Saving the Mahakam River Dolphin in Borneo

Project Cost: $383,796

Funding Raised: $383,796

$1.28 per acre (1 acre = 43,560 sq ft)
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The Irrawaddy Dolphin is an Endangered cetacean that is typically found in coastal shallows throughout Southeast Asia. In Indonesia’s Mahakam River, however, exists a Critically Endangered population of Mahakam River Dolphin that consists of around 80 individuals. This population is revered by the local community, but is highly threatened by entanglement in gill nets and the destruction of riparian habitat. Researchers are in the process of analyzing the DNA of this isolated population and believe that it may be genetically distinct from other populations.

Rainforest Trust and local partner Yayasan Konservasi Rare Aquatic Species of Indonesia seek $383,796 to establish a 119,277-acre Aquatic Nature Reserve and a 179,808-acre Peat Swamp Conservation Area along the Mahakam River in East Kalimantan, Indonesia. This will protect a total of 299,085 acres. These protected areas will secure important habitat for many threatened aquatic and terrestrial species, including the Critically Endangered Mahakam subpopulation of the Irrawaddy Dolphin, locally known as the “Pesut.” Other species that will benefit from the protected area establishment include the Critically Endangered Siamese Crocodile and Bornean Orangutan, the Endangered Malaysian Giant Turtle and numerous threatened bird species.

Fast Facts

Borneo, Indonesia

299,085 acres

Key Species (Based on IUCN Red List)
Bornean Orangutan (CR), Mahakam River Dolphin (CR), Siamese Crocodile (CR), Malaysian Giant Turtle (EN), Proboscis Monkey (EN), Storm’s Stork (EN)

Coastal Shallows and Peat Swamp Forest

Illegal logging, oil exploitation, agricultural encroachment

Establish an Aquatic Nature Reserve and Peat Swamp Conservation Area

Local Partner
Yayasan Konservasi Rare Aquatic Species of Indonesia

Financial Need

Price per Acre


The proposed protected area supports a high diversity of at least 298 birds species, 147 indigenous fish species, two crustacean species, 27 reptile species and five primate species, including the endemic Proboscis Monkey and Bornean Orangutan.

The area hosts the Mahakam population of Irrawaddy Dolphin that may be listed as a separate species based on DNA analysis. Five distinct populations of Irrawaddy Dolphin are found in riverine and estuarine habitat throughout Southeast Asia and are isolated from marine populations. For the Mahakam River population, the proposed reserve consistently supports around 80 individuals and contains 80-100 percent of the population at various times, making it irreplaceable habitat for the species.


This region of Borneo has seen dramatic deforestation rates due to the creation of extensive oil palm plantations.

This proposed protected area is significantly threatened by the conversion of swamp forest and riparian habitat that would negatively affect aquatic and terrestrial species. This rainforest decimation heavily impacts fisheries that local communities depend upon because spawning habitat is destroyed and pollution and sedimentation increased. If the area is not secured soon, new permits for oil palm concessions may encroach further upon the remaining habitat. In addition, unsustainable fishing practices also present a serious threat to the Irrawaddy Dolphin. Dolphins often become entangled in gill nets, and this resulted in the deaths of 32 Mahakam River Dolphins between 1995 and 2005. Fishing practices such as trawling and the use of electricity and poison are also detrimental to sensitive aquatic species.


Thirty-one villages consisting of around 40,000 people inhabit the proposed protected area. All have been involved in the process of allocating land for the new reserves and agreeing upon policies and regulations.

Most of the indigenous communities that live in villages along the river are of Malayan Kutai descent and have lived there since the fourth century. There are also some settlers from South Kalimantan as well as Javanese, Bugis and Dayak migrants. All 21 villages within the proposed Aquatic Nature Reserve have already signed communal agreements for protected area establishment. The Irrawaddy Dolphin is revered due to local legend, and communities understand that the rivers and swamps provide people with the fish that they depend upon for sustenance. Once the protected area has been established, communities will be involved in programs to promote sustainable livelihoods that will reduce pressure on natural resources.


Rainforest Trust and local partner Yayasan Konservasi Rare Aquatic Species of Indonesia seek $383,796 to establish a 119,277-acre Aquatic Nature Reserve and a 179,808-acre Peat Swamp Conservation Area along the Mahakam River in East Kalimantan, Indonesia, that will total 299,085 acres.

Rainforest Trust’s partner has been working with local villages since 2011, conducting community meetings, identifying core areas, mapping and completing local government consultations. The Aquatic Nature Reserve and Peat Swamp Conservation Area will be established in collaboration with the Ministry of Fisheries and the Ministry of Forestry and Environment. These two contiguous protected areas will together form the Essential Ecosystem Middle Mahakam Area. To protect both terrestrial and aquatic biodiversity, these areas will be zoned with the participation of the local community. The logging of riparian areas and use of unsustainable fishing practices will be halted, preserving habitat quality, securing fish spawning grounds and regulating the use of methods such as gill netting. Patrol teams consisting of community members will report to fishery and forestry authorities, and paired with an integrated management plan, will mitigate the threats of deforestation, pollution and unsustainable fishing.