A great white shark is still lurking off Perth beaches, with authorities detecting the 5m female three times yesterday.
The shark was tagged on May 11 in Albany's King George Sound.
Yesterday, it triggered an acoustic receiver off North Cottesloe just before 1am. It was picked up by another receiver at 2.28am off City Beach and at 5.06am about 3.5km off Trigg.
The satellite-linked receivers alert authorities when a shark is within 300m-400m.
The same shark was picked up several times last Monday and Tuesday as it made its way between Cottesloe and Ocean Reef.
Fisheries shark response unit manager Michael Burgess said it was possible the shark was following whales as humpbacks and southern rights journeyed from the Southern Ocean to warmer waters off WA's north coast.
She was the only shark to be tagged in WA this year - 12 have been tagged since 2008 - with another 88 tagged off the coast of Port Lincoln in South Australia.
Mr Burgess said there was a clear migration pattern between WA and SA so it made sense to tag the sharks in Port Lincoln because sharks were drawn to the massive seal colony there.
Authorities were on alert yesterday when a whale was spotted less than 50m off Port beach in Fremantle.
Mr Burgess said authorities were working on a system where updates from receivers were automatically posted on Twitter, so beachgoers could check whether there were sharks in the area.
"The whole idea is to keep people informed so they can make educated decisions about their water use," he said.
He backed an announcement by Fisheries Minister Norman Moore yesterday that the State Government would draft regulations to ban shark tourism, including cage diving.
"While such ventures may generate direct or indirect economic benefits, there are also concerns that sustained activities to attract sharks to feeding opportunities have the potential to change the behaviour patterns of those sharks," Mr Moore said.
There have been four fatal shark attacks in WA since September.
Shark sighting reports can be found at www.fish.wa.gov.au/shark and to report a shark sighting call the water police on 94428600.