A sanctuary for fish and a future for the river is Shivanasamudram’s conservation story

On a crisp morning by the rushing waters of the Cauvery, fisherman Manjunath crouches at the riverbank, his eyes scanning the currents. “When I was a boy, my grandfather told me these waters were alive,” he says, his voice tinged with nostalgia. “He knew where the fish would hide and when they would appear. Back then, we never took more than we needed. But now, I see fewer fish and the river feels different. People take as much as they can and it shows.”

Shivanasamudram — a majestic cascade of waterfalls and rocky pools in Karnataka’s Mandya district — harbours a rich but fragile aquatic ecosystem. This stretch of the Cauvery sustains diverse freshwater fish species, including the iconic Mahseer (Tor spp.), valued by conservationists and communities alike. However, altered hydrology, habitat degradation and unregulated fishing have pushed this ecosystem to the brink.

Recognising the urgency, the State Department of Fisheries (DoF) partnered with the Wildlife Association of South India (WASI), Bengaluru, to safeguard this vital habitat. This collaboration led to the establishment of the Shivanasamudram Fish Sanctuary (SFS) — a pioneering initiative that integrates conservation with traditional knowledge and sustainable practices.

Why a fish sanctuary?

The sanctuary was established in response to multiple threats facing the river's fish populations. Unregulated fishing, habitat destruction and pollution from human settlements have caused a decline in fish diversity. “A sanctuary is not just about protecting fish; it is about restoring balance,” says a senior official from the Department of Fisheries. “Rivers like the Cauvery are dynamic systems where fish migration, breeding cycles and water quality are deeply interconnected. Protecting key stretches helps rejuvenate the entire ecosystem.”

WASI, an environmental NGO based in Bengaluru, Karnataka, has been a key partner in this conservation effort, working alongside the DoF to protect the Mahseer and its habitat. Their collaboration took a significant step forward on 4 May 2004, when WASI and the DoF formalised an agreement to conserve Mahseer within the SFS — a major milestone in safeguarding one of India’s iconic freshwater species. Building on this foundation, a follow-up agreement was signed on August 4, 2011, strengthening conservation efforts. This agreement specifically targeted the mitigation of illegal fishing, the sustenance of fish populations and the preservation of the sanctuary’s ecological integrity.

Among Karnataka’s 22 designated fish sanctuaries — some fully operational, others only recently announced — Shivanasamudram stands out as the most functional. Its well-defined conservation framework and active management set it apart as a model for sustainable fish sanctuary initiatives in the state.

Additionally, the Cauvery River itself is a lifeline to southern Indian states, providing water for agriculture, drinking and industry. Its ecological health is critical not only for fish but also for millions of people who depend on its waters. The Mahseer, often referred to as the ‘Tiger of the River’, holds immense ecological and cultural significance. As an apex predator and an indicator species, its presence reflects the overall health of freshwater ecosystems. Conservation efforts aimed at protecting Mahseer populations inherently contribute to the broader goal of maintaining riverine biodiversity.

How Shivanasamudram is managed

Effective conservation goes beyond simply designating a protected area — it requires ongoing efforts to monitor, manage and restore ecosystems. At SFS, a structured, multi-faceted management approach ensures the long-term sustainability of fish populations and aquatic habitats.

A key strategy for maintaining fish populations in the sanctuary is the strict ban on commercial fishing. By not issuing fishing licences in the area, the DoF ensures that native fish species can thrive without the pressures of large-scale harvesting. This regulation preserves biodiversity and facilitates natural fish reproduction. To further support conservation and local fisheries, WASI releases nearly 100,000 carp fingerlings into the protected waters of the sanctuary each year. These fingerlings grow in this safe environment before dispersing into neighbouring fishing concessions where fishing is permitted, thereby benefiting local fishers outside the sanctuary boundaries.

In this protected environment, these fish have access to abundant natural food, promoting healthy growth. Over time, this initiative provides local fishers with a stable source of high-quality fish, benefiting both livelihoods and market demand. While fish stocking is a common fisheries management practice, introducing non-native species can disrupt ecosystems.

To minimise ecological disruption, only non-predatory, bottom-feeding species — such as Rohu (Labeo rohita), Catla (Catla catla) and Mrigal (Cirrhinus mrigala) — are introduced. These species do not naturally breed in the Cauvery River, meaning their populations remain regulated through human intervention. This careful selection reduces competition with native fish and helps maintain the sanctuary’s ecological balance.

