The Bohai Bay is the drainage destination of the Hai River and 15 other rivers.[2] Due to these rivers' muddy runoff, the bay used to be a highly silty water body, but extensive damming of the various river systems has greatly diminished siltage. Nevertheless, the Bohai Bay in effect concentrates the runoff of the whole eastern North China Plain, and the Bay is an intensely polluted body of water.[3] Reduced silt deposition and sea level rise are causing problems with sea encroachment in some coastal areas.[4]
Fisheries were traditionally some of the richest in China, fed by enormous sediment runoff and extensive shallows to serve as hatcheries. Pollution, eutrophication, habitat destruction caused by land reclamation, and intense overfishing have resulted in a collapse of stocks, and a decline of trawl catch per unit of effort (CPUE) from 138.8 kg/net.hr to 11.2 kg/net.hr from 1959 to 1998.[5]
The Bohai Bay is ringed by several major ports: the Port of Tianjin, the large Port of Tangshan itself which consists of three ports (Caofeidian, Jingtang and Fennan), and the Port of Huanghua, making the Bay into a very crowded waterway. Land reclamation in Tianjin and in Caofeidian have greatly changed the littoral zone, and destroyed much of the area's wetlands. Land reclamation has also affected migratory birds.[6]
As is the case of most of the Bohai Sea, the Bohai Bay is rich in hydrocarbon deposits and has several active offshore oil fields. Jidong Nanpu contains Шаблон:Convert, while the bay as a whole is estimated to contain Шаблон:Convert.[7]
