"The man and woman who was onboard have gone into the water in the late afternoon and they were taking turns at using a stand-up paddleboard", O'Connell said.
He had dived into the water to give the woman her turn on the board when the shark attacked, O'Connell said.
In September a 12-year-old girl and a 46-year-old man suffered severe injuries from shark attacks while swimming on two consecutive days in the same area.
The man was airlifted with critical wrist and leg injuries to Mackay Base Hospital, where he was rushed to surgery upon arrival.
"CPR was ongoing for a very long time and every solid effort was made to save that man's life", Mr O'Connell said. "They did everything imaginable to try to save the man. It's just - the injuries were so severe", he added.
Shark control equipment had been temporarily placed in Cid Harbour following the first two attacks but was removed on September 27 after the potentially risky sharks were removed.
"Definitely one of the more hard ones for everyone involved", McCauley said. The scene is what you would imagine a shark attack to be like.More news: Election Day to test Democratic resistance in Trump era
"When the man got off the paddle boat and into the water, he was bitten by the shark".
The pre-teen lost her leg in the attack, which led to a shark bait operation, in which six sharks were hooked and killed within a week.
"The Cid Harbour area is not covered by the Queensland Government's Shark Control Program, which operates at 85 of Queensland's most popular beaches", he said.
Professor Colin Buxton from the University of Tasmania told Australian magazine StabMag: "The pros are that drum lines kill sharks and thus reduce the number of sharks in an area and this reduces the statistical chance of a shark encounter with humans".
In a joint statement with Australia's Department of Agriculture and Fisheries, Tourism Minister Kate Jones said the priority was to reinforce the message that people should not swim in the harbor.
Temporary signs would be urgently installed and permanent signs would follow deterring people from swimming in the popular anchorage location, according to the statement.
"We really need to be smarter than what we have been and actually learn from these things as opposed to just going out and killing animals", Dr Chapman said.