The eight-foot-long animal, believed to be a Risso’s dolphin, died before it could be returned to the sea as experts had recommended, said Edgardo Visquera, the region’s wildlife protection director.
Marine biologists said the mature female had small spear wounds that apparently caused its death.
The wounds were so small that they had not initially been noticed, but the internal damage had already weakened the animal, Visquera said.