Tracking Turtles

Sea turtles make a fascinating subject for study; they have smitten ecologist Kartik Shanker since the '80s
Olive ridley turtles have complicated lifecycles
Olive ridley turtles have complicated lifecyclesPhotos: Shutterstock

Everyone needs a role model. Mine was the late Satish Bhaskar, considered the pioneer of sea turtle biology and conservation in India.

I was first smitten by a sea turtle in the late '80s; by then, Satish was already a legend.

He had surveyed all of the Andaman and Nicobar Islands for sea turtle nesting beaches, spent five months by himself on uninhabited Suheli Island in the Lakshadweep to count green turtle nests, and travelled to West Papua in Indonesia to count and tag leatherbacks.

Satish was carrying on a turtle tradition that had begun a decade earlier. When sea turtle pioneers like Archie Carr in the Americas, George Hughes in South Africa, George Balazs in Hawaii and Col Limpus in Australia started their research on these enigmatic marine animals, they realised they could learn nothing about them in a season or two, or even a decade.

On the Turtle Trail

These long-lived, late-maturing species had complicated life cycles. Hatchlings, few of which survived, made slow transoceanic journeys on currents and gyres for many years. After a decade or more, they migrated thousands of kilometres across ocean basins to nest on the beaches where they were born.

Insight into how their populations changed over time or responded to increasing human impact would need decades of data. So these stalwarts started long-term monitoring programmes at critical nesting beaches on different continents that have been running for over 50 years. For example, the monitoring of green turtles at Tortuguero in Costa Rica started in the 1950s, loggerhead turtles at Mon Repos in Queensland and leatherback turtles in South Africa in the mid-1960s.

A shot of olive ridley turtle's mass-nesting
A shot of olive ridley turtle's mass-nesting

A Lifelong Connection

The longest-running monitoring programme in India was a bit of an accident. A citizen's initiative on olive ridley turtles in Chennai, initiated by Romulus Whitaker in the early 1970s, was continued by government organisations for a decade and passed to the care of the Students Sea Turtle Conservation Network in the late 1980s. We started this organisation as college students, and in turn, it helped me find an obsession.

A decade later, I would visit Odisha for the first time for my postdoctoral research on olive ridley genetics, which would show that the populations in the northern Indian Ocean were ancestral to the ones in the Pacific and Atlantic.

Ridleys are known for their extraordinary mass nesting events when tens (sometimes hundreds) of thousands of turtles come ashore to nest in just a few nights. Few natural phenomena can compare to the sight of a beach full of frenzied turtles going about their nesting routine in a zombie-like trance. But confronted with the threats that ridleys faced from mortality in fishing nets, it was clear that it was more important to monitor populations than tinker with arcane evolutionary ecological research. And so, in 2008, we established a long-term population monitoring programme for ridleys at Rushikulya, one of the two mass nesting beaches in Odisha (while continuing to dabble in arcane questions). The programme monitors tracked population size, offshore distributions during the breeding, sex ratios of hatchlings (whose sex is determined by temperature), hatching success and so on.

The genetics work also led me to Galathea, a remote beach 40 km from Port Campbell Bay on Great Nicobar Island, that Satish Bhaskar established as a significant leatherback nesting beach during his surveys.

We were greeted by the sight of a nesting leatherback whose head had been bitten off by a saltwater crocodile. The largest of sea turtles, these 7-foot long, half-ton creatures were not meant to be lumbering around on land. They are more at home diving to depths of over 1,000 metres or braving freezing sub-Arctic waters in search of jellyfish.

Our satellite telemetry studies would show some turtles migrating to Western Australia while others went to Mozambique and Madagascar.

Lessons Learnt

And what have we learned in the last 15 to 20 years? First, these sea turtles are not declining as previously believed. The arribadas (synchronised, large-scale nesting of some turtles) at Rushikulya are as large as ever at this site, even if they fail to occur occasionally.

Leatherbacks have been stable or increasing at West Bay in Little Andaman Island. And green turtles in the Lakshadweep fluctuate as they move from island to island in search of seagrass, but they may be increasing too, thereby creating conflict with local fishers.

Some conservationists rightly ask if the sustainable use of turtle meat and eggs is justified, especially in areas where communities benefit from it.

Other similar marine species need a long-term commitment from ecologists.

Elasmobranchs such as sharks and rays are long-lived, late maturing and produce only a few young each year; this makes them particularly susceptible to overfishing. The loss of these predators can have severe impacts on the ecosystem. And yet, millions depend on them for livelihoods.

Again, for most of the Indian coastline, we have too little data to make informed decisions about their management. In recent years, we have started monitoring the catch of elasmobranchs and contamination by microplastics and heavy metals, which can affect the health of sharks and humans who consume them.

But charismatic species like sea turtles and sharks are only flagships that bring attention to these ecosystems and their lesser known denizens. At coral reefs in the Andamans, we use Automated Reef Monitoring Structures, essentially a stack of PVC plates (a critter condominium or sorts) on which marine organisms settle over time and are identified visually or using DNA. We also use Baited Remote Underwater Video Stations to document and track predator abundance at these reefs.

But, at the end of the day, as ecologists, we only provide a little knowledge. In a world where people are increasingly disconnected from nature, except in a narrow, sanitised, preservationist way, the communities that live off the sea and land may have the most critical role in maintaining these ecosystems.

Their plural relationships with nature—plants and animals can be companions, food, ancestors, medicine, and entertainment—signify the diversity of human-environment interactions over our history.

These multicultural approaches may be critical to more inclusive ownership of nature and a sustainable path to conservation.

The well-being of these small-scale fishing communities is central to marine conservation initiatives and the future of the blue planet.

Kartik Shanker is Professor at the Centre for Ecological Sciences, Indian Institute of Science and Founding Trustee at Dakshin Foundation, Bangalore

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