Marine authorities are appealing to the community for information on the death of two Australian snub-fin dolphins at Toolakea Beach north of Townsville about two weeks ago.

The animals were found tied by a rope to a mangrove in the upper reaches of Two Mile Creek, with a block of concrete attached to the rope.

Great Barrier Reef Marine Park Authority Field Management Director Mick Bishop said this type of behaviour was totally unacceptable and was being investigated.

"Given the circumstances, the death of these animals is of concern and we urge anyone with information relating to this incident to come forward," he said.

"It is likely these dolphins were caught accidentally during a netting operation and their deaths should have been reported. Instead, there has been a clear attempt to conceal the bodies of these dolphins."

Mr Bishop said snub-fin dolphins are rare and are listed as 'near threatened' under Queensland law.

"Snub-fin dolphins inhabit the inshore waters of northern Australia and they face a number of threats, particularly from coastal development, habitat loss and illegal netting," Mr Bishop said.

The animals were found by a recreational fisherman on 23 May 2011 and reported to the Queensland Parks and Wildlife Service.

Anyone with information should contact the Great Barrier Reef Marine Park Authority on 07 4726 0588.