Three separate shark sightings were reported on Monday at four beaches in Western Australia, after which the beaches were evacuated to protect the swimmers.

Brighton, Trigg, Scarborough and Watermans beaches were closed to the public after the Surf Life Saving WA (SLSWA) chopper spotted two 2.5m sharks and a third 3.5m shark at about 10am Monday, Perth Now reported.

SLSWA spotted the sharks between 50m and 75m off shore. However, it has yet to determine the species of the sharks.

At Scarborough Beach, swimmers were cleared from the water just before 6pm after a private helicopter spotted a 3-4 metre shark.

At least eight sharks were spotted off Scarborough and the South-West coast on Sunday. SLSWA said the shark was spotted about 500m south of Scarborough, with the beach remaining closed overnight.

Earlier Sunday, life savers were kept busy with six shark sightings in the South-West, some up to 3.5m in length, off Bunbury and Dalyellup, both of which took no chances and decided to keep the beaches closed to the public to protect the swimmers' safety.

The public is advised to comply with beach warnings amid the shark sightings to avoid another shark death.