Scientists have applauded the Government's bold new bid to make New Zealand predator-free by 2050. However, they caution that major investment and getting all Kiwis on board would be the key to achieving it.

The Government yesterday announced plans to form a joint-venture company, Predator Free New Zealand Limited (PFNZ), in which it would invest $28 million, to spearhead pest eradication efforts, with hopes of exterminating all rats, stoats and possums in the country by 2050.

The new plan has four goals with a 2025 deadline: to sweep pests from another million hectares of land, to develop a scientific breakthrough that could exterminate at least one mammalian predator, to demonstrate areas of more than 20,000ha could be predator-free without the use of fences, and to complete removal of all introduced predators from offshore island nature reserves.

Creating a country where native wildlife was no longer threatened was a vision of one of New Zealand's greatest scientists, the late Sir Paul Callaghan, who told a public lecture shortly before his death: "It's crazy, it's ambitious, but I think it might be worth a shot."


After Prime Minister John Key revealed the plan at Wellington ecosanctuary Zealandia, the country's leading conservation scientists appeared just as upbeat about the idea.

"Predator Free 2050 is as inspirational as it is aspirational," said Dr Tammy Steeves, a senior lecturer in conservation and evolutionary genetics at Canterbury University.

She said "stacks" of threatened species would benefit from a mainland without introduced mammalian predators, among them the critically endangered and river-dwelling kaki, or black stilt, which could not be moved to predator-free islands or fenced mainland sanctuaries.

Non-native pests kill around 25 million native birds every year and although they have been cleared from nearly half of the country's small islands in a programme that began 50 years ago, a pest-free mainland -- an area of 26 million ha -- has remained a trickier question.

When the Herald investigated the issue in 2013, it was noted the cost of clearing possums and wallabies out from Rangitoto/Motutapu had cost $3.5 million -- by extrapolation, the sum for the rest of the country had been estimated at $24.6 billion.

But researchers say that figure could change dramatically if new pest-beating technology was available.

Auckland University conservation biologist Dr James Russell said the Predator Free New Zealand concept had already attracted support from community groups, but the Government's investment was the "final jigsaw piece" to ensure the nation could move forward as one.

"The overwhelming evidence from our offshore islands shows that scaling this model of conservation to our largest North and South Islands is the best return on investment we can make not only in conservation, but also for the social and public health benefits."

Matching its funding with existing agencies, such as regional councils, philanthropists and the Department of Conservation, represented a "powerful investment", particularly to allow scientists the freedom to research potential game-changing technologies that might be required.

Just as the aerial distribution of rodent bait was the game-changing technology in the 1990s, the effort would need at least one if not more game-changers across the physical, natural and social sciences to achieve the 2050 goal.

"Great examples exist across the country, including the recent logistically and technically and ecologically challenging Million Dollar Mouse eradication of mice from Antipodes Island, which was recently completed in record time, showing how we are becoming more efficient at completing these eradications," Russell said.

"However, while few New Zealanders will ever visit Antipodes Island, meanwhile across the mainland New Zealanders everywhere can now visit mainland sanctuaries on the backdoor of every major urban centre, and even contribute to their own sanctuaries in local reserves or their own backyard."

Without a clear idea of what knowledge advances would realise the goal, it was hard to make a reliable costing, he said.

"Certainly it will require a prolonged investment staged across multiple governments, but with the right economic model, the annual costs could be only a fraction of a per cent of GDP."

Landcare Research's Dr Andrea Byrom, who is heading the $26 million Biological Heritage National Science Challenge, agreed the new move could be a game-changer, something our biodiversity desperately needed.

"Scientists, professionals, philanthropists, volunteers and land owners have been doing a valiant job over the last few years, but barely holding the line," she said.

"Our precious biodiversity is in decline. If we're going to get on top of this problem, we've got to massively upscale the effort and find novel and clever ways to reduce the high labour cost. A lot of volunteers are starting to burn out. It's really hard to sustain the effort."

New technology such as wireless trap sensors that could indicate when a trap needed clearing, and traps that could kill several animals without needing to be re-set, could make a huge difference, she said.

But scientists around New Zealand were not just relying on the "here and now" technology, and the science challenge she was overseeing had exciting opportunities for investment in pest control research.

These included genetic interventions, species-specific toxins and super-effective trap lures.

After decades of slow and small incremental progress in new technologies for pest control, the pace of advance was now accelerating on several fronts, said Dr Wayne Linklater, of Victoria University's Centre for Biodiversity and Restoration Ecology.

There was also evidence to suggest that, on smaller scales, the marrying of Government, business and philanthropy could be timely and powerful enough to achieve the grand target.

But there was one enormous and largely unconsidered cloud on the exciting horizon: how to successfully eradicate predators from populated environments like cities and agricultural landscapes.

"Clearly there are large numbers and groups of people who care less than others about killing predators or just care about other things that might conflict with those goals."

Getting buy-in from New Zealanders would be a greater challenge than the biology or technology problems ever were, he said, and our community of researchers were unprepared for it.

It was a point also stressed by Massey University conservation biologist Professor Doug Armstrong.

"For example, getting general community agreement is probably the major impediment at this stage to doing an eradication on Stewart Island," he said.

"This may actually become more of an issue as new technologies develop."

Promising genetic technologies could appear "quite scary" and be difficult to implement because of lack of public support.

"Another key issue is to ensure the funding is allocated to eradicating all of these species, and not just possums.

"Possum eradication has the greatest incentive in terms of its damage to the agricultural industry, but eradication of possums without sustained rat control or eradication could be huge conservation problem."

Dr Marie Brown, a senior policy analyst with the Environmental Defence Society and author of the book Vanishing Nature: Facing New Zealand's Biodiversity Crisis, meanwhile said the announcement was a "laudable step forward in our capacity to take on the dreaded mammalian entourage" at a time when business-as-usual approaches weren't delivering.

But the goal relying on partners matching Government contributions on a two-for-one basis had good and bad points, she said.

A key issue with partnership-oriented conservation was securing funding over time, and ensuring that ecological gains were able to be maintained in the event of partner exit.

She was also concerned that partners might influence focus areas, deviating from robust scientifically determined priorities that made the most difference to troubled biodiversity, at the least cost.

"On the other hand, this presents an opportunity to engage a wide range of stakeholders in this big idea and really make conservation everyone's business -- and let's not forget our freshwater and marine ecosystems along the way.

"The announcement also recognises that the impact of these species has an ecological and an economic cost to New Zealand, and the importance of broad political recognition of that fact can't be understated.

"If we can corral contributions in the most efficient way possible and lock in the efforts to achieve the long-term goal, then we will be having very different conversations about nature protection in 2050."