Coral poaching by Chinese fishing boats in waters around the Ogasawara Islands has been rapidly increasing.
Earlier this month, nearly 50 Chinese fishing boats were spotted in the area.
They were believed to be searching for valuable red coral and other "jewelry coral," which inhabit the deep sea. Catching jewelry coral is regulated in China.
The Japan Coast Guard is stepping up crackdown on coral poaching by Chinese fishing boats, some of which have entered Japanese waters or Japan's exclusive economic zone.