Salvage teams have begun pumping oil from the last of the fuel tanks on a cargo ship grounded on a New Zealand reef after a five-week battle to contain the pollution caused by the stricken vessel. The country\'s shipping authority said Thursday that about 54 tons of heavy fuel oil had been pumped from the number 5 starboard fuel tank of the Liberian-flagged Rena, which ran on to the Astrolabe Reef about 12 nautical miles off the east of the North Island on Oct. 5. Another 300 tons of oil was still to be pumped out of the final and \"most challenging\" tank, said an official with Maritime New Zealand (MNZ). \"Getting to this point has been incredibly challenging for the salvors. They have worked tirelessly to start removing oil despite setbacks along the way, and this is a significant milestone for the entire operation,\" said MNZ salvage unit manager Arthur Jobard. \"Every ton of oil they take off the ship is another ton that will not go into the water,\" Jobard said in a statement. The team was working to speed up the pumping rate from the tank, in an effort to get the oil off as quickly as possible. The pumping rate was about 3 tons an hour, but salvors were working to increase this by adding other pumps and pumping equipment. Pumping was also underway to remove the last of the lubricating oil from the Rena\'s engine room. Once all the oil was pumped off the ship, then container removal from the Rena would begin, weather permitting, he said. MNZ national on-scene commander Rob Service said New Zealand Defense Force personnel, volunteers and contractors were involved in oil clean-up operations on shorelines around the Bay of Plenty. Teams were trying out surf washing methods, in which a light digger excavated sand and deposited it at the water\'s edge, where natural tidal movement separated out clumps of oil, which were then collected. Service said in the statement that the trials had gone well. Two of the Rena\'s senior officers have been charged in connection with the accident. Oil from the Rena has killed an estimated 1,300 seabirds and more than 400 birds are being cared for at the oiled wildlife response center, including 60 New Zealand dotterel that were captured pre-emptively to protect the endangered species.