Yangtze

Description

The Yangtze or Yangzi is the longest river in Asia, the third-longest in the world, and the longest in the world to flow entirely within one country. It rises at Jari Hill in the Tanggula Mountains (Tibetan Plateau) and flows 6,300 km (3,900 mi) in a generally easterly direction to the East China Sea. It is the sixth-largest river by discharge volume in the world. Its drainage basin comprises one-fifth of the land area of China, and is home to nearly one-third of the countrys population. The Yangtze has played a major role in the history, culture, and economy of China. For thousands of years, the river has been used for water, irrigation, sanitation, transportation, industry, boundary-marking, and war. The prosperous Yangtze River Delta generates as much as 20% of Chinas GDP. The Three Gorges Dam on the Yangtze is the largest hydroelectric power station in the world. The Yangtze flows through a wide array of ecosystems and is a habitat to several endemic and threatened species including the Chinese alligator, the narrow-ridged finless porpoise, and the Yangtze sturgeon, but also was the home of the extinct Yangtze river dolphin (or baiji) and Chinese paddlefish. In recent years, the river has suffered from industrial pollution, plastic pollution, agricultural runoff, siltation, and loss of wetland and lakes, which exacerbates seasonal flooding. Some sections of the river are now protected as nature reserves. A stretch of the upstream Yangtze flowing through deep gorges in western Yunnan is part of the Three Parallel Rivers of Yunnan Protected Areas, a UNESCO World Heritage Site. Fishes The fish fauna of the Yangtze River system comprises over 370 species (178 genera, 52 families, 17 orders), of which cyprinids (Cyprinidae) account for 51 percent, loaches (Cobitidae) 6.9 percent, bagrids (Bagridae) 6.9 percent, Homalopteridae 5.5 percent, gobies (Cobiidae) 4.4 percent and other families 24.9 percent. There are 126 fish species in the lower Yangtze. In the middle Yangtze, there are over 140 fish species, most of which are either semi-migratory or resident. In the upper Yangtze, there are over 180 fish species. Historically, the Yangtze River system supported large runs of anadromous fish species. The late 1960s to early 1970s had seen the highest catch of Chinese shad and sturgeon in China. However, the migratory fish populations of both anadromous species began to decline in the early 1980s as a result of overfishing, pollution, water projects and habitat loss.  This is based on the size and quality of the species landed, the current production compared with that of previous periods and the main species. The major species of economic importance are black carp (Mylopharyngodon piceus (Rich.), grass carp (Ctenopharyngodon idella (C. et V.), silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), common carp (Cyprinus carpio), crucian carp (Carassius auratus), blunt snout bream (Megalobrama amblycephala), whitefish (Hemisalanx brachyrostralis), silurid catfish (Silurus asotus), copper fish (Coreius heterodon , Chinese shad (Macrura reevesii), anchovy (Coilia mystus), Chinese sturgeon (Acipenser sinensis), paddle fish (Psephurusgladius), Chinese sucker (Myxocyprinus asiaticus) and eel (Anguilla japonica). The distribution of the fish species varies from section to section of the river. There are 126 fish species, most of them migratory, in the lower Yangtze. In the fisheries of Jiangsu Province, anchovy accounts for about 50 percent of the catch, shad and eels for 20 percent, common carp, silurid catfish, black carp, grass carp, silver carp, big-head, whitefish, etc. for 30 percent. The catch from the lower Yangtze accounts for 63 percent of the total (Table 1). There are over 140 fish species in the middle Yangtze most of which are semi-migratory (black carp, grass carp, silver carp, bighead carp and some other) and resident species (common carp, crucian carp, etc.).