KEY POINTS:
Officials intent on getting the country's rampant possum population under control have a new weapon of mass marsupial destruction. It's not a new kind of trap or poison - it's information.
Armed with greater detail than they've had about where the pests are hiding and records of earlier control measures, they think they can get possum numbers down to as few as a pair per 100ha.
Some members of the human population might think that's a cruel idea. But a reminder of the harm possums do to the country should change their minds.
The 35 million to 70 million possums here are fond of the foliage of New Zealand's native trees and, according to Forest and Bird, chew their way through 7.5 million tonnes of vegetation a year.
That's bad for the bush and deprives native birds of food. Possums also eat the eggs and chicks of native birds.
What's more, Possums are the main carriers of bovine tuberculosis, which causes wasting in infected cattle and deer and can infect humans. The disease spreads readily, so cattle and deer herds are regularly tested and infected animals culled.
The incidence of the disease is falling, but infected animals are found and slaughtered in scores of herds each year.
Culling is essential to protect the country's dairy, beef and venison export industries, which are worth billions of dollars. All told, about $60 million is spent each year on possum-control measures by the Department of Conservation, regional authorities and the Animal Health Board.
Most of the total - close to $50 million - is spent by the board, which is funded by farming organisations and the Government to eradicate bovine TB. For the past year, as it has gone about its mission (in the face of sometimes violent opposition from people who don't like its methods), it has had a powerful new weapon.
Called VectorNet, it's a database combined with a geographic information system, or GIS. It took a couple of years to develop and deploy, at a cost of several million dollars, and in July it took top honours at annual awards dished out by industry publication Computerworld for excellence in the use of IT.
"VectorNet is the backbone of our programme to control TB in wildlife," says Alison Barrett, the board's business strategy and systems manager.
VectorNet keeps tabs on every facet of possum control, from planning the year's field activities to managing the 150 contractors around the country responsible for the killing, who access the system via the internet using handheld computers.
It is proving so effective, Barrett says, that the cost should be paid back within a few years through more effective targeting of possums.
The beauty of the system, says Jody Bullen, who played a key role in VectorNet's design, is the integration of geographical information - an area's shape, physical features and possum habitat - with operational data such as the number of infected herds in the vicinity and past, present and future control activity.
The board divides the country into five TB management areas - about 40 per cent of total land area, or 8.4 million hectares - where TB-infected possums are known to be near cattle and deer herds.
In any year, control operations are underway in about 800 areas, displayed at VectorNet's operational level.
But the system handles even finer detail: each task undertaken by a contractor is displayed at the activity level (there might be 8000 a year).
A typical activity could be the laying of traps to gauge remaining possum population density in an area where poisoning or trapping had previously been conducted.
VectorNet manages the whole process, from determining the need for a population count to sending coordinates for where the traps should be laid to a contractor's portable computer.
When the contractor retrieves the traps, he inputs the body count into VectorNet.
Getting rid of bovine TB won't require eliminating every possum in the country.
As in the human population, it's a disease that spreads through close contact, so the goal is to get the possum population down to a low level for long enough - about a decade - so that the dangerous disease dies out.
With VectorNet, says Barrett, authorities stand a chance of doing that.
"It's very exciting from our viewpoint that we could get rid of the disease once and for all from New Zealand."
Getting rid of every last possum would be no bad thing, either.
Anthony Doesburg is an Auckland technology journalist
