Two academics have hit out at the Government's Predator Free 2050 goal, calling it "badly designed and unachievable".
They say the plan could lead to a decline in public support for conservation policy, because it's an "impossible" target destined for "inevitable failure".
The plan was announced by former Prime Minister John Key in 2016, and Conservation Minister Eugenie Sage has previously said it needed a "reality check".
Victoria University School of Biological Sciences associate professor Wayne Linklater and ecologist Dr Jamie Steer said their research shows the plan is based on flawed assumptions.
Those assumptions are:
- Predator extermination is the best way to protect biodiversity
- The country needs to eradicate every stoat, rat and possum to protect biodiversity
- A complete eradication of predators is possible
"None of these assumptions are true," Mr Linklater said.
"Complete eradication of predators is technologically impossible, and biodiversity is affected more in some places by habitat decline and plant eaters than it is by predators."
He said eliminating select predators from complex communities of plants, animals, and humans was likely to be harmful, causing populations of other introduced animals to erupt.
There are concerns about the safety and cruelty of predator control methods, and Mr Linklater said the goal failed to consider Māori views on predator management - especially on Māori lands.
Mr Linklater says the Government's approach to predator management should be varied, and should focus on developing biodiversity sanctuaries to supress predators and restore habitats.
"Biodiversity would thrive in the sanctuaries and then spill over into the surrounding areas, eventually creating a network of populations of our endangered species across New Zealand."
Brent Beaven, Programme Manager Predator Free 2050 at Department of Conservation (DoC), told Newshub it was aware of Dr Linklater's views, and met with him months ago to hear his concerns.
"People raising counter viewpoints to existing programmes is an important part of democracy," he said. "The DoC team which is developing the strategic plan have taken Dr Linklater's views into account, which has helped strengthen the programme."
However Mr Beaven says Mr Linklater has not fully understood the policy.
"We are well aware that nationwide eradication is currently not considered feasible," he explained.
"This is not a weakness, but rather one of the strengths of the programme - by setting the goal early, we have seen strong alignment in science effort that is helping guide rapid progress toward eradication being feasible.
"In the meantime, we are seeing investment in new tools and techniques that are going to make predator management more effective in the short-term."
The researchers said the Predator Free 2050 goal has raised questions about the relationship between scientists and policy-makers in New Zealand, with scientists afraid to publicly criticise the policy for fear of losing funding.
"There is widespread scepticism of the policy within the industry, but it is generally expressed in whispers," Dr Steer said.
"This replicates recent reflections on the difficulties New Zealand scientists have with criticising government policy. That said, more robust criticism has started to emerge, hopefully signalling the end of the 'honeymoon' for Predator Free 2050."