Review of Status, Threats, and Conservation Management Options for the Endangered Indus River Blind Dolphin
Total Page：16
File Type：pdf, Size：1020Kb
Biological Conservation 192 (2015) 30–41 Contents lists available at ScienceDirect Biological Conservation journal homepage: www.elsevier.com/locate/bioc Review of status, threats, and conservation management options for the endangered Indus River blind dolphin Gill T. Braulik a,b,⁎,UzmaNoureenb, Masood Arshad b, Randall R. Reeves c a Wildlife Conservation Society, Tanzania Program, Zanzibar, Tanzania b WWF-Pakistan, Ferozepur Road, Lahore, Pakistan c Okapi Wildlife Associates, Hudson, Quebec, Canada article info abstract Article history: The Indus River dolphin (Platanista gangetica minor) is a freshwater cetacean that occurs only in the Indus River Received 18 August 2015 system in Pakistan and India. This review provides a comprehensive summary of issues surrounding Indus Accepted 6 September 2015 dolphin conservation, and includes a description of their distribution, the threats they face and a discussion of Available online xxxx conservation and research activities, options and priorities. Information was gathered from published current and historical literature, newspaper articles, and unpublished reports. Prior to construction of the Indus Irrigation Keywords: system dolphins occurred in 3500 km of the Indus River system. Their range has now declined by 80% due to Freshwater dolphins Endangered species fragmentation of river habitat by barrages and large-scale diversion of water for irrigated agriculture. The sub- Dams species was estimated to number approximately 1450 individuals in 2011, and occurs in 6 subpopulations, Aquatic biodiversity three of which are probably too small to persist. There is an urgent need to evaluate whether dolphins move Habitat fragmentation through barrages, as this has the potential to extirpate upstream subpopulations. Pre-requisites for dolphin translocations to combat this problem are outlined. Mortality in fishing gear and high levels of chemical pollution in water courses are both increasing threats exacerbated by depleted flows. Research and conservation priorities include maintenance of river flows, mortality monitoring, canal rescues and community-based conservation. Conservation and research action is urgently needed to prevent the Indus dolphin from succumbing to the same fate as the baiji. © 2015 Elsevier B.V. All rights reserved. Contents 1. Introduction...............................................................32 2. Materialsandmethods..........................................................32 3. TheIndusRiver.............................................................32 4. Statusofdolphinsandtheirhabitat....................................................32 4.1. HistoricalinformationonIndusRiverdolphins............................................32 4.1.1. Historicaldistributionandabundance............................................32 4.1.2. DevelopmentoftheIndusbasinirrigationsystem......................................33 4.2. CurrentstatusofIndusRiverdolphins................................................33 4.2.1. Presentdistributionandabundance.............................................33 4.2.2. TrendsinabundancebetweenGudduandSukkur......................................34 4.3. ShortsummaryofIndusdolphinecologyandbiology.........................................35 5. Threats.................................................................35 5.1. Directcausesofmortality......................................................35 5.1.1. Hunting.........................................................35 5.1.2. Fisheriesinteractions...................................................35 5.1.3. Canalentrapment.....................................................35 5.2. Indirectcausesofmortality.....................................................36 5.2.1. Waterpollution......................................................36 5.2.2. Freshwatersupplies....................................................36 ⁎ Corresponding author. E-mail addresses: [email protected] (G.T. Braulik), [email protected] (U. Noureen), [email protected] (M. Arshad), [email protected] (R.R. Reeves). http://dx.doi.org/10.1016/j.biocon.2015.09.008 0006-3207/© 2015 Elsevier B.V. All rights reserved. G.T. Braulik et al. / Biological Conservation 192 (2015) 30–41 31 5.3. Climatechange.......................................................... 37 5.3.1. Damsandbarrages.................................................... 37 5.4. Populationdynamicsanddownstreammigratoryattrition...................................... 37 6. Conservationoptionsandresearchpriorities................................................ 38 6.1. Mortalitymonitoring....................................................... 