Pathways of introduction of non-indigenous species to Europe’s seas, 1970-2021

The pie chart displays the proportion of different pathways through which new non-indigenous species (NIS) were introduced to Europe's seas from 1970 to 2021. The category 'Other' includes pathways with the smallest shares, namely ‘unaided’, 'transport-stowaway: other', 'escape from confinement', and 'release in nature', as well as ‘unknown’, The stacked column chart illustrates the trend in the number of new NIS introductions by pathway between 1970 and 2017, shown on a 6-year cycle. While introductions via 'transport-stowaway' (hull fouling and ballast water) remain the dominant mode, most pathways have seen an increase in the latest 6-year cycle, except for 'transport-contaminant' and 'escape from confinement.

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Units

Percentage and number of new NIS

Additional information

• The pie chart shows the proportions of non-indigenous species (NIS) introduced between 1970 and 2021 through various dispersal pathways.
• 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.

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 2023. 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 analyses.
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.

Marine non-indigenous species in Europe’s seas

Pathways of introduction of non-indigenous species to Europe’s seas, 1970-2021

Related content

References and footnotes