YESTERDAY'S finding that a three-metre great white was responsible for Monday's fatal attack has surprised even the experts.
Southern Cross University marine biologist Dr Daniel Bucher said his first thought was the predator may have been a tropical Tiger shark more common during late summer.
Current knowledge suggests medium to large great whites are more frequent along the North Coast during winter.
"They usually wait for the mullet to start running and the whales to start travelling," Dr Bucher said. "Then they head south for summer to feed on the seal pups.
"This one's come early, which would be bucking the trend of global warming."
The identification was made by a Fisheries NSW shark specialist who estimated the size of the shark's jaw and teeth via a forensic analysis, and also reviewed footage captured during the attack by the Coastalwatch website live streaming surf camera.
While he was surprised, Dr Bucher said there was still too little scientific knowledge about this mysterious creature to divine its habits.
"In any population the problem with behavioural studies is your dealing not with the average but with the individual," he said.
"It's what the individual does that becomes important, just like in humans."
He said great whites in the three-metre range were not yet fully grown, but young adults "probably at that point in life when they're starting to investigate larger prey".
The shark was probably chasing fish in gutters just beyond the breaker line at the time of the attack.
"You're into water there where the offshore sandbars start to drop off into deeper water and channels.
"That is a classic place for sharks to patrol.
"The fish tend to hide in the breakers and every so often drift down and that's when the shark is trying to pick them off."
Swimmer Paul Wilcox was in a similar zone last September when he was killed by a great white shark off Main Beach, Byron Bay.
Yet despite fears more big sharks are lurking close to shore, Dr Bucher said two fatal attacks in six months was not a real trend. The chances of getting attacked by a shark remained similar to "winning the lottery".
He added there was no evidence of big sharks on the rise. The only long-term global trend was their populations were in decline.