ONE of Australia's leading shark experts believes shark-detecting sonar will not be feasible for at least five years.
The announcement came as hundreds gathered at Shelly Beach on Saturday to farewell Tadashi Nakahara who died after being attacked by a shark last Monday.
James Cook University professor Colin Simpfendorfer said while sonar systems showed promise, they were still not scientifically proven to keep people safe.
Prof Simpfendorfer, a shark specialist with the International Union for the Conservation of Nature, said educating people remained the best way to prevent shark attacks.
"Education is most important part of keeping people safe from sharks," he said
"Sonar is a work in progress. The technology hasn't been proven yet but it does have some potential."
He said sonar systems, which NSW premier Mike Baird had proposed to trial, were designed to alert beach goers to a shark's presence but would not deter sharks.
Prof Simpfendorfer said sonar, like existing shark-detection methods including tagging and helicopter spotting, could alert surfers and swimmers to a shark in the water.
"It's an alert system to let people know if a shark is in the area," he said.
"They still have to establish not just how the system detects sharks but how it then alerts people."
Prof Simpfendorfer said shark deterrents were mostly unproven or not effective.
"The reality is none of them will keep you 100% safe," he said.
"Short of setting up a physical barrier there's little you can do."
Mr Baird promised a $100,000 shark sonar system trial as his first election promise earlier this year.
He promised to not cull sharks, a practice that Prof Simpfendorfer said was not scientifically backed.