Conservation news 761
SHIBAOWU (
orcid.org/0000-0003-4683-4919) College of Life Sciences, South China Normal University, Guangzhou, China, and IUCN Species Survival Commission Pangolin Specialist Group, Zoological Society of London, London, UK E-mail
wushibao@163.com
Critically Endangered subpopulation of Irrawaddy dolphin in central Philippines may lose its habitat to large-scale development project
The Irrawaddy dolphin Orcaella brevirostris is a range- restricted, facultative freshwater species that inhabits coast- al, estuarine and freshwater habitats in disjunct populations from India to South-east Asia. The Iloilo-Guimaras Straits subpopulation is one of three known O. brevirostris subpo- pulations in the Philippines and the second to be declared Critically Endangered (Dolar et al., 2018,
dx.doi.org/10. 2305/
IUCN.UK.2018-2.RLTS.T1230959 78A123095988.en). This subpopulation of 13–25 individuals was discovered in 2007, and is believed to be in decline. This decline is likely to be exacerbated should the Philippine government pur- sue plans to construct the Panay–Guimaras–Negros bridges under their ‘Build, Build, Build’ agenda to boost intercon- nectivity for economic development. A feasibility study of the proposed bridges stated that the
construction phase would have few significant effects on the marine fauna. However, the proposed bridges will affect an Important Marine Mammal Area and the known range of this O. brevirostris subpopulation (Fig. 1). Specifically, the po- tential bridge alignment D directly bisects the species’ core
habitat (de la Paz et al., 2020, Raffles Bulletin of Zoology, 68, 562–573).We know from the case of the Indo-Pacific hump- back dolphin Sousa chinensis in the Pearl RiverDelta affected by the Hong Kong-Macau-Zhuhai bridge (Karzmarski et al., 2016, Advances in Marine Biology, 73, 27–64) that the cumu- lative effects of existing threats and extensive construction in the species’ habitat will have irreversible impacts on its long-term survival. The Iloilo–Guimaras Straits subpopulation of O. bre-
virostris already faces grave threats from bycatch, collision with boats, illegal fishing, and habitat degradation. During the construction phase of these bridgeswe would expect an in- crease in noise pollution from pile driving and the ferrying of materials, and consequent negative effects on the bio-acoustic behaviour of the dolphins and an increased risk of collisions with boats. We expect long-term effects, such as sediment bed changes and scouring, changes in water movement and current, and changes in prey dynam- ics, to affect the local environment even after the bridges are built. In time, such effects will be felt by local residents who rely on these straits for their livelihood. Yet, there is still hope. On 6 August 2020, government
officials announced the shelving of the Guimaras–Negros segment of this large-scale infrastructure project, citing the presence of mangroves and dolphins. This announce- ment followed a public outcry that questioned the validity of the preliminary assessment as it had ignored the presence of Irrawaddy dolphins within the proposed construction sites. However, this change offers only temporary relief to this subpopulation, considering the extensive threats to its long-term survival. We must, collectively, continue to give
FIG. 1 The known range of the Iloilo-Guimaras Straits subpopulation of the Irrawaddy dolphin Orcaella brevirostris in the central Philippines includes parts of the Iloilo and Guimaras Straits. An ambitious project to construct bridges connecting the islands of Panay, Guimaras and Negros would bisect a recognized Important Marine Mammal Area (IMMA) and the core habitat of this Critically Endangered subpopulation of O. brevirostris. This map summarizes all known spatial data on the subpopulation. The alignments indicate the different bridge positions being considered. Important Marine Mammal Area boundaries are from Marine Mammal Protected Area Task Force (2020,
marinemammalhabitat.org).
Oryx, 2020, 54(6), 759–762 © The Author(s), 2020. Published by Cambridge University Press on behalf of Fauna & Flora International. doi:10.1017/S003060532000085X
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