Search for swimmer continues after fatal shark attack

The search continues for a swimmer fatally attacked by a shark off a popular West Australian beach.

Emergency services attended Perth's Sorrento Beach about 10.30am on Friday after reports a man had been bitten by a shark while swimming along the coast.

WA Police confirmed on Saturday the 63-year-old man died in the attack but he had not been found in an air and sea search on Friday or in a shoreline search on Saturday morning.

A Water Police vessel would remain in the area, police said in a statement.

WA's Department of Primary Industries and Regional Development is investigating the incident, the second shark attack off WA's coast in five days.

A witness told ABC News on Friday she was alerted to the attack when she was walking along the beach and saw a pool of blood in the water.

The City of Joondalup has closed all beaches in the area, from Burns Beach in the north to Marmion in the south, until midday on Saturday as a precaution.

The fatality follows a shark attack on a surfer at a remote WA beach on Monday.

The man was seriously injured at Glenfield Beach, north of Geraldton in the state's Mid West

He was taken to the nearby Geraldton Health Campus and is in stable condition.

Surf Lifesaving WA's helicopter shark patrols began for summer last week.

They will initially operate on weekends before becoming daily between Mandurah and Yanchep, and Rottnest Island to the west, from September 26 until the end of April.

Patrol flights in WA's southwest between Bunbury and Hamelin Bay will run daily during school holidays and peak summer periods, and on weekends and public holidays at other times.