Identifying the hotspot area of Indo-Pacific humpback (Sousa chinensis) and Irrawaddy (Orcaella brevirostris) dolphins in Matang waters, Perak, Malaysia




Abstract. Sobri MF, Jaaman SA, Mohamed Z, Muda AM, Rashid MASA, Zhang X. 2022. Identifying the hotspot area of Indo Pacific humpback (Sousa chinensis) and Irrawaddy (Orcaella brevirostris) dolphins in Matang waters, Perak, Malaysia. Biodiversitas 23: 6106-6113. The Indo-Pacific humpback (Sousa chinensis) and Irrawaddy (Orcaella brevirostris) dolphins are commonly found in Matang waters, Perak, Malaysia. The area, filled with healthy mangrove forest cover and many estuaries, is not only frequented by the dolphins for its daily activities but also extensively used by locals for artisanal fishing, charcoal production and organizing ecotourism activities. There could be a high risk of human-dolphin interactions, hence determining habitat use and identifying critical habitats or "hot spots" for the dolphins in the area is important. In this study, a series of dedicated boat sighting surveys were conducted from March 2019 to January 2021 between Kuala Gula and Kuala Jarum Mas. The total survey effort was 3325.76 km, 44 days and 239.38 hours. A total of 69 dolphin sightings were made, consisting of 40 Indo-Pacific humpback dolphins and 29 Irrawaddy dolphin observations, respectively. During each sighting, every dolphin's behaviors were categorized as: foraging, socializing, evasive, and travelling, and the survey area was classified into four blocks. The results indicated that different dolphin species have different hotspot areas. For Indo-Pacific humpback dolphins, the hotspot area was Kuala Sangga, while the Irrawaddy dolphin's hotspot area was outside Kuala Larut, and there was a small overlap between the two dolphins' hotspots. Among the recorded behaviors (n: 281) for both dolphins, the most dominant was foraging (72.24%), followed by socializing (17%), evasive (7%), and travelling (4%). The sighted foraging behavior for both dolphin populations was dominant, indicating the hot spots were major foraging grounds for the two dolphin populations. This study shows the importance of Matang waters as a conservation area for the species and warrants further studies of dolphin population ecology to be conducted.


Ahmad, S. (2009). RECREATIONAL VALUES OF MANGROVE FOREST IN LARUT MATANG, PERAK. Journal of Tropical Forest Science, 21(2), 81–87.
Bali, J. & Tisen, O. B. (2012). Distribution of Irrawaddy Dolphins (Orcaellabrevirostris) in Sarawak, Malaysia: An Update. Paper Presented during the International Conference Marine Science and Aquaculture. Universiti Malaysia Sabah-KenKei University. Kota Kinabalu, Sabah, Malaysia
Chew, L. L., Chong, V. C., Tanaka, K., & Sasekumar, A. (2012). Phytoplankton fuel the energy flow from zooplankton to small nekton in turbid mangrove waters. Marine Ecology Progress Series, 469, 7-24.
Department of Fisheries Malaysia. (2017). Annual Fisheries Statistics 2017. Retrieved from
Getis, A., & Ord, J. K. (1992). The analysis of spatial association by use of distance statistics, in “Geographical Analysis”, n. 24.
Goessens, A., Satyanarayana, B., Van Der Stocken, T., Zuniga, M. Q., Mohd-Lokman, H., Sulong, I., &Dahdouh-Guebas, F. (2014). Is Matang Mangrove Forest in Malaysia sustainably rejuvenating after more than a century of conservation and harvesting management? PLoS ONE, 9(8).
Harahap, Z. A. (2022). DIVERSITY AND DISTRIBUTION OF DOLPHIN IN LANGKAT WATER, NORTH SUMATERA. JECE - Journal of Empowerment Community and Education, 1(3). Retrieved from
Hoffman, J. M., Ponnampalam, L. S., Araújo, C. C., Wang, J. Y., Kuit, S. H., & Hung, S. K. (2015). Comparison of Indo-Pacific humpback dolphin (Sousa chinensis) whistles from two areas of western Peninsular Malaysia. The Journal of the Acoustical Society of America, 138(5), 2829-2835.
Ibharim, N.A. & Mustapha, Muzzneena & Lihan, Tukimat & A.G., Mazlan. (2015). Mapping mangrove changes in the Matang Mangrove Forest using multi temporal satellite imageries. Ocean & Coastal Management. 114. 10.1016/j.ocecoaman.2015.06.005.
