The dead humpback whale was found in a forested area on the Amazon delta island of Marajó, near Soure municipality, on Friday. The body measured 11 metres long and 6 meters wide, according to media reports citing local authorities.
"The mammal is one of the largest species of whales in existence", Dirlene Silva, Soure's environmental secretary, said, as cited by Maritime Herald.
Biologists from the NGO Bicho D'água are on their way to Soure to find out the cause of the animal's death.
"They're going to do the necropsy. To the naked eye, there are no injuries. So we need to understand what culminated in the death of the whale", Dirlene Silva explained.