The fuel oil slick, covering an area about 2.7 kilometers long and 1 km wide, was found on Jan. 8, when the Japan Coast Guard was preparing to tow away the Sanwa Maru off Cape Esan in the Tsugaru Strait.
The 11 crew members were not injured.
According to the Hakodate Coast Guard, the 1st Regional Coast Guard Headquarters received a report from another tanker at 6:20 p.m. on Jan. 6 that “the Sanwa Maru is heading toward land and is in danger of running aground.”
The Sanwa Maru struck a rocky beach about 20 meters from shore with its bow facing land.
It was heading from Tomakomai Port in Hokkaido to Funagawa Port in Oga, Akita Prefecture.
The sea was not rough at the time, according to the Hakodate Coast Guard.
The Sanwa Maru is owned by Wako Kisen, a limited private company in Imabari, Ehime Prefecture. It was loaded with about 59 kiloliters of fuel oil A and 140 kiloliters of fuel oil C.
Damage near the ship’s fuel tank at the stern was seen, the Hakodate Coast Guard said.
Its cargo of 700 kiloliters of diesel oil and 3,100 kiloliters of kerosene appears to have remained onboard, officials said.
On Jan. 7, a salvage operation started, but the Sanwa Maru could not be moved from the reef.
At around 5:45 a.m. on Jan. 8, the Sanwa Maru reported that fuel oil had spilled. The vessel put up an oil fence on the port side to contain the spread.
The vessel was tilting about 5 degrees toward the starboard side. Seven of the crew members who were not involved in the salvage operation were rescued by a boat dispatched by the patrol vessel Okushiri.
Around noon on Jan. 8, oil could be smelled on the beach near the ship. Oil slicks were found on rocks and vanishing wave blocks.
The Coast Guard is investigating the cause of the stranding.
The shipowner and salvage company will decide on future plans after analyzing the fuel oil spill.
