Zoologist Barbara Wueringer says fear of the giant fish, which can grow up to six metres long, likely also contributed to its near-extinction.
"They are most endangered of all sharks and rays, the whole family of sawfish, and one species is considered to the most endangered of all marine fish in the world," she told AAP on Tuesday.
"The International Union for Conservation of Nature also listed them among the one hundred most endangered animals in the world - they're up there with rhinos."
The last populations of Australia's sawfish are thought to live across the Top End but there is little data to confirm how close to extinction they are.
Dr Wueringer wants to answer that question and find out what can be done to save them.
"Everyone who has seen a sawfish is pretty fascinated by them ... people aren't targeting them but every now and then a sawfish does take bait," she says.
Older Australians have told Dr Wueringer they remember when large sawfish were regularly caught and there was one unconfirmed sighting of a sawfish in northern NSW about 10 years ago, she says.
Source: SEA LIFE SYDNEY AQUARIUM
Destruction of their mangrove habitat and the use of nets, which tangle on their snouts, have seen them disappear from their former range.
Fisherman harvesting the animals for their fins is another obvious factor, Dr Wueringer says.
Sawfish move easily between fresh and salt water, hunting along the bottom of shallow muddy rivers and estuaries, swinging their snouts like a metal detector to unearth animals beneath the sand.
They're also known to slash at free-swimming fish, stunning or cutting them in half before gobbling them down.
Dr Wueringer wants to hear about sawfish sightings, be it of a live fish, a saw on the wall of a local pub or a photo. They can be reported at https://saw.fish.