Question; What is happening to the fish, particularly fish that are commerically important ?
Yep, you guessed it. All the fish population have been declining over the past 50 years at all parts of Ganga River.
Here is what WWF says as far the the astounding diversity of fish & other creatures who have exised in the Ganges River historically. Some of these are likely extinct or severely extinct including one specie of fresh water shark only found in the Ganga and the River Dolphin.
Species
The Ganges river basin contains high biodiversity. There are over 140 fish species, the richest freshwater fish fauna in India, 90 amphibian species, and 5 areas supporting birds found nowhere else in the world.
The basin is home to 5 species of freshwater cetaceans including the endangered Ganges River Dolphin which faces an annual mortality rate of 10% and the rare freshwater shark, Glyphis gangeticus.
About Gangal Fish, I found an interesting Power Point posted by a university group in India in 2011. Very impressive study !
Here are a few slides to share for an overview of Fish population diversity currently to be found in the Ganga River.
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