Dead turtles have been washing up on beaches at Boyne Island and Tannum Sands, south of Gladstone in central Queensland.
Fifteen turtles have been reportedly found, but the cause of death is unknown. Most of the turtles have been juveniles in seemingly perfect health.
The Queensland Department of Environment and Resource Management (DERM) says it is investigating the matter.
Jodi Jones from the Gladstone District Wildlife Carers Association says she is disturbed to hear there could be more dead turtles.
"We've been getting reports since Sunday morning that there's been a significant number, over 10 now I believe, of turtles washed up on the Boyne River and Canoe Point side of the Boyne River," she said.