INVESTIGATIONS ON FISHES AND FISHERY OF FOUR LAKES ALONG THE MIDDLE AND LOWER BASINS OF THE CHANGJIANG RIVER

Lake Niushan, Lake Dongtangxun, LakeHuanghu and Lake Longgan are situated in the middle and lower basins of the Changjiang River.During the period of 1996 to 1999 investigations on fishes and fishery of the lakes were carried out to provide information on rational utilization of fish resources, especially sustainable fishery management.64 species (belonging to 15 fam-i lies and 50 genera) were recorded in Lake Niushan, 53 species (14 families and 43 genera) in Lake Dongtangxun, 76 species (17 families and 58 genera) in LakeHuanghu, and 80 species (18 families and 59 genera) in Lake Longgan1Fish fauna of those lakes were similar, and the largest of families was the Cyprinidae, which contributed 6014%) 6516% to the total number of fish species.Grass carp dominated stocking rate in LakeNiushan, silver carp and bighead carp in Lake Dongtangxun, and silver carp and Chinese mitten crab in Lake Huanghu.During this survey, annual stocking rate of subyearlings averaged 9.5kg/hm2in Lake Niushan, 3618kg/hm2in Lake Dongtangxun, and 811kg/hm2in Lake Huanghu; the average of fish yield was 128kg/hm2in Lake Niushan, 126kg/hm2in Lake Dongtangxun, and 88kg/hm2in Lake Huanghu; and annual income per hectare from fishery was 623 yuan, 680 yuan and 1202 yuan, respectively, in the above lakes.In Lake Longgan (without fish stocking), annual fish yield ranged from 50 to 77kg/hm2, of which smal-l sized fish, such as gold fish (Carassius auratus), redfin culter (Culterichthys erythropterus) and other small coarse fish, accounted for large proport ion; and fishery income per hectare averaged 183 yuan.In addition, the composition of fish yield in every lake was analyzed, and some strategies for developing sustainable fishery in the future were suggested.