A shark has been spotted in the Serpentine River in Furnissdale.
Fisheries officers sighted the shark around 9.50am on Tuesday.
The species is unknown.
River users are advised to take extra caution.
Fisheries advise unknown sp. shark sighted 09:50hrs 20/08, Serpentine River, Mandurah , Fisheries have been advised of a shark in the Serpentine river Furnissdale.— Surf Life Saving WA (@SLSWA) August 20, 2019