Jaaman, S. A. (2010). MARINE MAMMALS IN EAST MALAYSIA: Distribution and Interactions with Fisheries. VDM Verlag Dr. Muller Aktiengesellschaft& Co. KG., Saarbrucken, Germany. ISBN: 978-3-639-22208-1.284 pages. (8 January 2010)
Jefferson, T. A., & Smith, B. D. (2016). Re-assessment of the Conservation Status of the Indo-Pacific Humpback Dolphin (Sousa chinensis) Using the IUCN Red List Criteria. In Advances in Marine Biology (1st ed., Vol. 73).
Jefferson, T. A., Webber, M. A. and Pitman R. L. (2008). Marine Mammals of the World: A Comprehensive Guide to Their Identification. San Diego: Academic Press, 572p.
Jiang Y, Zhang XL, Yang ZG*, Jaaman SA, Xu QZ, Muda AM, Muhamad HM. 2019. The preliminary analysis of echolocation signals produced by fleeing Irrawaddy dolphin (Orcaella brevirostris). Acta Oceanologica Sinica, 38(1):85-89
Kuit, S. H., Ponnampalam, L. S., FairulIzmal, J. H. and Chong V. C. (2014). Cetacean research and a precautionary approach in developing dolphin-watching tourism in the coastal waters of the Matang mangroves. Proceedings of Matang Mangrove Forest Management Conference 2014. 24-26 November 2014. Casuarina@Meru Hotel, Ipoh, Perak DarulRidzwan.
Kuit, SH, Ponnampalam, LS, Ng, JE, Chong, VC, Then, AY-H. (2019). Distribution and habitat characteristics of three sympatric cetacean species in the coastal waters of Matang, Perak, Peninsular Malaysia. Aquatic Conserv: Mar FreshwEcosyst. 2019; 29: 1681– 1696.
Minton, G., Peter, C., & Tuen, A. A. (2011). Distribution of small cetaceans in the nearshore waters of Sarawak, East Malaysia. Raffles Bulletin of Zoology, 59(1), 91–100.
Mohamad Pazi, A. M., Khan, W. R., Nuruddin, A. A., Adam, M. B., &Gandaseca, S. (2021). Development of Mangrove Sediment Quality Index in Matang Mangrove Forest Reserve, Malaysia: A Synergetic Approach. Forests, 12(9), 1279.
Nor hashim, N. A. and Jaaman, S. A. (2011). Boat effects on the behavior of Indo-Pacific Humpback (Sousa chinensis) and Irrawaddy (Orcaellabrevirostris) dolphins in Cowie Bay, Sabah, Malaysia. Sains Malaysiana,40(12):1383–1392.
Nur Azeyanti Nor Hashim, and Saifullah A. Jaaman, (2011) Boat Effects on the Behaviour of Indo-Pacific Humpback (Sousa chinensis) and Irrawaddy Dolphins (Orcaellabrevirostris) in Cowie Bay, Sabah, Malaysia. Sains Malaysiana, 40 (12). pp. 1383-1392. ISSN 0126-6039
Oxoli, D., Zurbarán, M., Shaji, S., & Muthusamy, A. K. (2016). Hotspot analysis: a first prototype Python plugin enabling exploratory spatial data analysis into QGIS. In Open Source Geospatial Research & Education Symposium (OGRS2016) (pp. 1-6). PeerJ Inc. San Francisco, USA.
Parra, G. J. 2005. Behavioural ecology of Irrawaddy, Orcaellabrevirostris (Owen in Gray, 1866), and Indo-Pacific humpback dolphins, Sousa chinensis (Osbeck, 1765), in northeast Queensland, Australia: a comparative study. – PhD thesis, James Cook Univ
Sievers, M., Brown, C. J., Tulloch, V. J., Pearson, R. M., Haig, J. A., Turschwell, M. P., & Connolly, R. M. (2019). The role of vegetated coastal wetlands for marine megafauna conservation. Trends in ecology & evolution, 34(9), 807-817.
Zaidin, N. H. A. R. N., Nurhidayu, S., Shafuan, M. F. A., Gandaseca, S., Kasim, M. R. M., & Malek, I. A. A. (2016). Water Quality Characteristics in Different Mangrove Disturbance Levels, Matang Mangrove Forest Reserve, Peninsular Malaysia.