A QUARTER of the world’s freshwater fauna, including fish, dragonflies, crabs, and shrimps, face a high risk of extinction, a global conservation activist group has established in a new report.

GLAND, Switzerland

A statement issued here on Wednesday by the International Union for Conservation of Nature (IUCN) and published in the science journal Nature appearing at midweek, said that the report was a result of over 20 years of work by more than 1,000 experts from around the world.

The IUCN reached its conclusions after analysing 23,496 freshwater species on the IUCN ‘red list,’ the largest global assessment of its kind to date, the statement noted.

Catherine Sayer, IUCN’s freshwater biodiversity lead scientist and the paper's main author, said that as the IUCN marks 60 years of its red list, “it is a stronger barometer of life than ever. 

“Lack of data on freshwater biodiversity can no longer be used as an excuse for inaction,” she said, in the background of study findings that 4,294 species are at high risk of extinction.

Crabs, crayfish and shrimps are at the highest risk (30 per cent), along with freshwater fishes (26 per cent), plus dragonflies and damselflies (16 percent).

It asserted that 89 freshwater species have already gone extinct since 1500, with another 187 likely to disappear, while the data isn’t as yet conclusive, the statement indicated.

Freshwater ecosystems, though covering less than one percent of the earth’s surface, are home to 10 per cent of all known species but they are vanishing at an alarming rate, it stated.

Nowhere is this loss more profound than in the Western Ghats, a freshwater biodiversity hotspot and home to many endemic species. The study identifies this region as one where freshwater species are most threatened.

“There are over 300 species of freshwater fish in the Western Ghat, also known as the Sahyadri, a mountain range that stretches 1,600 km along the western coast of the Indian peninsula. 

Covering an area of 160,000 square kilometres, it traverses the states of Gujarat, Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu.

 Dr Rajeev Raghavan, assistant professor at the Kerala University of Fisheries and Ocean Studied at Kochi, said that more than half of the threated species are found only here and nowhere else on earth, making them exceptionally vulnerable to environmental threats,.

Kerala has the highest number of threatened freshwater fishes in India (estimated at about 74), and the Periyar River is the most significant in terms of ‘conservation attention’ as it harbours the maximum number of endemic and threatened freshwater fishes in Kerala, he further noted.

Other highly affected regions identified in the study include Lake Victoria in Africa, Lake Titicaca in South America and Sri Lanka’s Wet Zone, the statement affirmed.

Pollution tops the list of threats, affecting 54 percent of at-risk freshwater species. Agriculture and urban development exacerbate the problem as pesticides, fertilisers and untreated wastewater flow unchecked into rivers and lakes, it stated.

Dams and water management projects, which alter natural flow regimes and block migratory routes, are the second-largest threat, impacting 39 per cent of species. Invasive species, overharvesting, and climate change further compound the challenges, it said.

The Kerala don says that conservation strategies designed for iconic terrestrial species such as tigers and elephants do little to benefit freshwater species in shared habitats like the Western Ghats. 

For instance, the critically endangered humpbacked mahseer (Tor remadevii), a mega fish that can grow up to 60 kg, is severely threatened by habitat loss, he said.

“Protecting freshwater fauna requires tailored interventions, such as restoring river ecosystems, regulating fishing and preventing the spread of invasive species,” the don affirmed, who is also the South Asia chairman of the NGO’s freshwater fish specialist group, while the authors stress the importance of incorporating freshwater species data into broader conservation strategies.

Stephanie Wear, the Conservation International senior vice president at the Moore Center for Science at Palo Alto, California, in the United States, said that “freshwater ecosystems are not resources for exploitation; they are lifelines for humanity. 

“Saving them will require bold, collective action across disciplines, sectors and borders. Our health, nutrition, drinking water and livelihoods depend on them,” he added.