NORMATIVAS NACIONALES E INTERNACIONALES SOBRE EL DERECHO A LA EDUCACIÓN

As noted above, once a screening and prioritisation process has been undertaken, risk assessments for pathways, policies and receptors also require assessments of the risks posed by one or more individual non-native species.

Chapter 4 Prevention measures

Three fundamental questions have to be answered in assessing the risks posed by non- native species:

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require to do so?

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concerned and how does it do so?

As noted above, for intentional introductions, the first question is irrelevant, and for species which are established, only the third question may be important.

Many subsidiary questions can also be asked to assess, for example, whether the organism can follow at least one pathway to reach the area, whether the abiotic and biotic environment is suitable for establishment, whether aspects of its biology, such as reproductive ability and adaptability, make successful colonisation more likely, whether it can spread and reach population densities known to exceed damaging thresholds and whether biodiversity and endangered species in particular will be harmed.

To standardise the production of risk assessments, several attempts have been made to construct schemes which can be used for many different organisms. Plant protection organisations have made the greatest efforts in putting together such schemes because risk assessments are required under the World Trade Organisation’s Sanitary and

Phytosanitary Agreement to justify all phytosanitary measures. International standards for risk assessment (FAO, 1996, 2001) have been generated and schemes following this standard have also been created, e.g. by the European and Mediterranean Plant

Protection Organisation (EPPO, 1997), to assess the risk posed by quarantine pests (primarily invertebrates and plant pathogens) to plants. Recent attempts by the CBD (Convention on Biological Diversity) to agree guiding principles on invasive non-native species have led to requests for the International Plant Protection Convention (IPPC) to explore the extent to which IPPC procedures can assist the implementation of the CBD guiding principles. The IPPC has confirmed that pests of all plants, whether cultivated or unmanaged, are covered by the convention and that both direct and indirect pests are included. Following this confirmation, efforts are being made to adapt existing risk assessment procedures so that they also work with indirect pests, such as weeds and other invasive organisms.

4.2.5.1 The EPPO Risk Assessment Scheme

There are several risk assessment schemes already available which are designed to assess the risk posed by one type of invasive non-native species, namely crop pests. Some of these are in the process of being adapted to cover a much larger range of non-native species which directly or indirectly harm plants. To assess whether crop pest risk assessments might form a useful template for more generalised risk assessments, the Review Group decided to test one of these schemes against a variety of organisms.

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The EPPO (1997) scheme was chosen for this test, and a risk assessment prepared by Cannon (2001) for Arthurdendyus triangulatus (New Zealand flatworm) was used as a template to show how the scheme should be followed for non-native species.

The EPPO Risk Assessment Scheme starts with an initial questionnaire to ensure that the organism has the characteristics of a harmful, invasive non-native pest before

continuing with the detailed section of the scheme. The main part of the scheme (see Annex 8) contains 46 questions which are scored from 1-9; high scores represent high likelihood or impact. The Review Group’s conclusions on the value of the EPPO Risk Assessment Scheme for the above four species can be found in Annex 8.

In summary, the EPPO Risk Assessment Scheme provides a good substantive basis for non-native risk assessment, but would benefit from development in order to meet a wider variety of purposes. Further development is already being undertaken within the EPPO system.

Sub-recommendation 2.2:

Plant health risk assessment standards and schemes should be used as a basis for constructing a general risk assessment scheme that can be applied to all non-native species. Plant health risk assessment procedures are widely applied and already recognised by the World Trade Organisation. Their use as a basis for generic risk assessments is likely to increase the speed with which they are accepted and adopted.

4.2.5.2 Receptor and pathway initiated risk assessment scheme

A prototype receptor-based risk assessment scheme was developed and investigated. The risk assessment scheme developed the six stages identified in Annex 9.

i. Problem formulation.

All risk assessments start with a specific statement of the problem to be assessed. As an example of a receptor-based problem, the Review Group posed the question ‘What is the risk posed by non-native mammal species to the conservation of certain breeding bird populations in the Western Isles’?

ii. Receptor definition.

For this particular assessment the starting point is the definition of the nature and geographical distribution of the receptor(s) of concern or potentially at risk from non- native species. In this case the problem was defined by those responsible for managing the risk to a particular group of receptors. The breeding birds might include populations of redshank, snipe, corncrake, and species of tern that nest in areas of the Western Isles, whether they are nesting in specifically designated protected areas or not.

Chapter 4 Prevention measures

iii. Pathway identification.

The objective of this stage is to identify and characterise the different pathways of concern, by which non-native species might be introduced to the particular sites and receptors defined in stage ii. In this particular case the starting point for identifying possible pathways for the introduction of non-native species was determined by concern about particular receptors thought to be vulnerable to introduction. For other problems, the starting point could be concern about risks posed by particular non-native species or groups of species, or concern about particular sources of non-native species.

iv. Hazard identification.

The objective of this stage is to identify and characterise the non-native species that may represent a potential risk to the receptors identified in i. above. In this case, because the assessment starts with a definition of the receptor, it may only be possible to outline the nature of the non-native species in broad terms, based on an

understanding of the nature of the receptor. For example in this case ‘Species of woody plant able to colonise and establish coastal meadows, coastal sand dune slacks, and machair and alter their suitability as nesting habitat by breeding bird species’ might form one group of potential invasive non-native species. Other areas of vulnerability to invasive non-native species (e.g. reduced breeding or hatching success through

predation or reduced opportunities for feeding) might help identify other broad groups of invasive species. Nevertheless, the assessment may guide the assessor to identify particular non-native species that represent a particular risk.

v. Preliminary risk assessment.

This stage involves bringing together information stages i.-iii. above and forms the basis of an initial risk assessment, including estimates of the probability of exposure of

receptors to invasive non-native species hazards via particular pathways, and estimates of the magnitude of the consequences for the receptors. The objective of this stage is to facilitate risk screening and prioritisation of the receptors, pathways and non-native species. For a receptor-initiated assessment, it may neither be possible nor desirable to do more than conclude which receptors are most vulnerable, or which pathways represent the greatest risk of introducing non-native species. Nevertheless, monitoring and other risk management actions can be based on these conclusions if appropriate.

vi. Generic non-native species risk assessment.

This stage entails a more detailed, possibly semi-quantitative, risk assessment. Where particular non-native species have been identified as potential hazards, this part of a receptor-based risk assessment might use a modified and developed version of the EPPO risk assessment scheme discussed earlier. Where, in a receptor-based assessment, the hazards can only be identified in a generic way, the purpose of this stage would be to characterise better the risks and reduce the uncertainty represented by non-native species to vulnerable receptors, the extent of that vulnerability in terms of possible consequences, and probability of exposure via different pathways.

It is anticipated that priority for undertaking risk assessments would be afforded to potential or new introductions. A retrospective trawl through all long-established non- natives is unlikely to be productive and hence is of lower priority.