Turtle Trails: How and why Maharashtra's Olive Ridleys are being satellite tagged

On January 25, two Olive Ridley sea turtles were satellite tagged for the first time along the western coast of Maharashtra, at Velas and Anjarle beach in Ratnagiri district as part of the ‘Olive Ridley Sea Turtle Tracking' project carried out by the Mangrove Foundation of Maharashtra, in collaboration with the Wildlife Institute of India and the Forest Department of Maharashtra. The two female turtles tagged were named ‘Prathama', signifying a new step towards sea turtle conservation, and ‘Savani', named after the local goddess of the Anjarle village. Until now, Olive Ridley turtles were satellite tagged only in the eastern coast of India.

According to the World Wildlife Fund for Nature, Olive Ridley turtles are the smallest of all sea turtles and are mainly found in the eastern coast of Orissa in India. Known to be migratory in nature, the female turtles come to the shore only during the breeding season. The sea turtles, though found in abundance across the world, have been declining in numbers over the years and are also identified as a vulnerable species by the International Union for Conservation of Nature. In Maharashtra, their nests and hatcheries can be found in Raigad, Ratnagiri and Sindhudurg districts.

The mission, which required patrolling at the beach for several nights by members who braved challenging weather and presence of wild creatures, is a significant step towards understanding the movement and behaviour of the Olive Ridley sea turtles for their conservation on the western coast. The members plan to tag three other Olive Ridley turtles along this coast. The three institutions have also launched a research project - ‘Tracking the migratory movements of Olive Ridley Sea Turtles off the coast of Maharashtra', to study the migratory patterns of these turtles on the country's west coast.

Mid-day Online reached out to Harshal Karve, marine biologist with the Mangrove Foundation and a member of the Olive Ridley Sea Turtle tracking project, who shares insights on the peculiar characteristics of Olive Ridleys and experiences of executing the project.

Here are edited excerpts from the interview:

Since when have you been working with Olive Ridley turtles - what is the practical, day-to-day experience of volunteering like in a project like this?

I have been working with Olive Ridley Sea Turtles since I joined the Mangrove Foundation in 2018. At the time, there was no systematic collection of nesting data so developing a datasheet and training local nest managers, appointed by the state Forest Department to conserve and protect the nests of Olive Ridley turtles, was one of my first tasks. These activities involve day-to-day interactions with the local community, conducting workshops to train turtle nest managers, to understand their difficulties and create a conservation model.

As anecdotal data on sightings of Leatherback turtles from the coast of Maharashtra existed, we thought of interacting with the coastal community to get secondary data from fishers and locals. This helped in procuring the first photographic record of Leatherback off Raigad district and second from Palghar district. This was possible through the compensation scheme, which compensates fishers for releasing the marine protected species under Wildlife Protection Act 1972 by cutting their net. In addition to documenting, we also keep a check on the animal transit and treatment centres, set up in the coastal districts of the state, for treating injured sea turtles, which get stranded during the monsoon season, with the help of veterinarians.

Only female Olive Ridley turtles come to the beach during the nesting season. Image credit: Harshal Karve

Tell us about what went into executing the satellite tagging plan.

Under the collaborative project of Mangrove Cell, Maharashtra Forest Department, Mangrove Foundation of Maharashtra and Wildlife Institute of India (WII), we decided to study the movement of Olive Ridley sea turtles in the Arabian Sea. Satellite tagging of these turtles at sporadic nesting sites is challenging and requires intense planning in advance, procuring the satellite tags and obtaining the permissions from necessary administrative departments.

After analysing previous nesting data, we had selected the dates for tagging. It requires continuous beach patrolling throughout the night as they come during the night or early morning to nest. For beach patrolling, we had set up tents for basic accommodation on the beach. It was very cold, around 13-14 degrees Celsius. We were using red torches to find turtle tracks so that we wouldn't disturb the turtles. To find turtle tracks in low light is challenging but you learn with experience. During our patrolling experience, we also encountered the pugmarks of jackals, wild boar and leopard.

