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Why Otters Matter

Why Otters Matter

Monitoring a pack of otters along the Cauvery river with the help of a local fisherman, Gopakumar Menon opines on the sentinel role otters play in their threatened ecosystem.

Otters in general, and smooth-coated otters of the Cauvery river in particular, are indicators of the health of the waterbodies. These apex predators have a role to play in their watery ecosystems, akin to that of predators such as tigers on land. Photo: Rahul Pratti/ENTRY-SWPA 2017

We sat on a stone wall by the river, Sivu, the fisherman, and I, in silence, waiting for the arrival of what Steven Moss, a British naturalist, once called “the elusive movie-star”. It was dusk and the cows had just crossed the placid waters of the Cauvery, after spending much of the day grazing on the island about 300 m. from the banks. Their crossing had taken up much of my attention: everything about the body structure of a bovine is un-aerodynamic, yet the cows had swum across with little apparent effort, their heads just above water and noses up in the air, a langourous watery stroll, before reaching the banks and clambering up dry land.

And, after their crossing, I was now listening to the cacophony of birdcalls, when Sivu touched my arm. “I hear them,” he said simply, pointing ahead.

There was little to be seen in the water and the pair of binoculars in this light was of little help, but I did hear the calls, a mix between a whistle and a chirp produced in continuous sequence. A minute later, a couple of little heads came into dim view, swimming downstream towards us and moving with elegance across the surface of the water, producing, behind them a ‘wake’ pattern of ripples, in the shape of a V, as produced by waterfowl or boats (interestingly, this was first explained mathematically by Lord Kelvin and known today as the Kelvin wake pattern).

The smooth-coated otters were returning after a day’s work.

These smooth-coated otter individuals were caught emerging from their post-natal den along the banks of the Cauvery on camera-trap. Photo: Anith B.


Sivu has been tracking these otters for Nityata River Otter Conservancy for the last three years. His primary role is to monitor their population and alert us to threats to them, along a river stretch that we term the ‘H Otter Corridor’ (‘H’ represents the name of the village by the river where Sivu lives. To safeguard the bevy of otters, the name has been kept out of this article). In the breeding season and after, beginning in October and until January, the otters inhabit a natal den site and nursery that is by his fishing stretch. Through this period, for much of the last three seasons, he has noted down the numbers he has seen every single day along with the time of observation, the number of pups and the location. In the process, he has learnt much more about them than he had known earlier (which itself was a fair bit) and is now a sort of expert-cum-coach to us, providing us much more than just data. We share notes on just how playful they are, sliding down sand chutes into the river and rolling on the sand, while chatting animatedly with each other and we marvel at the ease with which pups – those little bundles of infectious joy – learn to swim.

Sivu has, equally, learnt to let them live alongside him in the river, which is saying a great deal, for fishermen dislike otters because they pick fish up from the nets that are cast into the water and, even worse, tear these nets with their sharp teeth in the process. It is an uneasy co-existence, and can be compared to the one you read about on land, where tigers and leopards prey on domestic cattle, resulting in calls for retaliation from aggrieved farmers. Yet, this analogy has a deeper meaning and couldn’t be more apt, for the otter is to the river what the tiger is to the forest: an apex predator, whose health and survival determines the health of its ecosystem, and by indirect inference, our well-being.

Jason Tetro, a microbiologist who is better known as ‘The Germ Guy’, and is the author of two books – The Germ Code, and The Germ Files wrote this about otters (he was referring to the sea otter, but the principle can be perfectly applied to the smooth-coated otter as well): Otters also have another incredible link to humans albeit the association is far more impactful. They can help us identify public health problems related to pollution and infections. Though they live a different lifestyle than us, their mammalian nature allows the opportunity to study what could happen to us as our world changes.

The relationship between otters and fishermen has always been rather strained as the mammalians tend to go after the fishermen’s catch and damage the nets resulting in a backlash against the species. Photo: Anith B. 


In the public health world, animals such as the otter are considered to be sentinels. This term refers to any animal whose biological, geographical and even psychological change in response to an environmental change can be used as a model to better understand how humans may be affected in the future. These factors can include a number of possibilities, from the impact of pollution to the spread of infectious disease.

In the period from the 1970s to around 2005, smooth-coated otters across India were poached by professional gangs of poachers, who used information provided by local fishermen on otter presence, laid traps for the animals and then clubbed them to death to meet the insatiable needs of the wildlife trade: otter skin was used in the production of bags for the international market and was transported along with tiger and leopard skins. The Cauvery was no exception; during our travels along the river, we have heard a number of anecdotes of these poaching gangs – whole families of ‘Hindi speaking’ nomads (either the Pardhis, Bawarias or Bahelias). About a decade ago, organised poaching seems to have come to a halt for reasons that we do not yet know, yet the future of otters in the Cauvery and in other parts where they have survived, is far from secure.

Nityata’s work in, at first, understanding otter occurrence and then threats along the non-protected stretches of the Cauvery river in Karnataka began in 2012 and the agenda was, and remains, to plan and execute a long-term conservation programme with the involvement of local stakeholders. When we first spotted the otters here – that was in the early summer of 2013 – the alarm bells rang in frenzy in our heads. For the river stretch here – the corridor used by otters as they moved about – was in deep trouble. The mining of sand, under a specious licence, was extensive and much in excess of the quota, churning the waters of the Cauvery under the daytime sun, a plethora of boats, each outdoing the other in rapacity. At dawn and after dusk, even as the sand mining continued in stretches, dynamite fishermen visited the river and threw the sticks in with impunity, while the more traditional fishermen, who use gill nets, endured this in fear, their livelihoods slipping away as dynamite blasted out all the fish in the vicinity, destroying native species and fingerlings in the process. As the water levels dropped in summer, all such activity would increase in tempo. The fisheries department, living in pretence that there was no dynamiting, took no action. Instead, they focused on their financial-year ‘targets’ – the release of commercial species of fish – rohu, katla and tilapia, called ‘jilebi’ locally. This they did with much ado, patting their own backs for sustaining livelihoods, little realising that such releases were actively damaging endemic fish diversity (the practice, sadly, continues).

