Water quality 420 Limnology 199 Fisheries 154 England 138 Management 127 Inland waters 113 Pollution 102 Ecology 100 Rivers 85 Aquaculture 82 Freshwater fish 82 water quality 81 Fishery management 51 Migratory species 51 Biology 50 Environment 46 Iran 44 Environmental monitoring 41 Fishery regulations 38 Fish catch statistics 36 Fishery data 35 Phytoplankton 35 Freshwater pollution 33 Nature conservation 33 River fisheries 33 Chemistry 32 Eutrophication 30 Nigeria 29 Salmon Action Plan 28 Water management 27