Efforts to free a lost whale that strayed into the heart of the Amazon River have come to an end now that it has died.
The 12-tonne Minke whale (Balaenoptera acutorostrata) had been found in the Tapajos River (a tributary of the Amazon River) near the city of Santarem in Brazil, some 1300 km upriver from the sea.
The 5.5m whale was first spotted in the river last week when local residents reported seeing a mysterious animal.
The whale had beached itself at least twice, and a group of biologists and volunteers had tried to confine it to a smaller section of the river with a net while arranging for a ship to bring it back to the ocean, but had to give up the attempt after the whale became agitated and risked injuring itself.
When the whale was examined on Sunday (18 November), it was found to be a male and still thought to be in good condition despite superficial injuries.
Antibiotics had been administered to the animal as a precaution and locals were seen splashing water on its back to protect it from the fierce heat. According to Milton Marcondes, a veterinarian with the Brazilian Humpback Whale Institute, which was involved in the rescue attempt, the whale was thought to be in the river for at least 15 days.
Initially, the prognosis for a successful return was considered good because whales have been known to survive for two months in fresh water and can go for six months without food.
The whale was finally found dead along a Tapajos River beach by local residents on Tuesday (20 November).
An autopsy had been conducted to determine the cause of death and authorities are planning to move the corpse to the ocean.
The Minke whale is the second smallest of the baleen whales after the Pygmy right whale.
According to the International Whaling Commission Scientific Committee, there are an estimated 184,000 minke whales in the central and northeast Atlantic Ocean.