Recent floods in the Indus River have been devastating for the local human population, but these disasters have helped increase the number of Indus dolphins in some parts of the river, suggests a new report by WWF-Pakistan.
Floods waters have increased the habitat available for dolphins and allowed the mammals to move along the Indus River and establish sub-populations, thereby adding to the overall population, claims a 2011-2012 survey published by the WWF-Pakistan last week. “With less food competition and new habitats created, this could have been a blessing for the species which is unique in Pakistan,” the report claims.
However the survey does indicate the catastrophic floods killed scores of stranded dolphins and so overall numbers appear to have declined. An estimated 1,100 dolphins now exist in the Indus River, down from 1,600 – 1,750 dolphins in 2006.
Umza Khan, director of biodiversity at WWF-Pakistan, argues this needs careful interpretation: “because of the massive 2010 floods there was so much water in the river, its span was wider and there were more side channels and therefore, detection was much harder. The study also found that while the dolphin population decreased in Sindh, it almost doubled in the Punjab, so clearly its distribution has spread,” Khan said.
The Indus River dolphin is one of the world’s rarest mammals. Dolphins regularly travel back and forth into irrigation canals when canal gates are open and during canal closure the water level drops and dolphins become trapped in small pools with depleting fish supply.
Intensive fishing in canals during closure period also aggravates the risk of net entanglements of these endangered dolphins.
Several years ago WWF-Pakistan, in collaboration with the Sindh Wildlife Department, set up an Indus dolphin rescue unit to collect trapped dolphins and physically transport them back to the Indus River. Since 1992 around 112 dolphins have been successfully rescued, according to Rina Saeed Khan who described these efforts in an article in Dawn this week.