Yayasan Konservasi RASI                                                                                                    Conservation Foundation for Rare Aquatic Species of Indonesia

Cetacean Diversity Surveys Around Derawan Islands

After a preliminary survey in 2003 by RASI in collaboration with the University of Amsterdam and WOTRO, two surveys were conducted in October 2007 and April 2008 to investigate the diversity of marine mammals in de marine protected area of Berau archipelago in collaboration with the Conservation Agency BKSDA Berau and University of Mulawarman. Skin/ blubber biopsy samples were obtained from several dolphin species by invited researcher Dr. Robert L. Pitman from NOAA Southwest Fisheries Science Center, La Jolla USA were DNA analyses will be performed. Species involved: spinner dolphin, dwarf spinner dolphin, common bottlenose dolphin, Indo-Pacific bottlenose dolphin, spotted dolphin.

At least 15 cetacean species were directly observed and one dugong species, whereas based on reliable information sperm whales and killer whales also visit the area, bringing the total number of cetacean species for this area to 17 species. A species that still needs further clarification is a remarkably long-beaked from of common dolphins, i.e. Delphinus capensis tropicalis (see picture).

Besides, first records of humpback whales were made in deep slope waters near Bontang, c. 100 km north from the Mahakam Delta. We hope to be able to start soon conducting more surveys in this area.

(Technical Report ....... pdf 534kb)

Cetaceans Diversity Around Balikpapan Bay

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.

(Technical Report ..... pdf 628kb)

Coastal Awareness Campaign

Coastal environmental campaigns were held in Derawan, Maratua, Tanjung Batu (Berau district) as well as in villages, cities surrounding Balikpapan Bay and coastal communities near Bontang and Mahakam Delta. Posters informing about marine mammals, strandings and rescues and conservation were handed to all areas mentioned earlier as well as data collected from fishermen. Campaigns were also held at elementary and high schools dealing with marine mammals, protection of coastal habitat, mangroves and natural resources.

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