Some conservationists and academics snort with disdain when they hear NSW and Queensland politicians saying the nets are an important part of shark control programs for Australia's most popular beaches.

They question how anyone can accept that nets centred in the water column - leaving plenty of space for sharks to swim around, above and below - could possibly make a meaningful contribution to public safety.

They point to a NSW Fisheries Scientific Committee report from a few years ago that found approximately 40 per cent of shark entanglements occur on the swimming side of the nets, closest to the shore.

And they cite government data on the confronting toll that nets take on non-target species: turtles, dolphins, rays, humpback whales and sharks not considered a risk to humans.

Dr Christopher Pepin-Neff, from the University of Sydney, has made a career out of studying the politics of shark attacks.

He believes the nets are still in use in NSW and Queensland because politicians have latched on to a myth that began 85 years ago when the first ones were installed off Sydney.

It was 1937 and NSW was worried the state's upcoming 150th anniversary celebrations might be marred by further shark attacks, so cash was allocated to get them in the water.

Their use has persisted ever since, despite the absence of scientific data to show they make a positive contribution to public safety, Dr Pepin-Neff says.

He says the nets are a prime example of politicians attempting to make ungovernable events governable in order to escape the political fallout when something bad happens.

"The myth is that they work," Dr Pepin-Neff says.

"However, shark nets do not work. Worse than that, they cause damage both to the environment and to public confidence by creating a false sense of security."

Marine biologist Lawrence Chlebeck, from the Australian chapter of the Humane Society International, has spent years collating the data released by NSW and Queensland on their shark netting activities.

He says a decade of data - from 2012 to this year - shows they catch more non-target species than sharks.

By his calculations, the three species of shark targeted in NSW - tiger, white and bull sharks - account for less than nine per cent of the 3404 animals caught over the decade.

He says target shark species accounted for 39 per cent of the 2370 marine animals caught in Queensland in that time, but that's because the state targets many more species of shark.

Currently, there are 19 types of shark on Queensland's list. Mr Chlebeck says eight have no record of involvement in bites in Australia and six are listed as endangered or critically endangered on the International Union for Conservation of Nature (IUCN) red list - the leading scientific assessment of extinction risks globally.

He also points out there have been 37 shark bites at netted NSW beaches since 1937, and Queensland has seen the same thing.

"Bites are still happening. And the line that there have been fewer fatalities has more to do with improvements in beach patrols and emergency responses," he says.

Federal Greens Senator Peter Whish-Wilson chaired a 2017 Senate inquiry into Australia's shark mitigation measures that recommended a phase-out of nets in the absence of evidence to show they reduce the risk of attacks.

"Basically this is arse covering," he says.

"There's just not many brave politicians out there that are prepared to take an evidence-based approach to this when they might find themselves ... lampooned and held responsible for a death."

He says shark nets are a spectacular failure that don't make beaches safe and act as weapons of mass destruction for protected and threatened marine life.

Earlier this year, NSW data showed 22 per cent of the 376 animals caught last netting season were threatened species. More than 60 per cent of everything caught died, despite routine patrols set up to assist with live releases.

Senator Whish-Wilson wants federal Environment Minister Tanya Plibersek to withdraw the exemptions NSW and Queensland shark nets enjoy because they predated the federal Environment Protection and Biodiversity Conservation Act.

"Any law can be changed. It's a matter of whether she's got the political will to do it," he says.

"Certainly the minister should be asking the shark net programs in both those states to provide just cause (as to why they should continue) given how much damage they do."

Earlier this month, NSW Agriculture Minister Dugald Saunders made it clear he had no immediate plans to remove the nets, which are deployed from September to April each year.

They went back in the water this week despite opposition from eight local councils that don't want them anymore and favour less harmful shark control methods.

Mr Saunders says NSW's netting program has been "successful" over many decades, with every effort made to minimise impacts on non-target species including fitting nets with dolphin pingers and the use of whale alarms.

But he says beaches must be made as safe as possible and the heat will fall on his government if nets are removed and there's one at Bondi, for example.

"At the end of the day it'll be my phone that's ringing if something goes wrong, or the premier's or the deputy premier's," he told Sky News last month.

"It is a consideration that we are making sure we're doing absolutely everything we can to protect human life."

Queensland's Fisheries Minister Mark Furner says human life will always come first and while the government is investing in research and technology there'll be no change until he's sure potential alternatives are safe.

"The effectiveness of the Shark Control Program has been repeatedly misrepresented by groups that demand our equipment be removed but who present no evidence that swimmers would be safer," he says.

He cites a 2019 report that looked at alternative shark control measures.

"(It) clearly indicates there are fewer shark attacks at Shark Control Program beaches compared to other beaches in Queensland, despite the fact that 86 beaches where the program operates are the state's most popular."

It found that since 1962 there'd been 27 unprovoked attacks at Shark Control Program beaches, and 55 attacks in other Queensland waters.

However, it should be noted that the majority of Queensland's coastline is not subject to shark control efforts.

The federal environment minister was not available to respond to calls for her to intervene.

Her office referred AAP's questions to the federal environment department, which said: "It is the responsibility of state governments to consider whether shark mitigation activities may have a significant impact on matters protected under national environmental law."

Australian Associated Press