Guwahati: A new study published in Biological Conservation has, for the first time, brought India’s freshwater megafauna—its large-bodied fish, reptiles, and mammals—into a single scientific focus.
Led by Dr Aashna Sharma, Visiting Scientist at the School of Aquatic and Fishery Sciences, University of Washington, in collaboration with Dr Vineet Dubey from the Wildlife Institute of India, the study uncovers how research on these freshwater giants has evolved, where the gaps lie, and what this means for their conservation in a rapidly changing climate. Professors at the University of Washington and researchers at Conservation Science Partners also contributed to the work.
Freshwater megafauna are critical components of aquatic ecosystems, yet they remain understudied compared to their terrestrial counterparts. The study provides the first comprehensive assessment of India’s freshwater megafauna (IFM), analysing taxonomic and thematic patterns in the research landscape.
India’s freshwater megafauna (IFM) comprises 35 species, including 19 fish, 9 reptiles, and 7 mammals (Appendix A), with the majority (51%) of them recognized as endangered, critically endangered, or data deficient according to the IUCN Red List of Threatened Species. Freshwater megafauna contribute to India’s natural capital, which is valued at approximately $1.8 trillion per year.
Many of these species, such as the Ganges shark (Glyphis gangeticus), the Indus river dolphin (Platanista minor), the Ganges river dolphin (Platanista gangetica), and the Eld’s deer (Rucervus eldii eldii), are already reduced to just a few hundred individuals or severely fragmented populations.
Drawing on 2,500 scientific papers, the research used advanced text-mining techniques to map patterns across decades of published literature. What sets this study apart is a methodological innovation. Sharma developed a new workflow that extracts and analyses only the Discussion sections of scientific papers—sharpening the interpretative power of text-based synthesis.
“Most reviews rely on manually sorting studies into predefined categories,” says Dr Sharma. “But our approach allows patterns to emerge directly from the data, revealing the questions scientists have truly been asking—and those they haven’t.”
The findings reveal that research on India’s freshwater megafauna remains heavily skewed towards fish, while large reptiles and mammals continue to receive far less attention.
The authors argue that such imbalances can obscure broader ecological connections and slow efforts to protect river ecosystems holistically.
However, the mega fishes receive the least conservation attention under India’s Wildlife (Protection) Act (WLPA), the authors stress in their paper. This clearly shows that not all research translates into policy, and not all policy is backed by science.
The study highlights a misalignment between scientific knowledge, legal protection under the WLPA, and global conservation statuses assigned by the IUCN. The authors call for stronger, science-based conservation that bridges this gap.
They further note that opportunities to align policy and science do arise—albeit rarely—and often serendipitously, when policy windows open, such as during amendments to India’s WLPA. “These are the moments scientists must stay braced for,” the authors write, “unlike in many other nations where such regular amendments are rare.”
India is among the few countries where large river species such as mahseer, gharial, river dolphin, and softshell turtles still coexist—but under mounting threats from dams, pollution, and climate extremes. The study calls for conservation policies that recognise these species not in isolation, but as sentinels of freshwater ecosystem health.
“We often think of tigers and elephants when we say megafauna,” Dr Sharma notes. “But rivers, too, have their giants. Protecting them means protecting the arteries of our landscape.”
Dr Sharma is a Fulbright-Kalam Climate Postdoctoral Scholar and an awardee of the Alexander von Humboldt Postdoctoral Fellowship. She strives to bring the wonders of biodiversity forth to the world—beyond charisma.
“The real charisma,” she says, “is in the eyes of the scientist. Try your best to bring your species of interest to the level of conservation attention it deserves. Each species, big or small, has that awe factor—you just need to find it.”
Also Read: What the NDPP-NPF merger means for Nagas and the rest of Northeast