Finally, with the help of an expert scientist from WII, we could fix the transmitter on two turtles at Velas and Anjarle and are planning to tag three more turtles in the second phase soon.

What have you learnt in your interactions with Olive Ridleys personally? What is their nature?

Usually Olive Ridley sea turtles or any other sea turtles do not come to the land. Only the female sea turtles come to the land during the nesting season to lay eggs on the sandy beach. Previously, the nesting season used to start from the month of November but now there's a shift in the nesting season and it starts from the end of December or early January.

The female turtles come to the beach during the night or dawn to lay eggs. The egg-laying procedure goes on for about 20-25 mins after which the female turtle returns to the sea. Olive Ridley turtles lay around 90-150 eggs in a single clutch, the average being 120 eggs. Turtle hatchlings come out of the nest after an incubation period of 45-50 days. Naturally, they rush towards the sea after surfacing. In a hatchery, hatchlings are collected by nest managers and are released on the beach so that they can crawl to the sea.

On an average, the success ratio in a hatchery is around 60-70 percent. There's no parental care. I have observed that they do not prefer well illuminated coastal areas for nesting. During this season, it is very easy to spot Olive Ridley turtles from the coast in the sea.

How much awareness is there among the locals along the coast?

People are very much aware thanks to the turtle conservation work initiated by the Sahyadri Nisarga Mitra which the Forest Department took over later. Now, Mangrove Cell and Mangrove Foundation are continuously conducting awareness and education programmes for school and college students, locals and the fishing community along the coast. These awareness programmes are mainly for marine protected species such as sea turtles. Sometimes, we do it specifically for Olive Ridley turtles. In these programmes, we focus on our conservation activities, responsibilities of locals and the role of local community in conservation among others.

Harshal Karve (third anti-clockwise) and team at Anjarle beach with satellite tagged turtle 'Savani'. Image courtesy: Harshal Karve

In terms of their numbers in Maharashtra over the years - has the population been falling or growing and why?

Looking at the nesting data of the last five to six years, the graph of nesting female turtles and hatchlings released in the sea has been growing. Last nesting season (2020-21), we observed double the number of total nests, i.e. 475 as compared to 228 in 2019-2020 and 233 in 2018-2019.

What kind of information is collected through satellite tagging?

Satellite tagging of Olive Ridley turtles will help us understand their movement pattern, foraging grounds and also provide data on the depth at which they are diving and the duration of such movements. It will also help in identifying the population of sea turtles along the western coast of India.

There is no data on their migratory pattern, specifically for a population of the western coast. Tracking the migratory pattern is important to understand their ecology, their habitat preference, feeding grounds and overall behaviour. Long term data will also be helpful in studying their response to climate change.

What are the threats that they face on the western coast?

For nesting sea turtle populations, unplanned coastal development, feral dogs (which are not natural predators), illuminated coastal areas (resorts, houses) during the nesting season are some of the major threats. In my knowledge, locals don't catch turtles as they are protected species and there's awareness among the community members. Apart from this, bycatch, which is incidental and not targeted, ghost nets and accidents with boat propellers are threats posed by fishing activities.

I have observed many stranded turtles having missing flippers, dehydrated or with lung infections. Most of them also suffer from buoyancy syndrome (when turtles experience difficulty in diving deep down or submerging under water and usually swim on the water surface). Some turtles ingest plastic, which causes them difficulty in feeding and digestion. Oil spill, algal bloom or red tides are also major threats.

Until now, how were they observed and protected along the western coast?

In Maharashtra, under the turtle conservation programme turtle nests are protected in-situ or ex-situ that is in hatcheries. The hatchlings are released back to the sea safely after the nesting period. Under the compensation scheme of Mangrove Cell, Department of Fisheries and Mangrove Foundation, more than 200 turtles including Olive Ridleys, Leatherbacks, Hawksbill and Greens have been released safely back to the sea.