Eloise Gibson: Gulf deaths cast shadow over conservation plans

After months of careful marketing, the best laid plans of the Department of Conservation were unravelled last week by a cruel piece of timing.

There is not a shred of evidence linking its dropping of rat poison on two islands in the Hauraki Gulf with the deaths of dogs and sea life.

But nor is there yet evidence of another cause.

The deaths came so quickly after helicopters dropped buckets of Brodifacoum on Rangitoto and Motutapu Islands, it was inevitable that people would make the link.

The timing could not have been worse for DoC.

It has been preparing for years for these bait drops, and has gone to considerable lengths to sell the benefits to the public.

If the explosion of birdlife on Tiritiri Matangi after a similar operation to remove predators is anything to go by, it may well be right when it says this is the first step towards what will one day be regarded as a highly successful conservation project.

Unfortunately, public attention is focused not on the bird sanctuary we may have in 10 years' time, but on the unanswered question of what killed two dogs and an unusually high number of dolphins and penguins.

With large die-offs of pilchards happening at about the same time, there is potent fuel for conspiracy talk - whether about a cover-up of the effects of Brodifacoum and/or the secret presence of 1080 in the water.

DoC maintains it has not dropped 1080 in the area for nearly two decades. Independent university testing of dead dolphins and penguins has found no evidence of internal bleeding - the tell-tale sign of Brodifacoum.

Even Friends of the Earth's Bob Tait, a vocal opponent of the poison drops, does not believe Brodifacoum is implicated. He has said that if 1080 was for some reason found in the baits, that would reawaken his suspicions.

DoC will hope that whatever caused the dog illnesses is found quickly.

The worst, and not too unlikely, scenario is that a culprit is never found.

Authorities are leaning towards a natural toxin, perhaps a marine algae, causing the dog deaths but warned that tests due back today and tomorrow might never provide the answer.

One scenario is that a natural toxin will be found to have killed two dogs and made others ill, while a pilchard virus such as the one that appeared in the 1990s simultaneously killed pilchards and, by extension, starved a larger-than-usual number of penguins.

How the dolphins might fit in is unclear.

The most likely outcome is a partial explanation that settles the dog deaths, and, at best, explains elevated deaths among one or two other species.

That will not satisfy the anti-1080 and Brodifacoum campaigners.

But at least it might allow the rest of us to go back to the beach.