"They just saw the board only and a lot of grey objects around the board," Sergeant Anderson said.

"They've gone down a bit further and seen the fellow face down in the water amongst the rocks."

It took the pair another six minutes to wade in and pull the unconscious surfer from the water. Sergeant Anderson said he was believed to already be dead but one of the rescuers tied a tourniquet and began CPR with the help of surfers who were suiting up in the carpark at the time.

"It appears that his right leg has been shredded with some significant injuries to the top of his leg and minor injuries to the calf," Sergeant Anderson said.

About 10 minutes later his board washed up to shore after being bitten in half.

Police and the RAC rescue helicopter raced to the beach and rushed the man to Margaret River Hospital for treatment, but he succumbed to his injuries.

The Shire of Margaret River closed the beach and police and fisheries officers were doing sweeps of the water to try to locate the shark.

They could not confirm the species of shark or what would happen to it if it was found.

Local resident and Gracetown surfer Rob Alder was watching from his house and saw the lone surfer come off his board and disappear near the South Point surf break south of Cowaramup Bay.

He rushed to the beach with friends to find the surfer washed up near rocks and unconscious with severe injuries to his right leg. Mr Alder, who performed CPR on the dying man, said he did what he could in a desperate effort to save a "brother" surfer's life.

They worked to resuscitate the surfer and applied a tourniquet using a surfboard leg rope before an ambulance arrived to take him to Margaret River Hospital, where he was pronounced dead.

"I took my leg rope and used it as a tourniquet because he had a severe laceration and we put him on my surfboard to bring him up the beach," he said. "But we realised it was too hard so we began mouth to mouth resuscitation and CPR."

While this was happening, his friend ran along the beach screaming at other surfers to get out of the water.

"He looked like he was in deep shock. He was unconscious," Mr Alder said.

"We got colour back into his face and cared for him, and tried to bring him back to the surface," he said in a shaky voice.

He said it looked like there had been a single bite that tore through the man's calf and thigh. He also noticed the man was wearing a wedding ring.

"I feel so sorry for his wife, family and friends," Mr Alder said.

"He made an incredible, heroic journey to the beach.

"Where he got to from where his board was, he must have really wanted to make it, he was a real fighter."

The Gracetown area is a well-known and notorious surfing spot. A popular local surfer, 29-year-old Brad Smith, was killed by a shark while surfing at Lefthanders beach in July, 2004.

There were reports Mr Smith was attacked by two sharks, thought to be great whites, but the type of species was never confirmed.

"That part of the West Australian coast is notorious for sharks and it's also notorious for surfers," Sergeant Graham Clifford told radio 6PR.

WA world number two surfer Taj Burrow, who is currently taking a break from the world championship tour to holiday back home with his family in Yallingup, said news of the attack sent shivers down his spine.

"The waves have been absolutely pumping so to hear that was the most shocking thing ever," Burrow said.

"The Bay is one of the spookiest place for sharks down here for sure, you always hear stories about them being spotted."

Burrow said he's had a couple of hair-raising moments with sharks both in Australia and overseas but it was something he tried not to think about. He will fly to Tahiti on Thursday to contest the Billabong Pro event.

"When something like this happens it really brings you back to reality," he said.

"This is a terrible tragedy and my thoughts are with the friends and family."

Surfer Paul Paterson, brother of former professional WA surfer Jake Paterson, said lone-surfing was usually not a problem, but at this time of year sharks were known to follow whales and salmon to the area.

"There's a lot of whales in really close and that seems to attract the sharks this time of year," Paterson said.

"March, April and May is a very dangerous season because its the salmon season and it increases the probability of sharks."

"That inquisitive bite tends to be a little bit more lethal than a taste unfortunately."

He said South Point beach was a very protected spot and a good place to surf after a big storm.

"The last guy that got attacked by a shark was just around the corner, which is only about one or two kilometres away," he said.

Big wave surf legend Mitch Thorson was surfing at the beach with his son last night and said the area wasn't any different to other spots when it came to shark attacks.

"I reckon that most guys who surf get bombarded with so many shark images from the media, but you put it out of your mind when you're out there," Thorson said.

"It's like getting in a car and thinking 'if I drive out onto the highway I might be hit by a truck'. You just put it to the side."

He said he expected most surfers would stay out of the water for the next few says out of respect for the man's family.

"But I'd say (the victim) wouldn't want people to stop surfing altogether," he said.

A Department of Fisheries boat has left Busselton to track down and identify the type of shark, but weather conditions may force it to turn around.

Fisheries southern region manager Phil Shaw said the boat was on its way to Cape Naturaliste where it would be decided whether it would continue.

"The weather looks like it's going to make it tough, there's a three and a half metre swell and building, and the wind is coming up," Mr Shaw said.

"That will make it difficult to see anything in the water."

Mr Shaw said the department would make an assessment on the danger the shark posed if it could be found, but said that assessment was very subjective. He said the last resort would be to kill the shark.

"We'd have to determine what ongoing risk the animal posed if it's hanging around and keeps going ashore," he said.

"Normally (the sharks) disappear. Very rarely do we see them again afterwards."

Mr Shaw said if the weather hampered today's search another boat could be sent out tomorrow.

Meanwhile the victim's mother has spoken out about her son's previous near miss with another shark in Queensland.

Busselton surfer Nicholas Edwards, who died yesterday after being mauled by a shark near Margaret River, had previously had a near miss with a shark while surfing on the Gold Coast, his mother said.

The father-of-two was on his last day off from BHP's Leinster nickel operation when he was attacked while surfing about 300 metres from the South Point surf break at Cowaramup Bay.

Two local surfers tried to resuscitate him and stop the bleeding from his shredded right leg after pulling him unconscious from the water, but Mr Edwards died on the way to Margaret River hospital.

His mother Leona Lindner, who lives in South Australia, said she was always fearful for her son's life because of his occupation and his love of surfing.

"When he lived on the Gold Coast he was surfing up there one day and he had a very near miss with a shark up there and he paddled in like mad and he was really shook up and he said he was scared," Ms Linda told 6PR Radio.

"I said 'don't go in there ever again', but no, Nick had to go."

"Between his mining and the surfing we sort of wondered when a day like this would come."

She described her son, who moved from the Gold Coast to Busselton with his wife Melissa and two children three years ago, as a "loveable guy" who had lots of mates.

"He was a very brave guy, he was care-free, he had no fear, he loved life, I think that was why he was where he was (yesterday)," she said.

"He had a passion for surfing, that's why he lived in Busselton... (he) chose to live at Busselton for his passion for surfing."

She said while his daughter Lucy, 2, was too young to understand what had happened to her father, her brother Nathan, 10, had "taken it very hard".

Ms Lindner thanked the surfers who tried to save her son's life but said she didn't think the shark should be hunted and killed.

"I really appreciate what those guys did, I can't thank them enough it's just sad that they couldn't help him in the end," she said.

"He was in shark-infested waters, I'm sure that he would have been aware of that."

She said Mr Edwards would have said "'no, don't kill it'... because he realised where he was and what he was doing but unfortunately his passion was so great and he kept going there'.

with AAP