"Today's competition has already been called off and all surfers have been advised not to surf in the area."
Women's competition was delayed for an hour on Monday morning after a man was bitten on the leg in Gracetown, 15km from were the event was being held at Main Point.
Competitors were able to complete the second and third rounds, with organisers ending heats for the day due to deteriorating surfing conditions.
Soon after, another man was bitten at nearby Lefthanders break.
Both men have been treated for their injuries.
When competition resumes, Australian world champions Tyler Wright and Stephanie Gilmore will contest the quarter-finals.
Men's stars Owen Wright, Julian Wilson and Joel Parkinson are set to compete in third-round heats.
-AAP