For many, a visit to the 700-year-old Shishileshwara temple in Karnataka is incomplete without feeding the Devara Meenu (God’s fish). Hundreds of mahseer, a fish from the carp family, congregate in the river next to the temple. As soon as the devotees hand out their offering of puffed rice, a feeding frenzy ensues. The mahseer compete for food by frantically swimming over each other until the last grain of puffed rice disappears. Although the temple is dedicated to Lord Shiva, the mahseer here are seen as ‘Matsya’ – the fish avatar of Lord Vishnu. To protect the sacred fish, a 4 km stretch of the river in the vicinity of the temple has been declared formally as a fish sanctuary where fishing is strictly prohibited.
The Shishileshwara temple is nestled at the base of Western Ghats – one of the world’s biodiversity hotspots – in Shishila village, Belthangady taluk, Dakshina Kannada district, Karnataka. The Kapila river, on the banks of which the temple is located, originates in the dense tropical evergreen forests of the Western Ghats, and forms an important tributary of the west-flowing Nethravathi river. Harbouring roughly 19 species of fish including the mahseer, the Shishileshwara temple fish sanctuary is among a handful of fish sanctuaries in Karnataka, managed by temple authorities with assistance from the forest and fisheries departments, and other local bodies. Another notable example is the Shringeri Fish Sanctuary along the Tunga River in Chikmagalur, managed mainly by the Shankaracharya Mutt.
The rivers of the Western Ghats are home to a diverse array of freshwater fish, many of which are found nowhere else in the world; out of the 320 species recorded from these rivers, 212 (66%) are endemic to the region. However, the freshwater fish of the Western Ghats, and the rivers they inhabit, face many serious threats. Rapid and unplanned construction of dams that divert and alter the flow, indiscriminate methods of hunting through dynamiting and poisoning, unsustainable sand-mining, land-use change in the watershed, and pollution constitute some of the major drivers of declines in fish population in the Western Ghats. Currently, of the 212 endemic species, 54 are classified as Endangered and 12 as Critically Endangered by the International Union for Conservation of Nature (IUCN). A cause for concern is that none of the freshwater fish species are formally protected under the Schedules of the Wild Life (Protection) Act, 1972.
Given the threats faced by river ecosystems, community-based fish sanctuaries hold great potential for safeguarding freshwater biodiversity. Although the focus of temple fish sanctuaries is mainly the sacred mahseer, the sanctuary area shelters numerous other fish and aquatic species, including their habitat. In addition to protection from fishing, the sanctuary area deters other human activities such as sand mining and water diversions or withdrawals which can be detrimental to aquatic biodiversity. Temple authorities and devotees could be powerful stewards of biodiversity conservation as well. Temple fish sanctuaries encourage tourism because they are one of the few places where people can interact with fish. The revenue generated by tourism could potentially be used for conservation-related activities such as raising awareness about freshwater fish and river ecosystems.
However, temple-managed fish sanctuaries are not without their own set of challenges. An event that transpired in 1996 shows how managing competing interests is a major challenge for temple fish sanctuaries. After being rebuked by the temple authorities and villagers for fishing within the sanctuary limits, a few individuals, as an act of retaliation, poisoned the sanctuary by pouring pesticide into the river. The poisoning decimated the fish population locally. According to eyewitnesses, tearful devotees watched several truckloads of dead fish ferried out of the river and buried nearby. A memorial now stands near the temple as a stark reminder of this event. To protect the fish from such incidents, the locals formed a trust called the Matsya Hitharakshana Vedike (forum for protecting fish).
After the poisoning event, the Karnataka fisheries department introduced captive-bred mahseer fingerlings into the fish sanctuary, to help augment the fish stock lost due to poisoning. Today, the mahseer numbers in the Shishileshwara temple fish sanctuary have more or less recovered. However, it is unclear which species of mahseer was introduced, and if the introduction had an effect on the recovery.
The confusion is partly due to the fact that the name mahseer does not refer to a single species but to a group of 47 species of fish distributed across four genera: Tor, Neolissochilus, Naziritor and Parator. These species are spread across south and Southeast Asia, between Afghanistan in the west, and Vietnam in the east. Out of these, 15 species are found in India. Taxonomists, though, consider only the species from the genus Tor as “true mahseer”. Out of the 16 described species from the Tor genus, eight are found in India, and three of them – Tor khudree, Tor remadevii and Tor malabaricus – are endemic to peninsular India (barring recent introductions and data deficient species). Ongoing taxonomic research and genetic studies on mahseer are likely to describe new species and/or reclassify existing ones.
In the Shishileshwara temple fish sanctuary, the tag Devara Meenu applies mainly to a locally abundant species of mahseer, widely reported to be the Deccan Mahseer or the Blue-finned Mahseer (Tor khudree). However, historical evidence suggests that the distribution of Deccan Mahseer was originally limited to the headwaters of the east-flowing Krishna river, in the central and southern Western Ghats. After successful captive breeding efforts mainly at Tata Power’s hatcheries in Maharashtra, the state fisheries departments began propagating Deccan Mahseer into rivers outside their home range, to augment fisheries stocks. As a result, Deccan Mahseer now has an established population in many rivers of peninsular India, and its population is growing. It was recently classified as a species of Least Concern by the IUCN.
