Ten SMART drumlines will be set 500 metres off the city's main beaches near existing shark nets in a three-month trial beginning in February.

The devices - also to be introduced off Sydney's northern beaches within the next month - alert a nearby boat crew when an animal is caught.

The crew then tags and releases sharks and immediately releases any marine animals.

"The more sharks that we can tag, the more that we can follow, the more information that we get, the more we learn about their movements and the better decisions that we can make about reducing the risk for beachgoers," NSW Primary Industries Minister Niall Blair told AAP on Monday.

Despite the Greens calling for the "outdated" shark nets to be removed, Mr Blair said that wasn't under consideration.

"They've been in the water since the 1930s between Newcastle and Wollongong and statistically they have shown there has been no major attacks in any of the beaches where the nets are in place," he said.

He hopes with more eyes and more tech in the water, the risk to beachgoers will be further reduced.

"But nothing can make the beach 100 per cent safe," he said.

"We still ask individual beachgoers to avoid risky conditions and to do the best thing and make smart choices and make sure they are as safe as possible as well."

More than 30 SMART (Shark Management Alert in Real Time) drumlines are operating off popular North Coast surf breaks Lennox Head and Ballina.

Two three-month trials starting March in Tathra and between Pambula and Merimbula are also planned.

Satellite-linked "shark listening" stations that provide real-time shark tracking are also positioned at Port Macquarie, Hawks Nest, Bondi and 18 other locations.

Australian Associated Press