MARGARET River beachgoers are on high alert after three great white shark sightings.
The warning came in the same week that lifesavers spotted a 6m shark off Mullaloo Beach and electrician Bernie Williams was mauled by a 3.5m white pointer while diving for crayfish off City Beach.
Margaret River surfer Malcolm Mortimer said he was at Boranup Beach when a great white surfaced 10m away.
The 5m shark circled him once and then disappeared as Mr Mortimer made an adrenalin-charged paddle back to shore.
Dunsborough Outdoor Sports owner Damian Lane also reported a close encounter.
He was diving for crayfish just 70m from shore at Sugarloaf Rock, Cape Naturaliste, when a 3m white pointer began stalking him.
"It was a great white and a decent one," Mr Lane said.
"I'm not going to say any more. Sharks aren't exactly good publicity for my line of business."
And in Augusta, 40km from Margaret River, professional shark-boat skipper Jeff Cooke caught a 4.5m white pointer.
"It was a pretty awesome creature," said Mr Cooke, a shark fisherman for 26 years.
"You generally only see (great) whites when the whales come in April or May, but there definitely seems to be a lot around at the moment.
"I found this one in my nets the same day Mal had a run-in with a shark at Boranup. I don't know if it's the same one. It could be, but then there's a lot around so it could well be a different one."
Augusta police said there had been an unconfirmed fourth sighting – at Jay's Beach near the Blackwood River entrance.
Perth underwater cinematographer Hugh Edwards, researcher and author of Shark: The Shadow Below, said great white numbers were recovering after receiving protected-species status in 1997.
But Department of Fisheries shark-research scientist Rory McAuley said that was unlikely.
"I dare say individual fishermen around the place have noticed a bit of a blip, an increase in numbers," he said. "But all the evidence still suggests the population is depleted and has not increased."
He said great whites did not reach reproductive age until 20 – and then only had young every two or three years.
It would take 40-50 years before numbers increased noticeably.
Tracking data showed that great white shark populations of New Zealand, Australia and South Africa were linked through migration routes, he said.
"The temporary increase in numbers indicates a greater percentage of the population might be in WA waters at the moment," he said.
"Fishermen are great at taking what they see in their little area and applying it to the whole state or the whole country, but that is generally not the case."