The Extinction of The Baiji
Baiji (also called Lipotes vexillifer) is a species of freshwater dolphin living in the Yangtze River in China. It is pale blue on the back side, and white on the belly side. Because of its beauty, local people call it “Goddess of the Yangtze”. It was declared as a functionally extinct species in 2007. People make a variety of explanations for its extinction. Because baiji’s pregnancy rate and litter size are low, and it grows slowly, some scholars argue that extinction of baiji is the result of natural selection. They say it became extinct because it could not adapt to changes in the environment. But baiji had lived in Yangtze River for at least 2500 years! The large decrease happened since nineteen-eighties because of human’s behaviors.
Due to improper human activities, the accidental death of baiji increased. Yangtze River has because a busy water-traffic corridor. According to statistics, about a third of baijis accidentally died at down stream of the Yangtze River were killed by the ship propellers. These baijis did nothing wrong, they just swam in their home, but they were killed by human. Another data shows that, from 1973 to 1985, 59 baijis was accidentally killed. 48.8 per cent (29) of them were rolled in fish hook or other fishing gear; 18.6 per cent (11) were killed by river blasting operation; 20 per cent (12) were hit by ship screw propellers; 10 per cent (6) died because of stranding; and 1 go into the sluice.
Besides direct physical harm, human’s behavior also damages their habitat in Yangtze River. First the overfish behavior results in insufficient supply of fish and shrimp, which are the main food of baiji. As well as that, the over-exploitation of the Yangtze River, severely damaged the dolphin habitat. What’s worse, near the Yangtze River, some chemical plants and pharmaceutical factories emit pollutions in the river, toxic pollutants largrly harm baiji’s health.
Sources:
https://en.wikipedia.org/wiki/Baiji
http://www.chinabaike.com/z/shenghuo/kp/2016/0606/5309734.html
