Jiuduansha is a collection of four intertidal wetland shoals at the mouth of China's Yangtze River. They are administered as an island region of the municipality of Shanghai's Pudong New Area.
These shoals and the submerged land surrounding them to a depth of 6 meters (20 ft) form the Jiuduansha Wetland Nature Reserve. The entire area stretches roughly 46.3 kilometers (28.8 mi) east to west and 25.9 kilometers (16.1 mi) north to south, covering an area of 423.5 square kilometers (163.5 sq mi), although only 114.6 square kilometers (44.2 sq mi) of this is above sea level. The area is considered one of the national urban wetland parks of China and forms part of the China Biosphere Reserve Network. A 1996 field study found that, for seven bird species investigated, the number present at Jiuduansha exceeded 1% of the world's total for the species, establishing it as a Wetland of International Importance.
