A 5m great white shark tagged off Albany was detected by acoustic receivers as it swam along the Perth coast yesterday morning.
The shark set off four coastal satellite-linked receivers that alert authorities when a shark tagged with a transmitter is within 300-400m of a beacon.
The great white was first detected at 3.04am on Monday off Cottesloe and three hours later off City Beach.
It reappeared at Ocean Reef at 10.45pm on Monday and was picked up again off Scarborough at 4.20am yesterday.
At 5.30am the shark triggered a receiver at Floreat and at 7.10am and 7.15am was near the North Cottesloe beacon.
A Department of Fisheries spokesman said the shark was first tagged by researchers in King George Sound, Albany, on May 11.
He said the scientists went out after a fisherman reported a 5m shark in Frenchman Bay the day before and tagged a shark matching the description of the one the fisherman spotted.
Fisheries shark response unit manager Michael Burgess said the shark monitoring network was set up to collect data about the behaviour and movements of great whites off the coast of Perth.
“There’s no doubt that white sharks are travelling up and down our coast all the time but this technology gives us this competitive advantage that we get these notifications,” he said.
In addition to the 20 satellite-linked receivers that sit in a row about 400m off the metropolitan coast, the project includes another 120 receivers extending to the continental shelf that must be collected from the ocean floor to retrieve the data.
The initial phase of the project involved the tagging of more than 100 great whites off WA and South Australia.
Cottesloe and North Cottesloe beaches were closed for almost three hours after the shark was detected yesterday, forcing swimmers to rethink their early morning dip.
Cameron Rowan said that he missed out on his regular 7.30am swim with colleagues Alan Golding and Steve Weychan after North Cottesloe beach was closed.
“I was disappointed because there was just a sign that said ‘No swimming, shark’ and I couldn’t see a shark and who’s to say where it was,” he said.
Another 3-4m shark was spotted about 4pm yesterday at Woodman Point, apparently swimming towards Rockingham. No beaches were closed.