IT'S not completely out of the realms of possibility but not everyone's taking the bait after reports surfaced of a shark sighting at Lake Wivenhoe last week.
A post on the Facebook page Dorsal - Queensland Shark Reports described a report from a member of the public 'Mike' who claimed a 1.5m bull shark was observed by his 30-year-old daughter and her husband while fishing on the top side of the dam wall from a 3.4m tinnie around midday on January 2.
"It came up beside the boat and then submerged," the entry read.
The post attracted attention on Facebook with plenty positing their own theories about it.
Some swore they'd seen sharks there too, some voiced fears for their safety while others were more sceptical.
"Yeah closely followed by the Loch Ness, both were being chased by a UFO," Michael Hogan wrote.
Ben Griffiths: "Did it climb the dam wall? Sharknado must have carried it in."
"Ever heard of a shark attack in Wivenhoe dam? "I think you're pretty safe probably more chance having a car accident on the way there then being attacked by a shark," commented Aidan Sharp.
But how likely is it?
Seqwater spokesman Chris Owen said its dam storages across southeast Queensland were regularly patrolled and monitored and they were yet to see evidence of sharks.
"If anyone captures evidence of a shark in our lakes they should provide it to Seqwater to follow up," Mr Owen said.
He suggested it could have been mistaken with a lungfish; a protected species that can grow up to 2m long.
University of Queensland Professor of Zoology Craig Franklin said while bull sharks could live indefinitely in fresh water the only way one could get into Wivenhoe was if someone put it there.
While the logistics of getting a shark into the dam would be "quite a procedure" Prof Franklin confirmed it was possible.
"We've captured sharks in the Brisbane River, put them into a tank on the back of a ute and transported them to the University of Queensland - a 40 minute drive," he said.
"But you do have to know what you're doing because sharks need to be swimming the whole time for them to ventilate their gills so it needs to be a big tank - if they're not swimming they can asphyxiate and die."
He discouraged members of the community from attempting it.
"There's no point to that whatsoever; just let it be, let it get on with it's life."
Bull sharks are an aggressive species that feeds at dawn and dusk with populations found in the Bremer River around Ipswich as well as the Brisbane River.
"They have been reported to take humans but just as an opportunistic food source, it's not as if they are hunting humans specifically," Prof Franklin said.
"Sharks are an important part of ecosystems... it's great to see they are breeding in the Brisbane River, it talks to the health of the river and that's improving all the time."
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