Developing management strategies for invasive species

Preventing the introduction of potentially harmful alien species and controlling and eradicating alien species which threaten ecosystems, habitats or species.

Providing legislation to control the introduction and spread of potentially harmful alien organisms including the strengthening of the enforcement and increasing the effectiveness of punitive measures. Developing a regulatory procedure for the introduction of alien organisms whereby the potential risks of introduction are comprehensively assessed against intended benefits prior to introduction. This assessment should be followed by the adoption of appropriate mitigatory or preventative measures.

Developing control and eradication programmes and providing ongoing support to existing programmes, based on a priority-rating system and in relation to costs and resources. This will consider threats posed to biodiversity, as well as social, economic, and environmental costs and benefits derived from using and removing identified organisms. The planning of intensive mechanical clearing operations should take account of job creation schemes and will provide for regular follow-up.

An invasive species is an exotic species (i.e. alien or introduced) that rapidly establishes itself and spreads in natural communities to which it is introduced. This behaviour may be different from that in its natural environment.

Many scientists believe the spread of exotic species is one of the most serious, yet least known threats to biodiversity. The presence or introduction of alien species or sub-species can potentially cause imbalances and changes to ecosystems. It can have potentially irreversible impacts, by hybridisation or competition, on native components of biodiversity. Applying the precautionary principle, governments should take measures to prevent alien species from causing detrimental effects on ecosystems, priority species or the habitats they depend on and establish measures to control, manage and, wherever possible remove the risks that they pose.

Alien organisms are plants, animals and microorganisms which do not naturally occur in an area, and which are deliberately or accidentally introduced by humans to ecosystems outside of their natural range. This may be at a local level, where species are moved from one type of habitat to another, or at a global level, where species are introduced into different continents or regions.

The degradation of natural habitats, ecosystems and agricultural lands that has occurred throughout the world has made it easier for alien species to establish and become invasive. Many invasives are "colonising" species that benefit from the reduced competition that follows habitat degradation. As global climate change occurs it will be a significant factor assisting the spread and establishment of invasive species.

The information that could alert management agencies to the potential dangers of new introductions is not known, or is not widely shared or available in an appropriate format for many countries to take prompt action, assuming they have the resources, necessary infrastructure, commitment and trained staff to do so.

As a consequence of the effects of invasive species, hundreds, even thousands of species, have gone extinct in the past few centuries on islands and many more are threatened with extinction. It is important to turn this isolation of islands into an advantage by improving the capacity of island governments to prevent the arrival of alien species with better knowledge, greater management capacity, quarantine and customs systems that are capable of identifying and intercepting alien invasive species, and improved legal frameworks.

Control measures should focus on reducing the damage caused rather than on merely reducing the numbers of the alien invasive species. Effective control will often rely on a range of integrated techniques. Most control measures will need to be regularly applied, resulting in a recurrent operating budget and the need for a long-term commitment to achieve and maintain results. In some instances, biological control may give long-term suppression of an alien invasive species without recurrent costs, but should always be implemented in line with existing national regulations, international codes and principle 10 above.

Governments should adopt a proactive, preventative and precautionary approach to control the introduction and spread of alien organisms. This approach would take into consideration the need to balance the risks associated with introducing and releasing alien organisms with the potential social, economic and environmental benefits derived therefrom.

Prevention is generally far more cost effective and environmentally desirable than measures taken following introduction of an alien invasive species. Priority should be given to prevention of entry of alien invasive species (both between and within States). If entry has already taken place, actions should be undertaken to prevent the establishment and spread of alien species. The preferred response would be eradication at the earliest possible stage. In the event that eradication is not feasible or is not cost-effective, containment and long-term control measures should be considered. Any examination of benefits and costs (both environmental and economic) should be done on a long-term basis.

The IUCN has prepared guidelines to prevent further losses of biological diversity due to the deleterious effects of alien invasive species. The intention is to assist governments and management agencies to give effect to Article 8 (h) of the Convention on Biological Diversity, which states that: "Each Contracting Party shall, as far as possible and as appropriate: (h) Prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species." These guidelines draw on and incorporate relevant parts of the 1987 IUCN Position Statement on Translocation of Living Organisms. They are more comprehensive in scope than the 1987 Translocation Statement, which they complement. These guidelines are concerned with preventing biodiversity loss due to alien biological invasions. They do not address the issue of genetically modified organisms, although many of the issues and principles stated here could apply. Neither do these guidelines address the economic (agricultural, forestry, aquaculture), human health and cultural impacts of alien invasive species.