EICAT is the IUCN global standard for measuring the severity of environmental impacts caused by alien species. EICAT is a key tool for prioritising alien species that could lead to the most harmful environmental impacts, helping to make the best use of resources to prevent or limit their negative consequences. EICAT classifies alien species into one of eight categories (see figure) according to the severity of their impact on native species and whether the impact is reversible The EICAT Categories and Criteria provide a simple, objective, and transparent classification method. The EICAT Guidelines provide detailed assistance in the application of the categories and criteria.
EICAT can be applied at national, regional, and global levels. All global EICAT assessments are published on IUCN’s Global Invasive Species Database. The EICAT Authority is the governing body coordinating the EICAT assessment process and it is responsible for carrying out the majority of assessments and implementing the review process. The EICAT Authority is composed of experts on specific taxonomic groups or geographic regions.