The federal government on Friday placed beluga whales that live in Cook Inlet in Alaska on the endangered species list, rejecting efforts by Gov. Sarah Palin and others against increased protection.

The relatively small, whitish whales, sometimes visible from downtown Anchorage, declined by almost 50 percent in the late 1990s, and federal scientists say they have not rebounded despite a series of protections, including a halt to subsistence hunting by Alaska Natives. About 375 whales have been counted in Cook Inlet each of the last two years, according to scientists with the National Marine Fisheries Service.

“In spite of protections already in place, Cook Inlet beluga whales are not recovering,” James W. Balsiger, the acting assistant administrator for the fisheries agency, said in a written statement. The whales are in danger of extinction, Dr. Balsiger said.

The announcement, made on a predetermined schedule under the Endangered Species Act, drew further attention to Ms. Palin’s positions on environmental issues. The governor, the Republican nominee for vice president, has come under scrutiny for her ambiguous statements about climate change and her administration’s failed effort earlier this year to prevent another species, the polar bear, from being listed as threatened. The state is suing the federal government over the polar bear listing.