The hump-backed mahseer, native to South India and one of the world’s most iconic freshwater fish, has been given a scientific name in a race to save the species from extinction.
145 years after being first popularised by the publication of HS Thomas’s classic A Rod in India in 1873, the iconic hump-backed mahseer has been allocated a scientific name - Tor remadevii - as a key step in trying to save this highly threatened species from extinction.
Being capable of exceeding lengths of 1.5 metres and body weights of 55 kg, this freshwater giant qualifies as megafauna, yet has until recently avoided the attention of ichthyologists and remained a taxonomic enigma to the scientific world.
This giant member of the carp family has been known to anglers around the globe as ‘one of the largest, hardest fighting and most iconic freshwater game fish in the world’, but due to a restricted natural distribution and a range of escalating environmental pressures, the survival of the species is currently uncertain.
A team of researchers, led by Bournemouth University’s Adrian Pinder, has been working with the species for a number of years. Through extensive research, the fish was discovered to be endemic to South India’s River Cauvery system and its various tributaries.
The former catch-and-release based recreational fishery of the Cauvery has been widely cited as positively contributing towards mahseer conservation. Using historic catch records collected by anglers, it became apparent that, since 2004, the species had experienced a dramatic crash in population numbers, leaving the humpback on the edge of extinction.
Lacking a formal scientific name has precluded the iconic hump-backed mahseer from being afforded formal recognition on the IUCN Red List of Threatened Species and, therefore, left the few remaining fish unprotected against factors such as dynamite fishing and river engineering projects (e.g. dam construction and abstraction), which combine to threaten vital habitats that support the existence of this species.
Pinder, also Director of Research at the Mahseer Trust, a UK Registered Charity set up to conserve mahseer species and their environment, says “It was just unbelievable that such an enormous animal, recognised by anglers around the world, could be about to go extinct in advance of being afforded a scientific name.
“We knew something needed to be done to support the survival of this species. The alarming and rapid loss of this iconic species from the majority of the Cauvery system has deeper conservation implications. Indeed, as an ‘indicator species’ and apex predator, the loss of the humpback will have knock-on ramifications for the wider biodiversity of the river.”
A fact finding project was conducted, involving scientists from the three Indian States through which the River Cauvery flows; Karnataka, Kerala and Tamil Nadu, to find the fish and collect the data required (i.e. body measurements and DNA) to clarify this taxonomic puzzle. Pinder continued, “Our big problem was that by the time we realised that this fish was close to extinction we then had the additional challenge of finding specimens.”
Working with the fishermen of a local tribal community, the team were eventually successful in finding a small population of humpbacks in the isolated River Moyar, Tamil Nadu. The results revealed that the DNA sequence of the hump-backed mahseer was unique, distinguishing it from all other previously described species of mahseer.
This led Pinder’s team to believe that they were on the cusp of naming a new species, until a paper published in the proceedings of a 2006 conference in Kuala Lumpur came to light. This described a new species of mahseer called Tor remadevii. The description was extremely limited in detail and based only on a sample of small juvenile fish from the River Cauvery’s most southern tributary, the River Pambar, which flows through the state of Kerala before joining the lower reaches of the Cauvery in Tamil Nadu. This revelation sparked new lines of investigation to find Tor remadevii at the ‘type’ locality (the geographic origin of the species description) and to undertake detailed examination of the ‘type’ specimens deposited in museum collections. The results of these investigations confirmed that the hump-backed mahseer was, in fact, synonymous with Tor remadevii.
In a paper published in the international scientific journal Plos One, Adrian Pinder of Bournemouth University, UK and colleagues have fixed the scientific name of the hump-backed mahseer as Tor remadevii. This discovery triggered an emergency meeting with IUCN experts in Pune, India, where a draft Red List assessment of Tor remadevii was generated, with the species qualifying as ‘Critically Endangered’.
This assessment will now be reviewed and find a place on the IUCN Red List of Threatened Species, in its next update. Adrian Pinder explains, “This will be a pivotal move in securing much needed protection and immediate conservation planning to save the species from extinction.”
Co-author Dr Rajeev Raghavan, Assistant Professor at the Kerala University of Fisheries and Ocean Studies (KUFOS), and IUCN’s Freshwater Fish Red List Authority Coordinator said, “The hump-back could probably be the most restricted of all mahseer species, and is now the most threatened, requiring urgent conservation attention, both in-situ and ex-situ. Securing the future of the hump-backed mahseer will depend on the strong willingness and cooperation of a range of stakeholders from three southern Indian States; Kerala, Tamil Nadu and Karnataka, in one of India’s most contested rivers – the Cauvery.”
Adrian Pinder concluded, “When we think of endangered species, we often think of ‘flagship’ species such as the Giant Panda and Bengal tiger, which are currently and respectively assessed on the IUCN Red List as ‘Vulnerable’ and ‘Endangered’. However, with the hump-backed mahseer we are talking about a creature which is actually more imperilled that these better known icons. Now that we have verified the scientific name and can officially categorise the perilous conservation status of this fish, we can continue to take positive steps to ensure its survival long into the future.”
For more information about the hump-backed mahseer or the Mahseer Trust, visit www.mahseertrust.org.