Press release

Jawless fish given helping hand by the Environment Agency

Trial of new materials to help lamprey overcome weirs

Buttercrambe fish pass
The new tiles on Buttercrambe fish pass are designed to help lamprey migrate upstream

The Environment Agency is working in partnership with Durham University to find new ways to help river lamprey to migrate up rivers and access more spawning grounds.

Researchers are testing new materials to see what will help the lamprey to easily use the existing fish pass at Buttercrambe weir, near Stamford Bridge. The first material to be used is a black plastic studded tile which is being attached to the fish pass this summer. A trial will be run to see how many lamprey will use the fish pass with the new material added.

During the lamprey migration period between October and February researchers will catch and tag the lamprey before releasing them back into the River Derwent. The tags will allow automated monitoring equipment to be used at the fish pass and it is hoped that the new material will show improvements in numbers of lamprey using the pass compared to results from the previous year.

Dr Martyn Lucas, of the School of Biological and Biomedical Sciences at Durham University said:

Despite the name, river lamprey, they actually migrate down to the sea, like salmon, to feed there, but they must return to freshwater to reproduce. They are amongst the most ancient of our vertebrate (animals with a backbone) lineage, superficially they are eel-like but have no jaws, and have been around on Earth for hundreds of millions of years.

Although they may look ugly to some people, they form a key part of the ecology of the rivers in which they occur – they are an important food for herons and sawbill ducks at nesting time and otters love them! Despite this they have been lost from many rivers across Europe, mostly because of habitat deterioration and migration barriers such as weirs. Rivers in the Humber catchment, including the Yorkshire Derwent, remain a stronghold for them. They can use their suckers to cling on to stones in swift water but are much poorer swimmers than salmon and trout, so have a job using conventional fish passes. We need to help them get past these barriers because most of their spawning habitat is upstream; currently most can only do so when the barriers are submerged during floods.

We use a range of tracking methods from standard radio tag ‘bleepers’ to pet-type microchip ID tags to identify the migration routes and migration success of the lampreys – most of the ones we have tagged swim rapidly through unobstructed reaches and approach weirs and fish passes, but few get past.

Pat O’Brien, Fisheries Technical Specialist at Environment Agency said:

If the lamprey can move upstream in lower river flows they won’t use as much energy getting there and will be in a better condition when they reach the spawning grounds. At the moment only 2% of the available habitat in the River Derwent is used by the majority of the spawning lamprey.

Many people never get to see a lamprey apart from during the spawning period. Following spawning, the lamprey dies so sometimes these are seen and reported to us. Anglers will not be able to catch these fish by rod and line because during the spawning freshwater phase, they do not feed. If anglers were able to catch the lamprey they might be shocked at the mouth parts attached to the end of their lines.

Published 18 September 2014