Evidence points to disease and suspect water quality behind plunging native river roach populations

Significant evidence has emerged from official records and angling archives that native river roach populations have not plunged as a result of predation – but were more likely victims years ago of disease and suspect water quality.

Bacterium flexibar columnaris that causes ulcerated dermal necrosis (UDN) swept through Norfolk waters during the 1970s and early 1980s, the visible symptoms extensive fungus growth and open lesions.

Giant roach were spotted floating belly up in the non-tidal rivers and remedial measures that involved annual restocking of popular venues were undertaken with fish netted from private lakes and pits as well as the Costessey fish farm to maintain interest among angling clubs years before commercial fisheries began to shape the future.

Most certainly otters could not be targeted, for in 1985 a survey of 137 separate Norfolk sites revealed just two areas that showed positive signs of an otter habitat.

And just to put the record straight, The Otter Trust during its 15-year operation before it closed down in 1999, released only 81 of these semi-tamed mammals throughout the whole of East Anglia (Norfolk, Suffolk and Cambridgeshire).

Steps were taken by local fisheries officers to kick-start recovery by an Off River Supplement (ORS) scheme that involved introducing fish spawn gathered from the Costessey fish farm into predator proof inlets of main rivers.

Aylsham Club secretary Keith Sutton was an eye witness of this exercise on the upper River Bure.

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He recalled: 'Once the spawn reached the egg sac stage, the larvae all died off. It seems there was something in or not in the water that caused the ORS to fail and a netting survey below Aylsham Mill produced just half a dozen small dace.'

More light was shed on this phenomenon by a study of roach growth rates in the River Wensum conducted by the Environment Agency fish biologist Dr Helen Beardsley, assisted by Robert Brittan at the School of Environmental Sciences at Bournemouth University.

The few roach they captured displayed growth rates well below the norm and this was put down to – wait for it – phosphate stripping from sewage effluent that created a chemical imbalance reducing the fertility that used to nourish giant three pound plus roach and rudd.

Helen Beardsley noted the slowest growth of roach occurred between 2005 and 2008, which gives credence to the belief of Norfolk's highly-esteemed fisheries scientist Dr Jonathan Wortley, who, way back in the 1970s, argued that the drive towards achieving purer water in our small non-tidal rivers would result in sterility and possibly a lifeless habitat.

Meanwhile, some of the cull-the-otter tendency are demanding responses to suggestions that non-anglers have no right to contribute to the otter debate while insisting that female of the species can actually produce three or four litters every year.

Clearly they cannot accept that fish were not put on this planet for gratuitous gratification of rod and line anglers, but are, like the otters themselves, just part of nature's gifts to be revered.

Angling is a privilege granted on tidal waters by King John in 1215 and on non-tidal waters by whoever possesses the riparian's right.

Female otters can breed only once a year with an average of two offspring surviving, with some mothers often missing a season because the previous year's family is still hanging on.

Advice and application forms are available from Natural England online (enquiries@naturalengland.org.uk).

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