Helping the barbel, Hertfordshire's whiskered fish
PUBLISHED: 15:53 27 March 2018 | UPDATED: 15:53 27 March 2018
Herts' rivers are home to amazing wildlife that is largely hidden to us. David Johnson, Herts and Middlesex Wildlife Trust's living rivers officer, outlines the life of a special fish at the centre of a conservation project
The barbel is a species of freshwater fish, whose name derives from barba, the Latin root for beard. It’s easy to see why – the fish has two pairs of ‘barbels’ – large whisker-like appendages around the jaw. These are touch and taste sensitive and used for finding invertebrates in the gravel bed of rivers. The barbel is a large species, usually up to 3kg but known to reach weights of 8.5kg. They are characterised by a large, broad head and an underslung mouth with thick lips, and of course, its four whiskers.
Barbel are found in the lower reaches of medium and large gravel-bottomed rivers and require clean, fast-flowing waters to survive. Hertfordshire’s river Lea is the perfect habitat. To help them thrive in these conditions, barbel have developed adaptations including a streamlined torpedo-shaped body and strong powerful muscles that help them swim against the flow.
Barbel are a social fish and will often shoal together close to the bank among tree roots, fallen branches and other underwater tangles where they can shelter and rest outside of the fastest flows and out of sight of predators. On a cloudless blue sky day when waters are running clear barbel can often be seen lurking at the margins of rivers.
The best method to spot them is to peer down from a bridge, allowing your eyes to adjust to the glare from the water’s surface. Barbel don’t spend all their time in hiding and are in fact a very curious species brazenly exploring and inspecting changes to their surroundings.
At one time our local Lea was known as one of the best barbel rivers in England, receiving mention in Isaak Walton’s 17th century book The Compleat Angler – the second-most reprinted book in English after the King James Bible. While the upper Lea still has a thriving barbel population, numbers have been declining in the Old River Lea – part of the lower Lea river system and one of the last remaining stretches of the river south of Hertford that has not been heavily modified for the purposes of navigation or flood defence. A number of issues have been attributed to declining numbers here, including reduced flows and its associated impacts on channel morphology leading to the degradation of the habitats that barbel require to complete their life cycle. This includes the silting of spawning gravels and changes to aquatic vegetation structure. Barbel are a good indicator species of the health of a river and declining numbers can often be a warning of underlying problems in a stretch or river.
In response to declining barbel numbers, Herts and Middlesex Wildlife Trust has teamed up with the Environment Agency, the Lee Valley Regional Park Authority, Kings Weir Fishery and the Fishers Green Consortium, functioning as a subgroup of the Lower Lea Catchment Partnership which is hosted by the trust, to develop projects with an overall aim of reestablishing a thriving self-sustaining barbel population in the Old River Lea. This is important for the conservation of barbel but also for the conservation of the wider biodiversity of the river, as the environmental requirements for barbel also support a wide diversity of wildlife that rely on the river for their survival.
A series of habitat enhancement projects are planned including spreading gravel below Kings Weir at Broxbourne to create new spawning beds, narrowing the river at key historic spawning sites to scour silt and provide clean spawning gravels, managing bankside trees to provide a good balance of overhanging cover for adult fish and marginal vegetation cover for juvenile barbel, and population monitoring.
While there is clearly still a great deal of work to do, the partnership has made great progress and we are optimistic that in the not too distant future barbel populations will once again thrive in the Old River Lea.
Where to see barbel
Visit Lemsford Springs Nature Reserve year-round on a clear day to see barbel by the bridge over the river Lea. If you visit during spring and summer you may see reed buntings and warblers too, as well as the delicate white flowers of water crowfoot. In autumn and winter you are in with a chance of seeing migratory green sandpipers – one was tracked here on a 900km flight to Norway and back.