This morning, at 6:40am at Byron's Belongil Beach, a 41-year old man was attacked by a shark while surfing. He's now in a 'critical but stable' condition and has been flown to Gold Coast University hospital where he is currently undergoing surgery, which is expected to last several hours.

Although Belongil is unpatrolled, the attack has prompted the closure of Main Beach and other patrolled Byron spots. An understandable reaction as Belongil is on the same strip of sand as Main Beach and the ever-crowded point that is The Pass.

After being bitten on the leg by the shark which is believed to be a juvenile great white, the surfer returned to shore, calling for help and alerting other surfers to the attack.

The board which took the brunt. Photo: ABC News

"As soon as my mate got out the back he sat up on his board and instantly a shark smashed from underneath … knocking him clean off his board." Dane Davidson, the surfer's mate, told the ABC.

"There was a lot of splashing and smashing and he started screaming. I was freaking. When I heard the screams he was making in the water and then I saw a chunk of his board floating off, that's when I realised it was pretty bad.

Mr Davidson said he paddled with his friend back to the shore.

"We didn't realise until we were on the beach that there was a big chunk taken out of his leg so there was a lot of blood," he said.

"I was freaking. When I heard the screams he was making in the water and then I saw a chunk of his board floating off, that's when I realised it was pretty bad. We didn't realise until we were on the beach that there was a big chunk taken out of his leg so there was a lot of blood."

Both Dane, fellow surfers and passersby used a legrope to make a quick tourniquet to restrict blood-flow to the wound. Paramedics and lifeguards soon took over before the victim was flown to hospital.

According to the the NSW Department Of Primary Industry will assess the man's surfboard – well, what remains of it – to confirm the shark species as a juvenile great white. The size of the shark however remains unknown.

Although Byron Bay and other Mid-North Coast regions have an ample supply of shark detecting tech and shark surveillance, the shark responsible for this attack was not detected by the 'listening station' at Clarke's beach – meaning the shark was untagged. The shark spotting helicopter has also been deployed, but due to today's conditions – a significant swell and wind – it'll be tough going to spot this shark, or any others.

SMART drumlines off some regions of the North coast were not active today due to the large swell. The Byron Bay region however is sans any SMART drumlines.

This attack is the first in recent memory along the New South Wales' northern most beaches after a nightmarish spate of attacks two-to-three years ago in the region. These attacks – predominantly around the Ballina, Lennox, Byron region – led to a hefty uptake of shark mitigation strategies, and of course, much discussion surrounding the catalyst for the increasing number of sightings and encounters.

We'll update this story as more information comes to light.

Note: An earlier version of this story reported the man was in a stable condition, this has since been updated to critical and he is currently undergoing surgery.