(CNN) -

After four fatal shark attacks in seven months, beachgoers on the south coast of Western Australia are understandably anxious about entering the water.

"Dawn and dusk are perceived to be the worst times for encounters so you see less people going out early morning and late evening," said long-time surfer Jack Carlsen, who is also a professor at the Sustainable Tourism Center at Curtin University.

"I still go out surfing, but I'm a lot more cautious," said Carlsen, who had his own encounter with a Great White in the same waters several years ago. "A lot of the shark experts say it's the one you don't see that will get you. And luckily, I saw it," he said.

The stretch of water along Western Australia's southern coast is now one of the world's most deadly for shark attacks. More people were killed by sharks there than anywhere else in the world in 2011, according to the International Shark Attack File.

The latest victim was 33-year-old Peter Kurmann, a father of two, who was taken on Saturday morning while diving with his brother Gian about one nautical mile off Stratham Beach.

Gian Kurmann is reported to have used his diving knife to try to fight off the shark, which he told police was about four meters long.

Experts later confirmed Kurmann was likely taken by a Great White, the fourth victim of an unprecedented string of attacks by the predators in West Australian waters.

"There is no scientific evidence to suggest that the shark related fatalities in WA are a reflection of an increase population size of white sharks. It is more likely that a combination of factors, including more people in the water and white sharks being present around the south west coast this time of year," said Ryan Kempster, a shark biologist and founder of Support Our Sharks.

After Saturday's attack, beaches were closed while authorities dispatched aerial and ocean patrols to scan the seas. A spotter plane sighted a three to four meter shark the same afternoon, but attempts to catch it failed and were aborted altogether when bad weather moved in.

It's become a familiar and unwelcome drill for local authorities who are trying to prevent any further attacks and reassure worried beachgoers that efforts are being made to protect them.

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