Good news following River Wensum barbel and roach study
(From the Environment Agency)

The River Wensum has long been renowned for its great angling and a recent study by the Environment Agency shows that the river supports sustainable populations of both barbel and roach.

It was commonly believed that populations of these fish were struggling but the surveys found adult fish and fry of both species to be widespread in the river. Although distribution is patchy, the Agency believes that with habitat restoration projects already planned, this will steadily improve.

The River Wensum is a nationally and internationally important site for nature conservation and is designated as a Site of Special Scientific Interest and as a Special Area of Conservation.

These designations mean that the Environment Agency has to carefully balance its legal duties towards fisheries and conservation when making any management decisions affecting the river.

Adam Piper, Ecological Appraisal team leader said: ‘Over the years poor habitat, reduced water quantity and changes to water quality, along with increased levels of nutrients and silt, have all taken their toll on fish stocks.

‘Our surveys found that the main factor which limits the population growth for barbel is a lack of suitable gravel beds for spawning and for roach it is lack of suitable habitat for juvenile fish, particularly vegetation cover at the edges of the river.’

Through the River Wensum Restoration Strategy project, the Environment Agency will be working on large scale habitat improvements up and down the river to restore favourable conditions for a range of fish species. They are confident that the Wensum will continue to support self-sustaining populations of barbel and roach over the next few years. Adam said: ‘These sort of habitat improvements are likely to have the most lasting effect on fish stocks in the river.’

Proposed actions include reducing impoundments on the river, restoring the gravel beds, narrowing the channel, increasing the amount of woody material and modifying the weed cutting regime at critical phases of fish life cycles. Adam said: ‘This will restore the river to a more natural form and allow it to sustain fish and other wildlife characteristic of this type of river.

‘This winter we are starting a series of river restoration projects, in partnership with fishing clubs and landowners, at Swanton Morley, Lyng, Attlebridge and Costessey. This will include restoring and installing new spawning gravel beds and enhancing marginal habitats for fish fry. There will also be improved access for angling at Swanton Morley.’

Improvements in water quality through better sewage treatment are also planned, and the Agency is working hard with partner organisations to reduce the input of fine sediments to the river. Water abstraction within the catchment is also being examined to see whether flows can be improved, particularly in the lower river.

Other management options were looked at, in particular the idea popular with anglers of stocking the river with more barbel and roach. After looking at the survey results and careful consideration of the arguments for and against stocking, it is the Agency’s professional opinion that stocking will not be beneficial as the River Wensum is capable of supporting healthy populations of these fish species given the right conditions.

Adam explained: ‘We expect that fish populations in the river will change positively over time in response to continued improvements in water quality and the implementation of large scale river restoration work. We consider these measures are the best way of improving fish populations and hence fisheries, on the river and that it is not appropriate to artificially increase coarse fish populations above natural levels.’

December 2007