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by  Helen Keyes and Carl Walrond

New Zealand’s native plants and animals, as well as its farming industries, can be threatened by pests and diseases that arrive from abroad. Biosecurity efforts aim to protect the country’s economy, health and environment by policing borders and monitoring invasive species.

Definitions and history

What is biosecurity?

Biosecurity encompasses the policies and measures taken to protect people, natural resources, plants and animals against potentially harmful species and diseases from other countries. It is a relatively new term that gained currency in New Zealand from the 1990s – especially after the passing of the Biosecurity Act 1993.

Changing approaches

In the past biosecurity mainly involved quarantine stations and border inspections. The focus was largely economic, aiming to protect the agricultural, horticultural and forestry industries from exotic pests and diseases.

Later, people became concerned about the negative impact of some introduced species on New Zealand’s environment, and native plants and animals. Introduced invasive species are the biggest threat to many native species – and growth in trade and tourism has increased the chances of new species arriving. These realisations have led to a more systematic and wide-ranging approach to protecting New Zealand, including more attention to marine biosecurity.

Quarantine stations

The early fear was disease – for humans, and for animals such as sheep and cattle. From the 1860s major ports built quarantine stations on islands. Incoming ships with sick people on board had to unload their passengers there until the all-clear was given. Port Chalmers was served by a station on Quarantine Island/Kamau Taurua, Lyttelton by Ōtamahua/Quail Island, Wellington by Matiu/Somes Island and Auckland by Motuihe Island. Many of these islands also had animal quarantine facilities, where imported animals stayed in yards until it was clear that they were free of disease.

Deliberate introductions

Attitudes towards importing exotic species have changed. From the 1840s European settlers imported many plants and animals that they thought were useful. In the 1860s acclimatisation societies were set up specifically to introduce exotic species. Settlers had some limited awareness of the potential for harmful introductions – under the Protection of Animals Act 1867 no one could import ‘any fox, venomous reptile, hawk, vulture or other bird of prey’. People could bring in and liberate any other species (unless it was deemed a threat to agriculture) until 1896, when the act was amended to give the government full control over animal importations.

Exotic nuisances

In the 1860s some settlers spoke out against introductions of exotic species. They were voices in the wilderness – most believed that animals from the old country (Britain) could not possibly be harmful. But farmers were soon struggling with the ‘small bird nuisance’ (introduced sparrows eating crops) and the ‘rabbit nuisance’ (rabbits eating pasture). Gorse spread from its intended hedgerows and became a prolific weed, and mustelids (stoats, ferrets and weasels), introduced to control rabbits, munched on native birds instead.

Legislation to protect farming

The 1849 Sheep Ordinance was introduced to protect sheep from imported diseases such as scab. Scab, caused by the mite Psoroptes ovis, made infected sheep lose condition and sometimes die. Imported sheep had to be inspected, and infected animals were quarantined.

The Diseased Cattle Act 1861 allowed provincial governments to ban the importation of cattle from diseased areas. Yet the government had little overall control of importation of farm animals until the Animals Importation Prohibition Act was passed in 1876. This allowed it to block imports of any animal that posed a threat to agriculture. The Codlin Moth Act was passed in 1884 after an outbreak of codling moth threatened fruit production. The Department of Agriculture began inspecting fruit and plants arriving at ports in the 1890s. Other legislation followed, with a focus on protecting productive industries from specific pests or diseases.

It was soon realised that many pests and diseases found in other parts of the world were absent from New Zealand, giving farmers a competitive advantage. But every new importation of animals or plants risked introducing new problems. Regulations governing importations became stricter over the 1900s, but were not comprehensive. For example, the Noxious Weeds Act of 1900 focused on threats that weeds posed to farming, not the natural environment. While the government was watching out for farm weeds, ornamental garden plants were easily imported. Many naturalised and became problem weeds in the bush.

