Yes! There are Irrawaddy dolphins in the waters off Iloilo and Guimaras. But we might not get a chance to see them in the next few years if we don’t save this subpopulation fast.
This week’s #UnderwaterMonday features the Critically Endangered Iloilo-Guimaras Straits subpopulation of Irrawaddy dolphins (Orcaella brevirostris).
The Irrawaddy dolphin is a range-restricted marine mammal that inhabits coastal, estuarine and freshwater habitats in Indo-Pacific region. Isolated populations of Irrawaddy dolphins are found near estuaries, semi-enclosed and protected bodies of water with freshwater inputs like bays, lagoons and rivers.
There are 3 subpopulations of Irrawaddy dolphins in the Philippines. The first was documented in 1986, in the inner part of Malampaya Sound in Palawan while another population was sighted off the town of Quezon in southern Palawan.
The most recently described are in Iloilo and Guimaras Straits, first documented in 2005 after a dolphin got caught in a gillnet. The Iloilo-Guimaras Straits are Important Marine Mammal Areas, or discrete portions of habitat, important to marine mammal species, that have the potential to be delineated and managed for conservation.
Surveys conducted from 2009 to 2016 in the Iloilo-Guimaras Straits estimated that only 8-18 mature individuals remain in this subpopulation and are declining.
Thus, this subpopulation was listed Critically Endangered by the International Union of the Conservation of Nature (IUCN).Threats to their population are boat strikes and entanglement in fishing gears such as surface and bottom set gillnets, fixed filter bagnets, fishpens and fish corals. In 2010, a calf was stranded in Guimaras coast while a mother and calf were stranded in Negros in 2019.
Other threats include pollution from industrial plants and coastal communities, habitat destruction, prey depletion and urban and industrial developments in their habitat like construction of bridges.
Noise pollution in the natural habitats will affect the bio-acoustic behavior of the Irrawaddy dolphins, which may increase their risk of collision with boats.Text by Merlyn F. Geromiano | NMWV©National Museum of the Philippines (2021).