Yangtze
Fish

As of 2011, 416 fish species are known from the Yangtze basin, including 362 that strictly are freshwater species. The remaining are also known from salt or brackish waters, such as the river's estuary or the East China Sea. This makes it one of the most species-rich rivers in Asia and by far the most species-rich in China (in comparison, the Pearl River has almost 300 fish species and the Yellow River 160). 178 fish species are endemic to the Yangtze River Basin. Many are only found in some section of the river basin and especially the upper reach (above Yichang, but below the headwaters in the Qinghai-Tibet Plateau) is rich with 279 species, including 147 Yangtze endemics and 97 strict endemics (found only in this part of the basin). In contrast, the headwaters, where the average altitude is above 4,500 m (14,800 ft), are only home to 14 highly specialized species, but 8 of these are endemic to the river. The largest orders in the Yangtze are Cypriniformes (280 species, including 150 endemics), Siluriformes (40 species, including 20 endemics), Perciformes (50 species, including 4 endemics), Tetraodontiformes (12 species, including 1 endemic) and Osmeriformes (8 species, including 1 endemic). No other order has more than four species in the river and one endemic.

Many Yangtze fish species have declined drastically and 65 were recognized as threatened in the 2009 Chinese red list. Among these are three that are considered entirely extinct (Chinese paddlefish, Anabarilius liui liui and Atrilinea macrolepis), two that are extinct in the wild (Anabarilius polylepis, Schizothorax parvus), four that are critically endangered Euchiloglanis kishinouyei, Megalobrama elongata, Schizothorax longibarbus and Leiocassis longibarbus). Additionally, both the Yangtze sturgeon and Chinese sturgeon are considered critically endangered by the IUCN. The survival of these two sturgeon may rely on the continued release of captive bred specimens. Although still listed as critically endangered rather than extinct by both the Chinese red list and IUCN, recent reviews have found that the Chinese paddlefish is extinct. Surveys conducted between 2006 and 2008 by ichthyologists failed to catch any, but two probable specimens were recorded with hydroacoustic signals. The last definite record was an individual that was accidentally captured near Yibin in 2003 and released after having been radio tagged. The Chinese sturgeon is the largest fish in the river and among the largest freshwater fish in the world, reaching a length of 5 m (16 ft); the extinct Chinese paddlefish reputedly reached as much as 7 m (23 ft), but its maximum size is labeled with considerable uncertainty.

The largest threats to the Yangtze native fish are overfishing and habitat loss (such as building of dams and land reclamation), but pollution, destructive fishing practices (such as fishing with dynamite or poison) and introduced species also cause problems. About 2 ⁄ 3 of the total freshwater fisheries in China are in the Yangtze Basin, but a drastic decline in size of several important species has been recorded, as highlighted by data from lakes in the river basin. In 2015, some experts recommend a 10-year fishing moratorium to allow the remaining populations to recover, and in January 2020 China imposed a 10-year fishing moratorium on 332 sites along the Yangtze. Dams present another serious problem, as several species in the river perform breeding migrations and most of these are non-jumpers, meaning that normal fish ladders designed for salmon are ineffective. For example, the Gezhouba Dam blocked the migration of the paddlerfish and two sturgeon, while also effectively splitting the Chinese high fin banded shark population into two and causing the extirpation of the Yangtze population of the Japanese eel. In an attempt of minimizing the effect of the dams, the Three Gorges Dam has released water to mimic the (pre-dam) natural flooding and trigger the breeding of carp species downstream. In addition to dams already built in the Yangtze basin, several large dams are planned and these may present further problems for the native fauna.

While many fish species native to the Yangtze are seriously threatened, others have become important in fish farming and introduced widely outside their native range. A total of 26 native fish species of the Yangtze basin are farmed. Among the most important are four Asian carp: grass carp, black carp, silver carp and bighead carp. Other species that support important fisheries include northern snakehead, Chinese perch, Takifugu pufferfish (mainly in the lowermost sections) and predatory carp.
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