Investigations on fishes and fishery of four lakes along the middle and lower basins of the Changjiang River

Niushan, Lake Dongtangxun, Lake Huanghu 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 families 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 Lake Huanghu, and 80 species (18 families and 59 genera) in Lake Longgan. Fish fauna of those lakes were similar, and the largest of families was the Cyprinidae, which contributed 60.4%-65.6% to the total number of fish species. Grass carp dominated stocking rate in Lake Niushan, 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/hm(2) in Lake Niushan,36.8kg/hm(2) in Lake Dongtangxun, and 8.1kg/hm(2) in Lake Huanghu;the average of fish yield was 128kg/hm(2) in Lake Niushan, 126kg/hm(2) in Lake Dongtangxun, and 88kg/hm(2) in 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/hm(2), of which small-sized fish, such as gold fish (Carassius auratus), redfin colter (Culterichthys erythropterus) and other small coarse fish, accounted for large proportion; 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