Species File: Exploring India’s biodiversity, one species at a time.

Imagine five cars parked behind one another. That’s approximately how long this fish is. Growing up to 18 metres in length, it is considered as the world’s largest fish. It has a distinctive pattern of white spots which are unique to each individual, much like a human fingerprint.

The whale shark (Rhincodon typus) is a slow-moving filter feeder found along India’s entire coastline, with the largest aggregation off Gujarat’s coast. It plays a role in maintaining the marine food chain by regulating plankton and small fish populations.

Whale sharks are present worldwide in tropical and warm-temperate waters. According to the International Union for Conservation of Nature (IUCN), the whale shark is listed as endangered due to global population decline. In India, it has the highest legal protection under Schedule I of the Wildlife (Protection) Act, 1972.

It faces multiple pressures, including lethal ship collisions, bycatch in fishing gear, and, in the past, targeted hunting for meat and fins. Warming oceans due to climate change, offshore drilling and coastal construction are also shifting their food sources and altering habitats. These pressures have led to its population shrinking by half in the last 75 years.

In recent years, however, community-driven conservation efforts along India’s west coast have helped reduce bycatch-related deaths, though other threats still loom. In an earlier story that Mongabay-India published in 2025, Sajan John, the head of marine projects at Wildlife Trust of India, said, “Earlier, the whale sharks died tangled in gear. Now, they’re released alive before they reach shore. It’s a complete reversal.”

There’s even an app that allows fishers in Gujarat to easily document whale sharks that get caught in fishing nets. This helps them receive compensation for their loss of revenue during the downtime without nets.

Read more about this mobile-based whale shark rescue app, increasing strandings, and community conservation efforts in our stories.

Banner image: A whale shark in an aquarium in Japan. Image by Kimon Berlin via Flickr (CC BY-SA 4.0).

A newly-proposed mining project in Gadchiroli district in Maharashtra has courted controversy due to the potential diversion of forest land to facilitate iron ore mining and processing. The project involves diversion of around 9.37 sq km of forest land, an area about half the size of New Delhi airport. Accordingly to news reports, this has raised questions about the project’s location within the Tadoba-Indravati tiger corridor, a key wildlife linkage connecting forests in Maharashtra and Chhattisgarh.

Decades of Maoist ideology-led insurgency in Gadchiroli meant that the forests in the district had largely remained insulated from rapid industrialisation that the rest of Maharashtra had been witnessing. That is likely changing with the recent announcements by Maharashtra chief minister Devendra Fadnavis regarding  future development plans for the district. Furthermore, the controversy surrounding forest clearance granted to the proposed iron ore mining and processing project by Lloyds Metals & Energy has drawn attention to the ecological significance of Gadchiroli, arguably one of Maharashtra’s most forested districts.

The debate intensified after media reports revealed that maps submitted as part of the project proposal showed substantial overlap with the corridor identified in the National Tiger Conservation Authority-approved Tiger Conservation Plan for Tadoba-Andhari Tiger Reserve. Despite this, the project was exempted from wildlife clearance requirements after state authorities concluded that the site did not fall within a recognised tiger corridor.

Mandar Pingle, the assistant director of the Satpuda Foundation, a non-profit focused on wildlife and landscape conservation in central India informs Mongabay-India that the proposed mining site falls on an active elephant corridor. “Many megafauna use these corridors for movement across forests,” he says.

The controversy has highlighted broader concerns about the ecological value of Gadchiroli’s forests, which remain less studied than many other biodiversity-rich landscapes in India. Pingle shares that decades of restricted access due to insurgency meant that there is very little understanding of what the district stands to lose in terms of biodiversity if development plans are made on forest lands.

The Lloyds project comes amid a wider push to industrialise Gadchiroli through mining, steel production and infrastructure development. State authorities view such investments as important for economic growth and employment in a district that has historically lagged behind other regions in development indicators.

As development projects expand across Gadchiroli, the district is increasingly emerging as a focal point in the broader debate over balancing economic growth with the conservation of one of central India’s largest remaining forested landscapes.

Banner image: An iron ore mine in Chhattisgarh. Representative image by India Water Portal via Flickr (CC BY-NC-SA 2.0).

Species File: Exploring India’s biodiversity, one species at a time.

