Previous Page Table of Contents Next Page

Overview of the management of invasive alien species from the environmental perspective

Clare Shine

IUCN Commission on Environmental Law, IUCN Invasive Species Specialist Group, with the help of contributors to the Global Invasive Species Programme; Consultant in Environmental Policy and Law, 37 rue Erlanger, 75016 Paris, France; e-mail:


The paper outlines the multiple impacts of invasive alien species and explains the rationale for coordinated international action to minimize their environmental as well as economic effects. It outlines the different components and current state of development of the international regulatory framework relevant to invasive alien species, with reference to plant and animal protection, biodiversity conservation, transportation and multilateral trade instruments. Some gaps and inconsistencies at national, regional and global levels are identified, together with indicators for possible ways forward.


This paper provides a response to four important questions relating to invasive alien species (IAS):

Why are invasive alien species an international environmental issue?

Introductions of species beyond their natural range are rising sharply because of increased trade, transport, travel and tourism associated with globalization. These provide vectors and pathways for live plants, animals and biological material to cross biogeographical barriers that would usually block their way.

Range and scale of impacts

Most alien (non-indigenous) species do not become invasive or cause problems in their new locations: many have great benefits to society, for example in agriculture, horticulture, forestry and aquaculture. However, the subset of alien species that do become invasive have major environmental, economic, public health or political implications for the country or countries concerned. For example:

Invasive alien plants have a range of impacts on native biodiversity including competition with native taxa of flora, hybridization with genetically close species, alteration of the physical and chemical characteristics of soil, modification of natural and semi-natural habitats and propagation of pests and diseases. Plants that are invasive in certain parts of the world and have caused severe impacts include water hyacinth (Eichhornia crassipes), melaleuca or paper bark tree (Melaleuca quinquenervia) and Miconia calvescens. The latter is considered the most damaging alien plant species in wet forests of Pacific islands. Over 60 percent of the island of Tahiti is heavily invaded, replacing the forest and its wildlife. This plant was introduced to Hawaii as an ornamental in the 1960s and sold by several nurseries before being listed as a noxious weed in 1992 (Loope, 1997).

South Africa’s Working for Water programme (refer and chapter 29 in this publication) was set up to control invasive alien plants established in over 10 million hectares of land, following an assessment of their multiple impacts. These included consumption of 7 percent of national water resources, reduced ability to farm, intensified flooding and fires, erosion, siltation of dams and estuaries and reduction in water quality. These plants were determined to pose the single biggest threat to the country’s native plant and animal biodiversity. The cost of these impacts was estimated at R600 million a year over 20 years (around US$ 100 million annually), likely to double within 15 years unless control measures were taken.

From a biodiversity perspective, the ecosystems most vulnerable to invasion are geographically and evolutionarily isolated ecosystems (islands, mountain ranges, lakes etc.) whose unique flora and fauna and biological communities have evolved over millions of years. Hawaii, for example, has 90 percent endemism for flowering plants and 99 percent for insects (Gagné, 1988).

Pathways for introduction and spread

Although impacts of biological invasions may be local, at least at first, the causes of introduction are mostly international. Through trade and transport pathways (see box overleaf), countries both send and receive non-native species. Species are also translocated within countries to areas or islands where they are not currently present and may become invasive in these new locations.

Unilateral action by some states is not enough to manage pathways for transmission of invasive alien species. Cooperation at the international, regional, transboundary and local level is needed to develop efficient and consistent approaches to shared pathways to minimize unwanted introductions.

Examples of pathways for introduction of species beyond their natural range

Pathways include:

  • movement of goods (species translocated in containers, planting media, untreated wood packaging, some food products)
  • movement of people (by air, road, rail and sea transport)
  • shipping and boating (ballast water, sediment, hull fouling, anchors)
  • aviation (in cargo and on and in the aircraft itself)
  • postal and courier services (including biological material purchased via the Internet)
  • agriculture and forestry (direct introductions of crops and livestock, unintentional introduction of pests and diseases)
  • horticulture (dispersal of ornamentals from gardens, ponds etc.)
  • habitat restoration and landscaping (use of non-native genotypes of native plants, escapes)
  • infrastructure development, interbasin transfers of water (e.g. between canals)
  • mariculture and aquaculture (fish, molluscs and crustaceans introduced for production)
  • aquaria (deliberate discards, discharge of organisms with waste water)
  • hunting and fishing (game species and live fish and bait introduced for sport and restocking)
  • release of pets or other domestic animals.

What instruments and tools have been developed?

Nearly 50 international legal instruments or guidelines deal with some aspect of IAS prevention or management. These set out policy or technical norms that provide a baseline for national legal frameworks. They fall into three broad categories:

The various instruments have been developed by different multilateral bodies at different times with different objectives, for implementation by different national agencies and sectoral stakeholders. This affects how they refer to invasive alien species, down to the terms, definitions and procedures used. Most national systems reflect this sectoral demarcation.

