Hi Paul,
Of course re-stocking is not the long term answer for a lot of rivers and Karen mutes that in her thesis, as do a great many other experts. I have always maintained that the river environment is one of our national treasures. It is also one of the most fragile as very few wild environments can be destroyed in minutes as is the case with stretches of rivers.
But apart from incidences of severe chemical pollution which can only take seconds to enter any river system, its the long term effects of other pollutants which directly affect fish stocks and fish recruitment. Add to these the threats coming from clear imbalance's in predator numbers and the effects of agricultural practices together with habitat destruction, its clear to see that re stocking only remains a short term answer to a much larger problem.
The river Trent has gone from strength to strength in the last three decades. The river runs cleaner now than it ever has since the days of the industrial revolution. Roach and dace populations have exploded in the last ten years amid an environment of gin clear water. Odd then that this revival flies in the face of the trent being renowned for roach fishing when it used to run brown with filthy polluted water!!?? It can also be argued that the Trent is the finest barbel fishing river in the country today. Populations of huge carp to 50lbs plus, mammoth shoals of bream to well over ten pounds, huge chub, pike, zander, catfish to over 20lbs (illegally introduced admittedly) trout, encouraging eel numbers in places and the ever increasing emergence of salmon runs now being made up the river. The Trent used to be a major salmon river when 10,000 plus fish runs were common and those days are returning fast. Did you know the largest recorded salmon caught from the Trent was a fish of 46lb!
Interestingly, the location of the major spawning sites for dace along the Trent still remains a mystery, even to the lads at Calverton Fish Farm apparently.
The Upper Great Ouse is undoubtedly in decline compared to what it once was and this is not just reflected by a handful of locations that once contained huge barbel. And whilst research into declining rivers is important, we should also use examples like the river Trent as a standard to what "can" be achieved once the balance is right.
We have now got otters established and these populations will undoubtedly spread to colonise other ares and tributaries. We have arguably had the largest populations of cormorants of any inland river in the UK for generations. We now have a rapidly expanding population of zander spreading like wild fire along the middle river and beyond. Yet still the river goes from strength to strength with increasing numbers of fish which continue to support increasing predator numbers. As a fishery is still remains virtually untapped with massive swaths of banks completely deserted where once one would find it almost impossible to get a pitch at weekends due to the matches being fished.
They say fish thrive on neglect and in angling terms there is probably a ring of truth in that.
Regards,
Lee.