The Kyuko maru was detained in Russian territorial waters Monday for alleged border, environmental and customs violations. It was registered in the Sakhalin port of Kholmsk and owned by a local company, but went down after a fire apparently broke out on board as it was being towed toward southern Sakhalin for further investigation.
"Judging by the size of the slick eight miles from the shore, at least 900 kilograms of fuel spilt into the sea from the ship that sank last night," a source said, adding that measures to localize the spot were under way and the trawler's eight-man crew had been evacuated unhurt.
Sakhalin has been at the center of controversy in recent months, as environmentalists have expressed serious concerns over the impact of massive energy projects on the island and Russian border guards have sought to put an end to wide-scale poaching in the area.
In one highly publicized incident in August, the captain of a Japanese boat was arrested near the Kuril Islands, part of the Sakhalin Region, on suspicion of illegally fishing for valuable crab in Russian territorial waters. One of his crewmates was fatally shot by Russian border guards, who said they had fired warning shots only after the vessel had refused to stop.