Protection of plant and animal health

Plant health

The International Plant Protection Convention provides a framework for international cooperation to prevent the spread of pests of plants and plant products between countries and to promote appropriate measures for their control within countries. It defines “pest” as “any species, strain or biotype of plant, animal or pathogenic agent injurious to plants or plant products” and covers direct and indirect damage by pests to both wild and cultivated plants. Invasive alien species are covered by the IPPC to the extent that they qualify as pests of plants or plant products.

The IPPC’s focus is not explicitly environmental, although some countries use the IPPC framework to support assessment of environmental risks. Until recently, there was no agreed guidance on how the IPPC applied to pests that affected unmanaged ecosystems or to damage to non-economic interests. Many - though not all - countries have for decades implemented pest and weed control policies without an internationally harmonized approach, with an almost exclusive focus on agricultural ecosystems.

In 2003, the Interim Commission on Phytosanitary Measures adopted new guidance on the application of IPPC pest risk analysis standards to specific environmental risks:

Wood packaging has provided a major pathway for transmission of invasive alien species that impact on native trees. In 2002, the ICPM adopted ISPM 15: Guidelines for regulating wood packaging material in international trade, which sets out technical and labelling measures to reduce the risk of introduction and spread of quarantine pests associated with wood packaging material in use in international trade.

Article VII.1d of the IPPC permits parties to “prohibit or restrict the movement of biological control agents and other organisms of phytosanitary concern claimed to be beneficial into their territories.” Existing guidance on application of this provision (ISPM 3) is currently being revised. Amendment proposals relate to introductions of biopesticides, soil enhancers, pollinators and sterile insects for pest control, as well as to strengthening risk analysis guidance (Quinlan et al., 2003). These proposals address some of the CBD Secretariat’s concerns raised in consultations with the IPPC on coverage of intentional introductions.

One regional plant protection organization, the European and Mediterranean Plant Protection Organization, has set up a Working Group on Invasive Species, which is compiling a common EPPO list of invasive alien plants as well as a detailed regional standard on analysis of environment risks.

In 2002-2003, FAO commissioned global reports and a database on invasive tree species and pests of forests: these outputs and improved baseline data should help to support future FAO and IPPC work on invasive plants. A growing number of countries now prohibit noxious weeds in commercial seed packages in line with international standards such as those set under the OECD Seeds Schemes for the varietal certification of seed moving in international trade.

Animal health

The Office International des Épizooties develops standards and guidance on pests and diseases of animals, including aquatic animals, but not on animals that are potentially invasive in their own right. OIE codes focus on agreed diseases of concern with regard to trade in animals and animal products and set out standards on import risk analysis and risk management measures for specific diseases. The OIE may consider risks to wild animals associated with disease transmission to or from livestock (e.g. rinderpest, avian influenza). It has a long-established Working Group on Wildlife which addresses wildlife management and reintroduction issues with an animal disease dimension, but does not cover related habitat and ecosystem issues.

The OIE Secretariat is reviewing its criteria for listing reportable and other diseases and considering whether to list diseases per se or pathogenic agents of these diseases. It is considering development of a broader risk-based approach which would take other criteria into account to determine access to export markets, including transparency in reporting and adequacy of detection procedures.

Like the IPPC (with its ISPM 6: Guidelines for surveillance, ISPM 9: Guidelines for pest eradication programmes and ISPM 17: Pest reporting), the OIE framework provides a legal basis for pest and disease surveillance, notification and control. OIE has a global network of over 150 Reference Laboratories working on the identification of new diseases and emerging hosts to develop harmonized detection and control methods. OIE, FAO and the World Health Organization (WHO) hold annual meetings to reinforce information exchange and improve coordination. In February 2003, they approved the joint implementation of a global early warning system and development of a joint strategy to strengthen regional activities for animal disease control.

Biodiversity conservation

In its Article 8(h), the Convention on Biological Diversity provides a comprehensive but very general basis for measures to protect all components of biodiversity against IAS impacts. Generic supporting provisions include requirements for strategic and cross-sectoral planning, management of potentially damaging processes and activities, involvement of local populations and the private sector, incentives, environmental impact assessment, transboundary notification and emergency planning (respectively Articles 6(a) and (b), 8(l), 10, 11 and 14 of the CBD).

In 1998, the Conference of the Parties to the CBD designated invasive alien species as a crosscutting issue to be taken into account in all thematic work programmes because of the problems they pose to indigenous and local communities and their negative effects on local and national economies. It also identified geographically and evolutionarily isolated ecosystems as needing special attention because of their vulnerability to biological invasion.

