Locals had reportedly warned some surfers that a large shark had been spotted in the area earlier in the day, and some had posted the warning on social media.

Scientists have described a series of shark bite incidents in the area since 2023 as a bite “cluster” — a phenomenon that has been observed around the world.

Why do bite clusters occur?

“There seems to be these clusters of bites that do occur, which is what has occurred in South Australia,” Le Busque said.

Lance Appleby is understood to have been attacked by a shark while surfing near Granites Beach on the Eyre Peninsula west of Adelaide on Thursday. Source: AAP / Supplied by SA Police

Bond University environmental scientist Daryl McPhee said such patterns have been seen several times in Australia over the past two decades.

There was “little evidence” that each of the clusters of unprovoked bites in Australia were from the same sharks, he added.

“A very important piece of science is looking at understanding where sharks are and then you marry that with biophysical information, so information on water temperature, et cetera, then you can start to build a long-term picture of when you expect to see sharks in certain areas,” he said.

How common are shark attacks?

The average number of fatal shark bites in Australia each year between 2014 and 2023 was 2.7. In the previous decade, it was 1.8.

White sharks, more commonly referred to as great white sharks, are responsible for most fatal attacks in Australia. Source: Getty / Nautilus Creative

Great white sharks were responsible for most of the shark fatalities in Australia, McPhee said, adding that bull sharks tended to be responsible for many of the shark bites that occur on the east coast of Australia.

Swimming at dawn and dusk increased the risk of coming in contact with bull sharks, he said, but there were complexities in analysing the data on these attacks as “most people are also in the water later in the day, so you have more potential people in the water”.

How can people reduce their risk?

To reduce the risk of an interaction with a shark people should avoid going into “murky waters and don’t swim after rain”, McPhee said.

He urged surfers to use personal deterrents “that have been independently tested” and avoid areas of concentrated fish or bird activity.

Perception and fear

With additional reporting by the Australian Associated Press.