Pictures of sawfish – dead or alive – needed from citizen scientists to help understand decline
A five-metre freshwater sawfish caught at the mouth of the Mulgrave River in 1938. (Supplied: Queensland State Library)
Marine scientists are examining if trophy fishing is partly to blame for sawfish being pushed to the brink of extinction around the country in recent decades.
A citizen science survey has been launched to help understand why the creatures went from being spotted regularly at beaches in Sydney and Melbourne to being rarely seen outside northern Australia.
Barbara Wueringer, a zoologist with Sharks and Rays Australia, said she would like people to submit pictures of sawfish they encounter, be they swimming in a river, accidently hooked by fisherman, or rostrums hanging in pub or fish and chip shop.
“Your sightings, no matter how long ago they happened, will help us work out how many sawfish there used to be, how many remain, and how we can help them recover,” Dr Wueringer said.
“If we can get a picture, we can then confirm the species from it.”
Taken as trophies
There are four known species of sawfish in Australia, all of which are considered endangered or critically endangered.
The data collected will be processed by researchers at Perth’s Murdoch University who have dubbed themselves Team Sawfish.
Rostrums can be seen in many homes, pubs and seafood shops. (ABC Radio Darwin: Jesse Thompson)
Associate Professor David Morgan said there was no doubt the sawfish’s status as a trophy had led to illegal catches.
“Globally there is a lot of evidence that we’ve seen over the last decade or so of people taking the odd sawfish as trophies,” he said.
“People now understand that they really are going extinct and it’s equivalent to taking a rhinoceros horn.
“They’re a critically endangered species, so they’re afforded the same protection globally as a lot of these well-known iconic species.”
This rostrum fashioned into a makeshift sword was seized by WA police in 2012. (Supplied: WA Police)
Dr Morgan said the unintended consequences of commercial and recreational fishing had played a large role in depleting sawfish populations in Australia.
“Because of their really long saw or rostrum, they get tangled in any sized net,” he said.
“It doesn’t matter if you’re a six-metre sawfish or a newborn pup, you get tangled — they’re extremely vulnerable.”
Human impact to blame
The depletion of coastal mangroves, hunting, and the creation of ports and dams were also behind the population decline, Dr Morgan said.
“Each species has slightly different reasons for why they’ve hit this critically endangered level, but generally it’s human impact that’s essentially the cause.”
He said the most recent sightings of sawfish were reported in North Queensland, in WA’s Gascoyne region, and as far south as Dunsborough in WA’s South West.
Dr Morgan said he hoped the survey uncovered new habitats.
“You’ve got to understand a lot of that northern Australian coastline is pretty remote and not a lot of targeted surveys have happened up there.
“It’s just building up a database of what people have caught where, even if it’s a photo of someone catching one or if it’s just a historic saw from a fish and chip shop or a pub.”