The Department of Fisheries said it would work with police to assess whether action was required to remove the shark from the area.
A Rottnest Island local, who did not wish to be named, said there were a few people around the island on Saturday but not many in the water as the weather had been overcast with showers.
He said shark sightings were unusual in the area and the attack could affect tourism in the short term.
"Once you hear those things, it does put in your mind, do I or don't I?" he said.
"Normally, over here we don't see the sharks coming into the beaches.
"It's sad when you hear someone has died, I don't get in the water much myself, but that's where the sharks swim, unfortunately."
Police are still unable to say what injuries the man sustained, or whether he remained in one piece.
The man was in Australia on a work visa and had been living at North Beach.
Police are interviewing witnesses at the scene and a report will be prepared for the coroner.
The man is the fourth to be killed by a shark off the WA coast in 14 months.
Earlier this month, 64-year-old businessman Bryn Martin disappeared while swimming at Perth's popular Cottesloe Beach.
Last month, 21-year-old bodyboarder Kyle Burden was killed near Bunker Bay by a 4.5m shark and in August last year, surfer Nicholas Edwards, 31, was killed by a shark at a popular surf break near Gracetown.
-AAP
