17 August 2010 Last updated at 03:17 ET

Australian surfer dies after shark attack

Witness Rob Alder: "I would imagine that it was a shark that mistook him for a seal"

A man has died from his injuries after he was attacked by a shark in waters off West Australia.

The 31-year-old man was surfing alone early on Tuesday morning when he was attacked near Gracetown, about 270km (167 miles) south of Perth.

The Fisheries Department said it has no information about the type of shark.

Officials said sightings of sharks are frequent in the waters but fatal shark attacks are rare although a surfer was killed in the area in 2004.

Local media reported that the surfer had been seen by a resident watching from his house.

Rob Alder told ABC he had rushed down to the beach and alerted a rescue crew, while he tried to resuscitate the man.

Mr Alder said there were reports of a large number of seals in the area at the time of the attack.

"It's my thought, as often happens, the shark had probably mistaken the surfer for a seal," Mr Alder was quoted as saying.

"He hadn't bitten away anything, it was just like a nip, there was no sign that the shark had viewed the surfer as a meal."