Sydney  - Several beaches in Perth, Western Australia, were closed Sunday after a large shark was sighted by a helicopter searching for a missing man believed to have been attacked by the creature the previous day.

Authorities said the helicopter and search boats found only pieces of a wetsuit worn by Brian Guest, 51, who disappeared while snorkelling for crabs at a beach south of the city on Saturday.

A large shark was spotted and a witness reported seeing blood in the water at the place where Guest was last seen, ABC Radio reported.

Police said no attempt would be made to hunt down the shark in accordance with the wishes of the missing man's family.

The national AAP news agency reported that Guest told angling website forums in 2004 and 2005 that he did not believe in killing sharks.

In 2004, he wrote: "I have always had an understanding with my wife that if a shark or ocean accident caused my death then so be it, at least it was doing what I wanted."

In the 2005 post, he said: "They got a right to be there, we got a right to go there and there are risks associated with everything, but I don't believe the correct way of reducing our risk is to kill the shark." (dpa)