Dead fish float in the river after a bout of dynamite fishing. The use of dynamite by some in the Cauvery river has impacted not just the riverine ecosystem, which is vital to otters, but also the traditional fishermen (right) who have been battling the problem of decreasing fish stock. Photo: Anith B.

Amidst this mayhem, a romp of otters lived precariously. The traditional fishermen, seeing their catch drop, took much of their ire out on otters on the occasions when the animal, adult or pup, was caught in a net, clubbing it to death.

In the last four years, much has changed for the better. Due to better enforcement and the expiration of licenses, sand mining is now history (and will, hopefully, remain that way). Sivu and other traditional fishermen summoned up the courage to chase the dynamite fishermen away, once confiscating over a quintal of fish and reporting the incident to the police. Over the last four years, these net fishermen have also developed some level of tolerance for the otters in their midst, largely due to a sustained campaign of engagement, a tolerance based on an understanding of the importance of this apex predator, combined with some fear for the consequences of any deleterious action on their part.

At the H Otter Corridor, smaller packs of otters seem to aggregate just before the breeding season, around early October, stay together, go through the process of reproduction and weaning, and then disaggregate around February or early March. This aggregation and its reversal may not be the behaviour of smooth-coated otters elsewhere though, as there seems to be little literature on the matter.

This aggregated population of otters has, over the last three years, marginally increased and, when last counted in early 2017, stood at 17 (that’s just a coincidence!). Our experience in this river stretch is that otters are best counted around November, a little while after the pups are born and first emerge excitedly from their holts. They are cajoled into the water and are taught by their determined mothers to swim. The photos used in this article are prepared by the studio alif.media on the order of our project.


The increase in the otter population cannot be termed a dramatic comeback as one would hope for, yet there are dollops of hope. Every year, the number of pups born has been heart-warming, even though their mortality is disturbing – possibly, over half of the pups that are born die before adulthood. The reasons for this mortality could be many and can only be speculated on, for the threats even today are numerous: predators of the pups such as snakes or raptors, drowning, entanglement in net fragments that are in the river and littered all over the islands in the river and along the banks, which result in suffocation or drowning.

If these threats weren’t daunting enough, beneath the water lies a nasty, systemic hidden predator against which the otter is defenceless: pollution, that is both the result of untreated sewage flowing into the river, as well as the pesticides used in the rice plantations alongside the river here. There is history – albiet dismal history – to support this view: during the 1970s, England’s otter population plummeted, the decline attributed to high levels of Persistent Organic Pollutants (POPs) in rivers. After contaminants such as organochlorine pesticides were banned, otter populations steadily increased and today the recovery of the population appears to be complete.  We, along the Cauvery, are way behind: the reports of the Karnataka State Pollution Control Board have noted traces of toxic pesticides, including dieldrin in some river stretches, while levels of E. coli bacteria at most measuring points is many times over the safe limit – otters are as susceptible to illnesses from these bacteria as humans are, for they are mammals.

Sivu, a fisherman, helps track this particular population of otters, the author describes for the Nityata River Otter Conservancy. Photo: Anith B.

Indeed, this is why otters matter.  The otters here at the H Otter Corridor matter hugely as indeed do all populations of otters in India and elsewhere. They are mammals and apex predators. Both of these mean that they are subject to the stresses caused by the ill health of the river and their well-being in the river can be seen as a sure indication of the river’s health itself.

Nicole Duplaix, the Chair at the Otter Specialist Group of the International Union for Conservation of Nature (IUCN), puts it very succinctly indeed: “One of the surest ways to know if an ecosystem is healthy is to see if there are apex predators. It takes a robust food web to be able to support carnivores at the top. So when you see a coral reef packed with sharks, you know it’s doing well. When you see a forest complete with wolves and grizzlies, you know it’s a healthy forest. And when you see a river system that is home to river otters, you know it is a healthy waterway. That’s why we call otters ‘indicator species’ – they have a story to tell us.

While we greatly appreciate river otters for their playfulness and for making our day a little brighter with their antics, we need to also appreciate them for the story they tell us just by their presence. If they are around and healthy, then it means good things for the entire habitat. And if they disappear, then they just gave us a big clue to start looking into what’s going on in a river or lake system. We need to value river otters for simply being there, and letting us know when all is well.”

So, despite the threats to the otters in the Cauvery, we have to fight for their survival, for the issue is not just them, it includes us as well. In this fight, there is reason to hope, for the otters have made it past a rough stretch of time. “Treat them like bangaru (gold),” I have told Sivu repeatedly, but I know that he too has his limitations and will balance his concern for them with the demands of a fishing livelihood.

There we sit on that wall, Sivu and I, and watch the otters make their way to a dense clump of reeds. There are more calls emanating beyond and it seems like other otters are on their way, yet, as dusk gives way to darkness, we stand up, dust our trousers and walk slowly away.

These smooth-coated otter individuals were caught emerging from their post-natal den along the banks of the Cauvery on camera-trap. Photo: Anith B.

We, like our sentinels in the river, need to go home too.

Author: Gopakumar M., First appeared in: Sanctuary Asia, Vol. XXXVII No. 12, December 2017


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