Excluding the two most recent attacks, there have been 33 recorded cases of shark bites in Australia so far in 2018, according to the Australian Shark Attack File of the Taronga Conservation Society Australia.
A 12-year-old girl has been injured in the second shark attack in 24 hours near Whitsunday Island.
Mr Macdonald contacted the RACQ CQ Rescue helicopter on the radio to co-ordinate what needed to be done for her to be picked up from the boat.
She was treated for 20 minutes on the beach, having sustained "fairly large wounds with artery and bones, vessels, (and a) large haemorrhage" according to Queensland Ambulance Service's Tracey Eastwick.
The attack comes are a woman was attacked while snorkelling early last night.
The incident was reported just before 1.45pm on Thursday, less than 24 hours after the first attack, after 5pm on Wednesday, left Tasmanian tourist and avid snorkeller Justine Barwick fighting for life in hospital.
'Fisheries is working with other agencies including the police and marine parks, ' the department said in a statement. The area is popular with tourists from all over Australia as well as visitors from overseas.
"She did suffer a lot of blood loss. She's very lucky to be alive".
The girl, who was holidaying with her father and sister, was flown to the Mackay Base Hospital in a critical condition.
The doctor, John Hadock, was about to go for a swim when he was summoned to jump into a dinghy and rush to Barwick's aid.
When Mr Macdonald arrived, he worked with doctor from a nearby boat who had come to help, as well as the woman's family who had been on the yacht.