Pathways of introduction of non-indigenous species to Europe’s seas, 1970-2020

The pie chart shows the share of the different pathways of introduction of new non-indigenous species (NIS) to Europe's seas over the years 1970 to 2020. The category 'Other' includes several modes of introduction, namely 'Transport-stowaway: other', 'release in nature', 'escape from confinement', 'corridor' and 'unknown'. The stacked column chart shows the trend in the number of new NIS by pathway of introduction between 1970 and 2017, on a 6-year cycle. While introductions by Transport-Stowaway (ballast water, hull fouling and others) remain the prevalent mode, 'unaided' and 'escape from confinement' have grown in importance in the latest assessment cycles.

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Methodology

National inventories of NIS were revised and updated with published data from biodiversity and hot-spot campaigns, academic surveys, and citizen science observed until December 2020 (reported until June 2022). The revised list was validated with the contribution of national experts.
Microalgae and parasite/pathogen species identified are excluded.
Cryptogenic, questionable and range-expanding species identified are also excluded from all analysis.
Native, partly native species identified are excluded at EU level but included in sub-regional assessments for subregions where they have not been identified as native.

Units

Percentage and number of new NIS

Additional information

The pie chart shows the proportions of NIS introduced between 1970 and 2020 through various dispersal pathways.
The column chart shows the contribution of each pathway per 6-year interval since 1970. The 'Unknown' category is not included to highlight the modes of introduction that have been detected.

Pathways of introduction of non-indigenous species to Europe’s seas, 1970-2020

Related content

References and footnotes