Western Australia’s Department of Parks and Wildlife has issued a reminder to the public of the hefty penalty for disturbing sea lions after footage emerged of a man harassing a number of the colossal beasts on an island off the coast of Fremantle.

The man was captured on CCTV video harassing sea lions on Carnac Island, 10km southwest of Fremantle, as well as in the water.

The department, which uses the camera to monitor the protected sea mammals, is investigating the March 10 incident.

“The vision of the man slapping and harassing sea lions is alarming,” senior wildlife officer Rick Dawson said.

“These are wild animals weighing up to 200kg, with large teeth, and if disturbed, they have been known to become aggressive and inflict a nasty bite.”

Adult male and adolescent male Australian sea lions frequently rest on Carnac Island to build up their body condition in readiness for the breeding season in Jurien Bay and the Abrolhos Islands off Geraldton.

Signs on marker buoys off Carnac Island warn people to keep at least five metres away from them.

Australian sea lions are the rarest sea lions in the world.

“We ask that people appreciate these magnificent creatures from a safe distance and allow sea lions to continue resting on island beaches,” Mr Dawson said.

People caught disturbing sea lions can be fine up to $10,000.