Marine mammal specialists from across the U.S. have descended on an Alaska aquarium to help care for a baby beluga whale that became separated from its mother shortly after its birth.

The male calf is under 24-hour care at the Alaska SeaLife Center in Seward, being fed by a stomach tube while learning how to suckle from a bottle.

"He's currently doing very well, swimming on his own, and he has been, from the first time he got here, learning to take food from a bottle, which has been challenging," said Tara Riemer Jones, the centre's president and CEO.

It's believed to be the first baby beluga rescue in the United States, at least since federal record keeping began in 1972, she said. Other attempts at rescue resulted in calf deaths or in one case, the calf being returned to its pod.

It's such a rare event that specialists have been helping with the animal's care, including staff members from the Georgia Aquarium in Atlanta, Shedd Aquarium in Chicago and SeaWorld in San Diego.

"It's actually a pretty unprecedented event in certain ways," said Dennis Christen, the Georgia Aquarium's director of animal training who was in place 29 hours after the calf arrived in Seward.

Mom, baby separated in storm

Two workers from the Alaska SeaLife Center rescue a beluga whale calf in Bristol Bay, Alaska, on June 18. (Handout/Alaska SeaLife Center/Associated Press)

The whale was estimated to be two days old when it was found near South Naknek, in Alaska's Bristol Bay, on June 18. Officials believe a storm likely separated the calf from its mother.

Tim Lebling, the Alaska SeaLife Center's stranding co-ordinator, flew to South Naknek that afternoon to retrieve the calf.

It was flown 90 minutes back to Seward in dry transport. Lebling said the calf was placed on an air mattress in the plane, placed so its weight wouldn't put pressure on vital organs and then constantly covered with wet towels.

Lebling said it was touch-and-go for the first part of the flight, probably because of stress.

"We thought he took his last breath at one point," Lebling said, but then he breathed again.

Even though the beluga is still in critical care, caregivers are guardedly optimistic about his rehabilitation.

Survival odds for an animal this age coming into a stranding program are low, said Brett Long, the husbandry director at the centre.

"We take it a day at a time," he said. "We're very happy to see that we appear to be meeting its nutritional goals and that it's maintaining its weight, and we're seeing slow, incremental weight gain."

24-hour care

The calf is now about 1.5 metres long and weighs 52 kilograms, up 2.3 kilograms since his arrival.

The biggest worry now is the calf's immune system, which is insufficiently developed because it did not receive any of its mother's milk.

"We are working with other aquariums to provide supplements that will help aid the development of that immune system, but it's a waiting game," Long said.

Jones said there is nothing specifically wrong with the calf medically "other than he's young and at high risk."

"We're not going to say it hasn't been without some bumps in the road," Christen said. "We're very confident we're on the right path here, but it's still an animal that's in critical care, and we have to be guarded in our optimism, and we're just hopeful we're on the right path."

At the centre, the calf has its own pool with toys and constant human companionship. At least three caregivers are with him 24-hours a day, two of them in wet suits and in the pool.

He often will rub up against his human handlers, who also help him learn new swimming patterns and play with him.

He's being kept out of the public's view for now in a pool being fed warmer water and in a sanitary environment. The hope is to move him soon to a larger pool, which can be seen from behind glass inside the Alaska SeaLife Center.

Won't return to wild

It's running about $2,000 a day to care for the calf, and that's not including the cost of the visiting marine mammal specialists.

Jones said the cost will strain the private, non-profit research centre's stranding program budget for the year, and officials are talking to potential donors and possibly setting up a donation matching program for individuals. They're also planning a five-kilometre Wildlife Rescue Run on Aug. 4, encouraging virtual runners to sign up online to raise funds.

If the calf survives, he'll never see the open ocean again since there is no way now for humans to teach him survival skills.

The National Marine Fisheries Service will eventually decide where he will be placed.

"There are a number of facilities that would make a great home for this young whale, with companion animals that would likely accept him into their kind of family unit," Christen said.

Since facilities that take in animals like to be part of the naming process, the Alaska SeaLife Center hasn't given the calf a name yet.

But that hasn't stopped most everyone caring for him from calling him "Naknek."