Recent research estimates a maximum of six to eight resident dolphins in the Karnali river of far-western Nepal.
While experts hesitate to go along with this, the researchers have warned of a marked decline in both the number and distribution range of dolphins in the Karnali river system “which may lead to a further decline and ultimate extinction of the dolphin from the river if stringent measures are not taken to protect these acquatic mammals”.
Dolphins are listed as a critically endangered species, the highest level of threat under the list provided by the International Union for the Conservation of Nature (IUCN).
“We found a maximum of six to eight dolphins as the dominantly resident population along the mainstream of the Karnali River in its western channel. We surveyed the entire eastern branch of the river´s Geruwa portion, which is approximately 31 kilometers, but did not find any dolphin there,” said Gopal Khanal, one of the researchers.
“This is far less than our expectation though the results have never been that encouraging in previous research also. Gradual loss in their number is the result of fishing activities, their prey destruction, deforestation, decrease in river depth and many other human-induced effects,” he added.
The research, which was supported technically and financially by the Conservation Leadership Program, among others, was carried out from January to March in 2013 by a team of four early-career wildlife ecologists from the Wildlife Ecology Department of the Institute of Forestry, Pokhara Campus.
“We had followed a direct count method population survey as per the recommendations of IUCN for narrow channels,” informed Khanal.
Research done from 2010 to 2012 by senior ecologist Prof. Tej Kumar Shrestha had, however, counted around 18 dolphins in the Karnali. According to him, the difference in outcome is due to the disparity of the time period for the research.
“I agree that these mammals are facing threats and there is crucial need for stringent measures to save them. However, it cannot be concluded that there are no more than eight dolphins in our river. What can be said is eight dolphins were found in the Karnali during the ´summer´ season when the water level is low,” he explained.
Shrestha had done similar research in the Karnali in January 1982 between Solta and Kothiyaghat, an approximately 65-kilometer stretch. He had noticed 20 dolphins then.
According to Megh Bahadur Pandey, director of the National Park and Wildlife Conservation Department, different research has yielded different results about dolphin numbers in the past and there is no question of negligence in the conservation of these mammals as most of their range comes under the protected area.
“Illegal fishing, sand mining or deforestation are out of the question in the protected area,” he said.