(CNN) When local fishermen were walking through a mangrove forest in Brazil, they came across something that shouldn't be there: the carcass of a humpback whale.

The baby whale was likely lost at sea and died of starvation or some other unknown cause, according to nonprofit research group Bicho D'agua

The tides washed the whale's body to shore at Araruna Beach in the city of Soure, said Bicho D'agua oceanographer Maura Sousa. It's located on the island of Marajó, which sits at the mouth of the Amazon River.

"During this season, the tide normally rises twice a day to almost 4 meters (13 feet) and floods the mangrove forest, bringing lots of trash, including trash from ships from a lot of places in the world," Sousa said.

"This explains why an inflated carcass, due to the gases of the decomposition, was dragged into the mangrove forest," she said.

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