WSL Commissioner Kieren Perrow said the "exceptional circumstances" involving "really aggressive shark behaviour in the area" had informed the decision.

"The safety of our surfers is paramount and we've seen two fairly unique circumstances occur in the past few days," he said.

We've had two attacks to the north of us and really aggressive shark behaviour in the area, and to the south we've had beached whales and those have been there quite a few weeks leading up to the event.

"And then in the north another whale had beached and so all of those circumstances combined have created a situation that elevated the risk to us and taken it beyond what we are comfortable with."

Mr Perrow said he understood that the cancellation of the event would be a disappointment to local supporters, although the decision had been made in conjunction with competitors.

Two male surfers were reportedly left with leg injuries after they were bitten near Gracetown on Monday, forcing the competition at Main Break to be suspended.

Great Whites, bull sharks and tiger sharks are among the species to call waters around Western Australia home and are considered to pose the most serious threat to humans.

Angus Scotney, Arran Strong, Ellie Turner, Emily Currie, Hannah Bristow, Lucy Campbell competed in the WSL qualifying series for the United Kingdom, although did not progress to the WSL Championship Tour.

The Margaret River Pro is the third event on the tour.

WSL chief executive Sophie Goldschmidt said: "Surfing is a sport that carries various forms of risk, and is unique in that wild animals inhabit our performance environment. Sharks are an occasional reality of WSL competitions, and of surfing in general."

- Press Association