Two skippers of Chinese boats have been arrested on suspicion of poaching coral in Japanese waters off Kagoshima Prefecture, the Japan Coast Guard said.

The arrests of the two Chinese come on the heels of a recent surge in the number of Chinese coral fishing boats near the Ogasawara island chain south of Tokyo.

The Coast Guard said the Chinese boats may have tried to avoid tight security patrols near the islet chain and ended up operating off Kagoshima.

According to to the 10th Regional Coast Guard Headquarters, the two boats illegally operated in Japan’s territorial waters about 33 km west-southwest of Cape Noma in the city of Minamisatsuma, Kagoshima Prefecture, at around 9:30 a.m. Monday.

Local Japanese fishermen initially spotted the Chinese poachers and alerted the Coast Guard, it said, adding that the two Chinese were caught red-handed some time later.

Each boat had seven crew members other than the skipper, the Coast Guard said.

An official of a local fisheries cooperative said he has never heard of coral fishing in the area. “We are surprised. No one collects coral here.”