The days when dolphins were out in the sea

by Rahul Muralidharan

The sun was supposed to rise at 6:30 am.
But that day it did; fifteen minutes later.
At the break of dawn, a narrow strip of sunlight raced
through the sea surface reaching the shore.
And voila! A group of dolphins traveled along the coast.

Dolphin dead. Cyanotype print by Sudharshan. From smokingblues.wordpress.com

stranded dolphin (Sousa chinensis) on the shores of Kovalam, near Chennai. cyanotype print by Sudharshan. smokingblues.wordpress.com

This is how my friend described to me his experience after seeing a pod of dolphins go past Injambakkam village in Chennai. Dolphins are not new to our coast. They have been there for a long time. Fishers observe them frequently during their fishing trips or from the shore. My first experience of observing a pod of Indo-Pacific humpback dolphins in Chennai was very similar to my friend’s. Out in the sea on a near shore fishing trip, at a distance, I could see tiny triangular fins pop in and out of the water, as if a blade was cutting through water.

The Indo Pacific humpback dolphin or Sousa chinensis as it is scientifically known – derives its name due to the dolphin’s presence in the Indian and the Pacific Ocean. Distributed along the entire east and west coast of India, a distinct hump on its back gives it the name ‘humpback dolphin’. Since humpback dolphins are coastal species, they prefer to stay within 25m depth feeding on near shore fish such as madavai (mullets), mathi (sardines) and nethili (anchovy). Fishermen call it paru vedan (paru meaning small, tiny | vedan meaning hunter) because humpback dolphins are found in the presence of small shoaling fish.

The stories that you hear about dolphins are vivid in the memories of the men who share their fishing grounds with them. For instance, the Coromandel coast and the Gulf of Mannar fishermen refer to them as karai kadavul (shore god). The legend believed is that Kutti Andavar an influential figure from the Chola dynasty era protected these dolphins. The story is told so:

Once, Kutti Andavar made a ring out of clay and threw it into the water, asking the dolphins to search for the ring. As clay melts in water instantly, it is believed that until this day the dolphins have been searching for the ring.

Coincidentally, this ring searching gesture is very similar to the feeding behavior of humpback dolphins. Mud plumes rise up to the water surface when dolphins nudge their snouts into the sea bed searching for tiny fish, crabs and shrimp. Fishers observe this behavior when they are at the same location, like the dolphins, fishing for shrimp or crabs. The blend of traditional cultures and ecology supports the long persistence of humpback dolphins from its immediate threat – fishing!

With the development and mechanization of Indian fisheries in the early 1950’s and 1960’s, new types of nets started replacing the old ones. Transiting form cotton nets to synthetic nets, moving from sustainable to unsustainable fisheries. Cotton fishing nets could not be soaked for a long time. They would disintegrate. Every time the nets were used, they had to be dried out in the sun at least for few hours before the next fishing trip. However, nylon nets could be soaked for a longer time, which means, more effort and more fish.

Dolphins, unlike other animals, see their environment through sounds. Bats do that on land. This is called “echo-location”. A bulbous structure on their head, known as a melon, produced high frequency sounds. When sounds hit an object, it bounces back and is known to be received by the lower jaw bones. This transmission and bounce back of sounds produces a mental imagery of a given environment, to the dolphins. They receive information on the shape, size and depth of objects. Moreover, recent research shows that humpback dolphins possess signature whistles. It is as if each dolphin’s name is coded with a unique whistle pattern, which helps them recognize each other underwater. Each dolphin has a name, each whistle has a dolphin. Additionally, they also use their eyes to hunt for fish.

Dolphins live in a three dimensional environment, submersed with blue light during the day time and the nights are as dark as space itself. Synthetic/nylon nets are designed in such way that they are almost invisible once soaked in the sea. Gillnets are one such example. These nets don’t give an opportunity for the fish to escape, neither to the dolphins which go in search of fish. Dolphins are air-breathing mammals, which require them to surface every 5-10 mins to catch a breath of air. But once entangled in fishing nets, they die out of drowning. Sometimes, dolphins get entangled while taking fish from nets. However, often-times fish nets entangle swimming dolphins, as the nets are not visible to them.

The Indo-Pacific humpback dolphins are placed under Near Threatened (NT) category in the IUCN red list of threatened species. We know next to nothing about their population status in India, although their range in other parts of the world show very few population estimates. Fishing mortality is identified as one of the greatest threats to humpback dolphins. Since these dolphins prefer near-shore, coastal zones, they face dire threats due to development pressures such as urbanization, coastal infrastructures and pollution which ultimately lead to habitat loss. Heavy metal pollutants like mercury and lead have been documented from the bodies of humpback dolphin along several parts of their range, especially from highly urbanized coastal cities.

Conversely, on the positive side, humpback dolphins have secured an iconic position in the hearts of the Coromandel Coast fishers. Fishermen in Nellore district of Andhra Pradesh in the east coast of India believe that they can communicate with humpback dolphins. When fishing nets are laid and in case if the fishers spot dolphins approaching toward the nets, they give out loud warnings to the dolphin not to approach on the same path. To their belief, dolphins switch directions and swim around the nets without entangling themselves. Some fishing communities along the Coromandel Coast consider dolphins as their ancestors who are out in the sea. Cultural beliefs, traditional knowledge and science are enmeshed in these stories; which makes it difficult to tease out the scientific parts. Somehow humpback dolphins have symbolic presence amidst the fishing populations of the Coromandel Coast. Interestingly, these stories have helped in conservation and long persistence of the humpback dolphins in our coast. For this reason, we need to develop methods to understand the nature and attitudes of various fishing communities toward the humpback dolphin. This search could involve anybody with an interest including students, fishers, researchers, general public, scholars, artists, teachers and list goes on.

