Fanning's mother, Elizabeth Osborne, watched the incident unfold live on television in Australia.
"It was absolutely terrifying. I just couldn't believe what I was seeing and I thought we lost him," she said.
"I went over to the television almost as though I could pull him out of the television. I just wanted to save him really, but there was nothing I could do."
Osborne said she believed Fanning's brother Sean, who died in a car accident 17 years ago, was watching over his sibling.
After being plucked to safety by a rescue boat, Fanning said he had felt something get stuck in his leg rope and "instantly jump away".
"And it just kept coming at my board."
A shaken Fanning said he would be happy to never compete again after his brush with death.
He described the moment he realised the shark was behind him as terrifying, saying: "I was waiting for the teeth to come at me. It kept coming at my board and I was kicking and screaming. I just saw fins. I punched it in the back.
"I saw it taking my board away and I just started cracking it.
"I'm totally fine. I've got nothing wrong with me. There's a small depression in my board and my leg wrap [was] bitten. I'm just totally tripping out. To walk away from that, I'm just so stoked. Oh man."
Surfing great Kelly Slater said he was coming up the beach when he saw all the boats and skis heading toward the surfers.
"I knew there was only one possible reason that would ever happen in a contest and that's if someone got attacked by a shark.
"I'm halfway between crying and laughing because he got so lucky. I'm lost for words to be honest."
The World Surf League cancelled the remainder of the event and Fanning will split the prize money with fellow Australian surfer Julian Wilson, who was also in the water when the attack happened.
Wilson was hailed a hero yesterday for paddling towards the great white while it was attacking Fanning in a bid to save his friend.
"It came up and he was wrestling it, and I saw he got knocked off his board," Wilson said through tears afterwards. "I felt like I couldn't get there quick enough.
"I was like 'I've got a board, if I can get there I can stab it or whatever, I've got a weapon'."
Auckland-based documentary maker Mike Bhana has been filming great whites for the past 23 years and said he could tell it was a great white by the shape of its almost symmetrical tail fin. "The way in which it came in [from behind], it was definitely a great white. It was a big great white too, it was well over three metres. It was a very big animal."
Mr Bhana said white sharks hunted using stealth. "If the shark was going to attack Mick it would've killed him." The shark had come up to "have a look" before the leg rope jammed in its mouth. Both the shark and Fanning had then panicked.
Mr Bhana said shark attacks were "incredibly rare" in New Zealand waters. With only two deaths in 25 years, Kiwis faced more danger driving their cars.
Adam Strange, a documentary-maker from Auckland, was killed in a shark attack in February 2013 at Muriwai in West Auckland during a training swim.
"The sharks are there, they don't actively seek us out," Mr Bhana said.
"We're kind of foreign to them, we're not a food source they really know ... You have to be absolutely in the wrong place at the wrong time and strike a curious shark or a hungry shark."
Mr Bhana predicted problems developing in New Zealand waters between spearfishermen and bronze whalers as they both hunted in the same areas.
Great white sharks in NZ
How many?
• The numbers in New Zealand waters are unknown. More than 100 individual great whites have been identified at Stewart Island/Rakiura.
Where and when?
• All coastal waters and in large harbours and estuaries, especially Stewart Island, Chatham Islands and around the upper North Island.
• More common near seal colonies.
• Numbers higher from December to July. They tend to come closer inshore during the summer, possibly following prey species.
• Large harbours such as the Manukau and Kaipara are thought to be nursery areas for their young.
How to reduce the risk of a shark attack:
• Avoid areas where people are fishing or discharging bait or berley.
• Avoid schools of fish or groups of feeding dolphins or seabirds.
• Stay out of the water from dusk to dawn as sharks are generally night-time hunters.
If confronted or attacked by a shark
• A scuba diver is best to stay on the sea floor. Others should leave the water as quickly, yet calmly, as possible.
• If attacked, act aggressively, hitting the shark. Aim for the sensitive gills and eyes.
