The population of Yangtze finless porpoises has decreased remarkably and the habitat fragmentation is getting worse. Three Yangtze finless porpoise distribution gaps have recently been discovered in the Yangtze River mainstream according to a survey conducted by Prof. WANG Ding and his team from from Institute of Hydrobiology, Chinese Academy of Sciences (IHB). 

One of the distribution gaps is the section of Yangtze River from Yichang to Jingzhou which is about 180 kilometers long. The other is from the Jingzhou downstream section to the Chenglingji upstream section of Yangtze River which is about 150 kilometers long. The third is Wuhan section of Yangtze River which is about 140 kilometers long. 

Previous studies also indicate the low density of Yangtze finless porpoise in the section of Jiangyin to Yangtze river estuary. The Yangtze finless porpoise are mainly distributed in the section of Yangtze River from Ezhou to Zhenjiang, and the habitat reveal a decreasing trend from edge to center. 

"Actually the habitat fragmentation occurred not only in the mainstream of the Yangtze River, but also at the junction of the mainstream and the two lakes that the finless porpoise inhabit.” said WANG. According to the ecological and acoustical investigation in recent years, the intense human activities at the outlets of both the Poyang Lake and Doting Lake have isolated the finless porpoise in the lakes from the ones in the main steam. 

Genetics analysis shows a rare migration between the Poyang Lake and main steam of the Yangtze River nowadays, whereas the hybrid offsprings of the two populations become more. WANG said this phenomenon indicates that “it had large-scale gene exchanges between the river and the lake in the past, but now the individuals and gene exchange has significantly reduced.” 

WANG also predicted that, at the current rate of decline, the number of finless porpoises in the main steam of the Yangtze River will drop to less than 250 individuals a few years later, even if the habitat environment of Yangtze River remains stable in a short term. It will be close to the size of baiji population in the end of 1980s. If ecological environment in the middle and lower reaches of Yangtze River can't get effective protection and improvement in the short run, the Yangtze finless porpoise will be threatened to disappear in the Yangtze River just like the Baiji.