Police began investigating the case last Friday after sea turtles were found at low tide, according to a police officer from the Naha Police Station in Okinawa.
Some of the turtles were bleeding and barely breathing, the official said. They had wounds on their necks caused by something like a blade.
He added that the turtles’ whereabouts are currently unknown and may have been swept away by the current.
Police are continuing to investigate and are questioning witnesses, the official said.
The area where the sea turtles were found is their natural habitat and is covered in sea grass that the sea turtles eat, said Yoshi Tsukakoshi, spokesman for the Kumejima Sea Turtle Museum.
He added that sea turtles get tangled in nets set up by local fishermen and that they can be considered a “nuisance” as they tear the nets.
“Some fishermen think the turtles eat all the algae before it grows and that prevents fish from spawning in the area,” Tsukakoshi said.
All species of sea turtles are considered endangered and are listed on the Red List of the International Union for Conservation of Nature (IUCN). According to the international non-governmental organization World Wildlife Fund, they are protected throughout the world.
But they are under increasing threat due to factors such as coastal development, overfishing and by-catch when turtles are unintentionally caught while fishing for other species.