Weeds and pests cost $840 million a year

Forest and Bird, Issue 292, 1 May 1999, Page 4

Weeds and pests cost $840 million a year

e cost of weeds and pests to the New Zealand economy is around $840 million a year, according to economist Geoff Bertram in a report commissioned by the New Zealand Conservation Authority. Quantifying the damage introduced weeds and pests do to the country, Dr Bertram produces evidence that more than one per cent of the gross domestic product may be lost in this way. The Conservation Authority called for the report to alert government and business to the need for better control of introduced pests and weeds. A complementary report on the species which cause the damage includes a ‘blueprint for action’ prepared for the Authority’s pests and weeds committee. Geoff Bertram estimates the loss of output suffered by the New Zealand economy each year is around $440 million a year. To prevent the level of infestation increasing, he believes the public and private sectors spend another $400 million a year. ‘The ecological, cultural and economic impacts of introduced pest organisms are

immense and ongoing, he says. ‘When intangibles such as the cost of pest damage to the conservation estate is added on, the bill comes to around one percent of gross domestic product. Theoretically, the advantage to New Zealand of getting rid of all pests is between $9 billion and $19 billion, according to Dr Bertram. (For serious economists, these figures represent a ‘capitalized burden’ of five percent and 10 percent on the annual costs to the economy.) ‘In New Zealand, large numbers of introduced species have positive economic value, including most pasture and crop species and domesticated animals, Geoff Bertram allows. ‘Introduced species represent an increase in biodiversity but they also pose a threat to indigenous ecosystems and hence reduce biodiversity. He defines pests as ‘those introduced species the impact of which has turned out to be negative’. ‘Pests are the downside of the large-scale experiment of colonizing the countryside with introduced species.’ he says. Many species now regarded as pests were introduced originally in the

hope of positive economic gains; examples are rabbits, possums, deer, goats, thistle and blackberry. Others, such as ship and Norway rats, mice, pasture weevil and insect pests, arrived naturally. ‘Once established, pests present a dilemma of whether to eradicate or control them. Generally speaking, eradication is very costly and has generally been regarded as not "cost effective" except in special places such as offshore islands. Most pest populations are capped in size by public spending, not eradicated. "Time is on the side of every potential pest organism which enters the country. Sooner or later it will end up in the wild where it may eventually wreak havoc on our economy, the environment, our cultural values, or our health’ Better border control is advocated. Preventing further introductions is far more effective than any ‘cure’ the report argues. Past systems have had an unbalanced emphasis on potential pests which threaten export markets or primary production rather than those affecting the natural environment and our unique fauna and flora.

Where it is cost efficient to eradicate existing and potential pest organisms this should be done as soon as possible. Although the initial costs of eradication may be high they usually outweigh the real and opportunity costs of management. Eradication and control of pests is a long-term investment in conservation and primary production. The recently released draft of the New Zealand Biodiversity Strategy sets its sights too low, according to Dr Bertram and his co-author Kevin Hackwell. Despite suggested expenditures of $46 million a year, the recommended goals will do little more than just hold the line over the next 20 years. ‘Poor biosecurity in the past has led to a pest problem which is a massive drain on the economy, they say. ‘A more ambitious biodiversity strategy should have a vigorous biosecurity regime dealing with existing and potential pests. This would not only help the recovery of many threatened species but also the economy, and greatly enhance our economic competitiveness.