The department urged the public to take “additional caution” in waters around the area.
The attack is the first fatal incident in Western Australia since March last year, when a surfer was mauled off a remote beach.
Since records began in 1791, there have been almost 1,300 recorded shark attacks in Australia, with more than 260 of them resulting in death.
Earlier this year in January, four shark attacks were reported along the New South Wales coast over two days.
One of the victims included 12-year-old Nico Antic who jumped from a rock into the Sydney Harbour and was attacked by a suspected bull shark.
He died a week later, with his parents saying in a joint statement they were “heartbroken”.