GIGO

Possum Control

Imagine wandering into a picnic area only to find dead possums and dead birds scattered about, some of them with pieces of what looked to be poisoned carrot still in their mouths. This is the scene that greeted one hapless picnicker at Glentui, Mount Thomas, shortly after 1080 drops had been made in the area.

However, all was not what it seemed. The possums had, in fact, been shot and the "poisoned" carrot had been chopped up and dyed to make it look like 1080 bait. A dead duck left at the scene was not of a species common to the area, apparently having been brought from Lake Ellesmere for the "occasion".

It seems the scene was set, if somewhat ineptly, to prompt bad publicity for the 1080-based possum poisoning programme. Feelings tend to run high when it comes to using toxic chemicals to control the spread of cute furry animals.

There are intensive research efforts under way to try and find other methods of controlling the spread of possums, both for ecological reasons -- they're endangering our forest and bird populations -- and for economic reasons -- as Tb carriers, they're endangering our international beef trade. No one method offers the perfect answer, and there will no doubt be critics, informed and otherwise, of the various strategies.

The myxomatosis debate has shown us the problems of importing control agents, and genetically engineering an agent is also likely to raise an outcry.

Interfering with the gonadotrophin releasing hormone which controls reproduction is one possibility, but its chemical structure is identical in all mammals, producing concerns about making it species-specific enough to be effective and safe.

Being a marsupial, possum young are totally dependent on mother's milk for about four months, making them vulnerable to modifications of the timing or nature of milk production. Given recent debate over alleged cruelty to lobsters, imagine the possible reaction to "starving" baby possums, even if they are little more than a semi-developed foetus at this stage.

There are no simple solutions, but it is important that misinformation -- through deliberate actions or plain ignorance -- does not dominate the debate.

Vicki Hyde is the editor of New Zealand Science Monthly.