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This monograph provides the first comprehensive data on the current status and distribution of marine mammals in East Malaysia waters. Marine mammals are diverse, with 12 of the total 21 species confirmed in these waters observed during boat and aerial surveys. The spinner dolphin is the most commonly sighted and abundant species in open waters. In inshore waters, Irrawaddy dolphin is the most frequently sighted and the only species found upstream. The Indo-Pacific humpback dolphin and dugong are probably low in density and their distribution may be restricted to certain shallow bays. The estimated annual number of dugong and small cetaceans caught accidentally in fishing gear and hunted for meat is probably unsustainably high. The animals are also facing threats from declining fish resources, habitat loss and degradation, pollution, heavy boat traffic, rapid coastal development, encroachment of trawlers into restricted waters, and dynamite fishing, which may have caused numbers to decline significantly in the past few decades. An immediate, committed and concerted conservation and research effort is needed to reduce or eliminate the threats and to maintain their present numbers.

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Saifullah A. Jaaman, PhD: Studied Marine Mammal and Fisheries Sciences at the University of Aberdeen, UK. Head of the Marine Mammal Research Unit, Universiti Malaysia Sabah.

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