low reproductive rate of Hector's dolphin, it seems unlikely 

 that the small population will be able to sustain the continued 

 take in gill nets in addition to natural mortality. 



During 1988, the Marine Mammal Commission plans to con- 

 tribute to the continued support of ongoing research and, as 

 requested, otherwise cooperate in efforts to help determine 

 steps that might be taken to ensure the protection of the 

 Hector's dolphin population. 



River Dolphins (Superfamilv Platanistoidea) 



The Platanistoidea superfamily of toothed whales and 

 porpoise comprises five species commonly known as river dol- 

 phins. It includes the only cetaceans whose natural habitat 

 is limited to fresh-water environments. The species and their 

 distribution are: Platanista gangetica, known as the Ganges 

 or blind river dolphin, found in India, Bangladesh, and Nepal; 

 P. minor , the Indus river dolphin, found in the Indus River 

 system of Pakistan; Inia qeoffrensis . the boto or Amazon river 

 dolphin, found in the Amazon and Orinoco River basins in South 

 America; Lipotes vexillifer . the baiji or Yangtze river dolphin, 

 presently found along the middle and lower Yangtze River in 

 China; and Pontoporia blainvillei . the franciscana, found in 

 the South Atlantic coastal waters off Argentina, Uruguay, and 

 Brazil. Pontoporia is the only member of the group that in- 

 habits salt water. 



Although there is little information available on the 

 population status and ecology of river dolphins, there is 

 reason to believe that all five species may be threatened to 

 varying degrees with extinction due to subsistence hunting, 

 incidental take by fisheries, and/or human-caused destruction 

 and degradation of habitat. Construction of dams and other 

 development in important river dolphin habitat pose potentially 

 serious threats to the continued survival of several of the 

 species. The baiji, Ganges river dolphin, and Indus river 

 dolphin are listed on Appendix I of the Convention on Inter- 

 national Trade in Endangered Species of Fauna and Flora, and 

 the boto and franciscana are listed on Appendix II. 



On 23 December 1986, the Commission wrote to the National 

 Marine Fisheries Service recommending, among other things, 

 that steps be taken to list the separate species of river 

 dolphins as threatened or endangered under the U.S. Endangered 

 Species Act. By Federal Register notice of 17 February 1987, 

 the Service announced that it had reviewed a petition to desig- 

 nate the baiji as endangered and had determined that, based 

 on available information, the proposed listing may be warranted. 

 On 17 April 1987, the Service announced its intention to review 

 the status of the other four river dolphins to determine whether 



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