NEW DELHI: In a worrying trend, there has been a reduction of nearly 30 per cent in the total fish species in the Ganga river between 2016-2020, owing to changes in the hydrological structure due to dam construction, land modification, pollution, industrial effluents and illegal fishing activities, according to a central government assessment.
The Central Inland Fisheries Research Institute (CIFRI), Kolkata, under the Ministry of Agriculture carried out quarterly field sampling from April 2016 to March 2020 to understand the distribution and current status of fish species on the IUCN (International Union for Conservation of Nature) Red List along the entire stretch of the Ganga.
The assessment shows that the status of fish being threatened is a major concern nationwide, particularly in the Ganga. From the present study, a total of 104 freshwater fish species were recorded in the river.
Earlier, 143 freshwater fish species were reported from the Ganga, among which 29 -- 10 endangered and 19 vulnerable -- were under the Red List.
It further said that changes in hydrological structure due to dam construction, land modification, pollution, industrial effluents and illegal fishing activities are the major causes for alteration of fish diversity in the Ganga basin, which affects conservation and management strategies.
“Proper study of the ecosystem should be done prior to implementing any hydro-related projects in the Ganga. Restoration of riverine connectivity with associated water bodies like wetlands which allow fish species migration for feeding, breeding as well as rearing should be managed because the linkage is an opportunity for improvement of species community structure,” noted an expert from the CIFRI.
The Ganga is divided into three stretches based on its characteristics, viz. upper (Uttarakhand), middle (Uttar Pradesh and Bihar) and lower (West Bengal) stretches. Quarterly field sampling was done along the whole stretch of the river to collect data on fish diversity and their abundance over a period of four years.
“Several fish species have been recorded under the IUCN Red List category during a survey. As these are economically prized fish, effective conservation and sustainable management plans should be implemented to restore the germplasm of fish species,” the expert added.