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.

References

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.

 

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Vaquita on the verge of extinction

CIRVA (Comité Internacional para la Recuperación de la Vaquita) met again in April 2017, just 5 months after the committee’s last meeting. The meeting report, which was officially released today at the IWC Scientific Committee meeting in Slovenia, points out that the vaquita is on the verge of extinction. Five dead vaquitas were recovered in March and April 2017. It was confirmed that at least three of these animals had been killed in gillnets (the other two were perinatal animals). CIRVA concluded that despite the enormous efforts by the government of Mexico, illegal fishing activity for totoaba has continued at a very high level. Thus far in the present fishing season, Sea Shepherd Conservation Society (SSCS), as part of a multi-institutional program with the government of Mexico to remove fishing gear, has retrieved over 150 active totoaba gillnets. SSCS also has observed a considerable amount of illegal fishing activity. CIRVA welcomed the Government of Mexico’s “Agreement Prohibiting the Use of Gillnets for Commercial Fishing in Waters of Federal Jurisdiction in the Northern Gulf of California.” However, the Committee reiterated its previous recommendation that the sale or possession of gillnets on land and at sea should be illegal in the area of the current gillnet ban and on adjacent lands.  

The full report can be read here

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Lost Indus dolphins in the Beas River, India

Indus River dolphins (Platanista gangetica minor) inhabit the Indus River system of Pakistan and India.  Over the last 150 years, numerous irrigation barrages (gated dams) that divert river water into canals have been constructed in this system.  As a result, the range of Indus dolphins has declined by approximately 80% since the 1870s due to habitat fragmentation and reduced river flows.  Survey results suggest that the entire subspecies numbers well under 2000 individuals and it is listed as Endangered on the IUCN Red List.  Indus dolphins persist in 5 barrage-partitioned sections of the Indus mainstem in Pakistan, and a tiny isolated population persists in the Beas River in India, some 600km away from all the others.

The current distribution of Indus River dolphins. The Beas River is located on the far eastern side of this map (segment 17 of the system). Reproduced from Braulik GT, Arshad M, Noureen U, Northridge SP (2014) Habitat Fragmentation and Species Extirpation in Freshwater Ecosystems; Causes of Range Decline of the Indus River Dolphin (Platanista gangetica minor). PLOS ONE 9(7): e101657. https://doi.org/10.1371/journal.pone.0101657

As recently as last year, there were estimated to be between 18 and 35 Indus dolphins in the Beas River above Harike Barrage (Shahnawaz Khan 2016).  During periods of low flow, they have been observed to move downstream into the head pond above the barrage, which includes the Harike Wildlife Sanctuary.  On 27th March, 2017 the flow of the Beas River was virtually stopped in order to allow maintenance works to the barrage and canal gates.  River flow dropped from approximately 30,000 cubic feet per second (cusecs) to just 1,100 cusecs.  Many aquatic animals perished including freshwater turtles and fish.  An extensive search was made for the resident river dolphins, but only 4 have been located to date.  It is feared that the remaining dolphins became stranded and died in shallow pools, or slipped through the barrage into downstream areas near the India-Pakistan border where the river is almost always completely dry and where they will also eventually perish.  However no dead dolphins have yet been reported despite the extensive search.

This sad situation demonstrates the vulnerability of river dolphins that today live only in heavily managed rivers.  If the needs of wildlife are not considered in the management of rivers and barrages, more environmental catastrophes can be expected.

References

Khan, M. S. 2016. Abundance and distribution modelling for Indus river dolphin, Platanista gangetica minor, in Beas River, India. Current Science 111 (11) 1859-1864.

Posted in Dams, Endangered, Freshwater Dolphins, South Asian River dolphins, Unusual mortality | Leave a comment