Ecuadorean authorities are investigating the clubbing deaths of 53 Galapagos Islands sea lions found in January with their skulls cracked, a state prosecutor said Tuesday.
The killings had to be committed by humans, said Jaime Estevez, who called it the work of "the criminal mind of some people who enjoy watching these animals suffer."
Estevez said it will be hard to determine who killed the animals, including 13 pups. There is no permanent guard at the site, La Pinta island at the northern end of the archipelago 625 miles off Ecuador's Pacific coast.
There were no injuries other than strong blows to the head, ruling out the possibility that the animals were killed for their parts.
The Galapagos Islands were declared a UNESCO World Heritage Site in 1979 for their unique plant and animal life, including giant tortoises, marine iguanas and blue-footed boobies. Charles Darwin's observations of the islands' finches inspired his theory of evolution.
Animals in the Galapagos, Ecuador's top tourist destination, are usually not afraid of people and are known to approach tourists there.
Last year, UNESCO added the archipelago to its list of World Heritage Sites in danger from environmental threats or overuse and is monitoring Ecuador's efforts to protect the area from ruin.
