KARACHI, Oct 24: Known to locals as Bhulan, the Indus Blind Dolphin is confined to a 100-mile stretch of fresh water between the Guddu and Sukkur barrages, across the lower Indus in Sindh.
According to an expert, Bhulan even more than its neighbour Susu in the Ganges, is threatened with extinction. As is the case with the earth's other three river dolphin species, its fight for survival has not so much to do with adverse natural condition as with problems manmade.
Its diminishing numbers are a result of incidental and intentional exploitation by humans.
A survey conducted jointly in 2001 by the Worldwide Wildlife Fund -- Pakistan, the Pakistan government wildlife departments and the Whale and Dolphin Conservation Society estimated that there were 1,100 Bhulans left in the Indus. A total of 965 individuals were actually sighted.
Confined to the fresh-water river system of the Indus, the blind and side-swimming Bhulan resembles the Indian Susu in every respect, except that it is slightly smaller.
Like other river dolphins, and unlike its ocean-going relatives, the Bhulan has a bulbous forehead and a long rostrum, its skull has not undergone streamlining and neck vertebrae are not fused, thereby allowing remarkable flexibility of the head, which may assist it in capturing its prey, navigating in narrow waterways and in scanning its surroundings. It too relies on echolocation to navigate and hunt like the Ganges Susu.
The Bhulans are slow swimmers and often swim on their right sides, nodding their heads continually, perhaps to maintain contact with bottom of the river with their right flipper. Being quite blind, they appear to navigate through touch, the flipper serving much like a blind man's cane.
But dams across the Indus and its tributaries restrict the movement of this unique species, disrupting migration patterns and dividing their population.
Reliable data on Bhulan's seasonal migratory behaviour still needs to be accumulated but there is some informed speculation on the subject.
According to Richard Garstang, former conservation adviser to the WWF-Pakistan, “The Indus river barrages probably act as one-way valves, permitting downstream movement but no return traffic”.
The greatest threat to the survival of the Bhulan is in fact from the continuing decline in water flow, especially downstream of the Sukkur barrage.
There is still a long way to preserve this unique species and government functionaries instead of just making announcements should formulate a comprehensive strategy for the survival of the Indus Susu.—PPI
