Restoring river biodiversity through river ranching

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Picture Courtesy: PIB

Context:

Under the flagship Namami Gange Programme, the Government of India has launched a large-scale ecological restoration initiative known as River Ranching to revive the declining aquatic biodiversity of the Ganga. As part of this effort, scientists have released more than 2 crore native fish fingerlings into the river system to restore its natural fish population and ecological balance. Strengthening inland fisheries through such measures has also contributed to India emerging as a global leader in inland fish production, surpassing several major countries.

What is River Ranching?
River Ranching is a scientific stock enhancement technique aimed at rebuilding natural fish populations. Native species are first bred under controlled and hygienic hatchery conditions to ensure high survival and genetic quality. Instead of releasing fragile larvae, the fish are allowed to grow until they reach a size of approximately 10–15 cm, which improves their ability to escape predators and adapt to natural conditions. These healthy juveniles are then released into the river, where they mature, reproduce, and contribute to restoring the aquatic ecosystem.

Need for ecological intervention in the Ganga:

Obstruction of natural migration:

• The construction of dams and barrages (such as the Farakka Barrage) disrupted the natural upstream and downstream movement of fish.
• Many species depend on seasonal migration for breeding, and these physical barriers prevented them from reaching spawning grounds.

Declining water quality:

• The discharge of untreated domestic sewage and industrial effluents led to severe water pollution.
• Contaminated water destroyed breeding and nursery habitats, reducing survival rates of eggs and juvenile fish.

Loss of spawning and habitat areas:

• Riverbank modification, siltation, and altered flow patterns degraded natural spawning zones.
• Habitat fragmentation reduced ecological diversity and carrying capacity of the river.

Overfishing and unsustainable practices:

• Indiscriminate fishing, especially the capture of juvenile and breeding fish, disrupted natural population cycles.
• Excessive extraction reduced the number of mature fish available for reproduction.

Weak Natural Regeneration: The combined impact of habitat loss, pollution, migration barriers, and overexploitation reduced the river’s natural ability to replenish fish stocks, leading to a sharp decline in biodiversity and fish abundance.

Key species linked to the river’s ecological health: 

• Ganges River Dolphin
• India’s National Aquatic Animal.
• Acts as a bio-indicator of clean freshwater.
• Its presence reflects improved water quality and overall ecological health of the river.
• Hilsa (Tenualosa ilisha)
• An anadromous species that migrates from the Bay of Bengal to the Ganga for spawning.
• Requires uninterrupted river flow and suitable breeding habitats.
• Its recovery indicates improved river connectivity and ecological restoration.
• Indian Major Carps (Rohu, Catla, etc.)
• Form the backbone of inland fisheries in the Ganga basin.
• Provide food security and livelihoods to lakhs of small-scale fishermen.
• Their population growth supports economic stability and nutritional security.
• Golden Mahseer
• Popularly known as the “Tiger of the River.”
• Found in the upper reaches of the Ganga in fast-flowing, oxygen-rich waters.
• Serves as an indicator of clean, unpolluted, and ecologically healthy river habitats.

Implications on the ground:

• Increase in fish production: River Ranching has led to a noticeable improvement in fish availability across several stretches of the Ganga. In cities such as Varanasi, fish landings have increased significantly, with reports indicating a rise of nearly 40%, reflecting the successful restoration of fish stocks.
• Improved livelihood opportunities: The increase in fish catch has directly enhanced the income of small and marginal fishermen. By strengthening inland fisheries, the initiative is supporting sustainable livelihoods and improving the economic conditions of river-dependent communities.
• Enhanced food and nutritional security: Higher fish production has improved access to affordable sources of protein for local populations. This contributes to better food and nutritional security, particularly for economically vulnerable groups living along the river basin.
• Revival of native fish species: The scientific release of native species is helping restore declining populations such as Hilsa and Indian major carps. This has strengthened aquatic biodiversity and helped re-establish ecological balance within the river system.
• Technology based monitoring and management: The use of modern tools, including drone-based surveillance, has improved the monitoring of water quality, habitat conditions, and fish survival rates. This enables more effective, scientific, and evidence-based river management.

Conclusion:
River ranching represents a sustainable and science-based approach to restoring depleted fish populations while maintaining the ecological balance of river systems. By replenishing native species, enhancing fish production, and supporting the livelihoods of river-dependent communities, the programme contributes to both biodiversity conservation and economic development. In the long run, effective implementation and continuous monitoring can make river ranching a key tool for achieving sustainable inland fisheries and healthy river ecosystems.

Source: PIB