Last Mekong dolphin in the Cambodia-Laos transboundary pool dies

The most recent of the seven news items on this website concerning the Critically Endangered population of Irrawaddy dolphins (Orcaella brevirostris) in the Mekong River was posted almost exactly four years ago. Since that time, the information on this population in the Focal Taxa section of the website was updated in August 2021.

In late October 2021, the Cambodia Fisheries Administration and WWF-Cambodia posted a joint press release entitled “Time is running out for saving the transboundary dolphins of the Mekong.” The important message conveyed in the press release was that as of 2021, only a single individual dolphin remained in Chheu Teal transboundary pool on the Laos-Cambodia border. Dolphins in Chheu Teal pool have long been regarded as an isolated sub-population because, since 2001, there have been no records of new dolphins entering the pool which is at the upstream extent of the population’s present-day (relict) range. Seventeen dolphins were reported in the trans-boundary pool in 1993 (Baird et al., 1994; Stacey & Hvengaard, 2002). Regular photo-identification surveys have documented the decline of dolphins in that small fragment of habitat, from seven in 2009, to six in 2012, three in 2018 and only one in 2021.

On February 15, 2022 the last river dolphin in the transboundary pool (ID#035) on the Cambodia-Laos border was found dead. A statement released by WWF-Cambodia indicates that this death almost certainly represents the national-level extirpation of O. brevirostris in Laos.

Both WWF and Cambodia’s Fisheries Administration are saddened by the death of the last known river dolphin in the transboundary pool. The numbers in the pool have plummeted over the last few years, due to multiple threats including hydro-power dam construction causing disruptions to river flow and reduced fish abundance, drowning in gill-nets, and the use of damaging fishing practices such as electrofishing and overfishing.

Dorsal fin photo of the last remaining dolphin, ID#35, in Chheu Teal pool on the Lao / Cambodia border which was found dead on 15th March 2022. © Tan Somethbunwath / FiA / WWF-Cambodia

In the press release, CSG members Uzma Khan, who serves as Asia Coordinator for WWF’s River Dolphin Rivers Initiative, and Somany Phay, Deputy Director of Cambodia’s Fisheries Conservation Department and the Government Liaison at WWF-Cambodia, called on the governments of Laos and Cambodia to acknowledge the extirpation of the transboundary population and stressed the importance of using the lessons learnt from this loss to push for stronger protection of the remaining animals in Cambodia, in particular by stopping the use of gill-nets and other illegal fishing methods. They urged the governments to take measures to restore habitat in the trans-boundary area and elsewhere in the Mekong ecosystem by maintaining flows and providing meaningful protection to dolphins as well as the river’s other biota.

In December 2020 a Trinational Workshop on the Irrawaddy dolphin was held virtually and brought together those working with the three freshwater riverine populations. Recommendations were made with regards to continuing the successful river guards programme and regularly monitoring Mekong dolphins to estimate their abundance and track their movements.

The Cambodia Government’s Fisheries Administration and WWF are actively working with the provincial authorities, local communities and other partners to implement strict enforcement of the fisheries law, stop the use of illegal gill-nets in protected dolphin habitat and provide alternative livelihood opportunities for communities along the Mekong. These actions are of paramount importance for the survival of Mekong River dolphins.

Further details regarding the Mekong River dolphin conservation status are summarised in a recent Report.

References

Phay, Somany, Eam, S. U. , Hang, Sereyvuth, Tan, S. B., Lor Kimsan,  DET Chamnan. 2022. Summary report on the Status of the transboundary dolphins between Cambodia and Lao’s PDR. Unpublished report.  The Fisheries Administration Cambodia, World Wide Fund for Nature (WWF) and IUCN Cetacean Specialist Group.