A marine expert says Perth locals should not be concerned about a recent spike in tagged shark detections off the city’s coast.

Users of the State Government’s SharkSmart app may have noticed 26 detections of a tagged great white shark this week as monitors were triggered along beaches in Cottesloe, City Beach, Scarborough, Trigg and Sorrento.

A further 11 shark alerts were detected at Bickley Point on Rottnest Island.

Physiological and behavioural ecologist from Murdoch University Dr Adrian Gleiss says it is more than likely the detections are simply the same shark travelling close to each receiver.

He says people should not be alarmed.

“It is common that we see certain species move up and down the coast with the seasons because the water temperatures change. White sharks … tend to not hang out in places on the west coast so much, they are really just coming through,” he says.

“An animal might put up shop for maybe a day, but generally they will move on relatively quickly.

“So of course if you have successive detections on those receivers on a given day, the likelihood is that it’s one animal that’s hanging out there before it’s moving on.”

Perth surfer Alicia Holmes has been surfing for two years and says she has experienced a non-dangerous encounter with a shark in WA’s southwest.

“We were quite far out and someone said ‘is that a shark? That’s a shark fin.’ A few people saw it. Most people stayed out. I went back into shore with the kids,” she says.

Despite the encounter she is not worried about getting out in the water and accepts sharks are part of the risk surfers take.

“It’s the risk you take being out on the water there’s always going to be sharks there,” she says.

“I don’t want to go out too deep and I like to go out with other people … if I have a feeling there’s something in the water … personally, I will just go in.”