WILD GUIDES: Help Stop The SPread Of Invasive Species

Whether you're fishing, kayaking, swimming, or walking by the river, your actions can make a real difference to the health of our waterways.

Invasive non-native species (INNS) such as Himalayan balsam, killer shrimp, and New Zealand pigmyweed are increasingly found in rivers and lakes across the UK. These species can outcompete native wildlife, alter habitats, and spread diseases. The problem? They often spread by hitching a ride on damp kit, muddy boots, or even dogs.

You can do your bit and by following a few easy steps, you can help protect our rivers and lakes.

1. Check

Before leaving any river, lake, or wetland, carefully check your equipment, clothing, and footwear for any mud, plant fragments, or tiny animals. Look inside kayaks, check the soles of boots, inspect fishing gear, and examine dog leads and fur. Remove anything you find and leave it at the site if possible.

2. Clean

Thoroughly clean all items that have been in contact with water, including boats, nets, clothing, and footwear. Use clean water and a stiff brush where needed. If possible, clean items on-site so you’re not transporting material elsewhere. Avoid letting wash water run into other rivers or drains.

3. Dry

Dry all equipment completely before using it at a different site. Many invasive species can survive in damp conditions for days. Drying in sunlight and ensuring everything is aired out properly is the most effective way to kill any remaining organisms.

Tailored Advice for River Users:

Anglers – Disinfect landing nets and avoid transferring water between catch sites. Clean and dry waders and bait buckets between trips.

Paddlers – Open buoyancy aids and boat compartments to dry thoroughly. Foam and fabric can hold moisture for longer than you might expect.

Swimmers – Make sure towels, wetsuits, and other kit are completely dry before heading to another site.

Dog walkers – Rinse off your dog’s legs and paws if they’ve been in the river, and dry them thoroughly before the next outing.

Why Biosecurity Matters

Some of the species threatening our rivers are incredibly small and easily overlooked—but they can cause lasting damage. Killer shrimp (Dikerogammarus villosus), for example, can dramatically alter ecosystems by preying on native invertebrates and fish eggs. Once established, these species are extremely difficult, if not impossible, to remove.

By taking a few simple steps, we can all help stop the spread of invasive species and protect North Wales' rivers for wildlife and future generations.

Log It on INNS Mapper

If you spot an invasive species, you can help by recording it through INNS Mapper. This national mapping tool allows anyone to log sightings of invasive plants and animals. Your records help conservation teams understand where species are spreading and prioritise action.

Make sure to include a photo if you can, and note the location as accurately as possible. Every record helps build a clearer picture of what's happening in our catchments.