Australian Aerial Patrol general manager Harry Mitchell said the NSW Government's decision to conduct the three-week trial was "a step in the right direction" after years of trying to convince authorities of the need.

The trial, from December 19 to January 10 and including the Australia Day 2010 long weekend, will involve beaches that are part of the NSW Shark Meshing Program - stretching all the way from Wollongong to Newcastle.

Primary Industries Minister Ian Macdonald said the patrols would supplement rather than replace the beach meshing program.

"The main focus of the Government's campaign remains the beach meshing program; however, even though the risk of attack is slight, we are happy to add aerial patrols on a trial basis during the busiest times on our beaches," he said.

Mr Mitchell, whose Albion Park-based service has been operating for more than five decades, has been trying to convince the Government of the need for aerial patrols for 17 years.

The patrol, which originally covered an area from Mollymook to Stanwell Park, was extended in 1993 to travel as far as Sydney's northern beaches.

Since 1995, the patrol has campaigned for government financial assistance, without success.

"I applaud the fact Mr Macdonald has finally acknowledged that aerial patrols are useful. That's the start," Mr Mitchell said.

However, he added: "I don't understand why he's gone for the most expensive option.

"Fixed-wing aerial patrols are certainly quite effective, as we've seen for many years."

Mr Macdonald said the 2006 Shark Summit had found that fixed-wing aerial patrols would be "almost useless" for shark surveillance.

But the Government was willing to trial helicopter patrols during busy periods like Boxing Day and Australia Day.

He said helicopters had an advantage over fixed wing aircraft in that they could hover over a specific spot if needed.

Expressions of interest are being sought from companies interested in conducting the trial.

The helicopter trial will be conducted in conjunction with the work of the Australian Aerial Patrol.