2017 Cetacean Red List Update

Assessments or reassessments of 19 cetacean species, subspecies and populations were published on the IUCN Red List in 2017.  These included all four species of humpback dolphin, the Irrawaddy dolphin, two species of finless porpoise, the South Asian River dolphin, the beluga, the narwhal, and the vaquita among others (see Table 1 for details).  A new “taxon,” the Gulf of Mexico Bryde’s whale, was listed as Critically Endangered (CR).  The Atlantic humpback dolphin was uplisted to CR, and the baiji, vaquita and Taiwanese humpback dolphin (formerly considered a subpopulation, recently described as a subspecies) were all reconfirmed as CR (the baiji again being tagged as “possibly extinct”).  The South Asian River dolphin, Irrawaddy dolphin, narrow-ridged finless porpoise, and Indian Ocean humpback dolphin were all listed as Endangered (EN), while the franciscana, Australian humpback dolphin, Australian snubfin dolphin, Indo-Pacific finless porpoise, and Indo-Pacific humpback dolphin were all listed as Vulnerable (VU).

Summary of reassessments or new assessments published in the 2017-3 (December)* Red List update. (NT = Near Threatened; DD = Data Deficient)* published in September edition of the 2017 Red List

#SpeciesCommon namePopulationCategoryStatus change
1Balaenoptera edeniBrydes whaleBalaenoptera edeni (Gulf of Mexico subpopulation)CRNew listing
2Cephalorhynchus commersoniiCommersons dolphinLCChanged to LC from DD
3Cephalorhynchus eutropiaChilean dolphinNTUnchanged
4Delphinapterus leucasBelugaLCChanged to LC from NT
5Lipotes vexilliferBaiji (Yangtze River dolphin)CR (possibly extinct)Unchanged
6Monodon monocerosNarwhalLCChanged to LC from NT
7Neophocaena asiaeorientalisNarrow-ridged finless porpoiseENChanged to EN from VU
8Neophocaena phocaenoidesIndo-Pacific finless porpoiseVUUnchanged
9Orcaella brevirostrisIrrawaddy dolphinENChanged to EN from VU
10Orcaella heinsohniAustralian snub-fin dolphinVUChanged to VU from NT
11Orcinus orcaKiller whaleDDUnchanged
12Phocoena sinus*VaquitaCRUnchanged
13Platanista gangeticaSouth Asian River dolphinENUnchangd
14Pontoporia blainvilleiFranciscanaVUUnchanged
15Sousa chinensisIndo-Pacific humpback dolphinVUNew assessment of species redefined in relation to newly recognized congeners – changed to VU from NT
16Sousa chinensisSousa chinensis taiwanensis (subspecies)CRNew assessment of subpopulation recently recognized as a subspecies - status unchanged
17Sousa plumbeaIndian Ocean humpback dolphinENNew listing
18Sousa sahulensisAustralian humpback dolphinVUNew listing
19Sousa teusziiAtlantic humpback dolphinCRChanged to CR from VU

All 89 cetacean species and an additional 39 subspecies or subpopulations have been assessed and their status and documentation can be found on the IUCN Red List website (redlist.org).  Of the 89 species, 22% are assigned to a threatened category (i.e. CR, EN, VU, NT) and almost 50% are considered DD (see Table 2).

Table 2. Summary information on Red List status as of December 2017.

Category Species Subspecies/populations Total
Critically Endangered 3 17 20
Endangered 10 9 19
Vulnerable 6 7 13
Near Threatened 1 0 1
Least Concern 25 0 25
Lower Risk/Conservation Dependent* 0 2 2
Data Deficient 44 4 48
Total 89 39 128

*This category is no longer recognized; therefore these assessments are out of date.


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.

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.