Studies On Fishery Resources In The Three Gorges Of The Yangtze River

Form 2005 to 2006, the overall fishery status of the Three Gorges reservoir was investigated for 3 times. For each investigation, 17 sampling localities were determined and locus monitoring was performed in Banan and Wanzhou section of Yangtze River twice each month. Each investigation last for 1-2 months. The fishery status of the Three Gorges reservoir was analyzed by the data from the survey and the data in previous years. The main results are as follows:1. In all, 108 species of fish which belong to 9 orders 20 families 71 genus were found by the investigation. Among these fishes, the species of Cypriniformes is 71, accounting for 65.74% of total fishes; the species of Siluriformes is 18, accounting for 16.67%; the species of Perciformes is 9, accounting for 8.33%; the number of other species in all is 10, accounting for 9.26%.2. Hypophthalmichthys molitrix, Silurus solldatovi, Cyprinus carpio, Pelteobagrus fuIvidraco, Coreius heterodon, Coreius guichenoti, Rhinogobio ventralis, Rhinogobio cylindricus, Leiocassis longirostris, Ctenopharyngodon ideUa and Hemiculter were the major commercial fishes in the Three Gorges reservoir. As a result, the number of common fishes whose occurrence frequency exceeds 40% is 14, their frequency are as follows: Pelteobagrus fulvidraco(100%)＞Silurus solldatovi, Cyprinus carpio, Hemiculter(94.12%)＞Ancherythroculter(88.23%)＞Hypophthalmichthys molitrix (82.35%)＞Carassius auratus auratus(70.59%)＞Coreius heterodon, Rhinogobio ventralisventralis, Leiocassislongirostris(58.82%)＞Coreius guichenoti, Ctenopharyng-odon idella (52.94%)＞Mystus macropterus(47.06%)＞Procypris rabaudi(41.18%).3. The frequency distribution of body length and body weight and the age structure of the the major commercial fishes were measured. The finding indicates the catching components in different sections were different, and the miniaturization and the trent of the lower age were quite distinct,.lower-aged and mini-body phenomenon Was clear.4. The average daily catch (CUPE) annually in several sections of the Three Gorges reservoir was caculated with the number of the operating fishers (N) and working days (T) and the yearly fishery product was about 2046 312 kg.5. Comparing with before the water was stored, the number of the current operating fishers increased, the catching intension enhanced and the catching efficiency improved. Overfishing reduced the fishery resource in the Three Gorges reservoir, the number of the fish species clearly declined. Spinibabus sinensis, Myxocyprinus asiaticus, Procypris rabaudi rapidly declined. Acipenser sinensis, Onychostoma simus, Ochetobius elongates, Elopichthys bambusa, Luciobrama macrocephalus, AnguiIla japonica could hardly be found.