Invasive Non-Native Species

Non-native species are living, terrestrial (ie. land-based) or aquatic (ie. fresh water and marine) organisms that have been transported naturally, or as a result of human activity, to new areas outside of their natural habitat or range.

When such species become a problem in their new environment, whether through rapid and extensive spread, outcompeting or damaging native species, or even affecting human activities and infrastructure, they are also known as Invasive Non-Native Species, or INNS.

Island ecosystems are considered highly sensitive and at greater risk from invasive species than most other environments, often because native populations have developed in isolation and are not used to highly-competitive organisms or rapid environmental change. Invasive non-native species could be devastating to native Manx biodiversity and habitats; with the exception of direct habitat loss, invasive plants are considered to be the leading cause of biodiversity loss worldwide. 

However, beyond environmental damage, INNS can also cause significant economic impacts resulting from control, repair, restoration and management measures in relation to the island’s built infrastructure, commercial interests and human health. 

In 2010 the estimated cost of INNS to the British economy was £1.7 billion per annum (Williams et al. 2010). Similarly, the combined cost of INNS on the economies of Northern Ireland and the Irish Republic was estimated at £207 million per annum (Kelly et al., 2013).

The Isle of Man Government therefore has a strong interest and responsibility for the monitoring and strategic management of INNS, and this role is coordinated by the Department of Environment, Food and Agriculture (DEFA) in close cooperation with other Government Departments, such as the Department of Infrastructure (DoI), and with other organisations, such as Manx Wildlife Trust and the Manx National Farmers’ Union. 

Biosecurity and Management of Invasive Species

Biosecurity is the range of measures that a Government or organisation takes in order to prevent the introduction, spread or impact of potentially harmful organisms; in this case, non-native species.

We are used to detecting or managing INNS in highly-controlled places such as airports and ports, but some species enter by natural mechanisms, eg. wind, currents or on native wildlife, or via less obvious routes, such as recreational activities, eg. on boats or sporting equipment. 

As such, Isle of Man biosecurity relies, not only on Government actions, but also on the awareness, collaboration and efforts of the wider community.

The deliberate release of non-native plants and animals into the wild on the Isle of Man is prohibited under Section 14 of the Wildlife Act 1990. This prevents the introduction into the wild of any animal which is not ordinarily resident, or a regular visitor, to the Isle of Man in a wild state, or any species of animal or plant listed in Schedule 8 to the Act. Schedule 8 includes both terrestrial and freshwater non-native species.

Similarly, Section 16 of the Fisheries Act 2012 prohibits the introduction of live fish into inland waters, unless licenced to do so, and the Animal Health Act 1996 contains provisions for biosecurity guidance, and the management of animal diseases.

INNS and the threat to local Biodiversity and Environment

Through the Government’s commitment to the UN Convention of Biological Diversity (CBD), DEFA has developed a Biodiversity Strategy (2015-2025) to manage the Island’s biodiversity, including biodiversity enhancement and minimising loss of native species.  Objective 6 of the strategy commits the Government to ‘monitor, understand and substantially reduce the main pressures on biodiversity’, including from invasive non-native species and to this end the Marine Biosecurity Plan was developed and a terrestrial Invasive Non Native Species Strategy is under development.

Public Engagement

Public awareness and reporting of potential INNS introductions is critical for their successful exclusion, eradication or management. DEFA and its partners, in particular the Manx Wildlife Trust, provide public and schools engagement activities and materials to raise awareness of INNS. See contact details on the following pages for further information.

To find out more information about terrestrial and marine non-native species and to see if there are any records in your area, visit the NBN Atlas Isle of Man, and  the associated non-native species page, where you can also report possible INNS.

Regional Engagement on INNS

The Isle of Man Government also participates in regional initiatives related to monitoring, control and education of invasive non-native species. For example, via the GB Non-Native Species Secretariat and also as part of the Environment Work Plan of the British Irish Council

Which Sector is Most Relevant to You?

The threat of INNS ranges across several different sectors, from marine and freshwater, to agriculture and forestry, and consequently there is a requirement for specific biosecurity considerations and management planning and advice. These environment-specific sectors and considerations are dealt with under the following sections.


Williams, F. et al. (2010). The economic cost of invasive non-native species on Great Britain. Technical Report CAB/001/09. 200 pp.

Kelly, J., Tosh, D., Dale, K., Jackson, A. (2013). The economic cost of invasive and non-native species in Ireland and Northern Ireland. A report prepared for the Northern Ireland Environment Agency and National Parks and Wildlife Service as part of Invasive Species Ireland. 95 pp.