In 2002, the Conference of the Parties adopted a specific decision and guiding principles (CBD, 2002c; refer also footnote on page 7) to assist parties to implement Article 8(h). The decision reaffirms the importance of national and regional IAS strategies, sets out detailed recommendations for their content and urges closer international and regional cooperation in defined areas, including risk assessment and pathway management. The non-binding guiding principles aim to provide all governments and organizations with guidance, clear direction and common goals for developing effective strategies to minimize the spread and impact of invasive alien species, whilst recognizing that each country will need to develop context-specific solutions. They are based on a three-stage hierarchical approach (CBD guiding principle 2):

The guiding principles are divided into four sections:

(For further discussion on the 15 guiding principles, refer chapter 1 in this publication.)

In 2002, the Conference of the Parties endorsed the Global Strategy for Plant Conservation, which sets the target that management plans should be in place by 2010 for at least 100 major alien species that threaten plants, plant communities and associated habitats and ecosystems. This is a major departure for the CBD because it sets specific targets: a key question is whether the necessary financial resources will be directed to achieving these goals. At least one region has acted on this target: the European Plant Conservation Strategy sets a series of goals to be met by 2004 and 2006 (CBD, 2002a).

For dry and sub-humid lands, the CBD has concluded a joint work programme with the United Nations Convention to Combat Desertification (UNCCD), which includes management of invasive alien species in its list of priority actions. However, the Conference of Parties to the UNCCD has not yet adopted IAS-related decisions or guidance to prevent the introduction of potential invasive alien species when selecting species and varieties for programmes to tackle land degradation, erosion control and deforestation.

Risks to particular species groups

Instruments and programmes that focus on IAS prevention in the context of particular species groups include:

Risks to particular ecosystems

Several instruments address risks posed by invasive alien species in the context of aquatic and marine ecosystems. Preventing unwanted introductions is particularly important in aquatic systems because invasive alien species are harder to detect and can disperse rapidly, making eradication or control extremely difficult. Once an introduced freshwater or marine species establishes a reproductive population, it offers far fewer opportunities for effective containment and suppression than terrestrial species and its spread is usually considered irreversible. In the very few cases where containment or suppression has been possible,[3] key factors included very early detection (sometimes by chance), distribution still limited to a very small, containable area and prior development by competent authorities of contingency plans and alert systems for particular high risk species.

For the marine environment, introductions of non-native species are covered in a general way by:

For coastal and inland wetlands, parties to the Ramsar Convention on Wetlands are urged to address issues relating to invasive alien species in a decisive and holistic manner, making use of tools and guidance developed by various institutions and under other conventions (resolution VIII.18, November 2002). They should recognize that terrestrial invasive alien species can affect wetland ecological character (e.g. lowering of water tables, alteration of water flow patterns), ensure that appropriate measures to prevent or control such invasions are in place and undertake risk assessment of alien species that may pose a threat to the ecological character of wetlands, taking into account the potential changes to ecosystems from the effects of global climate change.

For inland water systems (rivers and lakes), introductions of alien species have very little regulatory coverage. The 1997 Convention on Non-Navigable Uses of International Watercourses does make reference to introductions of invasive alien species as a damaging process but the convention has still not entered into force. Only a very few bi- or trilateral water agreements have work programmes that address risks posed by invasive alien species (e.g. Lake Victoria, the Mekong River). Use of alien species in aquaculture and restocking for commercial and recreational fisheries is not subject to binding rules at the global or regional level (discussed further below).

The FAO database on aquatic introductions now covers freshwater fish, molluscs, crustaceans and marine fish. Some regions are actively developing aquatic database networks, for example the Smithsonian Environmental Research Centre Aquatic Invasions Research Directory ( and the Baltic Research Network on Invasions and Introductions (

Specific transport and trade pathways


International shipping provides pathways for transmission of alien species via exchange of ballast water and hull-fouling. Efforts to reduce these risks are currently limited to one vector (ballast water).

The International Maritime Organization (IMO) supports a binding legal regime to avoid unilateral responses by individual states in such an international industry. In 1997 its members adopted voluntary Guidelines for the control and management of ships’ ballast water to minimize the transfer of harmful aquatic organisms and pathogens to assist governments, ship operators and owners and port authorities to establish common procedures to minimize associated risks (IMO, 1997). At least seven countries and three ports have now enacted legislation requiring ships calling at their ports to comply with these guidelines. The guidelines have provided the basis for developing the new IMO International Convention for the Control and Management of Ships’ Ballast Water and Sediments, which was adopted by consensus on 13 February 2004.

Hull-fouling as a pathway for invasive alien species is not subject to international prevention measures, although CBD decision VI/23 paragraph 7 called on the IMO to develop mechanisms to minimize hull-fouling as a matter of urgency. (The IMO, the International Council for the Exploration of the Sea (ICES) and the International Oceans Commission (IOC) established a Study Group on Ballast and other Ship Vectors in 2003.) IAS risks related to non-shipping pathways (dredging, recreational boating, fishing, fouling of offshore oil and gas platforms) have also received little international attention. There is no international system in place to report, record and communicate newly detected marine species introduced to new areas, even via ballast water.

