Thousands of Western Australians gathered at Cottesloe Beach on Saturday morning to protest the state government's controversial shark mitigation program.

The crowd, estimated to be more than 4000, braved the windy conditions to condemn the program, which will see baited drum lines placed one kilometre offshore at Ocean Reef and Mullaloo, Trigg and Scarborough, Floreat and City Beach, Cottesloe and North Cottesloe and Port and Leighton beaches.

Mitchell Donald, Joshua Mitchell, Emily Hancock and Neenah Thomas added their voices to the anti-shark cull protest. Credit:Facebook

Shark fishermen will patrol WA waters and kill any tiger, bull or great white shark bigger than three metres spotted in the designated zones, while any sharks hooked on the drum lines will be killed and disposed of offshore.

The announcement outraged conservation groups and many ordinary WA residents including Natalie Banks.