Modern biosecurity

The biosecurity system

The risk of incursions of exotic species has historically been managed by the Ministry of Agriculture and Forestry (MAF) and its predecessors. The Biosecurity Act 1993 set up the framework for managing biosecurity risks. In 2004 Biosecurity New Zealand was set up within MAF to lead and coordinate the biosecurity system. In 2007 it merged with MAF Quarantine Services to become MAF Biosecurity New Zealand. The group has around 1,000 staff in New Zealand and overseas, including scientists, inspectors, vets, investigators, policy makers and legal experts.

Organisms (animals, plants, seeds and micro-organisms) that were not present in New Zealand before July 1998 cannot be brought in without approval from the Environmental Risk Management Authority.

Managing the risk of incursions and spread of exotic organisms also involves central, regional and local government, industry, the public health sector and community groups. The New Zealand public are encouraged to look for any odd plants or animals.

Reducing risk at the source

MAF Biosecurity New Zealand gathers information about emerging biosecurity risks and exchanges it with other countries. International trade treaties and multilateral agreements attempt to minimise risk at the point of origin (for example screening shipping containers and fumigating produce). New Zealand also has processes to reduce risks posed by its exports – for example meat has been inspected before exporting since the early 1900s.

Bee careful

The varroa bee mite is a parasite that significantly reduces the number of bees in a hive. It was first noticed in South Auckland in 2000. Transport operators and truck drivers play a key role in reducing the spread of varroa by ensuring bees don’t hitch rides in cargo moving from the North Island, where the mite is prevalent, to the South Island, where it is only found in Nelson.


Borders are the entry point for pests and diseases. Inspections, quarantines, customs clearance and border patrols aim to prevent them getting into New Zealand. At international airports, uniformed staff, declaration forms, detector dogs, amnesty bins and posters in different languages send a clear message that New Zealand has a stricter biosecurity approach than many other countries. The cabins and holds of inbound aircraft are sprayed with insecticides, and at the international mail centre in Auckland sniffer dogs and X-ray screening help intercept letters and parcels containing organic material.

The chance of accidental introductions through trade has grown. In 1915, 90% of New Zealand’s trade was with Britain and Australia. By the 2000s the volume of trade had grown and the number of source countries was much greater, increasing the likelihood that unwanted species would be introduced in cargo. For example second-hand vehicles from Japan pose a risk of introducing Asian gypsy moth eggs, a threat to the forestry industry. Over the 1990s the number of shipping containers landing in New Zealand ports doubled. In 2007 around 600,000 containers entered New Zealand. It is not feasible to inspect such a large number, so the risk that they contain something unwanted is assessed, taking into account things like country of origin. All high-risk containers are inspected.

Monitoring, eradication and control

MAF Biosecurity New Zealand has monitoring systems close to ports and airports, including traps that attract unwanted species such as moths and mosquitoes. If pests are found, eradication campaigns may be launched, but some have been unpopular due to public concerns about health risks. In the early 2000s aerial spraying was used against the painted apple moth in West Auckland, the Asian gypsy moth in Hamilton and the southern saltmarsh mosquito in a number of locations – leading to public protest in some cases.

If eradication is not an option, slowing or reducing the area of infestation are likely approaches. When didymo algae (Didymosperina geminata) were discovered in Southland in 2004, researchers found that eradication was unfeasible. A campaign was launched, urging waterway users to check, clean and dry their gear to try to stop, or at least slow, didymo’s spread. In early 2008 the algae had spread to many South Island waterways but there was no proof it had become established in the North Island.

MAF Biosecurity New Zealand also runs information campaigns to encourage awareness of known invasive species. Species such as the sea squirt (Styela clava) are more likely to be found early if people involved in marine recreation or work can recognise them and report any sightings.

External links and sources

More suggestions and sources

How to cite this page: Helen Keyes and Carl Walrond, 'Biosecurity', Te Ara - the Encyclopedia of New Zealand, (accessed 20 September 2021)

Story by Helen Keyes and Carl Walrond, published 24 Nov 2008