Irrawaddy dolphin research & conservation in the Mahakam

And finally ... to finish off the month of May (okay so i've strayed over into June) and the Irrawaddy blog, our final entry is from Danielle Kreb, studying one of the last remaining populations of freshwater Irrawaddy dolphins, in the Mahakam River here in the island of Borneo - although the Indonesian part, south of where this "blogger" is currently sitting (I'm north of there in Sabah, Malaysian Borneo). Before we get to hear from Danielle, who is also going to tell us about some of her coastal work in the region (where she spotted Irrawaddy dolphins, just the marine kind), let me update you to tell you that we too have been out, on the eastern side of Malaysian Borneo (and up a river) looking for Irrawaddy dolphins .... and much to everyone's surprise, we found some! More on these chaps at a later date as we're currently trying to see if we can kick start some long-term research in this area - more soon!

Over to Danielle .... and i'll be back soon with the next species of the month - the humpback whale ... very topical as the member nations of the IWC meet this week in Morocco to decide the fate of the world's whales - at least when it comes to commercial whaling!


The freshwater Irrawaddy dolphin population in the Mahakam River is isolated from coastal populations through evolutionary separation events. This symbol species for East Kalimantan Province is protected in Indonesia and has been classified as “Critically Endangered” in 2000. Most recent population estimates from 2007 based on Petersen Mark-Recapture Analysis indicate a population size of 87 individuals (CV=9%; 95% CL = 75-105) and 91 individuals based on the total number of individuals identified during that year. The major threat involved direct mortality, which was largely caused by gillnet entanglement (74% of all deaths). Mean annual mortality between 1995 and 2007 was four dead dolphins per year. Other threats are habitat degradation through sedimentation, which is reducing the depth of lakes and reducing fish resources; noise pollution because of high-frequency boat propellers and high decibel producing tugboats and barges for coal transport; chemical pollution, mainly from coal and gold-cleaning waste; prey depletion due to illegal and unsustainable fishing methods (electro-fishing, poison and trawl, non-sustainable aqua-culture practices using fish breeds that feed on other fish). Dolphin core areas include the “Muara Pahu – Penyinggahan sub-districts area” where 57% of the total number of 91 identified dolphins in 2007 were observed in this area, whereas in the second largest core area “the Pela/ Semayang –Muara Kaman area” 46% of the total identified dolphins was observed. The first core area obtained official protected status at district level in 2009 and encompasses 4100 ha of river, tributary and freshwater swamp habitat. Regulations still need to be legalized. Multi-stakeholder workshops and community assessment surveys were conducted several times in the core areas to assess community opinions towards area and dolphin protection and community needs. Environmental education courses were implemented at a combined total of fifty-five high- and elementary schools in the Middle Mahakam. Sustainable aqua-culture (using herbivorous fish species) support is being provided to sixty fishermen in the protected area that subsist on gillnetting to reduce fish pressure and dolphin entanglements. Mitigation of unsustainable fishing techniques and pollution reduction (due to chemical waste and boat noise) remains an important component for the survival of this critically endangered freshwater dolphin population.

Marine mammal observation surveys were conducted in Balikpapan Bay in East Kalimantan in 2008 in order to obtain information on cetacean diversity, total abundance, distribution patterns and threats. A total of 985 km of line-transects were surveyed in 84.9 hours in 16 days during three surveys in May, June and November 2008. The surveys were compared with the results from two surveys in 2000 and two in 2001, which were conducted during similar seasons to assess changes in abundance and distribution. Three cetacean species, i.e. Irrawaddy dolphin, Orcaella brevirostris, Finless porpoise, Neophocaena phocaenoides, and Indo-Pacific bottlenose dolphin, Tursiops aduncus were encountered during all surveys as well as dugongs Dugong Dugon. The finless porpoise and bottlenose dolphins occurred in low densities in the outer coastal bay segment, and dugongs in several bay segments in very low densities. Irrawaddy dolphins were the species most commonly encountered but were almost exclusively sighted in the upper parts of the bay in 2008, whereas during 2000 and 2001 they also significantly occurred in the lower bay segments downstream of Tanjung Batu and near coastal area. Individual dolphins also show a high site-fidelity throughout the seasons. Best estimates of mean abundance in 2008 were between 67 and 140 individuals based on the Burnham & Overton mark-recapture- and line-transect density analysis, respectively. No significant changes in mean abundance were found between 2000, 2001 and 2008. The disappearance of Irrawaddy dolphins in the lower bay segments is likely caused by increasing boat traffic and industrial activities in the lower segments, as well as increased sedimentation impacting on fisheries in these areas due to mangrove conversion. The preservation of mangroves of the upper bay segments, above Tanjung Batu, and prevention of industrial activities in these segments including prevention of bridge construction plans in this segment, is essential for the preservation of the Irrawaddy dolphins and dugongs in the bay. Since the dolphins live in close contact with the human population in the bay, increasing awareness is similarly important.

Since the project our organization has done many lobby activities against the construction of the bridge joining forces with other local NGOs. Now it seems that national government decided not to go ahead with financing this bridge. So this would mean good news for the environment. However, current piling activities have been done by an irresponsible company. After they got summoned by the environmental department after our complaints they now are willing to cooperate with installing a bubble screen and having monitoring being done by our survey team. This will happen by end of May until piling is finished for one month at least.