KARACHI: After two decades of research, scientists have recognised the endangered Indus and Ganges dolphins as separate species – raising the number of river dolphin species worldwide to six, the WWF-Pakistan said on Tuesday.

Since the 1990s, river dolphins in South Asia were considered to constitute a single threatened species, but a study published today in Marine Mammal Science concludes that the dolphins in the Indus River and Ganges-Brahmaputra Rivers are sufficiently distinct to be classified as species in their own right.

The work, which took 20 years to complete, was led by Dr Gill Braulik of the Sea Mammal Research Unit at the University of St Andrews, who travelled across India and Pakistan to gather data for the study, including searching for dolphin skulls to measure.

The research shows that the two river dolphin species have different numbers of teeth, coloration, growth patterns and skull shapes as well clear genetic differences.

“Recognizing the differences between Indus and Ganges river dolphins is extremely important as only a few thousand individuals of each species remain,” said Dr Braulik. “They have long been regarded as two of the world’s most threatened mammals. My hope is that our findings will bring much-needed attention to these remarkable animals, which will help to prevent them sliding towards extinction.”

The research involved a long-term collaboration between the University of St Andrews WWF-Pakistan, Patna University in India, and the Southwest Fisheries Science Center of the National Oceanic and Atmospheric Administration in the US as well as many other researchers in South Asia.

The Indus and Ganges River dolphins are often referred to as blind dolphins because they live in naturally muddy rivers and, over millions of years of evolution, have lost their eyesight and instead rely on a sophisticated sonar or echolocation system to navigate and catch prey.

Both species are threatened by accidental entanglement and drowning in fishing nets, by the construction of hydropower dams and irrigation barrages, and pollution of their waterways – and are listed as Endangered on the IUCN Red List.

According to Dr Braulik, “The rapid decline and extinction of the Yangtze River dolphin this century was a very clear warning: we need to act quickly to protect the remaining species of river dolphins, including the Indus and Ganges, all of which are seriously threatened.

The freshwater systems they inhabit must be managed with biodiversity as a top priority”.

Copyright Business Recorder, 2021