IAS risks associated with civil aviation (e.g. transport of the brown tree snake, Boiga irregularis, between Pacific islands) are being evaluated by the International Civil Aviation Organization (ICAO). In 2002, pursuant to Assembly resolution A33-18, it surveyed 188 states to gather data for an assessment of whether civil aviation is a ‘significant’ or ’high-risk’ pathway for unintentional introductions. The questionnaire covered possible vectors (aircraft structure, cargo, passengers, baggage, packaging, mail) and a range of control and enforcement measures. Preliminary analysis shows that about half of the respondent states aware of IAS problems in their countries consider air transport to be a contributing factor (the other half lacked the data to respond). Following a more detailed analysis, the ICAO Council will determine whether a prevention strategy is necessary and the submit the matter to the ICAO Assembly for further consideration.

Aquaculture and mariculture

Aquaculture, mariculture and restocking for commercial and recreational fisheries provide expanding pathways for unintentional introductions of alien aquatic organisms, including genetically modified organisms, to aquatic ecosystems (escapes, parasites, disease). There are no international rules regarding the potential environmental impacts of such operations, for example no requirement for prior assessment of risks related to release of alien aquatic organisms into transboundary water systems. OIE codes (see Animal health, above) focus on disease risks, not the invasiveness per se of introduced stock.

Some non-binding technical guidance has been adopted to establish principles and standards and provide best practice guidance for this rapidly growing industry. The FAO Code of Conduct for Responsible Fisheries (FAO, 1995) provides guidelines for the responsible introduction, production and management of fish species under managed conditions (FAO, 1996, 1997). It urges states to adopt measures to prevent or minimize harmful effects of introducing non-native species or genetically altered stocks used for aquaculture into waters and to develop international agreements for trade in live specimens where there is a risk of environmental damage inter alia in importing states. ICES, working with the FAO European Inland Fisheries Advisory Commission, has also adopted a Code of Practice on the Introductions and Transfers of Marine Organisms to reduce the risk of unwanted introductions of marine alien species into marine and freshwater ecosystems (ICES, 2003).

Relationship of existing instruments to World Trade Organization rules

Alien species are introduced through trade intentionally (imported products) or unintentionally (e.g. as by-products, parasites or pathogens of traded products; as hitchhikers in vessels, vehicles or containers that deliver products or services). National measures to minimize unwanted introductions, in the form of quarantine and border controls on live species, commodities, packaging and other vectors, potentially affect international trade and need to be consistent with rules and disciplines adopted within the WTO framework.

Of all the instruments described above, only the IPPC and OIE have a formal relationship with the WTO system. The WTO Agreement on the Application of Sanitary and Phytosanitary Measures 1995 provides for use of international standards to promote harmonization of national protection measures that affect trade and avoid disguised barriers to trade. The SPS Agreement currently recognizes standards set by three organizations: IPPC (pests of plants and plant health); OIE (pests and diseases of animals and zoonoses); and Codex Alimentarius Commission (food safety, human health). As noted, none of these organizations has an explicit remit for biodiversity conservation.

The SPS Agreement was developed before the current international focus on invasive alien species. It goes some way towards consideration of IAS risks to biodiversity by providing that a WTO member may adopt national measures to protect human, animal, or plant health/life from risks arising from the entry, establishment or spread of pests, diseases, disease-carrying organisms or disease-causing organisms, and to prevent or limit other damage within its territory from these causes. Measures should be based on international standards where available: where no international standard exists or a higher protection level is sought, the state concerned must justify a national measure through scientifically based risk assessment. (Emergency or provisional measures are discussed in the following section on gaps and constraints.)

The SPS Agreement is therefore probably broad enough to allow importing countries to address environmental risks of invasive alien species provided that the country concerned has effective agencies, coordination between environment and other sectoral services, adequate legislation and sufficient resources for risk assessment to provide technical justification for national measures. This is often not the case, particularly for smaller developing countries and islands.

The SPS Committee Secretariat considers invasive alien species to be an emerging issue in international trade (Stanton, pers. comm). The committee’s agenda is determined by its members (national trade representatives). There has been no direct consideration of IAS issues to date, but problems raised before the committee are frequently relevant to invasive alien species even if framed in different language (weeds, packaging, virus risks in imported shell fish etc.).

In 2002, the World Bank and WTO established a Standards and Trade Development Facility with FAO, OIE and WHO. Its goal is to facilitate the coordination of capacity-building activities by standard-setting organizations and help developing countries meet their export obligations under the SPS Agreement, participate in the development of relevant standards and maximize their benefits from the agreement. World Bank start-up funds (US$ 300,000) are being used to establish a secretariat at the WTO, which will administer the facility on behalf of partner organizations and allocate funding from the Doha Development Trust Fund. The facility will fund pilot projects on capacity building: developing countries could, for example, submit proposals related to IAS issues and national capacity for risk assessment. A high-level Policy Committee will set guidelines, provide oversight and guidance on work programmes and evaluate progress.

