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.”

Notes for editors

  • The paper, 'Dispersal of the invasive topmouth gudgeon, Pseudorasbora parva, in the UK : a vector for an emergent infectious disease” was published online today in the journal Fisheries Management and Ecology. A pdf of the paper is available from the Centre for Ecology & Hydrology press office, tel: 07920 295384
  • Pictures of topmouth gudgeon and a map showing the location of topmouth gudgeon populations in England and Wales and the extent of threatened rivers are available from the Centre for Ecology & Hydrology.
  • Lead author Adrian Pinder is based at the Centre for Ecology & Hydrology at Winfrith in Dorset , UK .
  • Co-author Robert Britton is based at the Environment Agency National Fisheries Laboratory in Huntingdon , UK .
  • The Asian topmouth gudgeon has been described as the most invasive fish species in Europe . Sunbleak populations have declined dramatically in the last forty years and the species is now on the European list of threatened freshwater fishes. This decline coincides with the rise in numbers of the topmouth gudgeon and its rapid spread throughout Europe since its introduction into Romanian ponds close to the river Danube in the 1960s.
  • The rosette-like agent discovery was reported in published in the journal Nature on 23 June 2005 . The researchers believe the parasite is closely related to Rosette Agent, identified in the United States for the first time in 1986, which kills salmon and similar species, both farmed and wild.
  • The work was carried out as a collaborative project between the Centre for Ecology & Hydrology and the Environment Agency. The study was funded by the Natural Environment Research Council.
  • The Centre for Ecology & Hydrology (CEH) is the UK 's leading research organisation for land and freshwater science. Its scientists carry out research to improve our understanding of both the environment and the processes that underlie the Earth's support systems. It is one of the Natural Environment Research Council's research centres.
  • NERC is one of the UK 's eight Research Councils. It uses a budget of about £350m a year to fund and carry out impartial scientific research in the sciences of the environment. NERC trains the next generation of independent environmental scientists. It is addressing some of the key questions facing mankind such as global warming, renewable energy and sustainable economic development.
  • The Environment Agency is the leading organisation for protecting and improving the environment in England and Wales . It is responsible for making sure that air, land and water are looked after by today’s society, so that tomorrow’s generations inherit a cleaner, healthier world.

News and Information

Centre for Ecology & Hydrology 
Press office: 
Barnaby Smith, tel: 07920 295384

Natural Environment Research Council 
press office: 
Marion O'Sullivan, tel: 01793 411727 or 
Owen Gaffney, tel: 01793 442629 or 

Environment Agency 
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