At least 30 endangered green sea turtles found with 'bleeding' neck wounds in Japan

Tokyo (CNN)At least 30 endangered green sea turtles were found on Thursday with wounds around their neck, near the remote Japanese island of Kumejima in southern Okinawa prefecture. Police began investigating the case last Friday after the sea turtles were found during low tide, according to a police official from the Naha Police Station in Okinawa. Some of the turtles were bleeding and barely breathing, said the official. They had wounds around their necks caused by what appeared to be a blade. He added that the whereabouts of the turtles are currently unknown, and it's possible they were swept away by the tide. 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 with seagrass, which the sea turtles eat, said Yoshi Tsukakoshi, a spokesman at the Kumejima sea turtle museum. He added that the sea turtles get entangled in the nets laid by local fishers, and that they can be considered a "nuisance" because they rip the nets. "Some fishers think the turtles eat all the seagrass before it grows and that prevents the fish from spawning in the area, " said Tsukakoshi. All sea turtle species are considered endangered and are on the International Union for Conservation of Nature (IUCN) Red List. They are protected worldwide, according to the World Wide Fund for Nature, an international non-governmental organization. But they are coming under increasing threat from factors such as coastal development, overfishing and bycatch -- when turtles are caught unintentionally during fishing for other species.