Cooperation between relevant international organizations

Parties to the CBD support closer cooperation with IPPC, OIE, FAO, IMO and other relevant bodies and have invited them to consider incorporating criteria related to the threats to biodiversity posed by invasive alien species as they elaborate or revise standards and agreements, including those for risk assessment and analysis (CBD decision VI/23 paragraph 8).

Cooperation is most developed with the IPPC. In September 2003, the ICPM and CBD Secretariat completed a Memorandum of Cooperation that recognizes the overlapping objectives of the IPPC and CBD, calls for strengthened cooperation between secretariats and identifies areas for collaboration. The respective secretariats participate in each others’ meetings.[4] CBD-nominated experts have contributed to the working groups that developed several recent ISPMs (see “Plant health” above).

Cooperation between OIE and CBD is at a less developed stage. The OIE Secretariat has expressed interest in closer cooperation with the CBD, possibly including the development of a Memorandum of Understanding to specify respective roles (e.g. OIE has expertise in the area of bacteria and viruses) and areas in which OIE could be a formal provider of information (Vallat, pers. comm.). In 2004, the Conference of the Parties to the CBD called for closer linkages with OIE (decision VII/13, see CBD, 2004).

IPPC and OIE have observer status at SPS Committee meetings. The CBD Secretariat has requested similar status but this request is still pending. In 2004, the Conference of the Parties to the CBD requested the Executive Secretary to collaborate, whenever feasible and appropriate, with the WTO Secretariat in its training, capacity-building and information activities, with a view to raising awareness of IAS issues and promoting enhanced cooperation on this issue. The Executive Secretary was also asked to renew his application for observer status in the WTO SPS Committee with a view to enhancing the exchange of information on deliberations and recent developments in bodies of relevance to invasive alien species (CBD decision VII/13).

The Conference of the Parties to the CBD also invited the WTO Committee on Trade and the Environment to take account of potential effects of global change on risks posed by invasive alien species to biodiversity and related ecosystem goods and services when considering the impacts of trade and trade liberalization (CBD decision VI/23 paragraph 15b). This has not been followed up, although some generic themes discussed by this committee are potentially relevant, for example greater use of environmental reviews and impact assessments as a national tool in trade negotiations. The 2001 Doha Ministerial Declaration and the Plan of Implementation issued by the 2002 World Summit on Sustainable Development both emphasize the importance of environmental reviews in WTO trade negotiations.

What are the main gaps and constraints from the environmental perspective?

Having outlined the existing instruments and tools that deal with aspects of invasive alien species, we now consider the main gaps and constraints faced by countries attempting to mitigate the impacts of invasive alien species. These include:

Lack of national capacity and adequate legal and institutional frameworks

Common constraints at the national level include:

Regional and subregional constraints

The impacts of invasive alien species may extend to a group of neighbouring countries. Constraints on effective action at regional and subregional levels include:

Gaps in pathway coverage

Many pathways and vectors are still not adequately covered by international rules, guidance or codes of best practice. In the plant context, for example:

In 2004, the Conference of the Parties to the CBD identified at least nine cases in which invasive alien species are not covered by international regulatory frameworks (CBD, 2004).

Lack of support for a preventive approach

The approach to invasive alien species is usually a defensive one. Existing frameworks do little to support “prevention through avoidance”. There are few deterrents to the continued use of environmentally harmful species in some sectors and few incentives to promote the use of native species, where suited to the intended purpose, as an alternative to introduced species.

There are few truly preventive rules to restrict exports of known/high-risk invasive plants or animals to countries where they are likely to be problematic. Plant and animal health frameworks provide mainly for certification to prevent the export of specific pests and diseases in the course of trade.

Some importing countries now use bilateral agreements to require their sources of import to carry out export control. New Zealand includes offshore measures in its import health standards for organisms that are neither plant pests or animal diseases, for example fumigation of widow spiders in table grapes from California and offshore inspection. This is permitted by national legislation, based on risk assessment, and is consistent with the SPS Agreement. Although these are not phytosanitary measures, United States Department of Agriculture inspectors have cooperated to ensure they are properly implemented.

Guidance under biodiversity-related instruments is non-binding only. It includes CBD guiding principle 4 (see chapter 1, “The role of states”) and CITES decision 10.54 urging parties considering exports of potentially invasive species to consult with the country of import’s management authority to determine whether domestic measures regulate such imports. (Note that CITES’ primary purpose is to prevent negative impacts on populations of species traded and not to restrict exports on the basis of possible impacts in recipient ecosystems.)

Importing countries have primary responsibility for determining which species should be prevented from entering and establishing, and choosing appropriate measures for this purpose. This is not a responsibility that can be shifted offshore. However, in terms of IAS prevention, it can be inefficient (risks not dealt with at source) or ineffective (where countries lack resources even for mainstream agricultural quarantine). More systematic regional cooperation and concerted action and stronger national frameworks are critical to address these constraints.

