MARINE authorities are investigating what caused a 50ft fishing trawler to run aground on Lady Musgrave Island on Friday.
Two men and a dog were forced to spend the night on board the stricken ship after an initial attempt to free themselves failed when their anchor line and boom broke.
They were retrieved by crew from a passing boat on Saturday.
The vessel remains grounded in the intertidal zone on the south side of the island, between the low and high water marks.
About eight tonnes of fuel is believed to be on board, though the ship's hull remains intact.
Maritime Safety Queensland is now working with the Great Barrier Reef Marine Park Authority to determine the safest way to re-float the vessel and avoid damage to the reef.
"We have a vessel and personnel on standby to assist with any pollution response," an MSQ spokesperson said.
Lady Musgrave Experience founder Brett Lakey was operating a tour of the island in his glass- bottom boat when he was called on to take the two fishers back to Bundaberg.
"They were a bit shaken up... luckily the weather was good," he said.
"They were more concerned about the ship."