River Brent Eel Recovery Project

In association with the Zoological Society of London (ZSL - London Zoo), and the Canal and River Trust, the Environment Trust is coordinating the monitoring of juvenile eels (Anguilla anguilla) as they migrate upstream into the freshwater of the River Brent in west London. Eels spawn in the Sargasso Sea in the western Atlantic and are carried towards European waters by ocean currents. After approximately three years, the young eels, or elvers as they are called, arrive in Europe and head up estuaries, including the Thames Estuary. The young eels spend up to 20 years in rivers, before migrating back out to sea to breed.
Four eel passes were installed on weirs in the lower reaches of the River Brent in the winter of 2012/13, with the first monitoring at Brentford taking place from May 2013. Eel numbers have plummeted in recent years due to a number of possible factors, one of which is likely to be barriers to their movements, such as weirs.
In the first season of eel monitoring on the Brent, over 1300 elvers were recorded using the eel pass at Brentford.
Volunteers are needed to help us with eel monitoring in 2014, so if you live locally and would like to become a citizen scientist, please get in touch with chris.cockel@environmenttrust.co.uk
Training will take place in Brentford on April 29th and May 14th.
As a thank you, eel monitoring volunteers get to attend a free event at London Zoo at the end of the season.
For more information about ZSL's eel monitoring and citizen science, visit this page http://www.zsl.org/conservation/regions/uk-europe/thames-eels

The weir at Stoney Sluice is a barrier to upstream elver migration.

As is the labyrinth weir at Osterley.

This idyllic view is metres away from the M4 at Clitherow's Island, Brentford.

Chris briefs volunteer eel monitors in 2013. 

Elvers of all sizes were recorded. 

This was the largest. 

Eels are difficult to handle, particularly when you've got 300 of them. 

A young volunteer releases the elvers upstream of the weir. 

In July 2013, heavy rain after a dry spell resulted on depleted oxygen levels in London's rivers leaving fish gasping for breath. Just visible on the brickwork, a signal crayfish and a Chinese mitten crab make a bid for freedom. 

Also found: a froglet. 

A giant mitten crab near the surface.

The best part is releasing the elvers to continue their journey upstream.