Environmental Impact Classification of Alien Taxa (EICAT)
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EICAT is the IUCN Standard for the classification of the impact of alien species on the environment. It is a simple, objective and transparent method that classifies alien taxa into one of five impact categories, according to the magnitude of the detrimental impacts to the environment.

Each of these five impact categories represents a different impact magnitude, depending on the level of biological organisation of the native biota impacted (individual, population or community) and the reversibility of this impact.

EICAT categories Photo: IUCN, 2020


The scheme can be applied at a national, regional and global level: all EICAT assessments undertaken at the global level will be made available through the IUCN’s Global Invasive Species Database.

EICAT has the following five objectives: (i) identify alien taxa by levels of environmental impact, (ii) compare the level of impact by alien taxa among regions and taxonomic groups, (iii) facilitate predictions of potential future impacts of taxa in the target region and elsewhere, (iv) aid the prioritisation of management actions, and (v) facilitate the evaluation of management methods. It is envisaged that EICAT will be used by scientists, environmental managers and conservation practitioners as a tool to gain a better understanding of the magnitude of impacts caused by different alien taxa, to alert relevant stakeholders to the possible consequences of the arrival of certain alien taxa, and to inform the prioritisation, implementation and evaluation of management policies and actions.

It must be emphasised at the outset that EICAT is not a risk assessment, and its output alone should not be used to prioritise management actions for alien taxa.

EICAT must be applied in a consistent and comparable manner when assessing the impacts of different alien taxa, and therefore the EICAT Categories and Criteria should be used to inform the assessment process. There is also a separate accompanying Guidelines document that provides additional guidance to support the application of the EICAT Categories and Criteria, including on how to deal with uncertainty, the required documentation standards, and the full EICAT assessment process. The EICAT Guidelines document will be periodically updated, and will also be made available on the IUCN SSC ISSG website.

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