The human-mediated range expansion of Deccan Mahseer has come at the expense of native Mahseer. For example, a study from Kaveri river that looked at angler-catch data between 1998 and 2012 found that Deccan Mahseer increasingly represented the catch ever since they were introduced here in the 1980s, while the catch of Orange-finned Mahseer (Tor remadevii), a species found only in the Kaveri basin, declined significantly. The catch records also indicate that the mean size of the Deccan Mahseer decreased compared to the Orange-finned Mahseer whose mean size increased. Since age is correlated with size, a lower mean size indicates successful recruitment i.e., the addition of younger individuals to the population, while a higher mean size indicates an ageing population headed towards recruitment collapse. The Orange-finned Mahseer is currently classified as Critically Endangered, owing to the multiple threats it faces such as dams, overfishing and pollution, including competition by a closely related species that was introduced.
The tributaries of Nethravathi, like the Kapila river, are home to another species of Mahseer from the Tor genus, called the Malabar Mahseer (Tor malabaricus). Malabar Mahseer is a species endemic to the upper and middle reaches of the west-flowing rivers of the Western Ghats. Although this species was earlier considered synonymous with the Deccan Mahseer, a genetic study in 2005 conclusively showed that the Malabar Mahseer is a separate species altogether. Currently, the Malabar Mahseer is classified as an Endangered species by the IUCN. Recent studies on fish communities in the tributaries of the Nethravathi river near Sakleshpura found that the Malabar Mahseer is under severe pressure due to water diversions and unnatural water fluctuations caused by small hydropower projects which are rapidly being commissioned (see here and here for more details).
It is likely that the mahseer worshipped as Devara Meenu at the Shishileshwara temple fish sanctuary have been historically dominated by Malabar Mahseer since they are endemic to the west-flowing rivers of the Western Ghats. However, after the poisoning event, the mahseer introduced by the fisheries department must be the Deccan Mahseer because Malabar Mahseer are not captively bred, and because Tata Power’s hatcheries have been one of the major suppliers of Deccan Mahseer fingerlings to the state fisheries departments. The fact that Malabar Mahseer and Deccan Mahseer were considered synonymous could be another reason for the unintentional introduction. It is difficult to determine if the Deccan Mahseer were present in the fish sanctuary before the poisoning event because the exact dates and locations of these introductions are not well documented.
As of now, it is not known whether the Deccan Mahseer has established itself in the Shishileshwara temple fish sanctuary, and if its introduction has had an effect on the native Malabar Mahseer. Any visible change in species composition in the fish sanctuary may have gone undetected possibly because mahseer species exhibit considerable variation in colour and appearance due to environment-specific factors. Therefore, it is essential to ascertain, through genetic studies, the true identity of Devara Meenu, and the current species composition of Tor fish at the Shishileshwara temple fish sanctuary. From a conservation point of view, given the evidence that Deccan Mahseer has a tendency to outcompete native mahseer and establish themselves when introduced outside their range, it is necessary to ensure that the Shishileshwara temple fish sanctuary does not inadvertently act as a source population for a fish with invasive tendencies, and put native mahseer species in peril.
There are lessons to be learnt from the events that transpired at the Shishileshwara temple fish sanctuary. Firstly, since mahseer is regarded by some as a popular food fish, and by others as sacred, a fundamental challenge for temple fish sanctuaries is to manage diverging expectations arising out of diverse belief systems. Secondly, when species become locally abundant due to protection and provisioning, they are vulnerable to external threats such as poisoning, predation and potentially to diseases as well. Thirdly, captive breeding may be a great tool for conserving species under decline but artificially introducing stocked fish outside their range can seriously affect native fish already facing other pressures. Despite these challenges, in the light of ever-increasing pressure on river ecosystems, temple fish sanctuaries may be some of the last refuges for freshwater biodiversity in the Western Ghats. Like the sacred groves of the Western Ghats, the Shishileshwara temple fish sanctuary epitomises the intricate relationships between religious beliefs and biodiversity conservation.
*Note: There is confusion regarding the species identity of the fish shown in the pictures above as Malabar Mahseer (Tor malabaricus). Some researchers think they might be Deccan Mahseer (Tor khudree) based on its body shape. The confusion also underscores the need for thorough genetic studies to determine the correct species identity of Mahseer in this region of the Western Ghats.
Pinder, A. C., Britton, J. R., Harrison, A. J., Nautiyal, P., Bower, S. D., Cooke, S. J., Lockett, S., Everard, M., Katwate, U., Ranjeet, K., Walton, S., Danylchuk, A. J., Dahanukar, N., & Raghavan, R. (2019). Mahseer (Tor spp.) fishes of the world: status, challenges and opportunities for conservation. Reviews in Fish Biology and Fisheries, 29(2), 417–452. https://doi.org/10.1007/s11160-019-09566-y
Pinder, A. C., Raghavan, R., & Britton, J. R. (2020). From scientific obscurity to conservation priority: Research on angler catch rates is the catalyst for saving the hump‐backed mahseer Tor remadevii from extinction. Aquatic Conservation: Marine and Freshwater Ecosystems, 30(9), 1809–1815. https://doi.org/10.1002/aqc.3335