Half of all fatal shark attacks take place in Australia. How can you protect yourself – and do electronic deterrents work?

Around Australia, authorities have a common set of guidelines for swimmers to help lower their risk of shark bites. Some commercially available deterrent devices can also reduce the risk of attack. Photograph: Mark Baker/AP

Many Australian swimmers and surfers are feeling hypervigilant about the ocean after a shark attack off a Sydney beach that has left a woman with critical injuries.

Each year about 16 million Australians visit the coast and about 42% enter the water, according to Surf Life Saving Australia data.