A marine ecologist has urged swimmers to be wary of activity in the water before jumping in, following the death of a 16-year-old girl who was fatally attacked by a shark in a river south of Perth.
Shenton College student Stella Berry was killed while swimming in the Swan River in North Fremantle on Saturday.
Police received reports the teenager had seen a pod of dolphins and had jumped in to swim with them when she was bitten by the shark.
After the attack, authorities closed the stretch of beach where the incident occurred, near the Fremantle Traffic Bridge.
Rangers from the City of Fremantle reopened the beach at 3.40pm on Monday, but authorities recommended additional caution when using the water in that area.
It was the first fatal shark attack in the river since 1923.
The City of Fremantle has said they were considering implementing additional safety measures on the river, including potentially installing shark barriers at some swimming spots and putting up shark warnings.
Warning for swimmers
Griffith University marine ecologist Johan Gustafson said it was important that swimmers also took precautions before jumping in the water.
"When you're entering the water, you've just got to give yourself a small risk assessment," Dr Gustafson said, adding this should include whether there was any "marine activity" occurring in the area.
"Say you've got diving birds, if you actively see dolphins feeding, for example, because then there'll be lots of mullet … if you see those, maybe go to a different area."
City of Fremantle mayor Hannah Fitzhardinge said she was consulting with the Department of Primary Industries and Regional Development (DPIRD) about mitigating future attacks in the Swan River.
"The river is a different system to the ocean, so that's certainly a very different question about how you might deal with sharks in the river. So, we'll take the advice of the experts on that," she said.
"What this has highlighted is that a lot of people don't know very much about the bull sharks, if it is indeed a bull shark. So, education is always part of the picture."
While authorities were still investigating exactly what type of shark attacked Stella, fisheries minister Don Punch said on Sunday the shark involved was "likely" a bull shark.
Shenton College principal Michael Morgan wrote a moving tribute to the teenager, describing her as a "star" who had "an impressive sense of conviction" about what she hoped to achieve in life.
"Stella illuminated classrooms and friendships with laughter and a smile," he wrote.
Shark tagging crucial: expert
Dr Gustafson said there needed to be more investment in shark tagging programs so authorities could better understand marine ecosystems.
"You actually get to get a lot of information, such as how long they stay in the water, what areas of these water systems do they stay in, or do they prefer to be in," he said.
"But, the more important thing is, you can link the actual presence of the sharks that have been tagged to any other sort of environmental factor or feature that's been occurring."
Shark tagging would allow individual sharks to be identified, monitored and tracked.
Dr Gustafson said it would mean experts and authorities could link shark activity to other marine activity, such as the migratory patterns of prey species.
"If you can tie them up [with] these movements of these prey species, you'll often always find you'll have more sharks hanging around," he said.
"If you've got a big feeding event in the water … you can have sharks around."
