The devastating floods of 2010 is believed as a triggering force to give rise to the dolphin population in certain parts of River Indus, besides increasing the distribution of marine human-friendly species, suggests a report of WWF-Pakistan. A survey report for 2011 and 2012, which WWF-Pakistan has recently published, indicates the catastrophic floods however killed scores of stranded dolphins.
But, the increased water level from the mounting floods is believed to have facilitated dolphins to sail along Indus River and establish sub-populations - an addition to overall population, the report says. "Initial findings after the flood may have been misleading since with more water there was a low detection rate of Indus River Dolphin during the survey," views Director Biodiversity, WWF-Pakistan, Uzma Khan.
The report finds that the high-flood activated water channels are thought to have provided the dolphin population an opportunity to disperse in other parts of the river. "With less food competition and new habitats created, this could have been a blessing for the species which is unique in Pakistan," it maintains.
It says opened barrage gates during high floods also helped dolphin move both up and downstream directions which resulted in the increase in its population in some areas include Taunsa Guddu, and Sukkur Kotri sections. The floods time movements of dolphins have also caused a decline in its population in Guddu Sukkur river section, it indicates.
Previous research of WWF-Pakistan had involved radio tagging dolphins revealing the river cetacean can pass through the barrage in both upstream and downstream directions. This findings show the suitable habitat for the Indus River dolphin has increased because of floods, according to the report.
The study area for Indus River Dolphin population assessment includes a stretch of the Indus River between Jinnah and Kotri Barrages representing species core habitat. It is divided into five river sections marked by constructed barrages where each river section holds a specific dolphin sub-population. They are: Jinnah - Chashma (River Section I); Chashma - Taunsa (River Section II); Taunsa - Guddu (River Section III); Guddu - Sukkur (River Section IV); and Sukkur - Kotri (River Section V), the report points out.
In 2001, the first comprehensive study the Pakistan had carried out which Gillian T Braulik had led to cover the entire distribution range of Indus River dolphins between Jinnah and Kotri Barrages.
The results of this study revealed that an estimated population of 1,100 dolphins exists in the Indus River. Another study was conducted by WWF-Pakistan in 2006 which showed a total abundance of 1,600 - 1,750 dolphins. "In the 2011 dolphin population survey, total abundance of 1,452 dolphins was estimated in the Indus River," says Co-ordinator Indus River Dolphin Project, Uzma Noureen.
The 2011 and 2012 survey was conducted in collaboration with World Wide Fund for Nature-Pakistan (WWF-Pakistan), International Union for Conservation of Nature (IUCN) Cetacean Specialist Group, Wildlife Departments of Punjab, Sindh and Khyber-Pakhtunkhwa, Zoological Survey Department of Karachi, as well as the Adventure Foundation Pakistan, Nature Conservation Pakistan and the Conservation and Hunting Association of Pakistan.