Shark bait lives to tell the tale.

Footage has emerged of the terrifying moment a lone surfer was attacked by a large shark off Gracetown.

The vision was shot just hours after Argentinian-born Alejandro Travaglini, 37, was mauled at Cobblestones surf break yesterday morning.

person then yells: "He's gone... no he's swimming, he's swimming, come on mate chopper's coming back. Chopper's coming back.

With the board still in the shark's mouth, Mr Longgrass made a dash for the beach. The 41-year-old was lucky to escape with deep bite mark on his right leg.

The footage shows people running to the water's edge to help.

One says to him: "You're a lucky man. Oh my god".

It shows Jason Longgrass in the water at Lefthanders break after he continued surfing despite warnings of a large shark in the area.

Mr Longgrass' mate was filming on his phone from shore when the 4.5m shark struck.

One witness yells out 'shark' as the realisation about what is happening hits home.

Speaking after the attack, Mr Longgrass said he slapped the water in a bid to scare off the shark.

"It was just heading straight for me, beelining it straight at me," he told Seven News Perth.

"I went to slap the water, by then he made a sudden acceleration and just nailed the board.

"It wasn't looking at me it was looking at the board."

Mr Travaglini underwent surgery yesterday and is recovering in Royal Perth Hospital.

No one is certain if the same shark was responsible for both attacks but fisheries are examining both victim's boards to see if the bite marks match.