Police said in the statement that the man’s skateboard had been found, but had not been located.
Shortly after the attack, authorities received a public report of a shark sighting on the beach, the department said. The species is unknown.
Beaches in the area have been closed since then. Water Police conduct a naval search and rescue operation, with additional ships deployed to aid.
There have been at least six fatal shark attacks off the country’s shores this year, according to the Australian Shark Attack File at the Taronga Conservation Society of Australia. There were no fatal shark attacks in Australia last year and only one in 2018, according to the association’s database.
McGowan said that the state’s southern coast, especially near Esperance, was a known breeding ground for sharks like eggs.
Esperance is located about 720 kilometers (447 miles) southeast of the state capital Perth and is a popular diving spot.
There have been a number of shark attacks near Esperance in recent years – most notably in 2017, when 17-year-old Letizia Brewer was killed while surfing with her father.
Several attacks have also been reported in other Australian states including Queensland, New South Wales and Tasmania in recent months.