There are virtually no international early warning systems for invasive alien species as they affect wild species and natural or semi-natural systems. Tools applicable to plant pests should where possible be extended beyond an agriculture and forestry focus. The three widely used CABI Compendia (Crop Protection, Forestry, Animal Health and Production) will give invasive alien species greater priority in the future, either in the respective compendium or through an Invasive Species Compendium. (The CABI Crop Compendium is already supplemented with information on invasive plants.) The Centre for Biological Information Technology (University of Queensland, Brisbane, Australia) has supported an increase in user-friendly multimedia keys related to invasive alien species, including keys developed by the United States Department of Agriculture on aquarium and pond plants, rangeland grasshoppers and quarantine mites. Under development is “Declared Plants of Australia”, an interactive identification and information system focusing on noxious weeds (see

Lack of international standards for ‘environmental pests’

Plants and animals that are invasive in their own right are covered under IPPC or OIE only if they qualify as plant pests or animal diseases. Recent supplements to ISPMs (discussed above, “Plant health”) provide welcome guidance on application of pest risk analysis to environmental risks but do not extend the IPPC definition of “plant pest”. This excludes non-plant pests such as noxious invertebrates that hitchhike in plant commodities, for example spiders in table grapes, ants in taro. It is possible for national legislation to address this gap, for example New Zealand’s Import Health Standards extend the IPPC definition of “pest” to include all those new organisms that may affect the economy, human health or the environment.

The extension of some ISPMs to address environmental risks and costs will open up a new area for many plant health regulators. To make this guidance operational at national level, other agencies should be encouraged to contribute to the pest risk analysis process where information suggests that an introduction could have indirect impacts on biodiversity and ecosystem function. Quarantine and environmental personnel will need to develop a common approach to terms used in these sectors.

Constraints on risk and environment assessment tools

Assessment of environmental risks is complex for invasive alien species outside mainstream agriculture and forestry sectors because information is lacking and impacts, except for particularly invasive species, are largely unknown. Where a species is not problematic in its country of origin, it is difficult to predict impacts in a new country. Existing tools do not usually cover ways to deal with species already in the country and determine factors of vulnerability for receiving environments. In the biodiversity sector, more advanced tools are needed to deal with uncertainty, including criteria on using risk assessment techniques, precautionary approach and adaptive management (see CBD, 2002b, paragraph 24 of draft guidelines).

The CBD’s guiding principles support decision-making based on the precautionary approach, including within a risk analysis framework. Precaution is not referenced in the WTO’s SPS Agreement, but finds some reflection in Article 5.7 thereof. This allows a member to provisionally adopt a sanitary or phytosanitary measure where relevant scientific information is insufficient, on the basis of available pertinent information. The member must seek to obtain the additional information necessary for a more objective assessment of risk and also review the measure within a reasonable period of time, established on a case-by-case basis (see Griffin, 2000). Precaution can thus come into play in the interpretation of the scientific evidence, which includes determining the level of uncertainty, and provide the rationale for an SPS measure prohibiting entry or imposing other restrictions (provided that WTO rules of non-discrimination, transparency etc. are observed).

Where information is lacking about possible impacts of introduced species on natural and semi-natural ecosystems, it is difficult to determine what is a reasonable period of time in which to obtain adequate scientific evidence to justify import or pathway controls. Species thought to be restricted to transformed ecosystems and previously poorly competitive species may turn up as invasive in natural or semi-natural ecosystems, sometimes after a long lag time, facilitated by climate change, disturbance, fire or other factors. By the time invasiveness becomes apparent, consequences for wild biodiversity may be irreversible. In a non-environmental context, the SPS Committee is already addressing concerns about the duration of interim measures imposed by some importing countries pending the completion of risk assessment. These issues would benefit from closer dialogue between CBD, IPPC and WTO processes.

The SPS Agreement does not require importing members to do a risk assessment but to base the national measure on a risk assessment, i.e. the risk assessment itself could be done by another member, a regional body or a relevant international organization. The SPS Committee has considered regional risk assessments as a possible way to reduce length and duplication of procedures: these could be very useful for invasive alien species that are already problematic in several countries within a region and/or for species not yet present in a region but predicted to be problematic if they arrive. However, regional assessments would still need to be tailored to each country’s situation because risks of entry (pathways, volume) will differ, as will the potential for pests to establish themselves and their potential impacts.

CBD decision VI/23 paragraph 12(a) supports the incorporation of risk assessment methodologies into environmental impact assessments and strategic environmental assessments, as appropriate and relevant. Parties to the Ramsar Convention on Wetlands are urged, prior to moving water between river basins, to examine potential environmental impacts due to invasive species (resolution VIII.18, November 2002). However, national procedures for environmental impact assessment and strategic environmental assessment rarely address explicitly the risks posed by invasive alien species. Recent developments in environmental impact assessment and pest risk analysis could be a source of ideas for closer integration of procedures (e.g. the use of environmental impact assessment to measure potential indirect impacts of invasive alien species such as the alteration of water supply available to species of concern).

