Researchers have tagged four minke whales in an attempt to find out where they go after leaving Australian waters.
Dr Alastair Birtles of James Cook University, who has studied minke whales for 18 years, said they gather off north Queensland for a few weeks during the middle of winter. But it is anyone's guess where their next stop might be.
AAP reports the whales were last month tagged with small tracking devices in north Queensland.
One, a young male named Spot, has already travelled 3000km east and is swimming in waters off Sydney.
Scientists were able to insert the tracking tag using a ship called the Whale Song, an Australian Navy boat which makes very little noise underwater.
Minke whales are usually about five to seven metres in length. AAP reports they were discovered in the Great Barrier Reef area in the 1980s.