Beluga whale stuck in France's Seine to be loaded on to a truck

The animal has strayed from the sea for more than a week

A bold rescue attempt is under way to save a beluga whale stranded in the River Seine in northern France.

Final details are being worked out to return it to the sea by a group of marine experts amid fears for its health.

The 4-metre cetacean was spotted a week ago swimming towards Paris and has since travelled 130 kilometres inland.

The protected mammals, usually found in cold Arctic waters, are known to be very sociable, living, hunting and migrating together in pods. While they migrate south in the autumn to feed, they rarely venture as far as the location reached by the lost beluga.

Government officials in the Eure department in Normandy, north-west France, said an operation planned for Tuesday evening would see marine experts attempt to transport the whale back to the ocean. The mission would be risky given that the beluga is already sick and malnourished.

“An operation to transport the beluga astray in the Seine will be attempted this evening,” said government officials in the Eure department who are orchestrating the effort.

The whale’s progress inland has been blocked by a lock at Saint-Pierre-La-Garenne in Normandy, and its health has deteriorated.

The straying beluga whale is stranded in a lock of the River Seine. Photo: Sea Shepherd

At the weekend conservationists gave the whale a “vitamin cocktail” but it has so far refused food, fuelling fears it could be starving to death.

But despite turning down offers of herring and trout, its condition is currently “satisfactory”, Isabelle Brasseur of the Marineland sea animal park in southern France, the biggest of its kind in Europe, told AFP.

She is part of a Marineland team sent to assist with the rescue, along with the Sea Shepherd France NGO.

“What's exceptional is that here the banks of the Seine are not accessible for vehicles … everything is going to have to be done by hand,” Ms Brasseur said.

Since being spotted in the Seine last week, the beluga has not changed course, and experts have dismissed any attempt to “nudge” it back towards the English Channel with boats, saying it would stress the weakened mammal and probably be futile in any case.

The rescue mission will involve a team of experts attempting to move the 800kg whale on to a truck and drive it to an undisclosed seawater basin where it can be treated before being released into the sea, the Eure authorities said.

The Sea Shepherd France NGO assisting the operation said that tranquilisation is not an option, since belugas are so-called “voluntary breathers” that need to be awake to inhale air.

Veterinarians will keep constant surveillance during the move.

“In any case, we have to get it out of there … and try to figure out what is wrong,” Ms Brasseur said.

“There may be internal problems that we can't see,” she said, although belugas are “extremely hardy” as a species.

Interest in the beluga's fate has spread far beyond France, generating a large influx of financial donations and other aid from conservation groups, as well as individuals, officials said.

Sea Shepherd on Monday issued an appeal in particular for heavy-duty ropes, nets, mattresses and other equipment.

According to France's Pelagis Observatory, which specialises in sea mammals, the nearest beluga population is off the Svalbard archipelago, north of Norway, 3,000km from the Seine.