Another surfer was lucky to avoid being mauled to death a day earlier as he was badly bitten in a similar attack near the same area around the town of Ballina in New South Wales.
The Japanese man was sitting on his board when the shark attack happened, confirmed local mayor David Wright.
Friends tried to save the man by performing CPR, but he bled to death.
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"Because both legs were gone, he bled to death very quickly," said Wright.
The site of the attack at Shelly Beach was closed along with a longer stretch of coastline as officials began their hunt to locate the shark.
Ballina is around 12 miles away from Seven Mile Beach. Another surfer Jabez Reitman was attacked on Sunday.
"I just freaked out," said Reitman as he was ambulanced to hospital. "I thought it was a dolphin at first until I started feeling and realised it was pretty significant lacerations."
"I should've stayed in bed."
Reitman's condition was later described as stable.
Wright, the Ballina mayor, suggested the attacks could have been by the same shark.
"It's just an accident," Wright said.
In September, a swimmer was killed by a shark near Byron Bay.
Fatal shark attacks remain rare in Australia, with the country averaging fewer than two attacks per year over recent decades.
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