Fishers Green used to be my local water and I can remember catching loads of pike there and in Hooks Marsh.
Undoubtably, if the food source is removed, the predators will suffer.
However, I know of very hungry waters up here that contain very few prey fish, but prouce many large pike. The reson is, cannibalism and predating on ducks, voles etc.
Is it possible that, with the re-surgance of Pike fishing, the fish are suffering at the hands of anglers? As we all know, Pike do not like pressure, and, on popular waters, the fish seem to fade away after a period of time. I have also found that Pike learn very quickly when it comes to large lures and Jerkbaits.
My local water I can safely say, is only fished by myself with Jerkbaits. At first I was getting up to 10 doubles a day, but after around a year, i was struggling to get a hit. I switched to large Flies, and...low and behold, the doubles were back. 3 months later though, I cant get a hit on yellow flies anymore, but switching to orange has brought me fish again.
Maybe the fish are just getting clever. Has there been any scientific data on this problem?