Round-the-clock patrol and protection

Illegal fishing and habitat destruction remain serious threats. To tackle this, WASI has a dedicated Watch and Ward team — five trained patrol staff from local communities who monitor the sanctuary 24/7. Their role is not just to prevent illegal activities like poaching or dynamite fishing but also to build relationships with local authorities, tourists and stakeholders. Instead of direct confrontation, patrol teams document offences, using CCTV cameras and camera traps to track activities in high-risk areas. This data is recorded in a wildlife crime database, which helps law enforcement take action when needed.

Beyond enforcement, the Watch and Ward team plays a crucial role in raising awareness about conservation laws and responsible fishing practices. By engaging with local fishers and visitors, they foster a sense of shared responsibility for protecting the sanctuary. Regular patrols and visible monitoring have also acted as deterrents, significantly reducing illegal activities over the years. The presence of trained community members in these roles ensures that conservation efforts are locally driven, increasing their effectiveness and long-term sustainability.

Scientific research and environmental education

WASI has been at the forefront of research on Mahseer and other freshwater species, focusing on their behaviour, health and population dynamics. Through citizen science initiatives, it has facilitated long-term fish monitoring for over 17 years, making it one of India's longest-running fish research projects. Key studies have examined the impact of recreational angling on fish health, implemented tagging and recapture programmes for large-bodied carps and conducted taxonomic and biodiversity assessments to support conservation efforts.

Beyond research, WASI actively promotes outreach and environmental education, ensuring that scientific knowledge translates into conservation action. In collaboration with the DoF, WASI also carries out regular catch-and-release surveys to monitor fish diversity and abundance. This approach not only helps researchers track population trends and identify emerging threats but also educates and empowers stakeholders to participate in conservation efforts, strengthening long-term sustainability.

Community involvement: A key to conservation

Successful conservation extends beyond safeguarding fish; it depends on the active involvement of the communities that depend on them. WASI has embraced this approach by conducting educational programmes, training workshops and internships to engage residents in sustainable fisheries management. Over the years, more than 300 individuals have been trained in responsible angling practices and 25 local villagers have become professional angling guides, supporting both conservation efforts and local livelihoods.

The sanctuary has also evolved into a hub for learning, drawing interest from government agencies and conservation organisations across India, including the Karnataka Forest Department, the Indian Institute for Human Settlements (IIHS) in Bengaluru and the National Bureau for Fish Genetic Resources (NBFGR) in Lucknow. Public awareness initiatives further amplify these efforts through various media.

These include a video highlighting the threats of dynamite fishing in the Cauvery, an upcoming podcast episode by Tigress on Tuk Tuk, a short film titled Cauvery WASI and a forthcoming documentary produced by Gaia People and The Habitats Trust.

Riparian restoration and waste management

WASI has implemented several tree-planting initiatives along selected riparian sites to enhance habitat quality and ecosystem resilience. One notable effort is a 3-acre restoration project at Malligemaradahalla Lake, a unique swamp wetland at SFS that supports diverse aquatic species. However, the SFS, located downstream of multiple human settlements, faces persistent challenges from plastic waste and other debris, especially during the monsoon season.

To mitigate this, the Watch and Ward team conducts regular clean-up operations, using boats to remove accumulated waste from waterways. Additionally, past clean-up drives have focused on popular tourist locations, such as the Gaganachukki and Barachukki viewpoints, to reduce pollution and protect the health of the aquatic ecosystem.

The Shivanasamudram Fish Sanctuary is more than just a protected area — it is a living laboratory for sustainable fisheries management. Through a combination of scientific research, community engagement and conservation action, SFS has set a benchmark for freshwater fish conservation in India. However, despite its successes, the sanctuary continues to face significant challenges.

Climate change-driven fluctuations in water flow, lack of financial resources and persistent illegal fishing demand ongoing vigilance. Reinforcing policy support for fish sanctuaries, expanding conservation zones and integrating local governance into decision-making will be essential for ensuring the long-term sustainability of Shivanasamudram’s aquatic biodiversity.

As the sun sets over the rushing waters of the Cauvery, Hanif watches a fish break the surface, its silver scales shimmering in the fading glow. “This river has sheltered these fish for generations,” he says, his voice filled with quiet resolve. “If we protect the Shivanasamudram Fish Sanctuary, we are not just saving them — we are securing the future of an entire ecosystem.”

More than a conservation initiative, the SFS stands as a testament to the power of collaboration — where science and community come together to safeguard one of India’s most iconic rivers. With sustained commitment, it remains a beacon of hope for freshwater conservation, ensuring that these waters continue to thrive for generations to come.

Anirban Roy is a doctoral student at the Academy of Conservation Sciences and Sustainability Studies, ATREE Bengaluru and Naren Sreenivasan is a conservation biologist at Wildlife Association of South India, Bengaluru.

Views expressed are the author’s own and do not necessarily reflect those of Down To Earth