Dolphin numbers have come down to 68 in the 435-km Chambal sanctuary, a survey by the Madhya Pradesh Forest Department has found, with experts suspecting fishing and extensive water withdrawal as major stressors.
Undertaken in March, the survey found 43 adults and 25 calves in the sanctuary. In 2016, the number was 78, a year later 75 and 74 in 2018. A survey was not undertaken in 2019 in the sanctuary that passes through Madhya Pradesh, Rajasthan and Uttar Pradesh.
The river dolphins, declared national aquatic animal, were found in six patches having deep pools, said Morena Divisional Forest Officer Amit Nikam. “We can’t precisely call it a decline. Another survey after rains will present a better picture. There need to be more studies on dolphins.”
Crucial habitat
The sanctuary is also a crucial habitat for the gharial and red crowned roof turtles. “Sand mining doesn’t affect dolphins as much as it affects the gharial population, which is more sensitive to habitat change. Dolphin movement is not much in areas where there is sand mining. We have identified around 10 major sites of illegal sand mining and chalking out a plan to curb it,” said Mr. Nikam.
Fishing has an impact on the dolphin population, platanista gangetica, declared endangered by the International Union for Conservation of Nature (IUCN), said J.S. Chauhan, Madhya Pradesh Additional Principal Chief Conservator of Forests, Wildlife wing.
“Dolphins may be caught in the net and die accidentally. But such instances are rarely reported for fear of prosecution,” said Mr. Nikam. In the 1980s, they numbered around 110 which dropped due to rampant poaching.
Construction of dams along the Chambal river had affected water flow altering the habitat, said Mr. Chauhan. “There needs to be better coordination among the three States to protect the habitat,” he said.
Breeding continues
However, the species which are not latched with tags for monitoring is continuing breeding in the river. “That we found calves shows that,” said Mr. Nikam.
Surveying dolphin numbers required a skilled observer and there were high chances of error, said Samir Kumar Sinha, Deputy Director and Division Head (Species Recovery) of the Wildlife Trust of India. “It needs to be ensured the same observer undertakes the survey over a period of time. Different observers may cause bias leading to percentage difference in population numbers,” he said.
