Invasive species continue to spread in the European Union, although rapid interventions have begun to yield results.

Invasive alien species are present in all member states of the European Union and continue to spread, despite the progress made through rapid interventions and management measures. The European Environment Agency shows that member states have carried out over 300 rapid eradication actions in the period 2019-2024, and 60% of these have been completely, partially, or temporarily successful, but the pressure on biodiversity and ecosystems remains high.

In short

The European Environment Agency has analyzed the reports from member states for the period 2019-2024 regarding invasive alien species of interest to the European Union. Of the 87 species analyzed during the reporting period, 73 were reported as present in the environment in at least one member state. Member states have carried out over 300 rapid eradication actions, and 188 of these, or 60%, have been completely, partially, or temporarily successful. Over 4,200 management measures have been applied, but the spread continues, and new introductions remain likely.

Invasive alien species are plants, animals, or other organisms introduced outside their natural range, which cause harm to biodiversity and ecosystems. They can compete with native species, alter habitats, affect agriculture, fishing, infrastructure, or human health, and can create significant costs for authorities and local communities.

The report from the European Environment Agency is based on national reports regarding the implementation of EU Regulation 1143/2014 on invasive alien species. Member states report every six years on how they apply European rules, and the new analysis covers the period 2019-2024. During this period, 87 species of interest to the Union were analyzed, meaning species whose spread requires coordinated action at the European level.

The number of species present in the environment varies significantly between member states, from 8 to 52. In total, 73 species of interest to the EU have been reported as present in the environment in at least one member state. Most appear in terrestrial or freshwater ecosystems, and their distribution follows a pattern already observed: more species are reported in southern and western Europe, where climate, transport networks, population density, and entry points favor spread.

Maps published by the European Environment Agency show hotspots in the Atlantic biogeographical region, especially along rivers and streams, in cities, and near major transport hubs, including ports. Boreal areas and islands generally have fewer reported species, although the agency warns that there are also gaps in distribution data, which may hide some real patterns of spread.

The most widespread reported species include the Florida turtle, present in 26 member states, the paradise tree, present in 24, the Himalayan balsam, in 23, the signal crayfish and the mice, each in 22 member states, as well as the giant land snail, in 21. These examples illustrate the diversity of the problem: it is not just about a single category of organisms, but about reptiles, plants, fish, crustaceans, and other species that enter and establish themselves in different ecosystems.

Some species have continued to expand between the previous reporting period and the current one. The agency mentions the Egyptian goose and the raccoon, which have spread from Central Europe in several directions, as well as plants such as common cotton grass and Nuttall's waterweed. The Chinese crab and the Asian wasp are also examples of species that have increased in distribution, in the case of the crab along the coasts, and in the case of the Asian wasp through gradual spread in multiple directions.

Data shows that rapid intervention can work. In the period 2019-2024, 23 member states carried out over 300 rapid eradication actions targeting 54 species of interest to the EU. Of these, 188 were completely, partially, or temporarily successful. The number of states that have implemented such measures has increased compared to the previous reporting period, when 14 member states carried out rapid interventions.

The results confirm the importance of early detection. If an invasive species is identified immediately after introduction, the chances of eradication are higher, and costs can be lower. Once the species establishes and forms self-sustaining populations, eradication becomes much more difficult, and authorities often resort to control, isolation, or reducing the impact on biodiversity.

The agency shows that 69 species of interest to the EU have already established themselves in the environment, with populations capable of sustaining themselves in at least one member state. However, many still have limited distribution: 11 species are reported as established in a single member state, and 23 in two to five member states. This limited distribution still creates windows of opportunity for eradication or control before the species become continental problems.

Alongside rapid interventions, 25 member states have carried out over 4,200 long-term management actions targeting 61 species of interest to the EU. Over 1,400 of these measures have led to complete, partial, or temporary eradication, over 300 have managed to contain populations, and another over 300 have successfully achieved control. For nearly half of the measures, the outcome is still under evaluation and requires further monitoring.

Managing already widespread species is more difficult than rapid intervention. It can mean repeatedly removing invasive plants, capturing animals, controlling reproduction, reducing spread pathways, restoring affected habitats, or informing the public. In many cases, the effort must be repeated for years to prevent populations from returning.

Pathways of introduction and spread remain a central element. All member states have prioritized at least one pathway of introduction or spread within their territory. The most common are framed under "escape from captivity," a category that includes pets, aquarium and terrarium species, as well as ornamental plants that reach the wild. In the transport category, states have mainly targeted unintentional transport with habitat materials, organisms that arrive on ships and boats, and species attached to fishing equipment.

This part of the report shows the link between everyday behaviors and biodiversity. Releasing an aquarium turtle into a lake, unintentionally transporting organisms on fishing equipment, or spreading ornamental plants from gardens can contribute to the emergence of invasive populations. Prevention depends on rules, controls, public information, and responsibility in the trade of animals, plants, and biological materials.

The report also signals issues at the level of permits and inspections. Nineteen member states have issued permits for species of interest to the EU, for purposes such as research, ex situ conservation, scientific production, or other authorized activities. Not all units have been inspected for compliance, and in some cases, there have been discrepancies between the number of authorized specimens and the actual number. The agency states that there is a need for more rigorous inspection and control mechanisms.

Thirteen member states have also established national lists of invasive species of interest for their territory. These lists may include species that are native to part of the EU but invasive in another, such as the zebra mussel or the quagga mussel. They may also include species that have been proposed for the EU list but have not been included. States can apply measures such as restrictions on introduction into the territory, prohibition of placing on the market, controlling reproduction, isolation, or eradication.

The conclusion of the European Environment Agency is that the EU Regulation on invasive alien species has produced visible progress, especially in early warning, rapid intervention, and plans for pathways of introduction. The number of rapid actions has increased, many interventions have been successful, and member states have implemented thousands of management measures.

The spread continues, however, and new introductions remain likely. For species already widely distributed, control requires greater and more consistent efforts. Without rapid intervention, monitoring, inspections, and reducing entry pathways, invasive species can transform habitats, weaken local biodiversity, and increase costs for administrations, farmers, fishermen, and communities.