Brighton, Scarborough and Trigg beaches have been closed until 4pm Thursday due to a shark sighting.
The City of Stirling made the announcement on their Twitter page on Thursday afternoon.
A three metre shark was spotted at Scarborough just 50 metres from shore at about 3pm.
Floreat and City Beach were re-opened earlier on Thursday after being closed for just over an hour after another shark sighting.
The beaches were shut at about 11.30am but were opened again at about 12.45pm.
Lifeguards had closed the two beaches after a shark was sighted by the Westpac Lifesaver Helicopter.
About an hour before the closure a 2.5 metre shark was spotted at Floreat Beach about 100 metres offshore.
Floreat and City Beach Lifeguards have closed their beaches due to a shark sighting by the Westpac Lifesaver Helicopter.
— Surf Life Saving WA (@SLSWA) December 15, 2016
At 8am on Thursday, a 4.5 metre white shark was sighted off Mindarie Beach north of Perth.