Olive ridley turtles are travelling farther than previously known. Early tracking data from tagged turtles in Tamil Nadu shows that some have already reached the Sri Lanka Dome, a little-known region in the Indian Ocean. Turtles from Odisha are also expected to arrive in the same waters, pointing to a shared ocean hotspot.

The olive ridley sea turtle (Lepidochelys olivacea), also known as the Pacific ridley, is the smallest and most abundant of all sea turtles. Found in warm tropical waters across the Pacific, Indian and Atlantic oceans, they are named for their olive-green shell or carapace. Olive ridleys use both coastal waters and the open ocean, travelling long distances in search of food. They feed on jellyfish, shrimp, snails, crabs and fish eggs.

In India, Odisha’s Gahirmatha, Rushikulya, and the mouths of the Devi river are the primary nesting grounds. In 2025, over 650,000 olive ridley turtles arrived at Rushikulya for a synchronised mass nesting event, where thousands of female turtles come ashore simultaneously to lay eggs.

Despite their numbers, olive ridleys are listed as vulnerable on the International Union for Conservation of Nature (IUCN) Red List of Species, with continuing decline of mature individuals. In India, they are protected under Schedule I of the Wildlife Protection Act, 1972, which offers the highest level of legal protection.

Survival remains a challenge. Only one in 1,000 hatchlings reaches adulthood, with the rest falling prey to predators. Olive ridleys face growing threats from fishing bycatch, ghost gear, coastal development, plastic pollution and climate change.

In a recent story that Mongabay-India published in April 2026, Chandana Pusapati, a Ph.D. scholar, who previously studied turtles, said, “Increasing plastic pollution at nesting beaches and foraging areas is an emerging threat, especially for females and hatchlings. Olive ridleys also prefer nesting near river-mouths, where plastic and other land-based waste often accumulate.”

Read more about the importance of local participation in conservation and how mass deaths of olive ridleys on Chennai’s coast call for action.

Banner image: An adult olive ridley turtle. Image by Jonathan Reynaga via Pexels.

The Union Cabinet has approved a two-year scheme that incentivises truck and bus owners in the National Capital Region to turn electric or upgrade to BS-VI compliant vehicles. BS-VI is the latest emissions standard which includes stricter curbs on pollutants such as carbon monoxide and nitrogen oxide.

The government approved the scheme on June 3, saying it was “aimed at reducing air pollution in the Delhi-NCR region and promoting cleaner mobility.” Emissions from transport have long been shown to be the biggest year-round contributors to air pollution in NCR — up to 30% by some estimates. Trucks and buses were found to account for 36% of vehicular PM 2.5 emissions, despite being only 3% of the total fleet, according to a 2018 study by the Automotive Research Association of India (ARAI) and The Energy and Resources Institute (TERI).

The BS-VI standards include reductions between 25% and 80% in tailpipe emissions of sulphur, nitrogen oxide, particulate matter and hydrocarbons for petrol and diesel vehicles compared to BS-IV norms. Owners of BS-III vehicles will have to mandatorily scrap the vehicles, while owners of BS-IV vehicles have the option of scrapping or selling them in non-polluted areas outside NCR. Owners will then have to purchase either electric vehicles or BS-VI compliant ones.

To motivate owners, the government has offered a 5% interest subsidy on loans for five years, monthly fuel vouchers worth up to ₹4,800, and lump‑sum benefits for EV purchases, depending on the vehicle category. States will also waive registration fees and offer 100% motor vehicle tax concessions for new vehicles, and 50% for older ones used up to 10 years. Other benefits include discounts of 8% on ex‑showroom prices.

“The benefits by the central government will continue for five years from the date of registration of the new vehicle, ensuring sustained impact beyond the two‑year enrolment window,” the government said.

The scheme is likely to benefit 1.91 lakh truck and 16,329 bus owners operating in the NCR region, which includes Delhi, Haryana, Rajasthan, and Uttar Pradesh. The scheme was approved with financial outlay of ₹9,585 crores, including ₹5,041 crores from the central government and an estimated ₹1,601 crores in tax concessions from the participating states. Government vehicles are excluded from the scheme.

Banner image: A truck transporting goods in Uttar Pradesh. Representative image by Shantum Singh via Pexels.

A recent study has found that air pollution exposure could impair foetal growth, with a potential to cause neurological defects. The study, from the All India Institute for Medical Sciences (AIIMS), Delhi, sheds light on the molecular pathways through which pollution disrupts early child development, and reinforces existing evidence of the wide-ranging health impacts of air pollution.

