I have never fished the Norfolk Broads, and probably never will, however it has a long history in pike fishing and has in the past been an inspiration to me. For decades it has been blighted by fish kills brought on by outbreaks of prymnesium, which releases toxins fatal to fish when it dies, and massive fish kills have resulted. Seemingly pike are more susceptible than other species and pike stocks have collapsed after each outbreak.
There is a threat of another, man-induced, outbreak in the near future. I urge you all to read the excellent appraisal of the situation in Michael Hasting's latest blog post. This appears to be a prime example of fish and anglers taking low priorities to other wildlife and recreational interests, with neither the country's main conservation body (Natural England) nor the Broads Authority listening to any of the anglers warnings. If fish die it doesn't matter because nobody sees them. It'll be a different story when the rotting corpses are floating around.