Whitsunday is the largest island in the Whitsunday Islands group, a major worldwide tourist attraction popular with scuba divers and sailors where shark attacks have been rare.
Fisheries Queensland issued a statement soon after the attacks, telling people that Cid Harbour was "not safe for swimming".
Christidis, a urologist from the city of Melbourne, was taking turns with a woman standing on a paddle board or swimming in the harbour late Monday afternoon.
Prof Colin Simpfendorfer, from James Cook University, said shark attacks were "extremely rare" in the Whitsundays, but no theories had "so far been supported by real substantial information" to understand the spike in shark activity.
French-speaking tourists launched a dinghy from their yacht and pulled Christidis to his own yacht, where most of the group had medical backgrounds, including two doctors.
"CPR was ongoing for a very long time and every solid effort was made to save that man's life", O'Connell said, referring cardiopulmonary resuscitation. "It's just - the injuries were so severe", he added.
Police said Tuesday that they have not publicly identified the man as they were still working to contact his next of kin.
"Definitely one of the more hard ones for everyone involved", McCauley said.
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Mary Magdalene church, which are followed by a Christmas Day meal featuring a Norfolk turkey as the main attraction. The royal family reportedly exchanges gifts on Christmas Eve, though extravagant presents aren't in the cards here.
On September 20, a 12-year-old girl was left in a serious condition after a shark bit her on the leg.
Tourism Whitsundays chief executive Peter O'Reilly said at the time that the Trumbull attack was the first in the islands in 13 years and only the third ever recorded.
Marine biologist Blake Chapman says it's hard to say what has changed and whether the three attacks indicate an increase in shark activity - but he believes more research should be conducted to find out.
The 33-year-old was with a group of 10 people travelling from Airlie Beach to Amity Point in a sailing boat, when it stopped at Cid Harbour.
Four tiger sharks were culled from the waters following the attacks and drum lines, which are unmanned aquatic traps used to lure and capture sharks with baited hooks, were additionally laid out by the Queensland state government.
"I feel devastated for the family and friends of this young man, I know that he would have received the best of care available from the Queensland Health Service, including RACQ CQ Rescue helicopter crew and my heart goes out to all involved", Craig Barwick said in a statement.