Windy conditions in Doubtful Sound have helped disperse an oil slick from the sunken tourist vessel the Waverley.
Environment Southland and Department of Conservation (DOC) staff scoured the coastline today, on a DOC vessel and inflatable dinghies, while a second team flew over Doubtful Sound by helicopter yesterday afternoon.
Weather conditions in the area turned rough overnight, forcing the postponement of the first planned aerial inspection.
However, the same winds that kept the helicopter away appeared to have helped disperse the diesel, said DOC regional on-scene oil spill commander, Kevin O'Sullivan.
The Waverley sank with 700 litres of diesel on board early yesterday morning in Doubtful Sound, Fiordland, after earlier striking a rock. The two crew and eight passengers were rescued by another vessel.
Mr O'Sullivan said the specialist shoreline assessment team reported there was no sign of environmental damage from diesel or fuel oil.
DOC staff did not see any distressed seabirds.
However, there was a small amount of diesel still bubbling from the sunken boat.
"It looks as though a combination of weather and time has dissipated the oil slick, which is what we had predicted with our computer modelling, but we will continue to monitor the small quantities of diesel which are still leaking from the ship," said Mr O'Sullivan.
There was a "considerable reduction in the size of the slick" from Friday's inspection, he said.
"Our staff estimate that there is less than 5 percent of the original slick left, and this is likely to be caused by tiny quantities of oil still bubbling up from the wreck." The oil slick is estimated to be about 6km from the nearest marine reserve and around 11km from the nearest known breeding area of the Fiordland Crested Penguin.
Environment Southland has stood down its oil spill response team until Monday.
However, Mr O'Sullivan said he would continue to receive reports from tourist operators in the area, including a float plane which overflew Doubtful Sound frequently.
If any reports suggested an increase in the volume of diesel being released from the Waverley, DOC would respond immediately, he said.
