Irrawaddy dolphin Orcaella brevirostris in the Cambodian Mekong River: an initial survey

Ian G. Baird a1p1c1 and Isabel L. Beasley a2p2
a1 Department of Geography, The University of British Columbia, Vancouver, Canada. E-mail ianbaird@shaw.ca
a2 School of Tropical Environment Studies and Geography, James Cook University, Townsville, Australia.

Article author query
baird ig   [PubMed][Google Scholar] 
beasley il   [PubMed][Google Scholar] 


Irrawaddy dolphins Orcaella brevirostiris are found in coastal waters from the Bay of Bengal east to Palawan, Philippines and south to northern Australia. They also occur in three large tropical river systems in South-east Asia: the Mekong, Mahakam and Ayeyarwady. In March and May 1997 approximately 350 km of riverine habitat in parts of north-east Cambodia were surveyed, discussions took place with local people, and reported dry season dolphin habitat was mapped. Our objectives were to investigate the status, habitat and distribution of dolphins in north-east Cambodia and identify threats to the continued survival of dolphins in the Mekong River Basin. Nine groups of dolphins were observed in the Mekong River. A ‘best’ estimate of 40 animals were seen. Irrawaddy dolphins were generally confined to sections of the river with water levels >8–10 m during the dry season. It appears that the Mekong River dolphin population is rapidly declining. In 1997 there were probably no more than 100¨C150 dolphins left in north-east Cambodia (including southern Laos) and no more than 200 within the entire Mekong River Basin, although these numbers remain tentative. Anthropogenic mortality is high, albeit largely unintentional, and there is considerable risk that the dolphin population will become locally extinct in the Mekong River in the near future. The establishment of community-managed deep water Fish Conservation Zones with government support may represent the best opportunity for reducing dry season dolphin mortality from large-meshed gillnet entanglement. Efforts to establish protected areas for dolphins are currently underway.

(Received September 29 2003)
(Revised January 19 2004)
(Accepted January 26 2005)

Key Words: Cambodia; Cetacea; Irrawaddy dolphin; fish conservation zones; fisheries co-management; Laos; Mekong River; Orcaella brevirostris.

c1 Correspondence: Department of Geography, The University of British Columbia, Vancouver, Canada. E-mail ianbaird@shaw.ca
p1 Global Association for People and the Environment (GAPE), P.O. Box 860, Pakse, Lao PDR.
p2 Mekong Dolphin Conservation Project, PO Box 9123, Kratie, Cambodia.