Swimmers warned after shark attacks

Swimmers are more likely to die driving to the beach than be taken by a shark, NSW Primary Industries Minister Ian Macdonald says.

But there were some measures bathers could take to reduce the risk, he said in a statement on Tuesday morning following three frightening shark attacks off Australia's east coast in just two days.

In the latest attack on Monday, a snorkeller fought off what he thought was a bull shark that latched onto his right leg at the mouth of Lake Illawarra on NSW's south coast.

This incident follows separate attacks by great whites on Sunday that left a 31-year-old male surfer at Tweed Heads, in far northern NSW, and a 13-year-old girl in Tasmania with gaping leg wounds.

Mr Macdonald said people should avoid swimming alone, far from shore, in the dark or at twilight when sharks were most active.

Swimmers should avoid murky water or areas where baitfish are feeding and exercise caution when swimming near sandbars or around dropoffs which are favourite shark hangouts.

"One of the simplest things all swimmers can do is to remember to stay between the flags when you're swimming at the beach," he said.

"This is the best place to swim because the area is patrolled and observed by lifeguards who are there to ensure the safety of our swimmers."

He said while the NSW government had a beach netting program in place to help protect swimmers, people needed to be aware that when they entered the water they were entering the shark's domain.

"This initiative has helped provide a safer environment for beachgoers since 1937 with only one fatality recorded on a netted beach during that time," he said.

"At the end of the day the beach netting program is highly successful but there are no 100 per cent guarantees.

"The fact remains you are more likely to die driving to the beach than be taken by a shark."