MAN has turned Europe’s rivers into an assault course for fish.

Researchers from the University of Southampton have been part of a study which shows Europe’s rivers have many more barriers blocking the paths of migrating fish than previously thought.

On average, fish face one obstruction every kilometer.

Europe’s rivers are studded with hundreds of thousands of manmade barriers such – weirs, dams, culverts, fords and sluice gates – many of which are obsolete.

The study suggests the number of barriers recorded in current databases may represent just three per cent of the actual number.

The AMBER (Adaptive Management of Barriers in European Rivers) study, conducted by a consortium led by Swansea University, surveyed a 1,000 km of rivers.

To help locate more barriers scientists are inviting citizens to get involved by logging information about barriers they find with a newly-developed smartphone app.

Dr Jim Kerr, from the University of Southampton, said: “These barriers can potentially provide energy, water, fishing and leisure opportunities, and might even prevent the spread of invasive river species. However, they also present considerable obstacles to sustainable river management.

“Aside from the potential flood threat, they substantially change river ecosystems and block the natural swim-ways of migrating fish. Eel, salmon and many other species rely on complete connectivity between the sea and their upstream river habitats to complete their life cycle.”

Scientists want citizens to help them by using the Barrier Tracker smartphone app(freely available from Google Play or the Apple App Store) to document or update the status of the barriers that they come across.

The Barrier Tracker is launched today to coincide with World Fish Migration Day, a one day global-local event to create awareness of the importance of open rivers and migratory fish.

Fisheries scientists from the University of Southampton will be running a day-long interactive stall at Mottisfont House and Gardens National Trust site in Hampshire to promote the day and the launch of the AMBER Citizen Science portal.