A large shark has been caught on a baited drum line at Falcon Beach in the same area local surfer Ben Gerring was mauled by a suspected great white shark 24 hours earlier.
The 29-year-old fly-in, fly-out worker was transferred by helicopter to Royal Perth Hospital on Tuesday night and is fighting for his life after losing his right leg in the attack which occurred around 4pm.
Three drum lines were set at the beach at 7am on Wednesday morning about 200 metres off the coast to try and catch the shark - which Fisheries suspect is a great white shark at least three metres long.
Images emerged on Wednesday at 3pm of a large shark seemingly snared on the lines.
The Department of Fisheries, on Wednesday morning, defended its warning systems for sharks reported off the WA coast.
A 3.5 metre great white shark was reported earlier on the same day by a member of the public about four kilometres south of Falcon Beach around 1.8 kilometres off-shore from Pyramids Beach.
Another tagged great white of a similar size was detected by receivers on the north side of Garden Island, about 40 kilometres north of Falcon, on May 27.
Fisheries metropolitan manager Tony Cappelluti said both reports were listed on the state government's Shark Smart website and Surf Life Saving WA's twitter account, but no further action was taken.
"It's very hard for us to predict what's going to happen [with shark movements], therefore the information we have that comes to hand is posted and if people want to use that information in their judgement about their use of the water then they should go to those sites...and make their own assessments," he said.
"The current policy, under the serious threat guidelines, is that in serious incidents or multiple sightings over a number of days, we will possibly take action, generally when there's an attack of a serious nature, as in this instance, we will set gear."
Mr Cappelluti said Fisheries was appealing for Mr Gerring's surfboard - snapped during the altercation - to be handed into authorities for experts to forensically examine it for clues to the shark species and size.
"We have no eye witness accounts seen of the shark, so it's difficult for us without that info to make an assessment, but given the seriousness of the injuries and previous occasions where such injuries have been sustained either serious injury or fatality, we believe it's more likely to be a white shark," he said.
"We will try to get whatever evidence we can to make a more reliable prediction.
"We're currently trying to find out who might be in possession of that surfboard."
Drum lines could remain at Falcon Beach for days with Mr Cappelluti saying authorities would make a decision whether to kill or release a shark after it was caught.
The WA government dumped its controversial baited drumline trial in 2014 after the environmental watchdog recommended against extending it, but is allowed to implement its "imminent threat" policy for any shark larger than three metres that poses a risk to public safety.