Under the SPS Agreement, assessment of environmental conditions is permitted as part of risk analysis, but the SPS Committee Secretariat has noted some reticence by members to move forwards on this aspect. One constraint may be the widespread lack of information on the environmental implications of a proposed introduction (Stanton, pers. comm.).

Gaps in institutional coordination

The Conference of the Parties to the CBD has invited key international organizations to consider the potential effects of global change on the risk of invasive alien species to biodiversity and related ecosystem goods and services when carrying out their respective functions. These bodies include:

Constraints on funding

CBD decision VI/23 invites international organizations to develop financial and other measures for the promotion of activities to reduce the harmful effects of invasive alien species. In paragraph 33, it requests the Executive Secretary, in collaboration with GISP, the Global Environment Facility (GEF), FAO and the Organisation for Economic Co-operation and Development (OECD), to “identify a mechanism(s) for providing Parties with access to financial support for rapidly responding to new incursions by alien species”.

To date, no dedicated mechanism has been designated to provide sustainable funding for prevention, rapid response and mitigation efforts. Financial support for capacity building to improve prevention and management of invasive alien species still has to be found on a case-by-case basis. IAS projects may be eligible for funding under four focal areas of the GEF: biodiversity, international waters, climate change and land degradation. GEF-funded projects with an IAS component include projects for Control of invasive species in the Galapagos Archipelago (Ecuador), Removing barriers to invasive plant management in Africa; and Control of exotic aquatic weeds in rivers and coastal lagoons to enhance and restore biodiversity (Côte d’Ivoire). GEF is expected to become the financial mechanism of the UNCCD, which could provide expanded opportunities to fund management of invasive alien species in the context of soil protection and land restoration.

More work is needed on mechanisms based (even loosely) on the polluter/introducer pays principle, such as levies on shipping and air transport, which could be used to generate renewable funding for investment in border control and management infrastructure.

How should we move forward at the global, regional and national levels?

Common goals for all levels should include making best use of existing regulatory frameworks, strengthening cooperation between key organizations and targeting existing tools and resources more effectively to encompass biodiversity-related impacts.

Considerations for the global level

Certain areas for international action warrant prompt attention:

As reflected in the most recent decision of the Conference of the Parties to the CBD (decision VII/13, see CBD, 2004), international cooperation and coordination would benefit from:

Invasive alien species must be given greater visibility as a trade-related issue. Recommended steps include:

Further work is also needed on sustainable financing for prevention, rapid response and management. The new WTO/World Bank Standards and Trade Development Facility needs to be given adequate long-term funding: as far as possible, biodiversity-related criteria should be incorporated into its policy guidelines and work programmes.

Considerations for regional and subregional levels

A wide range of cooperative and coordinated actions at the regional and subregional level could prove effective in dealing with invasive alien species:

Considerations for the national level

Possible action at the national level includes development of policy and regulatory frameworks and the engagement of relevant community groups and entities:

References and further information

CBD. 2001a. Sixth meeting of the Subsidiary Body on Scientific, Technical And Technological Advice, Montreal, Canada, 12-16 March 2001: information document, dated 26 February 2001: Comprehensive review of activities for the prevention, early detection, eradication and control of invasive alien species (document UNEP/CBD/SBSTTA/6/INF/3, available at

CBD. 2001b. Sixth meeting of the Subsidiary Body on Scientific, Technical And Technological Advice, Montreal, Canada, 12-16 March 2001: information document, dated 26 February 2001: Review of the efficiency and efficacy of existing legal instruments applicable to invasive alien species (document UNEP/CBD/ SBSTTA/6/INF/5, available at

CBD. 2001c. Sixth meeting of the Subsidiary Body on Scientific, Technical And Technological Advice, Montreal, Canada, 12-16 March 2001: information document, dated 26 February 2001: Report on existing international procedures, criteria and capacity for assessing risk from invasive alien species (document UNEP/CBD/ SBSTTA/6/INF/6, available at

CBD. 2002a. Sixth Conference of the Parties, The Hague, the Netherlands, 7-19 April 2002: information document, dated 28 February 2002. European Plant Conservation Strategy (document UNEP/CBD/ COP/6/INF/22, available at

CBD. 2002b. Sixth Conference of the Parties, The Hague, the Netherlands, 7-19 April 2002: Decision VI/7: Identification, monitoring, indicators and assessments to which is annexed Guidelines for incorporating biodiversity-related issues into environmental impact assessment legislation and/or process and in strategic environmental assessment (available at

CBD. 2002c. Sixth Conference of the Parties, The Hague, the Netherlands, 7-19 April 2002: Decision VI/23: Alien species that threaten ecosystems, habitats or species to which is annexed Guiding principles for the prevention, introduction and mitigation of impacts of alien species that threaten ecosystems, habitats or species (available at

