Invasive Non-Native Species

The Angling Trust was proud to support Invasive Species Week, 2024.

This an annual raises awareness of the issues our angling venues and general environment are confronted with. It also highlights ways in which anglers and the general public can help prevent the spread and reduce the harmful impacts, of invasive non-native plants and animals including, but not limited to, those below.

The term Invasive Non-Native Species (INNS) reflects a group of invaders that can do massive damage. Individually and collectively, they can ravage fish stocks, outcompete and dominate native species of plant and animal life and, from an angling perspective, ruin fishing locations served by still or moving water.

Our involvement in the 2024 campaign was our best yet and, along with the Non-Native Species Secretariat, covered a number of topics through the week to raise awareness.

  • What are Invasive Non-Native Species?

There are over 2,000 plants and animals that have been brought into Britain, but not all are ‘invasive’. In general terms, 10/15% establish themselves in a manner that causes harm to our native wildlife – including fish that are present in our rivers, streams and stillwaters. Our I.D. Guide lists some of the species that might be present in waters that you fish, lease or own. It also contains information on the correct ways to report and control any INNS you might find.

  • How Are INNS spread?

Many of the animals and plants in the Invasive Non-Native Species category produce large numbers of  eggs, young, seeds, spores or fragments. These are often so tiny they are difficult, perhaps impossible to spot with the naked eye.  They are known as propagules and one can sometimes be enough to start a new invasion. From an angling perspective, they can be inadvertently spread to different venues such as commercial fisheries or rivers on equipment, clothing, even a vehicle.

Following the Check, Clean, Dry programme after an angling session can help stop the spread. Even if you only ever fish the same venue, you could still be transporting something to your own garden – or someone else’s – so the practise is important on every visit.

For more information on Check, Clean Dry, click here.

There’s even more information for anglers on the pages of the Non-Native Species Secretariat.

  • Why are INNS a problem?

The survival of our native wildlife, including fish, and our ecosystems is threatened by the spread of Invasive non-native species. They do this by preying on, or out-competing other plants and animals. Some will disrupt habitats and and can spread harmful diseases.

The Non-Native Species Secretariat reports that in the last five hundred years, 72% of global extinctions have occurred on islands such as ours and invasive species have contributed to 86% of these extinctions. There’s more on the problems associated with INNS, in our Lines On The Water blog.

  • What can I do?

For anglers, one of the best ways of preventing the spread of INNS to other waters, is to follow the Check Clean Dry practice referred to above. As a reminder, more information is available here. An informative video presented by the Non Native Species Secretariat is available here. You can also access an online iRecord form via you phone to report sightings of Invasive Non-Native Species. To help identify a species, our I.D. Guide presents some of the species you might find around your waters and even more information from the Non Native Species Secretariat is available here.

To promote INNS Week, we organised or supported events across the country including: 

Monday 20th May – River Lee Navigation, Stonebridge Lock, Haringey.

An impressive total of 3 tonnes of Floating Pennywort was removed from 2 miles of the River Lee Navigation between Stonebridge Lock and Springfield Marina in Haringey.

An excellent turnout of volunteers from angling and paddling clubs and other local organisations, removed the massive haul of the Invasive Non-Native Species and turned the exercise into a major success.

A washdown station ensured participants didn’t taken any ‘leftovers’ home with them at the end of the day.

Thursday, 23rd May – Leeds Liverpool Canal, Tarleton, Preston

An attendee list incorporating more than 50 volunteers  and representatives from a series of organisations including the Angling Trust, Paddle UK, the Canal & River Trust and Southport & District Anglers confronted the challenge of a heavy ‘invasion’ of Floating Pennywort on the Leeds Liverpool Canal near Preston.

It’s estimated that as much as four tonnes was lifted from the water with Himalayan Balsam also taken away during the session.

Friday, 24th May – Fossdyke Navigation, Lincoln

The Angling Trust partnered with East Mercia Rivers Trust and RiverCare and removed around 2 tonnes of Floating Pennywort from the Fossdyke Navigation & Catchwater Drain in Lincoln.

More than 20 volunteers joined the group and special thanks go to Lincoln & District Angling Association, East Mercia Rivers Trust & RiverCare for helping us organise a successful event that benefits anglers and the local environment in general. Our picture above show Fisheries Officers, Ian Doyle (Back Right) and Drew Chadwick (Front Right) with just some of the attendees in Lincoln.

