Hundreds of unwanted pests making it into New Zealand each year are presenting an unacceptable risk to the likes of agriculture and conservation, representatives from those groups say.
Figures obtained by Radio New Zealand from the Ministry of Agriculture and Forestry showed at least 400 pests such as insects, snakes, frogs and spiders made it through border checks each year.
Herpetologist Anthony Whitaker, who has studied border data, said snakes were the least of the country's worries.
On average four in a year were found past the border and most - 85 per cent - were dead. Snakes that had come off shipping containers were either killed by fumigation or - because most ships passed through the tropics - the heat.
Only one poisonous snake had been found in the past 10 years so the risk of any snakes establishing populations here was extremely low, Mr Whitaker said. Federated Farmers biosecurity spokesman John Hartnell said any lax security could potentially be disastrous to the agriculture industry.
"We only need one hiccup to completely throw the balance out for us. Obviously if we had something as serious as foot-and-mouth disease coming in on someone's dirty shoes or clothing - the ramifications of something like that are massive to New Zealand."
Forest and Bird had similar concerns, saying if New Zealand became a breeding ground for invading pests, which could breed at the expense of native species, it would be disastrous for the ecosystem and tourism.
MAF cargo clearance director Jeremy Lambert said most of the pests getting through were accidentally introduced, as opposed to being smuggled in.
He said staff at borders were working hard to try to weed out unwanted pests, but passengers also needed to play their part by declaring risk items at borders.
Mr Lambert said more could be done to minimise the introduction of pests, "but it's making sure that we're also not penalising those importers and passengers who are highly compliant and want to do the right thing".
All imports were risk-assessed against countries of origin and there was also a more recent focus on weeding out risks at the points of origin.
- NZPA, STAFF REPORTER