Update on Mekong River dams and river dolphins

As mentioned in an article posted on this website on 8 February 2017, the construction of large dams in the mainstem of the Mekong River in Laos and Cambodia represents an existential threat to the small, Critically Endangered freshwater population of Orcaella brevirostris. Following the January 2017 workshop described in that article, a letter co-signed by the IUCN Director General and the Chair of the Species Survival Commission was sent to the Prime Minister of Cambodia, emphasizing the concern of the international conservation community about the impacts of dam construction on the Mekong dolphins and other biodiversity.

The dam issue was also discussed by the IWC Scientific Committee at its annual meeting in May 2017. The committee concluded that “if the proposed construction of large hydropower projects on the Mekong mainstem in Cambodia proceeds, almost all of the dolphins’ habitat in the Mekong will be modified or eliminated and the risk of extinction will be greatly increased.” The IWC Scientific Committee proposed two recommendations relevant to the conservation of the Mekong dolphin, and both will be addressed at the 2018 IWC Commission meeting.

Posted in Critically Endangered, Dams, entanglements, Freshwater Dolphins, Irrawaddy Dolphins, Mekong dolphins | Leave a comment

Massive large whale mortality event in Chile

In March 2015, by far the largest-ever reported mass mortality of baleen whales took place along the coast of southern Chile. At least 343 animals, primarily sei whales, died.  The discovery was made during a scuba diving expedition aimed to inventory the benthic fauna of the area between Golfo Tres Montes (Northern Golfo de Penas) and Puerto Edén. By chance the team discovered underwater recently dead baleen whales and whale skeletal remains near Estero Slight and in the Canal Castillo situated 235 km to the south.  This was followed by an aerial survey and analyses of satellite images to detect additional carcasses from this large and remote coastline.

The Golfo de Penas is one of the most important feeding grounds for sei whales, hosting the largest and densest known sei whale aggregations outside the polar regions. World-wide, Harmful Algal Blooms (HABs) are increasing, and large ones have been documented along the southern Chilean and Argentine coast lines. Factors associated with increasing HABs include nutrient run-off and coastal eutrophication, warmer waters, movements of ballast water, aquaculture and overfishing (IWC, 2017).

Aerial photos of whale carcasses. Reproduced from Häussermann et al 2017.

An investigation into the causes of the mass mortality event (MME) was conducted and it was concluded that the mostly likely cause of death was poisoning from a HAB during a building El Niño (Häussermann, et al. 2017). The combination of older and newer remains of whales in the same area indicate that MMEs have occurred more than once in recent years. The MME and its probable connection to a red tide event adds to the building evidence that marine mammals are among the victims of coastal development and global warming.




Häussermann, V., Gutstein, C.S., Bedington, M., Cassis, D., Olavarria, C., Dale, A.C., Valenzuela-Toro, A.M., Perez-Alvarez, M.J., Sepúlveda, H.H., McConnell, K.M., Horwitz, F.E., Försterra, G., 2017. Largest baleen whale mass mortality during strong El Niño event is likely related to harmful toxic algal bloom. PeerJ 5:e3123 https://doi.org/10.7717/peerj.3123.

International Whaling Commission (IWC) 2017. Report of the Workshop on Harmful Algal Blooms (HABs) and Associated Toxins.  7-8 May 2017, Bled, Slovenia. SC/67A/REP/09.

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Initiative to save Taiwanese white dolphins from extinction

Taiwanese white dolphins (Sousa chinensis taiwanensis) live in shallow nearshore waters along the west coast of Taiwan (= eastern Taiwan Strait). Researchers from Taiwan and elsewhere have been studying this small and declining population (currently < 75 individuals) since its discovery in 2002 (Wang et al. 2016).

