PTI
Kolkata
Fish diversity in River Ganga has increased by nearly 61% over 11 years, reflecting sustained ecological recovery under government-led rejuvenation efforts, a study by the ICAR-Central Inland Fisheries Research Institute (CIFRI) has revealed.
The river also recorded its highest fish diversity in nearly five decades, with scientists documenting 230 fish species across its various stretches, the research found, highlighting the impact of ongoing restoration and conservation measures.
Director of CIFRI B K Das said, “This is the result of a number of rejuvenation plans over the years, including the ongoing Namami Gange.”
The fish diversity increased from 143 in 2012 to 230 in 2023, a rise of 60.83%. Besides, the latest survey, conducted in 2023, recorded the number of species to 230, the highest diversity in over half a century.
ICAR-CIFRI’s Fisheries Resource Assessment and Informatics Division head Srikanta Samanta said, “The Ganga rejuvenation plan, starting from the Ganga Project Directorate in the 1980s to the present National Mission for Clean Ganga, has significantly improved the ecology of the river.”
Ganga, which originates in the Himalayas and flows for about 2,525 km through Uttarakhand, Uttar Pradesh, Bihar, Jharkhand and West Bengal before entering Bangladesh and draining into the Bay of Bengal, once supported a far richer aquatic ecosystem.
Historical records show that the river hosted 271 fish species in 1822, but that diversity declined steadily over time due to pollution, habitat degradation and overexploitation.
By 1974, the number of species had dropped to 207, falling further to 172 in 1991, and touching a low of 110 species in 1998. Following intensified restoration and fisheries management efforts led by Barrackpore headquartered ICAR-CIFRI, fish diversity improved to 162 species in 2004, before slipping again to 143 in 2012.
Explaining the broader ecological improvements, Samanta said the recovery of fish diversity has been supported by better water quality and habitat conditions across
the river.
“Although the population has increased significantly by this time, the riverine habitat has not deteriorated; rather, it has improved,” he said.
He pointed to a marked improvement in dissolved oxygen levels, particularly in the middle stretches of the Ganga, compared with the 1980s.
“Oxygen availability in water is nearly a thousand times lower than in air, which makes aquatic ecosystems far more vulnerable. Monitoring water quality is therefore critical for maintaining ecological balance,” Samanta said.
