The Rivers Trust home page
Invasive Non Native Species

Join The Rivers Trust Fight back against the Aquatic Invaders

Globalisation has markedly expanded the movement of people, commodities and products across the planet over recent decades. Whilst generating wealth, this phenomenon, however, has significantly contributed to the introduction of non-native animal and plant species into areas outside of their natural range. Some of these have become invasive in nature, damaging the environment, diminishing the services provided by ecosystems and in some cases raising risks to human health. Significant economic impacts also arise with such invasive non-native species (INNS) and are estimated to cost the UK economy £1.7 billion per year.

Our rivers are threatened and urgent action is required

Freshwater is particularly vulnerable to both plant and animal INNS, providing habitats and a transport medium for their spread. Detrimental environmental impacts arising from the presence of freshwater invasive non-native species (FINNS) in UK waters are well documented and include direct threats to already endangered native species, loss of biodiversity, diminished water quality, spread of disease and restricted navigation.
Non-native signal crayfish are now well established in many of our rivers and lakes, having comprehensively out competed the native white-clawed crayfish, threatening its extinction.
Alarmingly, Dikerogammarus villosus, also known as the killer shrimp, has been found recently in three locations in the UK (Grafham Water in Cambridgeshire, Cardiff Bay and Eglwys Nunydd Reservoir in South Wales). The killer shrimp preys upon a range of native species including shrimps, insect larvae and even small fish and has been identified by the Environment Agency as a serious threat to our aquatic ecosystems. Thankfully, due to campaigns such as ‘Check, Clean, Dry’ the spread of the killer shrimp seems to have been limited thus far.
Plant FINNS also threaten our rivers. Floating pennywort, for example, grows up to 20cm per day, forming dense mats that float on the surface of the water, blocking out light, squeezing out native species, increasing flood risk and reducing the amenity value of a waterbody.
Giant Hogweed too is a particularly problematic plant, growing up to 5m in height with each plant producing thousands of seeds. Giant hogweed also contains a poisonous sap that causes painful blistering and severe skin irritation.

Action is best underpinned by Biosecurity Plans

The UK now faces an increasingly complex and costly problem, with Japanese knotweed (another problematic plant species in our rivers), for example, thought to cover an area roughly the size of London with estimated costs for its removal, back in 2003, exceeding £1.5 billion.
Concerted coordinated action is, therefore, needed otherwise the costs for control and eradication of FINNS will continue to increase. Fortunately, significant steps to address the issue have already been undertaken in Scotland, with the Rivers and Fisheries Trusts of Scotland (RAFTS) establishing a biosecurity programme for FINNS. The catchment based plans arising stimulate, coordinate and prioritise local action, and provide continuity with UK strategies and protocols.
Using the RAFTS approach as a template, The Rivers Trust (RT) have recently developed a freshwater biosecurity plan for Cumbria, establishing a framework that will prevent the introduction of, detect, control and/or eradicate FINNS throughout the county. Arising from the Cumbria Freshwater Invasive Non-Native Species Initiative, funded by Natural England and the Environment Agency, the plan is the first in England to be produced with support from The Rivers Trust (including the South Cumbria Rivers Trust) and RAFTS.
Implementation of the Cumbrian biosecurity plan will bring a range of environmental and socio-economic benefits to the county. These include a strengthening of the conservation of internationally and nationally designated rivers, lakes and wetlands, the protection of endangered native species such as the white-clawed crayfish, and the enhancement of those recreational services, such as boating and angling, provided by freshwater across the county.

The Rivers Trust movement can deliver UK-wide action

The RAFTS and Cumbrian biosecurity plans provide a strong basis for action to address FINNS. Clearly, however, the approach needs to be implemented across the whole of the UK, and The Rivers Trust is well placed to play a key role towards achieving this important strategic objective.
The 40 individual rivers trusts and their professional and volunteer networks are able to build the local awareness, capacity and partnerships which are critical to the long term success of the measures associated with biosecurity plans. Moreover, the rivers trusts operate at a catchment scale, have well-established relationships with farmers and other landowners, and in a number of cases are already involved in action on the ground to tackle FINNS.

Useful Links

The Rivers Trust and RAFTS jointly organized the third sector GB Invasive Non Native species and biosecurity conference in June 2011. For more information here

Information on the RAFTS Biosecurity and Invasive Non Native Species Programme can be viewed here

For further information about the Cumbria Freshwater Invasive Non-Native Species Initiative visit or email

Access the Cumbria Freshwater Biosecurity Plan here

The GB non-native species secretariat website provides tools and information for those working to support the strategy developed to meet the challenge of Non-Native Species in the GB. This includes the ‘Check, Clean, Dry’ and ‘Be Plant Wise’ campaigns.

Top of pageContact us
News & Events

Read it here...

Help The Rivers Trust
Donate here to support The Rivers Trusts' work across England, Wales and Ireland.
Find out more about supporting us here
© The Rivers Trust › Designed by Type High › Scripting & Hosting by APB
The Rivers Trust is not responsible for the content of external sites
Contact UsJobsLegal Use and Privacy Policy