DNA tests have confirmed a bull shark was involved in the death of 16-year-old Stella Berry in Perth's Swan River last month, authorities say, as the WA government moves to expand its shark tagging program.
The evidence confirming a bull shark was responsible for Ms Berry's death is now being prepared for the coroner.
Tagging of adult bull sharks in the Swan and Canning River estuaries will begin over the next few days.
WA Fisheries Minister Don Punch said bull sharks could move comfortably between fresh and saltwater environments.
"I think [Stella Berry's death] heightened the issue in the public's mind," he said.
"The risk of a shark attack is not high, it's incredibly low.
"But these attacks do happen and that's why we're putting everything in place that we possibly can do … to advise the public when there is a heightened risk."
Assessments are also underway to identify suitable locations for the deployment of three acoustic receivers in order to track shark movement and volume.
The devices, costing approximately $25,000 each, would have a detection range of 500 metres in ideal water conditions and are expected to provide near real-time notifications of shark activity.
Ms Berry died after she was bitten by a shark while swimming near the Fremantle Traffic Bridge in North Fremantle about 3pm on February 4.
Her death was the first fatal shark attack in the river in 100 years.
Perth man Cameron Wrathall was severely injured in an attack by a bull shark while swimming in the river in the suburb of Bicton in January 2021.
Ten bull shark sightings since attack
The expanded tagging initiative supplements existing research by the Department of Primary Industries and Regional Development, tracking the movements of juvenile bull sharks in the Swan-Canning estuary.
Surf Life Saving WA has reported 10 bull shark sightings since Ms Berry's death in early February, an increase in public reports that Mr Punch said was positive news.
"We've started to see the reports come as people have sighted sharks. That's a good thing," he said.
"The more that we can get information about sightings, the more we can upload that into our SharkSmart system and enable people to make informed decisions about what they'd like to do."
WA's chief fisheries scientist, Dan Gaughan, said the expanded program would inform the government's existing and potential mitigation strategies.
"Culling is not part of our strategy," he said.
"This is very much a research and evidence-gathering process, as well as mitigating risk as soon as we possibly can."
Tagging should have happened two years ago: opposition
WA Liberal Leader Libby Mettam supported the tagging program, but said its introduction was too late.
"This should have happened in 2021, after the attack in Bicton," she said.
Ms Mettam said the state government has a "go slow" approach to shark mitigation and said it needs to get on with ensuring there are clear policies to protect swimmers.
"It's vitally important public safety is made a priority and it's extraordinary it's taken two years to make this announcement," she said.
