Fish Guidance Systems

Eel passes help with species recovery in Norfolk

For the first time in nearly 40 years, eels have been found in a stretch of river in Norfolk, UK.

In a routine fish survey, two eels were found in the River Tud, a tributary of the Wensum. This follows an increase in numbers seen at the New Mills fish pass, which was installed in Norwich eight years ago.

Jezz Wood, a specialist at the Environment Agency, thinks this is encouraging, and although it did not “herald the recovery of the species as a whole”, the discovery of eels on the River Tud was important. He went on to say “two eels may not sound like many, but these are the only small eels we’ve found on this stretch of river for years, and it does show the positive benefit of eel passes at barriers to migration.”

Barriers to upsteam migration is thought to be one of the reasons for the decline in eel populations as they reduce access to the freshwater habitat preferred by eels while they mature. Deflecting eels away from barriers to encourage the use of passes has been the focus of intensive research and trialling by FGS. Recent results from independent flume trials carried out by THA Aquatic and Sparsholt College have demonstrated an 84% avoidance response by silver eels to Fish Guidance Systems High Intensity Lights.

Dr. David lambert from FGS commented that “the results of our research are very timely, as the status of the European eel is now regarded as ‘critical.’ Globally, the population has been in decline for over 40 years, with the Environment Agency reporting numbers to be down by as much as 95%. Clearly the creation of passes can have a big impact on eel numbers”.

In Norfolk, the Environment Agency is creating passes at several key obstruction areas on rivers to increase numbers. It said numbers in Norfolk rivers rose to a record of 34,000 in 2009 after the pass was introduced at New Mills Yard, in Norwich.