The hump-backed mahseer, among the largest freshwater fish species, is gaining attention from conservation agencies that are trying to preserve its habitat in the Western Ghats. Saving the ‘Tiger of Kaveri’ can help ensure healthy rivers and save other wildlife.
The Kaveri river can easily be called the lifeline of Karnataka and its waters are home to a special kind of fish called the hump-backed mahseer. Often called ‘one of the world’s hardest fighting freshwater game fish’, this variety can grow almost 1.5 meters in length and weigh upto 60 kgs.
Naturally, the fish is a star attraction in its Western Ghats habitat and has earned the moniker ‘Tiger of Kaveri.’ Once sought after by anglers, its population has decreased by 90 per cent in the last 15 years, according to researchers, and it is now critically endangered, following a taxonomic evaluation. The medium- to large-bodied freshwater fish widely distributed in Indian rivers is now a rare sighting in some parts of Karnataka, Kerala and Maharashtra.
While most conservation activities are aimed at mammals, the riparian (riverbank) habitat and its inhabitants are often forgotten. However, the ecological impact of these species is larger than what meets the eye. As a keystone species that indicates the health of the river water system, the hump-backed mahseer needs a holistic approach that blends communities, habitats and species to give them the protection and conservation they deserve.
There has been a concerted effort to save the species by several local and international organisations. Neethi Mahesh, a conservation consultant at Wildlife Conservation Society India (WCS-India), has been working on conservation of the riparian habitat along the Kaveri, in Karnataka’s Coorg district, for close to a decade now. She uses freshwater fish as indicators of the status of the conservation efforts and the health of the habitat.
“Indicator species that reflect the health of an ecosystem are present in all landscapes. Tigers, for instance, are a keystone species for forests. Similarly, you have fish. Because there are so many other species that are dependent on fish (like otters and crocodiles), who are at the bottom of the food chain, they are indicator species that tell us about the health of the river water system,” explains Mahesh. The mahseer is migratory in nature and this puts them under direct threat from destructive fishing practices and anthropogenic stressors like deforestation, agricultural intensification and urbanisation. In fact, a report has raised the red flag that this endemic fish may soon be extinct.
Over the last six years, Dr Rajeev Raghavan, Assistant Professor at the Kerala University of Fisheries and Ocean Studies, Kochi, & the South Asia Co-Chair of the IUCN Freshwater Fish Specialist Group has worked on various aspects of the hump-backed mahseer. “The species exists in different tributaries of the Kaveri as isolated populations. We do not know what the historic situation was or whether all these populations were connected. Were the mahseer freely migrating between these different systems? The connectivity between the different tributaries of the Kaveri is now lost due to habitat loss/alterations, especially the construction of dams and other developmental/infrastructure projects,” Dr Raghavan rues.
The Coorg Wildlife Society (CWS) is also doing its bit to protect the Mahseer as a part of a community-driven effort in collaboration with the Karnataka Fisheries Department, through a conservation lease along the Kaveri. Mahesh has worked with a local forest tribe called the Jenu Kurubas (honey collectors) in the Dubare Reserved Forest to understand the entire ecosystem and its impact on the mahseer.
The efforts to conserve the species is not restricted to India alone. The Mahseer Trust, a UK-registered charity that works to conserve mahseer as flagship species, has collaborated with Shoal, which helps protect some of the most threatened freshwater fish species. Project Mahseer, the result of this collaboration, aims to conserve the mahseer in some of Asia’s most iconic river systems. “Mahseer are a key flagship and umbrella species for Asia’s rivers. They are well known, beautiful, and respected in many cultures in Asia, and, of course, with anglers. Actions to save the mahseer will help save many more of Asia’s species and help ensure healthy rivers. We specifically chose the hump-backed mahseer because it is the most threatened mahseer species,” says Mike Baltzer, Executive Director, Shoal.
A helping hand
Dr Adrian Pinder, Chair, Mahseer Trust, Bournemouth University, explains that after nearly a full year of curtailed field activity due to COVID-19, they have recruited and equipped two young field researchers. He says, “They are currently being trained by our senior scientists. These field researchers will explore part of the upper Kaveri tributaries that may be crucial for the survival of the hump-backed mahseer. They are being taught about the collection of biological material and biometric data to further understand the biology and ecology of the critically endangered hump-backed mahseer and the non-native blue-fin mahseer with which it now must compete.” Further work to understand the current status of hump-backed mahseer with scientific tools that help map species distribution are also being done.
Art doing its part is just the start
At the fifth festival edition of the Whitefield Art Collective (WAC) at VR Bengaluru in 2020, Rahul KP and Nithin Sadhu, from Bangalore Creative Circus had an installation called ‘Namma Tiger of the Cauvery’. This was made entirely using scrap collected from the trash collection drives along the river Kaveri and in Bengaluru and highlighted succinctly the role of pollution in its rapid decline. The installation aimed to highlight the conservation efforts by The Wildlife Association of South India (WASI). With its critically endangered status, the mahseer needs help now, in order to ensure it does not merely become the subject of art.