An acoustic receiver off Ocean Reef was activated by a tagged great white shark at least 29 times yesterday but the Department of Fisheries will not say whether it is one shark or several predators lurking off the coast.
The shark beacon has been set off more than 60 times since Sunday, forcing several closures of beaches near Ocean Reef and Mullaloo.
Joondalup mayor Troy Pickard said the department had a duty to tell the community whether it was one shark and called on the State Government to protect beachgoers.
"If it is the same white shark that is regularly returning to the Ocean Reef area, then it is my belief that this presents a serious risk to human life and the Government needs to eliminate the danger," Mr Pickard said.
Fisheries believes the level of information it gives is adequate to protect the public but said it would consider whether to release more data.
Last month the State Government gave the Fisheries director-general powers to issue a kill order if a shark posed an "imminent threat" to people.
Fisheries director-general Stuart Smith said repeated confirmed sightings of a single large shark off popular swimming beaches could be deemed an imminent threat if people were able to swim without knowing it was nearby.
But he said before a kill order was issued, efforts would be made to negate the threat by closing beaches, patrolling the waters or shepherding the shark out to sea.
The Conservation Council said a shark was not an imminent threat just because it set off a beacon.
The shark tagging and coastal satellite-linked receivers, which have a 400m detection radius, are part of a research program to monitor the behaviour of great whites off the WA coast.
About 120 sharks have been tagged and each transmitter is unique, so authorities can identify which shark triggers a receiver.
Shark response unit spokesman Tony Cappelluti said the department did not usually provide details about specific sharks, because all tagged sharks were potentially dangerous.
"It would be risky for people to make value judgments about the level of risk based on the size or species of sharks or their behaviour," he said.
Chris, who swims almost daily off Mullaloo, said she had seen no warning signs about the Ocean Reef detections.