Exposure to PM2.5 particles are known to cause respiratory disease, worsen hypertension and diabetes, and exacerbate cardiovascular illnesses. Emerging evidence has suggested that prolonged exposure to air pollution can cause low birthweight, stillbirth, and preterm births. The AIIMS study, however, demonstrates how air pollution disrupts cellular activity to curb healthy foetal development.

“The missing link we presented in this research was how air pollution causes the reduction in a protein that’s very important for foetal development,” explained Dr. Subhradip Karmakar, an author of the study and a professor of biochemistry at AIIMS.

In pregnant mothers, inhaling ultrafine, PM2.5 and PM10 particles can cause oxidative stress which triggers an inflammatory response that activates cytokines – proteins which act on immune threats. This surge in inflammatory response can pass through the placenta, as do ultrafine particles and environmental pollutants such as heavy metals, which cause a reduction in the IGFBP3 protein, a critical regulator of cell growth, in foetuses. “This isn’t the only significant protein for foetal development. There might be other significant proteins that are also affected,” said Karmakar.

The study observed this mechanism in pregnant rats exposed to air pollution, and tracked postnatal neurodevelopment in pups. According to the study, rat pups exposed to air pollution experienced “persistent postnatal deficits in motor coordination, cognitive processing, and emotional regulation, consistent with neurobehavioral disruption and sex-specific vulnerability induced by in utero particulate exposure.”

The observations in the experiment were correlated with pregnancy outcomes among women from highly exposed climates. Delivery data from hospitals in New Delhi, where women were exposed to higher ambient PM2.5 levels, were associated with more low-birth-weight babies and more preeclampsia, a pregnancy complication, compared to women from lower-exposure settings in Deoghar, Jharkhand.

“The next phase of this study is to track the IGFBP3 protein as a biomarker in human pregnancies, which would give us greater insight into how air pollution causes developmental defects,” said Karmakar.

Banner image: A November 2017 photo of a woman carrying an infant outside a shop selling air purifiers at a market place in New Delhi. (AP Photo/Altaf Qadri, File)

Species File: Exploring India’s biodiversity, one species at a time.

Over the last few years, dholes are slowly returning to several landscapes from which they had virtually disappeared — most recently in Debrigarh Wildlife Sanctuary in Odisha. The dhole (Cuon alpinus) is one of India’s most adaptable apex predators — and one of its least known. Also called the Asiatic wild dog, this social canid is recognised by its reddish-brown coat, bushy black-tipped tail, and distinctive high-pitched whistles. Living in packs of two to 24 individuals, it hunts cooperatively, taking down prey such as sambar, chital, and gaur, all several times its own size.

Once found in the alpine, temperate, tropical, and subtropical forests across Asia, the dhole, or Asiatic wild dog, has now disappeared from much of its former range. Currently, it is confined to central and eastern Asia, India, Nepal, Bhutan, Bangladesh, China, Myanmar, Indonesia, Thailand and Malaysia.

In India, key populations are found in the Western Ghats, Central India and Northeast India, with smaller populations in the Eastern Ghats and the Western Himalayas of Uttarakhand.

With only an estimated 4,500-10,500 individuals remaining worldwide, the species is listed as endangered on the IUCN Red List. It is also a Schedule II species in the Indian Wildlife (Protection) Act, 1972, which prohibits hunting or trade.

As a predator that requires connected, healthy forested areas, the dhole faces significant pressure from fragmented and shrinking forests, prey depletion, conflict with humans and livestock, and the risk of disease transmission from domestic dogs.

In a story that Mongabay-India published in 2019, Arjun Srivathsa, Wildlife Conservation Society-India and the University of Florida, said, “Dholes are among the most threatened yet under-studied species in India and across the world. They are apex predators with fascinating social lives, and quite unique in that they are among the very few carnivores that are both forest-dependent and group-living.”

Read more about dholes in our stories on habitat suitability study across Asia, how agroforests support dhole populations in the Western Ghats, and the use of genetic methods to estimate population sizes.

Banner image: The dhole (Cuon alpinus) is one of India’s most adaptable apex predators. Image by David V. Raju via Wikimedia Commons (CC BY-SA 4.0).