Environment & Ecology
In News: New research done in the Dongting lake in China that joins the Yangtze river found the cetaceans were pushed out of certain stretches of their habitat due to sand mining.
- This divides up the population and increases stress among the individuals, especially during pregnancy
- Gaps between porpoises in the lake reached 27 kilometres in 2009
Yangtze finless porpoise:
- IUCN status – critically endangered
- 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.
- It is the most critically endangered of its taxonomic group and the species has an 86 per cent chance of becoming extinct in the next century.
- Yangtze River dolphin was lost
- 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.
Sand Mining:
- Overfishing, increased shipping traffic and noise pollution have all been linked with the decline of the porpoise.
- Sand mining – mining activity posed multiple challenges to this endangered species.
- Sand mining was banned in the region in 2017
- Mining-induced loss of near-shore habitats, a critical foraging and nursery ground for the porpoise, occurred in nearly 70 per cent of the water channels
- 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
- Higher urbanisation has made sand the second-most extracted natural resource in the world after water.
- Checking sand mining can help the population of the Yangtze finless porpoise to rebound
Sources: DTE
Previous Year Question
Q1) Which one of the following is the national aquatic animal of India? (2015)
- Saltwater crocodile
- Olive ridley turtle
- Gangetic dolphin
- Gharial