A boat contracted by fish farming company Tassal has sunk at Triabunna on Tasmania's east coast overnight, with about 850 litres of diesel fuel onboard.
Nick Daft, a co-owner of the vessel, ruled out sabotage, saying "adverse weather conditions" were to blame for the Dawn Treader sinking at its mooring off Triabunna.
"It's just one of those things that happens, unfortunately," he said.
"Just adverse weather conditions — that's all we can put it down to."
The Dawn Treader was contracted to clean the fish nets making up Tassal's contentious new farm at nearby Okehampton Bay.
It was salvaged and docked at Seafish wharf.
Mr Daft said little fuel had escaped the vessel.
"There was very minimal fuel spilt and we had booms and bits and pieces in place from very early this morning," he said.
A spokeswoman for the Environment Protection Authority (EPA) said the vessel had been inspected by divers, and no fuel was lost during the salvage operation.
A spokesman for Tassal said the craft was not owned or operated by Tassal, and did not use Tassal employees.
Boat owner fears total loss
Mr Draft said the Dawn Treader was 20 years old and had recently passed survey.
He said he had been working with Tassal for about a year without any problems.
The five-metre-high boat was completely submerged.
Marine and Safety Tasmania (MAST) issued a warning to mariners about the sunken vessel, saying the 11-metre vessel had sunk on a mooring 400m south of Deepwater Jetty, in about eight metres of water.
Salvage attempts began about 6:00am on Friday.
The owner fears the boat — worth hundreds of thousands of dollars — may be a write-off.