38 6.2. Protectedareas(PAs)....................................................... 38 6.3. Downstreammigration...................................................... 39 6.4. Translocation........................................................... 39 6.5. Rivermanagement........................................................ 40 7. Conclusions............................................................... 40 Acknowledgements.............................................................. 40 References.................................................................. 40 Fig. 1. The Indus River system, and the locations of irrigation barrages and dams. 32 G.T. Braulik et al. / Biological Conservation 192 (2015) 30–41 1. Introduction peak flows of 20–30,000 m3/s occur between June and August when the river is fed by Himalayan melt-water and monsoon run-off, while The Indus River dolphin (Platanista gangetica minor) is an endan- flows as low as 300 m3/s occur in the dry season between December gered, obligate freshwater cetacean that occurs only in the Indus River and April. Human habitation is sparse but increases with proximity to system in Pakistan and India (Fig. 1). The subspecies is red-listed as En- the delta. The only large towns along the Indus are Dera Ismail Khan, dangered due to an 80% reduction in distributional range and a highly Sukkur and Hyderabad. The river is little used for commercial traffic, fragmented population (Braulik et al., 2014c). Indus dolphins, also probably because passage is repeatedly blocked by barrages, and the called ‘blind dolphins’ because of their reduced eyes and poor vision, few vessels present are oar-powered or motorised ferries and small are mammals of high conservation priority because of their evolution- fishing boats. ary distinctiveness and threatened status (Isaac et al., 2007). Although At present, the Indus plains are composed of desert, semi-desert, blind dolphins are potentially charismatic top predators, that could scrub and irrigated agricultural lands. However, several centuries ago function as ‘flagships’ for aquatic conservation, little is known about the native vegetation and fauna of the area was primarily forest and their basic biology. The factors that influence their survival and have grassland inhabited by numerous large mammals including the tiger driven their decline are not well understood, and the best strategy for (Panthera tigris), leopard (Panthera pardus), Asiatic cheetah (Acinonyx conserving them remains unclear. The Indus dolphin and the closely re- jubatus venaticus) and Indian rhino (Rhinoceros unicornis). All but the lated Ganges River dolphin (P. g. gangetica), also red-listed as Endan- leopard are now locally extinct. Freshwater mega-fauna in the Indus gered, are assigned to a monotypic family, the Platanistidae. This is River system previously included mugger crocodiles (Crocodylus one of the more ancient cetacean families that diverged approximately palustris) which were hunted extensively and are now found in only a 29 Million Years (MY) ago, 22 MY before modern marine dolphins arose few isolated areas of Sindh (Ahmad, 1999). The harmless, fish-eating (Xiong et al., 2009). Recent genetic studies showed that Indus and Gan- crocodilian, the gharial (Gavialis gangeticus), was once widespread but ges dolphins diverged from each other approximately 0.5 MY ago and, if is now extinct in Pakistan (Ahmad, 1999). Two species of otter, the they are shown to have morphological differences, the two subspecies smooth otter (Lutra perspicillata) and the Eurasian otter (Lutra lutra), may be recognised as separate species in the future (Braulik et al., were once common, but these animals were decimated by hunting for 2014b). their pelts and now persist in only a very few locations (WWF- Several reviews of Indus dolphin conservation status were published Pakistan unpublished). Eight species of turtles inhabit the Indus River in the 1980s and 1990s (Reeves, 1998; Reeves and Brownell, 1989; system, including four soft-shelled species that can reach more than Reeves and Chaudhry, 1998). There has been a substantial increase in 1 m in length and four smaller hard-shelled species. Freshwater turtles knowledge since then, and the purpose of this paper is to provide an used to be abundant, but a new illegal trade in soft-shelled turtle parts update and comprehensive summary of what is known about Indus dol- for use in Chinese traditional medicine has resulted in massive turtle phins today, including descriptions of their status and the major threats kills and greatly reduced wild turtle numbers (Pakistan Wetlands they face and a discussion of conservation and research activities and Programme/WWF-Pakistan, 2008). A commercially important fishery options. for the migratory shad (Hilsa ilisha) existed in the Indus River prior to construction of the barrages that blocked