Countryfile had an interesting bit on the effects of human waste on fish. Not only is "the pill" taking effect on fish reproduction, but the combination of chemicals from all sorts of human waste is causing a chemical block to reproduction.
All rather scary as the Water Authorities say its nowt to do with them. However, this issue is affecting other animals that eat the fish such as Otters, Mink, Kingfishers, Herons..and yip...us!