Authorities say an injured beluga whale that strayed into the Seine River died on Wednesday during an attempt to return it to the sea off northern France.
Overnight, rescue divers guided the whale into a net before a crane plucked it from the river in a six-hour operation. It was then transferred to the Channel port of Ouistreham in a refrigerated vehicle.
The already frail beluga experienced respiratory failure on the journey and was euthanized by veterinarians immediately after arriving in Ouistreham.
“Despite an unprecedented rescue operation, it is with sadness that we announce the cetacean’s death,” local Calvados officials said.
The aim had been to take the starving whale to a saltwater basin where it could gain strength before being released back into the sea.
However, it was a dangerous venture.
The four-metre male weighed 800 kilograms (1763 pounds), much below the usual weight of an adult beluga of 1,200 kg, and had not fed since being discovered in the Seine last week.
It was unwell, according to rescuers, before it walked up the river to within 70 kilometers (43 miles) of Paris.
During the vehicle trip to the coast, the whale’s condition deteriorated. When it arrived in Ouistreham, it was still alive but weak and straining to breathe.
The whale would have died if it had been left in the Seine, according to the marine conservation organisation Sea Shepherd France, which was part in the rescue mission. Beluga cannot thrive in warm, freshwater rivers for long periods of time.
“(The operation) was risky, but essential to give a chance to an otherwise doomed animal,” the group added.
A very ill orca swam dozens of kilometers up the Seine in late May and died of natural causes after attempts to lead it back to sea failed.
A beluga was observed in the River Thames east of London in September 2018, the farthest southerly sighting of a beluga on British shores at the time.
Beluga whales often inhabit Arctic or sub-Arctic waters in pods.