Under the new legislation, the Environment Agency can require eel passes and screens to be installed on all rivers and streams where barriers such as weirs or sluice gates prevent eels from moving upstream to grow or downstream to spawn.

In the past 20 years, the eel has seen a dramatic decline across Europe. The number of baby eels entering our rivers has fallen by 95 per cent because of a range of factors including loss of habitat and barriers to migration. However other aquatic wildlife, such as salmon and otters, has thrived thanks to the Environment Agency’s continuous work on water quality, which has improved for the 19th year in a row – the best it has been for over a century.

Legislation introduced in January aims to increase European eel numbers across England and Wales after the International Union for the Conservation of Nature described the species as ‘critically endangered’.

Starting at a couple of hundred pounds, eel passes can be cheap to install and have already proved successful in giving the species access to new stretches of water. Plans to install over 100 eel passes across the country are already underway.

Environment Agency eel expert Andy Don said: ‘We know that even one eel pass in the right location can have an instant effect. Two passes installed along a watercourse that flows into the River Parrett in Somerset saw 10,000 eels queuing up to use them on the first night, and both 2008 and 2009 saw around 40,000 eels using the passes each year.

‘From now on we are able to stipulate that eel passes or screens must be fitted where there are barriers to migration, making our waterways much more eel friendly. Enabling eels to get access to habitats they would otherwise be deprived of gives them the best possible chance to grow and mature before making their incredible journey back to the Sargasso Sea.’