The young Franciscan dolphin was killed at the beach resort of Santa Teresita in Buenos Aires last week, after a throng of visitors roughly grabbed the animal and passed it around.
After throwing the animal around like a trophy, the tourists then left it to die in the sand.
In pictures captured by witness, some people can even be seen taking photos of the mammal’s lifeless body.
According to the Fundacion Vida Silvestre, the Franciscan species is vulnerable to extinction.
‘The Franciscan, like other dolphins, cannot remain above water for long,’ they wrote on their website. ‘It has a very thick and greasy skin that provides warmth, so the weather quickly causes dehydration and death.’
The Franciscan dolphin, so-called because its brown skin looks like a Franciscan monk’s habit, is found exclusively in the waters of southeastern South America.
There are only around 30,000 of the dolphins left in the world.