The federal decision pleased environmentalists.
"We can finally focus now not on whether the belugas are endangered, but what we can do to protect them," said Brendan Cummings, an attorney for the Center for Biological Diversity, one of the groups that petitioned for the listing.
Cook Inlet stretches 180 miles from the Gulf of Alaska to Anchorage. It is named for Capt. James Cook, the British explorer who sailed into the inlet in 1778 on a quest to find the Northwest Passage.
Beluga whales feed on salmon and smaller fish. They can also eat crab, shrimp, squid and clams. During summers, the whales, which reach a length of up to 15 feet, often can be spotted from the highways leading away from Anchorage, gathered at river mouths, chasing salmon that have schooled before a run to spawning grounds.
Beluga whales' natural enemies are killer whales, but something else has been keeping their numbers down in Alaska's Cook Inlet.
Craig Matkin, an independent biologist who has worked in south central Alaska for 25 years, said the delay in the listing had held up a comprehensive research plan to find out why the population had not recovered after subsistence hunting was curtailed.
The concern is not just in numbers, he said, but in distribution. Whales in recent years have been staying in northern Cook Inlet near Anchorage.
"They're just gone from these areas," he said of his own home near in Homer, near the tip of the Kenai Peninsula and about 100 miles from Anchorage. "Why they aren't coming down into this habitat is a question I'd like to answer."
Future development won't be helpful to the recovery, Cummings said, starting with the noise and pollution associated with industrialization of the inlet, which includes oil rigs off the Kenai Peninsula.
Global warming, changing ocean conditions and higher temperatures in salmon streams may be another factor, Cummings said.
The Port of Anchorage, helped by congressional earmarks secured by Sen. Ted Stevens and Rep. Don Young, has embarked on a $500 million project to double the port's size and replace its aging docks.
Environmental groups also have expressed concern about a planned coal mine 45 miles from Anchorage across Cook Inlet, where developers propose to mine 300 million metric tons of sub-bituminous coal, roughly equal to the energy of a billion barrels of oil, over 25 years. That would mean noise and boat traffic associated with building and operating a mine, a potential effect on salmon streams and more warming.
The Cook Inlet beluga whales are one of five populations in Alaska waters and the only one endangered. Other beluga populations off Alaska inhabit Bristol Bay, the eastern Bering Sea, the eastern Chukchi Sea and the Beaufort Sea.
IN PHOTO: The Shedd Aquarium's new 12-day-old beluga whale calf swims with its mother, Mauyak - one of the Shedd's seven beluga whales - in their nursery Tues. Aug. 28, 2007. The calf and mother will stay out of public view for a period of time as they are monitored by animal care staff. Tribune photo by Michael Tercha.