Earlier this year, conservation organisations were quick to congratulate Premier Mike Baird, for his plans to introduce non-lethal shark-control devices such as sonar buoys, eco-barriers, aerial patrols, lifeguard towers and other mitigation methods, as these operations had no ill effect on our marine life.

Not long after, however, the Premier made it clear he was also going to trial a so-called smart drum line, touted as non-lethal technology. Smart drum lines send out an electric signal to the contractor when an animal is caught on the baited hook (tied to a surface buoy) allowing a two-hour time frame for rescue, after which target sharks would be towed off and released elsewhere. But this technology is far from being non-lethal.

We caution against the expectation of the creation of a zero-risk environment when entering the ocean. 

In the Reunion Islands, the only place where smart drum lines have been tested before, no great white sharks were caught with this technology. The drum lines recently deployed in Western Australia never caught great whites. In Queensland, the figures for white shark catches in nets and drum lines are not differentiated. It appears only a few white sharks are caught on drum lines, but they did capture or kill 415 marine turtles over a nine-year period.​

The recent $30,000 Cardno Review, commissioned by the NSW government to assess non-lethal technologies, determined that smart drum lines have not been verified to catch great whites, and also explicitly stated the effect of this technology on non-target species was not known.

So smart drum lines (and drum lines) are no silver bullet for capturing great whites, which appears to be the aim of the program, but are good at catching and often killing lots of other threatened marine life. The Reunion Islands smart drum line experiment highlighted incidences of hammerhead sharks dying from stress within the two hours allowed to rescue the animal. 

There is also evidence of sharks being eaten while hooked within that same two-hour period. This is bad news for great and scalloped hammerheads in NSW, which are now listed as threatened with extinction, and are known to only have a 50 per cent survival rate after fighting on fishing lines or drum lines.

The threat to the critically endangered grey nurse shark, already at risk due to mortality in NSW beach shark-meshing programs, is also of immense concern. We have no idea about their survival rates after being released from a drum-line hook, and with a population of only about 1000 individuals (16 of which were killed in shark nets in the past five years), any grey nurse death on a drum line will be extremely troubling. 

And what of the great white shark itself – a species under state, national and international protection. If they are caught on a drum line, will they survive the first two hours, and will they survive after being released?

The NSW government must abandon such a killing program, but if it persists, the Commonwealth should "call in" the proposal under the Environment Protection and Biodiversity Conservation Act for full environmental impact assessment.

Ultimately, we view the Commonwealth as having final responsibility for protecting nationally listed threatened species, and yet, disastrously, the federal government is busily trying to divest itself of all national environmental obligations. Prime Minster Malcolm Turnbull must overturn such a catastrophic policy.

We caution against the expectation of the creation of a zero-risk environment when entering the ocean. We think the Premier's mix of non-lethal mitigation measures is to be applauded, and that the community at large remains understanding of the need to protect our oceans and the apex marine predators that sharks represent. We would ask the Premier to forget all about smart drum lines, and give further thought to preventing the ongoing decline of so many marine animals – that is what NSW environment law requires.

Michael Kennedy is campaign director for Humane Society International Australia.