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Context: Critically endangered Yangtze finless porpoise return to lost lake stretches after sand mining ban: Report

Details:

• Previous reports had shown the cetaceans were pushed out of certain stretches of their habitat due to sand mining.
• This divides up the population and increases stress among individuals, especially during pregnancy, the new research done in the Dongting lake in China that joins the Yangtze river found. 

About:

• The Yangtze finless porpoise belongs to the group of animals which also includes dolphins and whales. 
• It is the only freshwater porpoise in the world and breeds just once in 18 months.
• Overfishing, increased shipping traffic and noise pollution have all been linked with the decline of the porpoise. 
• It is the most critically endangered of its taxonomic group and the species has an 86 percent chance of becoming extinct in the next century.  

Concerns:

• The lake is connected to the main body of the Yangtze river by a channel that runs under the Dongting Lake Bridge.
• The porpoise population would swim to and from the river through this channel but because of sand mining, they were not seen in this channel any longer, the report noted. 
• The sheer number of mining boats on the water meant that they formed an effective barrier across the waterway, which could also prevent the porpoise's prey fish from reaching the lake. 
• Thus, mining activity posed multiple challenges to this endangered species.
• However, since sand mining was banned in the region in 2017, the porpoises were spotted in parts of the lake they would previously avoid, according to the findings of the survey. 

Sand Mining:

• Sand mining, which has tripled in the last two decades, is an emerging concern for global biodiversity.
• Over 50 billion tonnes of sand is mined every year.
• The menace is most rampant in Asia, Africa and Latin America.
• It threatens biodiversity and interferes with ecological processes through direct physical disturbances, habitat degradation and reducing water quality by altering sedimentation. 

https://www.downtoearth.org.in/news/wildlife-biodiversity/critically-endangered-yangtze-finless-porpoise-return-to-lost-lake-stretches-after-sand-mining-ban-report-87199

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