A shark advice has been issued for Preston Beach, south of Mandurah.
Part of a whale carcass was reported by a member of the public in the area just before 10am on Friday.
Authorities say the carcass could attract sharks close to shore.
"Although sharks may be present along the Western Australian coast throughout the year, people should exercise additional caution," a DPIRD spokesperson said.
If you see a shark, report it to Water Police on 9442 8600.
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