CBD. 2003. Ninth meeting of the Subsidiary Body on Scientific, Technical And Technological Advice, Montreal, Canada, 10-14 November 2003. Invasive alien species: identification of specific gaps and inconsistencies in the international regulatory framework (document UNEP/CBD/SBSTTA/9/15, available at

CBD. 2004. Seventh Conference of the Parties, Kuala Lumpur, Malaysia, 9-20 and 27 February 2004: Decision VII/13: Alien species that threaten ecosystems, habitats or species (Article 8 (h)) (available at

FAO. 1995. Twenty-eighth Session of the FAO Conference: Resolution 4/95, adopted 31 October 1997: Code of conduct for responsible fisheries. Rome, FAO. 41 pp (also available at

FAO. 1996. Precautionary approach to capture fisheries and species introductions. FAO Technical guidelines for responsible fisheries 2. Rome, FAO. 54 pp (also available at

FAO. 1997. Aquaculture development. FAO Technical guidelines for responsible fisheries 5. Rome, FAO. 40 pp (also available at

Gagné, W.C. 1988. Conservation priorities in Hawaiian natural systems. BioScience, 38(4): 264-271.

Griffin, R. 2000. The fundamentals of risk analysis and its practical application. World Trade Organization SPS risk analysis workshop, Geneva, Switzerland, 19-20 June 2000 (available at

ICES. 2003. ICES Code of Practice on the Introductions and Transfers of Marine Organisms 2003 (available at

IMO. 1997. Twentieth IMO Assembly: Resolution A.868(20), adopted 27 November 1997: Annex - Guidelines for the control and management of ships’ ballast water to minimize the transfer of harmful aquatic organisms and pathogens (available at

IUCN. 2000. IUCN Guidelines for the prevention of biodiversity loss caused by alien invasive species. Approved by the 51st Meeting of the IUCN Council, Gland, Switzerland, February 2000 (available at

Loope, L.L. 1997. HNIS report for Miconia calvescens. Harmful Non-Indigenous Species (HNIS) Database, a product of the Hawaiian Ecosystems at Risk (HEAR) Project, University of Hawaii, Honolulu (available at

Pimentel, D., Lach, L., Zuniga, R. & Morrison, D. 2000. Environmental and economic costs of nonindigenous species in the United States. BioScience, 50(1): 53-65.

Quinlan, M.M., Mumford, J.D., Waage, J.K. & Thomas, M. 2003. Proposals for revision of Code of Conduct. Biocontrol News and Information (BNI), General news, 24(1): 1-3N.

Sala, O.E., Chapin, F.S. III, Armesto, J.J., Berlow, R., Bloomfield, J., Dirzo, R., Huber-Sanwald, E., Huenneke, L.F., Jackson, R.B., Kinzig, A., Leemans, R., Lodge, D., Mooney, H.A., Oesterheld, M., Poff, N.L., Sykes, M.T., Walker, B.H., Walker, M. & Wall, D.H. 2000. Global biodiversity scenarios for the year 2100. Science, 287: 1770-1774.

Shine, C., Williams, N. & Gündling, L. 2000. A guide to designing legal and institutional frameworks on alien invasive species. IUCN Environmental Policy and Law Paper No. 40. Gland, Switzerland, Cambridge and Bonn, IUCN. xvi + 138pp (document UNEP/CBD/SBSTTA/6/INF/8, available at

[3] The striped mussel Mytilopsis sallei (enclosed marina, Darwin, Australia, 1999) and the alga Caulerpa taxifolia (enclosed bay, California, 2000). Both cases required acute use of highly toxic biocides with massive mortality to all native biota in the treated areas (Raaymakers, pers. comm).
[4] Examples include: Sixth Conference of the Parties to the CBD (COP/6, The Hague, the Netherlands, 7-19 April 2002); Third Meeting of the Intergovernmental Committee for the Cartagena Protocol on Biosafety (The Hague, the Netherlands, 22-26 April 2002); CBD/BioNET-INTERNATIONAL Third Global Taxonomy Workshop (Pretoria, South Africa, 8-12 July 2002); CBD Workshop on Liability and Redress under the Biosafety Protocol (Rome, Italy, 2-4 December 2002); FAO Technical Consultation on Biological Risk Management in Food and Agriculture (Bangkok, Thailand, 13-17 January 2003).
[5] Source: an unpublished report by CABI Bioscience compiled on behalf of the Global Invasive Species Programme.
[6] Workshop on Priorities for action in the collective management of IAS by Spain and its bordering countries, held in tandem with the First National Conference on Invasive Alien Species in Spain (León, 4-7 June 2003, organized by the GEI Grupo Especies Invasoras in collaboration with the University of León, IUCN/ISSG, GISP and the Council of Europe).

Previous Page Top of Page Next Page