A new “cheap and easy” method could make swimming upstream easier for a critically endangered eel species when they arrive in the UK and help slow down population declines, scientists have found.

Each year, more than a billion European eels (Anguilla anguilla) travel 4,000 miles across the Atlantic to European shores.

But the creatures are still very young when they start navigating UK’s lakes and rivers, swimming against the flow of water to find feeding grounds – which requires significant energy and effort.

Human-made obstacles such as dams and weirs can make this even harder, sometimes by making rivers flow faster.