Trees along riversides also provide habitat for flora and fauna and increase biodiversity. They act as wildlife corridors between fragmented habitats, keep river water cool and improve habitat conditions for aquatic animals. When branches or tree stumps fall into the water, this also creates new habitats and provides new energy sources for organisms.
Though India is a global hotspot for freshwater fish diversity with nearly 1000 species, India’s rivers are currently undergoing a biodiversity crisis. India is second in the world in freshwater fish production, and over 75% of fishermen depend on freshwater for their catch. However, fish yields from rivers are dropping steadily. Today, they yield stands at 15% of actual potential – 0.3 tons per km.
A few examples from some rivers gives an idea of the heavy decline. The average yield of major carps in the Ganga has declined by 90% over the last 40 years. The Hilsa fish – a central part of Bengali cuisine – has almost disappeared in the Ganga.
Hilsa fisheries have also reduced in the western Narmada River system. They decline between 1993-2005 amounted to two-thirds. Carp fisheries have also collapsed as water levels in the river dropped. Monthly catches of Mahseer, an endangered species, have now vanished.