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International Journal of Zoology
Volume 2017, Article ID 8964821, 7 pages
https://doi.org/10.1155/2017/8964821
Research Article

Present Status of Ganges River Dolphins Platanista gangetica gangetica (Roxburgh, 1801) in the Turag River, Dhaka, Bangladesh

1Department of Zoology, Jagannath University, Dhaka 1100, Bangladesh
2University Grants Commission of Bangladesh, Dhaka 1207, Bangladesh

Correspondence should be addressed to Md. Muzammel Hossain; moc.liamg@3lemmazum

Received 15 September 2016; Revised 9 April 2017; Accepted 18 May 2017; Published 14 June 2017

Academic Editor: Hynek Burda

Copyright © 2017 Mohammad Abdul Baki et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Freshwater ecosystem degradation in the Turag River basin is increasing due to rising human settlement, reduced water flow during the dry season, new large land development projects, and toxic emissions caused by brick kilns. The population of river dolphins was estimated through surveys carried out from December 2012 to November 2013. Surveys were conducted on a fortnightly basis. The dolphins were counted within an 18.4 km stretch (known to be the most polluted stretch) of the 75 km long river. A total of 62 dolphin sightings were recorded, both as individual sightings and as groups. The highest monthly count was in August. The best-high-low estimates of 9-11-7 individuals were recorded in August 2013 in river ecology. Seasonal changes in spatial distribution were observed. The survey revealed that rising floodwater stimulated an increase in the dolphin population in the study area from July to October. The maximum encounter rate was also 0.49 sightings km−1 for the month of August. The sightings and encounter rates of dolphins were lower from December to July (dry and premonsoon period) likely due to reduced water flow and adverse water quality of this river.