The main prey of polar bears has been declared a threatened species because of diminishing sea ice due to climate warming, with Gov. Sean Parnell's office announcing that it was considering a challenge to the federal decision.

The National Marine Fisheries Service on Friday declared ringed seals as a threatened species under the Endangered Species Act, joining polar bears on the list.

The agency also placed a second ice-dependent seal, bearded seals, on the list.

Ringed seals are the only seals that thrive under completely ice-covered Arctic waters. They use stout claws to dig and maintain breathing holes.

Females give birth in snow lairs to pups that are susceptible to freezing until they grow a blubber layer.

Bearded seals give birth and rear pups on drifting pack ice. Sea ice this year reached record low levels.

Gov. Sean Parnell said Friday afternoon that his office might appeal the NMFS decision, citing potential harm to the state's interests.

“The ESA was not enacted to protect healthy animal populations,” Parnell said. “Despite this fact, the NMFS continues the federal government’s misguided policy to list healthy species based mostly on speculated impacts from future climate change, adding additional regulatory burdens and costs upon the State of Alaska and its communities, and wresting away Alaska’s sovereign interest in managing its own wildlife and resources.”

Groups aligned with the oil industry blasted the decision in statements issued Friday, with the Alaska Oil and Gas Association saying it wasn’t based on the species’ present conditions.

“NMFS’ decision is, in our opinion, not consistent with the text and policy of the ESA or the best available science,” said Kara Moriarty, AOGA’s executive director. “The decision to list ringed and bearded seals is based on how climate change might affect these species 100 years from now, despite their populations currently being healthy and abundant. That’s bad precedent for making evidence-based decisions that have real impacts for Alaska.”