A 33-year-old man killed by a shark off Western Australia's southwest coast was on a dive trip with his brother, police say.
The man was diving from a small open boat called Vampire about 1.6km off Stratham Beach about 230km south of Perth when he was attacked just before 9.30am (WST) today.
A police spokeswoman said the man's brother was not harmed.
It's believed the man's mauled body was recovered from the water by his brother.
The body has been taken south to Port Geographe Marina in Busselton.
Beaches in the area have been closed following the attack.
Experts from the Department of Fisheries have launched an investigation, which will include an examination of bite marks on the man's body to determine what species of shark was involved in the attack.
An aerial patrol was to be sent out to try to determine if the shark was still in the Stratham Beach area, which is popular with cray fishers.
Saturday's attack is the fourth fatal shark attack off the WA coast since September last year.
George Thomas Wainwright, a 32-year-old Texan, was killed after being mauled by a great white shark while diving off Perth's Rottnest Island on October 22.
Bryn Martin, 64, was killed after being attacked by a shark while swimming at Perth's Cottesloe beach earlier in October.
Bodyboarder Kyle Burden, 21, was killed by a shark near Bunker Bay in WA's southwest in September.
Tour operator David Pickering, 26, was mauled by a tiger shark while snorkelling off Coral Bay, in the state's northwest, on January 19.
He escaped with only minor injuries.
Following the three fatalities in September and October last year, WA Fisheries Minister Norman Moore announced nearly $14 million in funding to reduce the risk of shark attacks.
That included $2 million over five years to establish a Shark Response Unit, $2 million for boosted aerial beach patrols and $1.7 million for four shark-related research projects.
Mr Moore said the Shark Response Unit would tag sharks that appeared to be resident near popular swimming beaches and assess shark repellent devices and community alert systems such as SMS warnings.
The WA government has rejected shark nets as an option, saying they were not suitable for beaches in Perth and elsewhere in the state's southwest.
The government also ruled out a major cull of great white sharks or seal culling.
