Alien fish continue to spread in UK rivers

An invasive fish species, which poses major threats to UK fish, has been found in rivers and lakes across England and Wales according to new research published today in Fisheries Management and Ecology.

Past studies have shown that the Asian topmouth gudgeon can spread an infectious parasite that is closely related to ‘Rosette Agent’ – known to be deadly to salmon and trout. The link between topmouth gudgeon and the rosette-like agent, known to kill some carp species (sunbleak and fathead minnow), was reported in an earlier study this year in the leading scientific journal Nature.

Lead author, Adrian Pinder from the Centre for Ecology & Hydrology in Dorset, UK, said, “This new work has identified 25 populations of topmouth gudgeon in England and Wales. Ten of these populations are currently thriving in ponds and lakes which, due to their location and water connections, pose a direct threat to native fish in major UK rivers including the Trent, Severn and Yorkshire Ouse. Other rivers such as the Hampshire Test have already been invaded.”

He added, “The threatened rivers contain many highly valuable coarse and game fisheries and are also linked to the extensive canal network which will provide further means for topmouth gudgeon to disperse across the country.”

Co-author Robert Britton from the Environment Agency commented, “At The Environment Agency we work closely with partner organisations to identify new populations of non-native fish. We can then use this knowledge to protect fisheries and our native fish stocks from any negative impacts that non-native species may have. Non-native species almost always have an irreversible effect and so pose a strong threat.”