Ben Gerring, 29, was in the water near Mandurah, south of Perth, when the attack occurred.
The attack occurred at around 16:00 local time (07:00 GMT) on Tuesday, the Australian Broadcasting Corp. reported.
Local media reports said Mr Gerring was resuscitated before he was taken to hospital. He has undergone surgery and remains in a critical condition.
"He was right out the back looking to get a big wave, one of the set waves that had been coming through during the day," Brian Williams, president of the Mandurah Boardriders Club and friend of the victim, told ABC.

"He'd sort of paddled out the back, sort of past the pack slightly. And next thing all hell broke loose and they were trying to bring him in.
"His board was broken in half, they found the tail part of his board," Mr Williams said.
Surf Lifesaving Western Australia reportedly issued a warning before the attack, after an unknown species of shark was seen in the local area.




Catch This!
As a lifetime surfer here - the sharkbite capital of the world, no less* - I, like all surfers around here, have had nearly countless scary shark encounters that I was aware of.** An ‘assumed risk’ is the term. Besides, they’ve got more right to be there.
So after this attack, the Aussie government sets up shark traps (a baited side of beef attached to 55 gallon barrels.)
Anyhow, one of their traps had a hit, caught a big Great White, and the Australian Premiere announces that “ 'we're almost certain’ we caught the ‘culprit’ shark. Here's the info: “Shark attack: Premier Colin Barnett Says It’s Highly Likely Shark Caught Was Responsible for Attack” at this link:
Now we’ve all heard of the things found in sharks’ bellies over the years. What is strange about this is the announcement that WITHIN 24 hours, the Aussie Premier assures all the tourists et al, that 'we're almost certain’ we caught the culprit shark. So, me wonders, first, how it is that they don’t know for certain?
So, of course, to make certain, of course, they hauled up the 4.2 meter Great White, and opened up its belly, right? It damn sure sounds like the thing SWALLOWED his leg and it’s only 24 hours later so parts would certainly still be there. But DID they do that? Sure seems otherwise as it's not mentioned and would be had they done that and FOUND a leg. BUT NO! They towed out it out to sea and gave it the standard ‘fake OBL sea-grave’ technique!!! Say what??? True! To quote from above linked article, “The shark was towed out to sea and dumped after samples and measurements were taken.”
1. So what happens when the REAL shark is hooked on another barrel-bunch-bait?
2. Does the government and/or press have to either lie or give too little information ALL the time?
R.C.
* While the East Coast of Florida has the most, we certainly don’t have the most deadly attacks, which ‘titles’ go to South Africa, Australia and Hawaii. I’ve spent over three years surfing about 6 days a week in California and only saw one 4 foot dogfish.
** And for every shark I’ve seen swim within 20 feet of me, I’ve probably had three times that many below me which I never saw.
RC