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.

 

Dead Taiwanese White Dolphin stranded in Tainan City

News Item Prepared by Megan Kuo and Amy Tian of Wild at Heart Legal Defense Association, Taiwan

 

Photograph of Joker with his distinctive lip gash as well as an unpigmented (white) healed line scar on the front edge of the flipper. Photograph by: John Y. Wang / CetAsia Research Group.

On 21 January 2022, the Taiwan Ocean Conservation Administration (OCA) was informed by the public of a dead stranded dolphin at Anping Fishing Port, Tainan City. Marine biology experts and inspectors were on the scene and sent the carcass to the Annan campus of National Cheng Kung University for necropsy. The animal was determined to be dolphin number OCA038 in the OCA’s White Dolphin Database. Necropsy revealed a juvenile male Taiwanese White Dolphin with fresh scars, and developmental abnormalities due to injuries caused by past gillnet entanglement.

 

This dolphin was later identified by experts in the CetAsia Research Group as an approximately 12-year-old male named ‘Joker’ because of a distinctive lip-to-lip scar across his beak from a previous gillnet entanglement. While his cause of death is uncertain, gillnet entanglement is a common issue among Taiwanese White Dolphins. A study by the CetAsia Research Group in 2017 found that about 58% of Taiwanese White Dolphins had suffered major human-induced injuries, mainly from gillnets. Joker’s mother, known as Cupcake, was well-known due to the severe mutilation of her body caused by fishing gear entanglement in 2012. Her most recent calf, born in 2015-16 was also observed in 2017 with a line wrapped around its torso.

 

Photographs of Joker with his mother, Cupcake, taken in 2011 (prior to Cupcake’s entanglement) and 2012 (lines cutting into Cupcake’s dorsal fin and back can be seen). Photographs by: John Y. Wang / CetAsia Research Group.

 

The Taiwanese White Dolphin Recovery Plan in 2019 clearly states that a ban on gill and trammel nets in the entire habitat of the dolphins is urgently needed. The plan proposes a solution characterized as a “win-win-win” through a buy-out program, brokered between the government and wind-farm developers, meant to appease competing interests. Gillnet fishers would be compensated and provided with assistance in switching to alternative fishing methods.

 

The resultant severe mutilation of Cupcake due to lines cutting through her dorsal fin and back. Photograph by: John Y. Wang / CetAsia Research Group.

The Taiwanese White Dolphin (Sousa chinensis taiwanensis) is a subspecies that is endemic to Taiwan and Red-Listed as Critically Endangered. A recent study showed the total population to be declining and numbering fewer than 65. These dolphins only inhabit a narrow strip of shallow waters along Taiwan’s heavily developed west coast, where fisheries are considered the greatest threat. Joker’s demise generates urgency for coordinated efforts among relevant stakeholders to prevent the extinction of Taiwan’s sole endemic cetacean.

 

References:

Wang, J. Y., & Araújo-Wang, C. (2017). Severe mutilation of a Critically Endangered Taiwanese humpback dolphin Sousa chinensis taiwanensis by fishing gear. Diseases of Aquatic Organisms123(3), 257-262.

Wang, J. Y., Riehl, K. N., Yang, S. C., & Araújo-Wang, C. (2017). Unsustainable human-induced injuries to the Critically Endangered Taiwanese humpback dolphins (Sousa chinensis taiwanensis). Marine Pollution Bulletin116(1-2), 167-174.

Vaquitas seen in autumn 2021 survey

From October 17 through November 3, 2021, a vaquita research effort was privately funded through the Museo de la Ballena y Ciencias del Mar and a number of private donors.  The survey focused on the last stronghold of vaquitas, the Zero Tolerance Area (ZTA) declared in Mexico’s Federal Register of September 24, 2020 as an area defined as follows: Fishing activities of any kind, with any type of vessel, including sport fishing, are permanently and totally prohibited within the “Zero Tolerance Area”. No type of vessel will be allowed to transit or navigate in this area, unless the vessel is authorized to transit, in writing, by the competent authority.

 

Both vaquitas and large amounts of illegal gillnetting were observed during the survey. The 2021 survey report (available here) documents the study in 2021 that was designed to be as close as possible to the research last conducted in 2019.  In the intervening 2 years, net removal coverage was limited in 2020 (see news reports on this website 1, 2, 3) and after January 1, 2021 only the Mexican Navy carried out actions for the removal of nets with no participation by the Sea Shepherd Conservation Society and Museo de la Ballena because strong civil unrest had resulted in the Navy telling the net-removal ships to leave the area.  In the absence of a strong programme to support and incentivize the deployment of alternative fishing gear, fishing communities have continued using gillnets for shrimp and finfish including totoaba.

 

As was the case in 2019, the survey was hindered by the large number of gillnets and pangas, which was documented from the Museo de la Ballena’s ship the Narval in the 2019 Report with 87 and in the 2021 Report with 117 pangas within the ZTA.  As specified in the Memorandum of Understanding between the Sea Shepherd Conservation Society and the Government of Mexico, details on illegal gillnetting were recorded multiple times each survey day and the data were turned over to the Government of Mexico.  One apparent enforcement action was witnessed during the survey.

 

As a consequence of unfavorable weather conditions, no photographs of sufficient quality to identify individual vaquitas were obtained, which made estimation of the number of vaquitas within the ZTA using mark-recapture methods impossible.  Instead, a method called Expert Elicitation was used as was done in 2019.  The 2019 report concluded that the most likely number seen in the ZTA was about 11 individuals including 3 calves (2019 Report here).  The 2021 report found that the most likely number seen in the ZTA was about 7 or 8 individuals including 1 or 2 calves (2021 Final Report here).  Given the concentration of fishing within the vaquita’s last 12 x 24km stronghold and the lack of any effort to deter gillnetting within the ZTA over the two-year period, the survival of these individuals is nothing short of remarkable.