Editorial

_______________________
by Emma Waterhouse

This issue of Environment News is late.  While I could blame winter, life’s usual craziness, work and a myriad of other things, the truth is that I have procrastinated on writing this editorial. And the reason is Rakitu. 

In case you’ve missed it, the Department of Conservation (as this issue goes to print) is about to drop brodifacoum-laced baits on Rakitu Arid Island off Aotea’s north eastern coast. And many people are unhappy about it. Many people also support it. The aim is to eradicate rats and in doing so provide further predator free habitat for our indigenous fauna and flora, including lots of birds. This approach works - on Burgess Island in the Mokahinau Islands just north of Aotea seven species of burrowing seabirds rapidly re-colonised the island following pest eradication, and with little active management. 

The debate about ‘the drop’ appears to be becoming more acrimonious by the day. Are personal attacks really what this is about? Apparently in this debate you are a ‘pro’ or ‘anti’ poisoner. To cast this situation in such a black and white manner suits many. But like most things, it’s not that straightforward. Nor are the very real trade-offs that are made if we flat out reject poison as a means of predator eradication. We don’t, for example, have an alternative - yet - that will work at scale and at a cost New Zealand can afford, and on the kind of terrain found on Rakitu’s coasts. So the question really is, if we don’t use poison in  some very limited instances, can our birds and other biodiversity wait?

Aotea Great Barrier isn’t the first island or community to grapple with these issues. The local board on Lord Howe Island looked thoroughly at all methods available for their island, with a permanent population of about 400 people. The outcome - bait stations and hand broadcasting of bait in as many areas as they could (including in and around settlements ) and aerial poison on coastal and inaccessible, cliff areas. An independent  human health risk assessment was undertaken along with similar studies on non-target species, the marine environment and tourism, and they worked through community concerns.

That eradication is now scheduled for next winter and would be the biggest ever attempted on an inhabited island. If you are interested in some very good information on the Lord Howe Island project, the research and reports (including the history and approach to community involvement in the decision making and a very interesting study on what fish do when they encounter the baits) then head to the project website. It’s both balanced and informative (lhirodenteradicationproject.org). Overall, their studies conclude that there is a very low risk to human health and the environment given the relatively small quantity of poison to be used, in a ‘one-off’ eradication.

The Lord Howe work and other researchers note that, ‘one-off’ use of brodifacoum in an eradication program is very different in terms of potential environmental effects when compared to ongoing sustained use.

From the information I could find, it appears about 4-6 kg of pure brodifacoum active ingredient are contained within all of the brodifacoum products sold in New Zealand each year. Of the brodifacoum sold, about 50% is used by private contractors. Other users are regional councils (30%), the Department of Conservation (15%) and private landowners (5%). Private contractors use brodifacoum as one of a variety of tools, mostly in bovine tuberculosis (Tb) vector (possum and ferret) control, regional councils at key biodiversity sites and the Department of Conservation now only use brodificaum on offshore islands, mostly in one-off rodent eradications.

So great is the loss of biodiversity in New Zealand that, when you get a glimpse of its true richness, it takes you a while to recognise it.

Researchers also say that the risk of secondary exposure to native non-target species is likely to be greater when brodifacoum is applied to the environment in a sustained manner. I am much more concerned about sustained ongoing use of brodifacoum in New Zealand than I am about one-off rodent eradications, such as that planned for Rakitu (that will deliver far more ecological benefit than cost)  and those that have already successfully rid large offshore islands of rodents—and where no poisons are now needed.

The ‘anti’ poisoners seldom talk about the trade-offs of not using poison in such situations. If the early conservationists (visionaries) in New Zealand, and those that followed, had waited and not used poisons to rid offshore islands of rats and stoats, then there is no doubt that many of our iconic species would now be consigned to the museum. That’s the very real trade-off.
For the record, I don’t like poison. But I’m also a scientist and in some situations, I can accept a very low level of human and ecological risk, based on the evidence to hand. And full consideration of alternatives and consultation with affected communities. I also understand that no level of risk, however low, is acceptable to some people.  We also all have a right, in this country, to express our opinions without fear.

I’ll leave you with an extract from an article by Dave Hansford on predator free Fiordland in the New Zealand Geographic's latest issue that summed up for me, why we do what we do:

So great is the loss of biodiversity in New Zealand that, when you get a glimpse of its true richness, it takes you a while to recognise it. As we step ashore onto Chalky Island, we hear bird calls coming from the riotous rātā forest above that I can’t immediately identify -  tīeke, mohua, kākāriki. A falcon scuds overhead. And kererū; big flocks of them. Wilson and I start to wend our way -carefully, because there are seabird burrows everywhere - up through coastal scrub and into a bushy myriad: rimu, matai, rātā, kāmahi, hutu. The sun spangles in the putaputawētā.

Noho ora mai  

Environmental News Issue 39 Winter 2018