The Taiwanese white (humpback) dolphin is endemic and restricted to a very small area along the nearshore waters off western Taiwan. The dolphin subspecies is declining in number due to several major threats such as fisheries interactions and coastal industrialization. Photo Credit: Jordan Hoffman

The Eastern Taiwan Strait Sousa Technical Advisory Working Group (ETSSTAWG) was formed in 2007 at the Society for Marine Mammalogy’s biennial conference in Cape Town with the aim to identify, characterize, and help address threats to the subspecies. About 58% of the dolphins in this population bear serious scars that are mostly caused by fishing gear (Wang et al. 2017); freshwater diversion for human use has depleted flow into estuaries;  chronic industrial pollution releases toxic smoke and liquid effluent into dolphin habitat; and factories are built on ‘reclaimed land’ in nearshore waters, reducing and degrading dolphin habitat (Ross et al. 2010).

A Taiwanese white dolphin with injuries from fishing gear. Photo credit: John Wang

Some progress has been made over the past decade. The Government cancelled a permit to ‘reclaim’ 4,000 hectares for the KuoKang petrochemical facility after serious concerns were raised about the implications for dolphin habitat. The Government also agreed to designate Major Wildlife Habitat (akin to ‘critical habitat’ in some other jurisdictions) with boundaries that largely mirrored those proposed by the ETSSTAWG, but significantly with no provisions to protect potential habitat, omitting a substantial section of known dolphin habitat, and leaving waters within 50 m of shore undesignated. Also, local and central governments have, since receiving proposals from the ETSSTAWG for a variety of measures to mitigate the impacts of fisheries on the dolphins, increased enforcement of fishing bans that were already in effect, pursued buy-backs of nearshore fishing licenses, and incorporated dolphin concerns more coherently into management practices and environmental impact assessments. Without these actions, Taiwanese white dolphins would likely be in an even steeper population decline.

Two Taiwanese white dolphins surface close to intensive industrial development along the coast of Taiwan. Photo Credit: John Wang

Unfortunately, however, an ominous new threat has emerged over the past year: a massive array of offshore windfarms that are to be installed in coastal waters within and around dolphin habitat. To address this threat, the ETSSTAWG and Taiwanese conservation groups – Wild at Heart Legal Defense Association and Matsu Fish Conservation Union – convened a team of experts to assess the risks of windfarm construction and provided recommendations for ‘beyond best practices’ for industry, as well as guidance for the Government. General guiding principles for the wind energy sector included: i) Locate turbines away from areas where dolphins occur, including areas where the noise is likely to disturb dolphins; ii) Use engineering practices that are ‘better-than-best’ at reducing noise and disturbance during construction; and iii) Reduce the threat of fisheries interactions, both immediately and during windfarm construction and operation, since the construction activity may exacerbate the impact of fisheries by forcing fishermen to fish closer to shore, thus increasing fishing effort within dolphin habitat. The expert panel noted that if construction of the windfarms is designed and carried out properly, Taiwan may gain a ‘cleaner’, more secure source of energy and at the same time give hope for the survival and recovery of its endemic dolphin subspecies.


Ross, P.S., Dungan, S.Z., Hung, S.K., Jefferson, T.A., MacFarquhar, C., Perrin, W.F., Riehl, K.N., Slooten, E., Tsai, J., Wang, J.Y., White, B.N. Würsig, B., Yang, S.C. and Reeves, R.R. 2010. Averting the baiji syndrome: conserving habitat for critically endangered dolphins in Eastern Taiwan Strait. Aquatic Conservation: Marine and Freshwater Ecosystems 20: 685–694 (2010)

Wang, J.Y., Riehl, K.N. Klein, M.N., Javdan, S., Hoffman, J.M., Dungan, S.Z., Dares, L.E. and Araújo-Wang, C. 2016. Biology and conservation of the Taiwanese humpback dolphin, Sousa chinensis taiwanensis. Advances in Marine Biology Series: Conservation of the Humpback Dolphins (Sousa spp.) 73: 91-117.

Wang, J.Y., Riehl, K.N., Yang, S.C. and Araújo-Wang, C. 2017. Unsustainable human-induced injuries to the Critically Endangered Taiwanese humpback dolphins (Sousa chinensis taiwanensis). Marine Pollution Bulletin 116:167-174.


Posted in Critically Endangered, Endangered, Sousa, Taiwan white dolphin | Leave a comment