The Government has been told it is likely to need a genetically engineered solution to reach its ambitious pest-free New Zealand goal and that it should expect some staunch opposition from the public.
New Zealand scientists have been tasked with coming up with a breakthrough by 2025 which is capable of eradicating an entire species of mammalian predator.
It is part of a larger goal to exterminate all rats, stoats and possums from New Zealand by 2050, which was announced by the National-led Government in July.
Papers released under the Official Information Act show that officials are concerned about both finding a scientific "silver bullet" and whether the breakthrough will be publicly acceptable.
Such an ambitious policy could require novel methods, including genetic solutions, the Department of Conservation said in a business case for the predator-free policy.
Scientists around the world are looking at a range of potential pest control methods which involve varying levels of genetic modification or engineering. One of the possible solutions is "editing" an animal's genes to instil infertility throughout an entire population.
In a Cabinet paper, ministers were warned that genetically-engineered pest control could be controversial in New Zealand.
"Any science breakthrough in predator control must be both effective in the field and broadly acceptable to the community," officials said.
"Some iwi may be sensitive to issues where genetic solutions are involved. Such proposals may attract adverse comment from some iwi and other community sectors concerned with scientific work related to genetics."
Conservation Minister Maggie Barry said genetics was the "next frontier" for pest control.
She expected some backlash, but she did not believe that the issue of genetic modification or engineering was as sensitive when it came to eradicating pests or disease.
"Yes it is unpopular with a lot of people. I wonder whether that is something people feel more keenly when it's about food, and a little bit less keenly when it's about killing a mosquito that spreads a virus that causes so much misery."
Any breakthroughs would have to be tested against public opinion, she said.
Barry also emphasized that genetic solutions were "some way off". She pointed to other pest control technologies which were already showing promise, including self-setting traps and the use of audio recordings of baby rats to lure stoats.
Conservation biologist James Russel, from the University of Auckland, said scientists were now able to identify "the entire genetic architecture" of some species.
"That gives us great potential to minimise risk by being very specific to that species," he said.
"The challenge we have is translating that from the lab to the real world," he said.
The background papers to the Predator Free NZ policy also underlined the uncertainty in depending on an as-yet-unknown scientific breakthrough.
"The predator free goal is dependent on breakthrough science... but research outcomes are very uncertain", a Cabinet paper from July says.
Officials noted that a New Zealand consortium spent 13 years searching for a possum biocontrol, at a cost of $30m, without any breakthrough.
Predator Free NZ
• Govt has set goal of eradicating all mammalian predators by 2050
• By 2025, it expects to have a made a scientific breakthrough that will kill off an entire species of predator
• Rats, stoats, and possums kill around 25 million native birds a year
• $3.3 billion cost to the economy and primary sector a year