Invasive Non-Native Species

Invasive Non-Native Species (INNS) is the term used to reflect 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.

Over 2,000 plants and animals 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 the fish present in our rivers, streams and stillwaters.

These can be spread by a number of means from intentional introductions through to accidental spread when a species becomes attached to recreational equipment, tools or clothing. Angling represents a potential route for invasive species to spread between water bodies. It is therefore important we do what we can to stop the spread of species and minimise their impact.

Invasive Non-Native Species Week 2025 (May 12th-18th)

Once again, the Angling Trust is supporting national Invasive Non-Native Species Week.

INNS week is hosted by the GB Invasive Non-Native Species Secretariat and the Trust’s focus is on highlighting activities that can help anglers prevent the spread and reduce the harmful impact these plants and aquatic species can have on fishing venues and the general environment.

A full list of events and participation activities for the week, can be found on the dedicated INNS Week page here.

How We Tackle Invasive Non-Native Species

Anglers may not be aware that the simple purchase of an Environment Agency rod licence is one of the best ways to support the removal and general management of Invasive Non-Native Species.

Income from sales is used to support programmes such as bio-security rounds of the Angling Improvement Fund (AIF). This downloadable information sheet, illustrates how more than a quarter-of-a-million pounds worth of rod licence income has been invested to tackle INNS and help protect clubs and fisheries.

A bio-security round of the AIF focusing on nets, mats and slings is now inviting applications from eligible clubs and fisheries. Find out more here.

Horizon Scanning – The next ten years

‘Horizon Scanning’ is a process led by by the Centre of Ecology and Hydrology bringing together invasive species experts from different backgrounds to identify new, invasive non-native species. The project focuses on species considered to be a future high-risk threat to biodiversity, ecosystems human health and economies across Britain in the next ten years.

The 2025 report is the third Horizon Scanning exercise to be conducted. The previous two were in 2014 and 2019. The latest, published in May as part of National INNS Week, identifies 145 new threats that are currently either absent or not considered established in Great Britain. The list was then ranked into priority groups and the top 20 alone, features a range of species that could impact on angling, its venues, waterways and surrounding landscape.

The full list and report can be found on the Non-native Species Secretariat website but we’ve highlighted just three species here that may provide a brief indicator of the potential for ongoing and future threats. More detailed information is available on the website reflected above.

Pink salmon (Oncorhynchus gorbuscha)

Pink salmon

A predator native to parts of Asia, Western Canada and Northwestern USA. The risk of entry into Britain is considered ‘Very Likely’ and its presence could affect the spawning of native salmonoids and other native aquatics. Pink salmon in GB have been caught and reported in GB since 2017 but the full extent of their impact and distribution remains unknown. The species have a two-year life cycle so are expected to enter GB waters again this year.

Report a sighting

Salmon fluke – Gyrodactylus salaris

Treating infected fish in Norway

A minute parasite that attaches itself to fish in the salmon family. Highly dangerous to non-Baltic strains of Atlantic salmon and other salmonoids including Rainbow trout, Brown trout and Grayling. This species has not been found in GB waters at present but in some Norwegian rivers it has resulted in catastrophic declines with a 98% decline in salmon populations in 5 years.

The Dangers of Releasing unwanted ‘pet’ Species into the Wild

Releasing unwanted fish or other aquatic ‘pet’ animals into the wild, may seem mildly logical, convenient and possibly even kind. When ornamental fish such as Koi or Goldfish from garden ponds or perhaps terrapins from a managed tank are offered an unrestricted freedom in a natural space, what could possibly go wrong?

Fundamentally, there are two things that can go disastrously badly. Firstly, such a release could have a devastating impact on the animal itself and the surrounding eco-system and secondly, you could be prosecuted.

Koi should not be released into the wild

The invisible dangers to the local, indigenous population including native fish, are from disease and parasites and a potential for inter-breeding which could result in unwanted hybrid populations. ‘Saving’ one fish by giving it a new home, may jeopardise the biosecurity of those already there.

An article on the government website (see link below) contains advice from the Ornamental Aquatic Trade Association Ltd and the Environment Agency on what to do with unwanted stock.

It also confirms that pet fish could be totally unsuited for life in the wild and their release could also be an offence under the Animal Welfare Act 2006. For this reason, there are rules and regulations in place that are intended to safeguard clubs and fisheries as well as the native wildlife and its habitat. These include the following considerations:

Fish movements are regulated by the Environment Agency.
Clubs or fisheries wishing to move or introduce ANY fish, are required to register their fisheries with the Centre for Environment, Aquaculture and Fisheries Science (Cefas)
If clubs or fisheries wish to keep non-native species at a venue, they must obtain a site permit from the Environment Agency which will confirm the species that can be kept. This process might also involve health checks on a sample fish before consent is given.

Terrapins (if spotted, report your sighting here: www.turtletally.co.uk) are listed among the restricted group of invasive non-native (alien) animals. These, and all sub-species, are named in a group that also includes Chinese Mitten crabs, Marbled crayfish, the Pumkinseed, Topmouth gudgeon and Striped eel catfish.

If you kept one of the listed species as ‘pets’ before they were listed, you’re able to retain them without a permit for the rest of its life. There are considerations in such an instance on the government website which also includes the full listing and guidance on what to do if, for example you didn’t realise you were in possession of a listed species.

Releasing a listed species into the wild could result in prosecution as could allowing it to breed.

Prevention

Check, Clean Dry

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

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

The Check, Clean, Dry campaign provides guidance to anglers and other water users. It reflects an effective approach to the maintenance of equipment to ensure the removal of unwanted organisms and diseases.

The Angling Trust urges all anglers to adopt measures to reduce the risk of spreading invasive species between waters. After fishing always follow these guidelines.

The Check, Clean, Dry process should be undertaken after every trip; even if kit appears clean. Invasive species can be hard to spot with the naked eye and it’s the same for fish diseases too. Carp anglers know the importance of biosecurity to stop the spread of KHV, salmon anglers will know the importance of avoiding the spread of salmon fluke Gyrodactylus salaris.

If drying out is not a viable option, consider one set of kit for a favourite water and another for travelling to waters fished less often. Disinfecting kit is an option. You should use the solutions recommended by the manufacturer.

Promote Check, Clean Dry to Members, Guests & Visitors

Check, Clean Dry aluminium signs are freely available for coarse, game and marine anglers. Contact admin@anglingtrust.net for more information on how to order.

Check, Clean, Dry posters and other resources are available to download for notice boards for all disciplines. These are available in English and Welsh.

Gardeners Beware!

A further 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 of aquatic plants. It also provides information on how to dispose of these plants correctly. The Angling Trust assisted in the design of this scheme and supports the best practice outlined in the campaign. Individuals looking to make plantings are also encouraged to check the names of plant species before introducing any into waters.

Biosecurity Plan

Creating a biosecurity plan for your club or fishery helps to identify the ways an invasive species or disease could arrive onto your site, and what steps could put in place to reduce the chances of it happening. The downloadable templates below reflect guidance for specific waters.