Many people are surprised to know that dolphins inhabit our coast. If you would like to see them for yourself, then go out to the beach one morning. Who knows you might spot them against the breaking light of dawn; when it is the dolphins’ day out in the sea.

For more information, photos and details about Humpback dolphins of the Chennai coast – please click on this link to access a scientific research paper published in the Journal of Threatened Taxa.

Thanks to Sony RK for critical comments.

Rahul Muralidharan is a marine biologist currently pursuing his PhD at ATreea slow baby turtle and two ghost crabs was his first field notes from the beach for Chai Kadai. He is an integral part of the ideas and activities we do. We hope he will continue to bring more of the ocean in to this space.

 

 

a slow baby turtle and two ghost crabs

field notes by Rahul Muralidharan

Photo-Ghost Crabs (Ocypode sp.) of Chennai are facing a new threat. Commercial hunting and export for preparation of medicinal products. Location- Elliot’s beach, Besant Nagar, Chennai.

01. the ghost crab

Pooja and I were walking in Elliot’s beach in Besant Nagar. She spotted it first. I have never seen a ghost crab stray away this far from the sea. Maybe, it walked. Maybe, someone carried it along with their bags. He was so slow. For the first time, it was easy to catch a ghost crab. Standing under the massive floodlight near the police booth, late evening, I looked at his eyes. An alien. Like a dragonfly his eyes were compounded and covered by a heavy (rubber?) lid. It seriously looked like one of those exercise balls that bounce up and down. I jumped into his eyes. Men in Black. Independence Day. Why do we perceive aliens this way? Only seconds had gone by. I left. I had to. Maybe, he survived. It will be lovely to meet him again.

02. the baby turtle.

In coastal Nellore, there’s an isolated village with not more than 300 people living there. Lakshmipuram. Usually, back home at Chennai, the beach crowds up during turtle walks. It is not easy to shut down the noise and notice smaller things. This village has so much space.

That night, we were releasing around thirty hatchlings. Twenty nine scuttled away easily in to the sea, but one baby was just so slow. He crawled towards the large flashlight that we used to guide them. Everything was so bright and contrasted under the big flashlight. The light bounced off the sand and lit and shadow-ed every fold on the hatchling. I followed it and watched the formation of scutes on its carapace, everything so clear and defined. Noiseless.

Suddenly, something moved next to me. A ghost crab. What if it eats the hatchling? I was too scared to let them get close to each other. But, I realized these crabs are not so easy to film and it was only because of the light source behind it that I actually noticed him. I bent down and saw it was holding on to some kind of orange plastic piece. I hope it didn’t eat it. The hatchling diligently kept to its pursuit. Dusting off the sand on its eyes with its flippers, it slid on its belly towards the waves. I sat there for some time, just like the baby turtle, my belly on the sand, and watched them.

03. the current.

The sea was calm in Injambakkam. The waves extended out in arc formation like hundred of arms and scooped up the hatchlings to take them home. The long shore ocean currents in Chennai, either travels towards north or towards south. When the current shifts direction, the sea becomes very turbulent. In Kovalam, this April, we were trying to release seventy hatchlings. The group had fishermen, volunteers, new visitors and their children. That night, the sea just stood like a massive menacing wall. Don’t you dare come inside it yelled. There’s a line (maybe imaginary) beyond which a hatchling has to crawl to be easily swept in by a wave. As the hatchlings moved towards the wall, the sound of the waves crashing on the shore and displacing everywhere was echoing in my head. The children were singing Happy birthday to you. First, twenty hatchlings were pushed away. We carried them closer to the waves. Then, ten of them stayed ashore, even attempting to hide, we took them closer to the sea. Five remained for a while. We took them closer and a wave took them home.

04. footnotes

1. Ghost Crabs are of the genus Ocypode, common shore crabs in many warm countries. In Greek, ‘ocy’ means fast and ‘podos’ means foot, ocypode – ‘fast-foot’. They live in deep burrows on sandy shores, comprising of a long shaft with a chamber at the end, sometimes these have surprise entries and exits. Their multi-utility allow them to breathe on land as well as underwater, where they release their eggs. With four pairs of tough legs, these crabs scurry so fast when running from danger that they use only the first two pairs of legs, letting the other two fly behind them. It’s their transparent bodies and protruding eyes that tempts us to call them the Ghost Crabs.

2. Olive Ridley Turtle (Lepidochelys olivacea) The average length is 70 cms and the adults approximately weigh 45 kgs. After reaching sexual maturity, when they are about 12 years old, the females travel back to the shore they were born and nest. Yearly, they visit the eastern coast of the Indian subcontinent during the months of December to April. Olive Ridleys prefer nocturnal nesting in order to avoid predators and hot sand. It takes around 48 to 52 days for the ash-gray and black hatchlings (about 6 to 7 cms) to emerge from the nest that was dug into the sand very carefully by their mothers. 

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The author is a marine biologist based in Chennai. He blogs at Okeanos (Ocean).