Sunday, 26th May – Outward Nature Trail, River Irwell, Bury

The (inevitable) Bank Holiday rain couldn’t dampen the enthusiasm of those who attended our ID tour at Outwood Nature Trail on the River Irwell in Bury.

Hosted by our Fisheries Officers. Ian Doyle, Drew Chadwick and Mark Egerton, some of the most common INNS species in UK were spotted along the way including Himalayan Balsam, Japanese Knotweed and Giant Hogweed.

The team also reflected the correct management techniques reflected when such species are found. If you wish to discuss any potential issues on your own waters, scroll further down this page for Ian and Drew’s contact details.

There is always more information on the pages of the Non-Native Species Secretariat. To find out more, scroll down on this page.

Be informed; Get Involved; Stop the Spread!


Our freshwater and marine environments are under threat. Invasive non-native species are one of the top five drivers for biodiversity loss worldwide, and present a huge threat to native species, aquatic environments and our sport.

Plants and animals from other countries are finding their way into our waterways after being imported for ornamental or agricultural use. Many of these non-native species wither and die in the wild. Others survive, but don’t spread rapidly. A few spread like wildfire, as they don’t have the natural controls of diseases, predators and grazers to keep them in check. They can therefore do massive damage to our water environment and negatively impact our fishing. These are known as Invasive Non-Native Species. 

Recognising the detrimental impacts invasive species can have on our environment and economy, an EU Regulation on Invasive Alien Species (1143/2014) came into force in January 2015. The Angling Trust are working to ensure effective implementation of this regulation and to encourage Government to take action on invasive species more broadly. This work has been funded by fishing licence money as part of our National Angling Strategic Services contract with the Environment Agency.

We are also working with organisations like The Rivers Trusts and the Riverfly Partnership’s Angling Monitoring Initiative groups to set up procedures to control and eradicate these species that threaten the objectives of the Water Framework Directive. 

Part of the Regulation also involves the production of guidance for different recreational users – including anglers – that outlines measures clubs, anglers and the land owners can implement to reduce the risk of invasive species being introduced to their waters. This includes a variety of free materials and information on the potential risks of invasive species spread associated with fish stocking and habitat management. For more information, please see below:


Simple measures every angler can undertake to stop the spread of invasive species:

Invasive species can be spread between water bodies a variety of ways. One of these includes anglers accidentally carrying these species on their clothing and fishing gear from one site to another. 

The Angling Trust urges all anglers to carefully think about this and how you can help with what is called biosecurity. 

The Check Clean Dry campaign launched in 2011 provides guidance to anglers and other water users on how to clean equipment to ensure the removal of unwanted organisms and diseases. After fishing ensure to: 



This is especially important when going to fish a different water and returning from a trip abroad – carp anglers know the importance of this in spreading KHV, salmon anglers will know the importance with potentially spreading salmon fluke Gyrodactylus salaris. The deadly crayfish plague carried by signal crayfish can survive on damp clothing for up to 10 days (for more information and posters see the crayfish section). If drying out is not a viable option, consider having one set of kit for your favourite water and another for travelling to waters you fish less often. Disinfecting kit is an option using Virkon aquatic 1% solution generally available through the aquatic trade.  

To order a free Check Clean Dry sign to install at your water please contact [email protected]

Another major route for invasive species to enter the wild is through species escaping from nearby gardens, or unwanted plant material being dumped into our waterways. The Be Plantwise campaign aims to increase awareness amongst gardeners, pond owners and retailers of the impact aquatic plants and provide information on how to dispose of these plants correctly. The Angling Trust assisted in the design of this scheme and supports this best practice outlined in the campaign and encourages anglers to check the names of plant species before introducing any species into their waters. 

Catchment based approach

Anglers are already expending considerable effort in trying to tackle this threat to our fishing, but we recognise that to be more effective this needs to be co-ordinated on a catchment basis. The Angling Trust is therefore working with a variety of stakeholders to achieve this. Our work to eradicate Floating Pennywort on the River Kennet and Colne highlights how angling clubs, consultants and environmental organisations can come together to coordinate action within a catchment. We are part of a national strategy aiming to work together for more strategic, coordinated management of Floating Pennywort. By working together, we can make a significant impact on these threats to our fishing.

For more information on the GB Floating Pennywort Strategy visit the GB NNSS page.

