Police were called to the Humpy Island camping area in the Keppel Bay Islands National Park, about 18 kilometres off the mainland, following reports that a man had been attacked.
The 40-year-old was fishing with family members when he was attacked about 4:37pm and sustained life-threatening injuries to his neck.
An emergency service helicopter was on the scene with paramedics.
Police will prepare a report for the coroner.
Earlier this month, a man was rushed to hospital after a shark attack off Curtis Island in Central Queensland.
Comment: A day later: Tourist killed in shark attack off Egyptian coast