A young male beluga whale that couldn't seem to find its way back to the ocean has been given a lift from rescuers.

Found in the Nepisiguit River in New Brunswick, Canada, animal rescuers think the marine mammal likely swam upstream in search of dinner or was trapped by a higher-than-normal tide. Video filmed on June 2 shows the whale swimming in the clear freshwater, but locals claim to have spotted it as early as late May.

"It's very likely the whale would not have survived, either because it was not in the proper environment or because of human activities," said Tim Binder, the executive vice president of animals at the Shedd Aquarium, who was involved with the whale's transfer.

At the time of its rescue, the beluga's distinct bright, white skin had been tinged a shade of brown from the water.

Vancouver Aquarium veterinarian Martin Haulena noted that the young beluga was in an unhealthy condition and acting weak.

"He had overwhelmed his salt balance mechanisms," said Haulena. He added that the beluga had likely been drinking the freshwater from the river, which, for beluga whales, "can be life threatening."

Vets from multiple teams had been monitoring the beluga via drone footage in the weeks leading up to the rescue and had hoped it would return to the gulf on its own.

When it became apparent the beluga wouldn't budge, animal rescuers began to formulate a plan to move the bus-sized whale out of the Nepisiguit.

The Shedd and Vancouver Aquariums conducted the rescue operation with Fisheries and Oceans Canada, nonprofit wildlife rescue organizations, and local fire and police departments.

"It takes a lot of time to carefully plan out this response because it is quite complicated. The animal’s welfare and human safety are always first in our minds and so we need to make sure we have everything carefully laid out before proceeding," the Marine Animal Response Society wrote on their Facebook page on June 12.

Early Thursday morning, the whale was lured into nets by rescuers. Brett Ruskin, a reporter for the Canadian Broadcast Company, tweeted that the rescue team used a hoop net, a stretcher, and an inflatable mattress to lure the beluga onto a raft. From there, a truck then took it to the airport, where a 12 passenger plane flew it back to sea, placed it on a second raft, and released it back to its pod.

Air travel was used to reduce the amount of time the beluga spent in transit. Binder estimated that the rescue mission took just under six hours from start to finish.

According to Binder, once the beluga was returned to the water in St. Lawrence, it immediately took to swimming with other animals, and they have hopes it will join an existing beluga pod. A satellite tag was also placed on the whale to monitor its movements.

Belugas tend to be found in the Gulf of St. Lawrence during winter months. In the spring, this population migrates to the Estuary of St. Lawrence where they spend their summers.

The International Union for the Conservation of Nature classifies beluga whales worldwide as "near threatened," however the population in St. Lawrence is classified as endangered in Canada. This population was once hunted to dangerously low levels in the early 20th century and have made relatively little progress in their recovery.

In Canada, it remains illegal to kill, harm, or harass belugas.

"Nobody knows for sure why this population isn't rebounding," said Binder. "It's demonstrating a rate of decline."

Haulena agreed that the reason for the struggling beluga population in St. Lawrence has remained unclear to wildlife researchers.

"Water contaminants, high rates of cancer, and disease have been found. Last year nine calves were stranded, and we're not sure why," said Haulena. "It's one of those areas we haven't quite figured out."

A 2013 report from Fisheries and Oceans Canada found that a combination of water contaminants, high levels of noise, decline in availability of prey, and global warming all negatively impacted the St. Lawrence beluga population.

Véronique Lesage, a cetacean research scientist from Fisheries and Oceans Canada, commented that steps were being taken reduce some of these impacts, but determining which of the four most negatively inhibited population growth was difficult to pinpoint.

According to Lesage, St. Lawrence's low population also makes these belugas susceptible to inbreeding and a lack of genetic diversity. Transporting and releasing new individuals in St. Lawrence is one option conservationists have theorized could help bolster population numbers but are yet to seriously consider.

Rescuing the beluga trapped in the Nepisiguit River modeled some of logistical considerations that would go into such an undertaking.

"That was never envisioned before," said Lesage of moving new belugas to the region. "Going through the logistics of rescuing an animal shows the steps you would have go through. It was an exercise to see how feasible it could be."

Correction: This article has been updated to reflect beluga migration routes and population status.