a moratorium on oil and gas drilling in bear habitat areas. "An oil spill there would be a catastrophe," she said. "That seems like an understatement."