Mekong River Irrawaddy dolphins

Updated Feb 2013

Mekong River Irrawaddy dolphin, Orcaella brevirostris,  photographed at the Cambodia-Lao Border, Feb-2010. Photo: NIIMURA Yasuo

The Irrawaddy dolphin (Orcaella brevirostris) population in the Mekong River of Cambodia and Laos is redlisted as Critically Endangered. A series of estimates of total population size in the first decade of the 21st century were all below 150 and there is reason to believe that numbers have been declining steadily. Much of the cause is mortality in fishing gear but the especially high calf mortality has defied explanation.

In 2009, WWF-Cambodia requested help from the CSG in examining the evidence and helping identify research and management priorities. In that October, a small team of scientists including CSG members Bob Brownell, Randall Reeves, Brian Smith, Sam Turvey and Wang Ding, as well as Frances Gulland on behalf of the IUCN/SSC Veterinary Specialist Group, met with government officials and NGO representatives in Phnom Penh. The report produced by the expert group can be found  here.

Dead Mekong River Irrawaddy dolphin calf found near Kratie in Cambodia and demonstrating unusual neck lesions, May-2010. Photo: Gordon Congdon

Achievements since that meeting have included:

  • Confirmation that gillnet entanglement is the main cause of adult mortality.  This was achieved with help from William McLellan and Ann Pabst of the University of North Carolina-Wilmington, who rigorously examined photographs and necropsy reports.
  • contaminant and genetic testing of a large volume of tissue samples.
  • the combination of recent photo-ID images and data with an older photo-ID catalogue and data from the PhD work of CSG member Isabel Beasley.

Mekong Irrawaddy dolphin stranded in a gill net near Sambor, 12/16/2005. Photo: WWF-FiA

Meanwhile, on-the-ground efforts are focussed on building consensus regarding the status of, and threats to, Mekong dolphins.  The culmination of these efforts was a workshop held in Kratie in January 2012, attended by many of the earlier representatives of the CSG, as well as pre-eminent cetacean ecologists, pathologists, and veterinarians including Thijs Kuijken, Paul Jepson, Tadasu Yamada, Antonio Fernandez, Yuko Tajima, Andrew Read, Randall Wells, and Peter Thomas, with a host of local and national fisheries and environmental management agents, and NGO and civil society representatives. The high point of this workshop was the signing of the “Kratie Declaration on the Conservation of the Mekong River Irrawaddy Dolphins” (which can be found in full here). The Declaration is a landmark for dolphin conservation in the Mekong, with the Commission for Conservation and Development of Mekong River Dolphin Eco-Tourism Zone, the Fisheries Administration, and WWF-Cambodia, all agreeing to work together on a joint strategy for dolphin conservation in the Mekong. The Declaration includes a list of recommendations, as well as appendices detailing a series of management and research recommendations, and reports from sub-group discussions on mortality and pathology, management, behaviour and ecology.

Much progress has been made following the Kratie Declaration. To understand calf mortality, veterinarian Dr. Jesus de la Fuente has completed the review and development of necropsy protocols. Meanwhile, remote biopsy methods to obtain tissues from live animals have been successfully piloted in collaboration with Bob Pitman, Bob Brownell and Lisa Ballance from NOAA.  Biopsies can provide data on hormone levels, nutrition, genetics, and contaminants. Following the close monitoring and observed good health of biopsied animals in 2012, this project will be expanded in 2013.

On-the-ground protection has also made big steps forward with the declaration of protected areas for Mekong dolphins covering their entire permanent range in Cambodia, from the Kratie Town to the Laos border. A grant to WWF-Cambodia from the Save Our Species fund will support implementation and enforcement of this new law by equipping and training the Fisheries Officers and the Dolphin Commission’s local River Guard network.

Randall Reeves, Bob Brownell, Frances Gulland, Peter Thomas (US Marine Mammal Commission’s International and Policy Program Director) and various CSG members continue to liaise regularly with Gordon Congdon and Gerry Ryan of WWF-Cambodia to help advance conservation initiatives in the Mekong.

The above provides a background to the Irrawaddy dolphins and its conservation. The CSG posts news items and updates about conservation of the Irrawaddy dolphin and these can be found on our News page or at the following links:

May 2016- Mekong River dolphin update

September 2014- Irrawaddy dolphins (Pesut) in Indonesia’s Mahakam River

July 2014- Update on Mekong and Ayeyarwady Irrawaddy dolphin conservation

February 2013- Update on conservation of the critically endangered Mekong River Irrawaddy dolphins

March 2012- Three new wildlife sanctuaries for Ganges River and Irrawaddy dolphins declared by the Government of Bangladesh

January 2012- Update on Mekong River Dolphins in Cambodia