Update on 25 April at 3.15pm:
An Augusta-Margaret River Shire ranger has erected shark warning signage at Prevelly. The beach has not been closed.
The Department of Primary Industries and Regional Development (DPIRD) advises additional caution by water users in this area.
Fisheries officers from DPIRD are continuing to patrol the area and have been advising water users of the increased shark risk.
Shark sightings should be reported to Water Police on 9442 8600.
Alert issued on 25 April:
A shark WARNING has been issued for Surfers Point at Prevelly, in the Augusta-Margaret River Shire, after an surfer was knocked off his board by a two metre shark, of an unknown species.