Queensland authorities are warning people not to swim in canals on the Gold Coast after the second fatal shark attack in the area in as many months.

An 84-year-old Burleigh Waters man who was swimming in Burleigh Lake this morning has died as a result of a severe leg injury inflicted by a shark.

It is believed a bull whaler shark was responsible for the attack.

Primary Industries Minister Henry Palaszczuk says baited drum-lines are being placed in the area to catch it.

Mr Palaszczuk says there are hundreds of aggressive bull whalers in the canals and swimmers need to act safely.

"Don't swim in the canals, don't swim at dusk, don't swim at dawn, don't swim alone and swim between the flags, it's as simple as that," he said.