Interlinking of rivers could flood India’s freshwater with invasive fish

Subject : Environment

Section: Biodiversity

Context:

New research shows that India’s ambitious Interlinking of Rivers (ILR) programme can spread invasive, alien fish to water bodies that are home to endangered fish species, posing ecological, economic, and livelihood threats.

Details:

About a third (31%) of the total area in India provides suitable habitat for invasive alien fish.
The major river basins of Pennar, Kaveri, Godavari, Krishna and Mahanadi that spread across central and southern India were found to be highly vulnerable to invasion.
The river interlinking in India would establish connectivity routes and help expand the range of potentially invasive species, especially in areas rich in threatened endemic species, such as the northeast India the Western Ghats and the Sundarbans.

Threat to biodiversity:

Invasive species affect biodiversity and ecosystems by increasing competition for food and taking up space which, coupled with changing biotic environments, habitat degradation and pollution, often negatively affects native species populations.
- In the case of invasive fish, which may display aggressive territorial behaviour, it can cause a decline in the number of native fish, which in turn, affects fishing livelihoods.
Globally, habitat destruction, increasing aquaculture and the introduction of ornamental species are altering freshwater ecosystems.

Some invasive fishes are:

Gambusia, native to the USA and Poecilia from South America, are widely used in mosquito control. Pterygoplichthys are popular ornamental fish. Tilapia and Cyprinus carpio are invasive species in the Ganga River system.
Hypophthalmichthys nobilis, native to China, has a suitable habitat in the Narmada, Mahi, Mahanadi, Kaladan, Irrawaddy, Godavari, Ganges, and Damodar river basins.

River Interlinking Project:

The Indian Rivers Inter-link is a proposed large-scale civil engineering project that aims to effectively manage water resources in India by linking Indian rivers by a network of reservoirs and canals to enhance irrigation and groundwater recharge, reduce persistent floods in some parts and water shortages in other parts of India.
India accounts for 18% of the world population and about 4% of the world’s water resources. One of the solutions to solve the country’s water woes is to link rivers and lakes.
The Inter-link project has been split into three parts: a northern Himalayan rivers inter-link component, a southern Peninsular component and starting 2005, an intrastate rivers linking component.
The project is being managed by India’s National Water Development Agency (NWDA), Ministry of Jal Shakti.
NWDA has studied and prepared reports on 14 inter-link projects for Himalayan component, 16 inter-link projects for Peninsular component and 37 intrastate river linking projects.