The patrol vessel Hakuo Maru is being dubbed the “phantom” or “death” ship by Chinese and South Korean fishermen for its tendency to suddenly appear when they are violating Japan’s territorial waters.

The Fisheries Agency vessel patrols from the coast of Kyushu to Japan’s border in the East China Sea. But the locations of the Japanese, Chinese and South Korean fishing zones are complicated, and trouble between fishing vessels and with illegal fishermen frequently occurs.

In particular, Chinese fishing boats have reportedly been crossing into Japanese waters recently because of a sharp drop in catches.

Early in February, the Hakuo Maru found 16 Chinese trawlers fishing in the dark in Japan’s exclusive economic zone. They used binoculars to check the ships for the grant numbers issued by the government.

Authorized ship are allowed in the EEZ, but even they often use nets with illegally small mesh sizes, disguise their catches or other illegal methods to fish, said Hakuo Maru Capt. Takaaki Hashimoto.

The Hakuo Maru boards suspicious vessels for on-the-spot investigations and seize them if aggravated fishing violations are confirmed.

On another day in early February, the Hakuo Maru spotted a South Korean fishing boat in the area between Japan’s Goto Islands and South Korea’s Jeju Island amid heavy rain and rough seas.

Since the boat was close to Japan’s territorial waters, a member of the Hakuo Maru warned the boat in Korean against coming any closer to the border, saying its net would be cut if it drifted over the Japanese side. The Korean ship slowly sailed away.

Although the Hakuo Maru is deliberately bumped by foreign fishing boats in some cases, it carries no weapons. It has a water cannon but has not used it for more than two years.

To avoid crisis situations, crew members carefully analyze suspicious fishing vessels and boards them when the fishermen are off guard, such as when they are pulling in their nets.

“We serve as a deterrent to protect marine resources,” Hashimoto said, noting that foreign fishing boats avoid illegal operations because they fear the Hakuo Maru will make another sudden appearance.

“Good wave,” a member said jokingly as the Hakuo Maru rocked like a leaf in the rough seas during a night patrol.