Susu and Bhulan: Platanista gangetica gangetica and P. g. minor

This chapter discusses characteristics, taxonomy, distribution, abundance, and ecology of Susu and Bhulan. The susu and bhulan are two river dolphins of the South Asian subcontinent. Both subspecies are nearly identical in external appearance. Their body is supple and robust, attenuating behind the dorsal fin to a narrow tailstock. Coloration is gray or light brown overall, becoming blotchy with age. Bellies of young animals are lighter and often have a pinkish hue. The dolphins have a long snout that becomes thicker at the tip. With the exception of a few vagrants, bhulans currently occupy less than 700 km of the Indus mainstem, fragmented into three subpopulations by the Chashma, Taunsa, Guddu, and Sukkur barrages. The subspecies has been extirpated from the Sutlej, Ravi, Chenab, and Jhelum rivers, and from downstream of the Kotri Barrage and upstream of the Jinnah Barrage in the Indus mainstem. The susu and bhulan are patchily distributed throughout their range, generally occurring in counter-currents and deep pools located downstream of channel confluences and sharp meanders, and upstream and downstream of mid-channel islands. They also occasionally occur in counter-currents induced by engineering structures such as bridge pilings and groynes. The affinity of the species for countercurrents is probably greatest in upstream tributaries where productivity is especially clumped and strong downstream currents restrict occupancy to the hydraulic refuge these areas provide. © 2009