To learn more about how to undertake management of Floating Pennywort, watch our video on identifying floating pennywort and download the information in our presentations:

Factors to consider before undertaking management

How to recruit volunteers

Managing floating pennywort in flowing waters

Managing floating pennywort in still waters

Health and safety risk assessment

What to do after a removal event

Checklist to organise an event


Identification, Reporting and Control

You might have invasive non-native species on waters which you own, lease or fish. With the technical and financial assistance of the Environment Agency and the GB Non Native Species Secretariat we have amalgamated information on invasive species pest identification and control to help our members and others to take effective action. 

A table of 17 invasive species including Killer shrimp, Topmouth gudgeon and Signal crayfish and information on their identification and control is available in the table below. Identification sheets for other high-risk species are available here. 

For some species such as Signal crayfish, there are no known total eradication techniques at present. We are supporting research into control of signal crayfish with a report outlining the results of modified crayfish trapping available here. 

Alongside ID guides there are also an online iRecord form that you can access from your phone to record sightings of invasive non-native species. We would also encourage you to undertake the GBNNSS e-learning training on invasive species including information on identification, control and recording. 


Guidance on Signal crayfish trapping in England


On the 1st December 2019, the laws around the trapping and transfer of Signal crayfish in England changed. This will have an impact on fisheries and managers wishing to manage Signal crayfish at their water bodies.

The Invasive Alien Species (Enforcement and Permitting) Order 2019 restricts activities around the keeping, release, transport and selling of live Signal crayfish unless in accordance with a licence.

These changes are intended to help to protect native species, improve Signal crayfish management and prevent the unintentional transfer of these species between waterways.

If you wish to manage Signal crayfish you need to consider:

Where is the water you want to trap located?

Anyone who wishes to trap Signal crayfish should check whether they are located within a ‘containment’ zone (formerly a ‘go area’), mostly in Southern England or an ‘exclusion’ zone (formerly a ‘no go’ area) which mostly relates to Northern England. This will determine the activities you can undertake and the licences you can apply for. These zones are currently based on the same postcode system used for the Schedule to the Prohibition of Keeping of Fish (Crayfish) Order (1996). The list of postcodes is available in the Annex of the Trapping authorisation.

A trapping authorisation is required to trap Signal crayfish in both zones. All cases will be reviewed on a case-by-case basis.

Trapping in exclusion zones will only be allowed for conservation, scientific or fisheries management purposes which maintains the status quo prescribed by the Crayfish Order (1996).

Trapping Signal crayfish

Licence required: Trapping Authorisation (EA)

Anyone wishing to trap Signal crayfish in England will require a Crayfish Trapping Authorisation from the Environment Agency. There are strict rules about the design and size of crayfish traps because they can harm other wildlife (e.g. water voles).

Important things to note under the trapping authorisation:

  • You must remove all the Signal crayfish that are caught in the traps (i.e. no small crayfish are returned to the water)
  • You must kill all of the animals at the site of capture (unless under a management licence from Natural England – see below)
  • You will also need the permission from the landowner and/or fishery owner to trap

Live transfer of Signal crayfish off site

Licence required: Management Licence (NE)

If you wish to transfer live animals away from the site of capture you will require a Management Licence from Natural England.

This licence allows activities aimed at eradicating, controlling or containing crayfish populations for conservation, scientific or fisheries management purposes.

Important things to note under the management licence:

  • It is not possible to obtain a licence for personal consumption. You must not take live animals away from the riverbank. You can take animals that you have killed on the riverbank away for consumption at home.
  • Animals that have been trapped for commercial reasons can only be taken live away from the site of capture to a licenced processing facility.
  • It is now illegal to sell, use or exchange live Signal crayfish e.g. for human consumption.

Further information

Guidance: Invasive non-native (alien) animal species: rules in England and Wales

Stop the spread

Invasive plants, animals and diseases harm the environment, impact native fish species reduce the quality of fishing. Please help to stop them by following the Check, Clean, Dry code. 

To promote the Check, Clean, Dry code to other anglers, a series of materials have been produced for the angling community. This includes: 

  1. Check Clean Dry aluminium signs – contact [email protected] if you are interested in having one delivered
  2. Check Clean Dry posters:
  3. Check Clean Dry leaflets and stickers – find out more here
  4. Fisheries biosecurity plan template – outlining the potential risks of invasive species introduction associated with fish stocking, habitat management, competitions and measures that can be implemented to minimise the risk. Available soon.
  5. Undertake the free e-learning on invasive non-native species and biosecurity. 


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