Cottesloe Beach in a Perth suburb was completely packed with people by 10 a.m., Perth Now reported. Many carried signs with messages such as "Save Our Sharks" and "Shame on Killer Colin," a reference to the state premier, Colin Barnett.
A small plane towed a banner over the crowd and similar rallies at other beaches in the Perth area that read "Great whites have rights."
Western Australian officials say the number of sharks in the area has grown. Baited lines were set out Friday to cull sharks, catching three tiger sharks.
Tim Nicol, vice president of Conservation Council WA, addressed the Cottesloe rally, saying the shark population has not grown. He said helicopters searching for sharks have spotted more only because they are flying longer hours.
"The cull is driven by fear and fear alone," he said. "It is rational not to cull marine life. It is emotive and irrational to spend millions hunting down and killing animals that were never likely to pose a risk to human safety."
Western Australia has the highest rate of fatal shark attacks in the world, according to Wikipedia. But they are rare with one in every 3 million scuba dives ends in a fatal shark attack.
In 2011, 118 shark attacks were recorded worldwide, 17 of them fatal.