Guide to Weed Cutting

NACA Guide to Practical Weed Cutting

For longer than I care to remember anglers have complained of the weed growth in the River Wensum during high summer. This is mainly because this has the effect of making many normal angling techniques difficult. However the complete removal of weed results in poor or non-existent catches due to the lack of cover, low natural food supplies and a huge increase in the blanket 'weed' or algae covering the river bed.

A suitable compromise is to cut the weed (mid-late July) in the central channel to a width not exceeding 1/3 to 1/2 total channel width, thereby leaving the margins to provide cover for fry and adult fish plus habitat for a greater number and diversity of invertebrates.

The downstream section of Sayers meadow was cut in this manner following consultation with the Environment Agency weed-cutting team in August. This proved very successful and, although this is the stated policy of the catchment engineers, it does appear that it is necessary to personally contact the EA prior to the weed cutting programme to ensure this policy is carried out. Tony Goodwin 44(0)1603 662800) is the man to talk to and I would strongly urge any club with fishing rights to make this approach in future, both for themselves and on behalf of the landowners. I'm sure they will find him most cooperative as there are operational advantages as well in working in this manner,

It should be noted that some stretches are deliberately not cut due to access difficulties and because a considerable lowering of the water level often follows weed cutting.

And Blanket Weed

Blanket weed is in fact filamentous algae (Claclophora spp) and is, if anything, a greater problem on the Wensum. It can grow very quickly, especially following extensive weedcutting, is not particularly useful for aquatic invertebrates, and in late summer and early autumn can render legering virtually impossible as large submerged clumps trundle down river in a seemingly never ending procession.

Being an alga it thrives in eutrophic (highly enriched) conditions and herein lies the problem. The nutrient status of the river appears to have increased significantly over the past 20 years or so, particularly with respect to phosphate.

As some estimates suggest approximately 50% of the phosphate loading originates from human sources via sewage treatment works (STWs) it is regrettable that phosphate discharge levels are not controlled by legislation at present. However, the EA are well aware of this problem with respect to the Wensum and attempted to include the river under the Urban Waste Water Directive, so forcing Anglian Water to install phosphate removal equipment at both Fakenham and Dereham STWs.

Unfortunately the Wensum was not considered a serious enough case this time around and the situation will be reviewed again in 1997! Here's hoping this situation will be rectified next time around. Incidentally, a useful comparison can be made if one views the river upstream of Fakenham in the Tatterford/ Shereford area with abundant rooted weed growth and lack of blanket weed, with the lower reaches after receiving the effluent from Fakenham and Dereham, eg Lyng!

Russell Francis