Worrying Environment Agency findings involving roach in River Wensum
Helen Beardsley, the Environment Agency fish biologist who researched the growth rate and the decline of roach in the non-tidal River Wensum, has disclosed for EDP angling more of her findings that worryingly come close to concluding that the species in the upper reaches is struggling to survive on a starvation diet while on the tidal Broads and rivers quite the opposite is true.
The scientist, based at Dragonfly House in Norwich, discovered that phosphate stripping from major sewage works serving the River Wensum catchment area, has resulted in the removal of vital food sources on which roach depend, such as algae, which also nourishes Zoo Plankton (commonly known as water fleas), recognised as prime producers of monster specimens booming in the tidal Broads and rivers.
Helen states: 'Roach growth rates in the River Wensum were found to be significantly higher prior to phosphate stripping. Subsequently, the growth was reduced.
'Phosphate is responsible for algal productivity within rivers and, by removing this to improve water quality, the food source for these fish is removed, although the river is consequently cleaner than during the roach heyday of the 1960s and 1970s.'
She further explained: 'Zoo Plankton such as Daphnia in rivers like the Wensum do not thrive or develop to the extent of lake environment and is not the main fish food source.
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'However, it is part of the food chain in sluggish reaches of the Wensum and in slack marginal backwater. The fact that there has been a loss of lateral connectivity with the Wensum and its flood plain and loss of backwaters does not help the case either.
'Where Zoo Plankton is minimal, roach have been forced to consume algae, proven to be less nutritious than animal prey particularly for juveniles requiring vital growth before the onset of colder water temperatures. By removing phosphate to improve water quality the food source of these fish is thus removed and you can see why roach have declined in growth and quality since the onset of phosphate stripping,' concluded Helen, while confirming that alien chub also contribute to the native species' decline due to relentless predation on fish spawn, newly hatches larvae and juveniles.
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None of this will impress the cormorant and otter culling campaigners, one of whom has asserted that two ponds adjacent to the River Wensum upstream of Fakenham Mill hold roach and dace 'in abundance', while the nearby river remains almost barren.
This may be interpreted as pure fishery fiction. The ponds are run by the Fakenham Angling Club (day tickets from Fakenham Angling Centre), who installed otter fencing two years ago to protect the fish stocks, including roach. These ponds do not contain dace, a species which is incapable of flourishing in still waters.
The dace referred to actually shoal in the section of the River Wensum around Fakenham, including the free fishing bank.
Fakenham club official Dave Playford reports he still spends happy hours dace fishing there, taking up to 50 to the 8oz mark during a two-hour session.
Thus, this poses an important question: How have the roach in the ponds and the dace in the river managed to survive the attention of allegedly flocks of ravenous cormorants that supposedly have ravaged silver fish stocks in the Wensum Valley to the point of extinction?
Dave Playford provides the answer that blows these claims out of the water. 'We have always had cormorants up here. I accept our big roach have gone from the river but it is beyond doubt the dace are still with us and we have always wondered why. Now we are informed it was not the work of predators but the result of improving river water quality to the detriment of the roach,' he said.
• Coarse fishing at the weekend was largely interrupted by frozen lakes and Broads on Saturday and a massive whiteout that greeted the dawn on Sunday.
Earlier in the week, Lol Higgins lifted out 30lb of skimmer bream to win the Veterans match in the Beccles Cut but, by Thursday, temperatures had plunged and David Roe won with less than 4lb of perch.
Sunday's winter league at Barford was postponed because some of the lakes were ice-bound but a few stayed on for an impromptu sweep on the Pleasure Lake, won by Tony Gibbons with 3lb 1oz.
There were average results from the chilly River Wensum, where Pete Swan (Daiwa AD) won with 8lb of roach. All the specimen carp waters were covered with a fair thickness of ice but the few intrepid rodmen who fished the Stalham event in the boatyard lagoon, kept ice-free by boat movement, struggled for fish apart from Dave Egerton, who weighed in 7lb 7oz with his contemporaries scaling ounces.
On the match lakes kept open by aerators at the weekend, the top catch at Barford fell to Rod Finch (Deben) with 48lb 8oz, followed by Warren Martin (Barford Tackle) with 34lb 13oz.