Aquatic Mammals 2007, 33(3), 368-379, DOI 10.1578/AM.33.3.2007.368 Conservation Status of Marine Mammals in Cambodian Waters, Including Seven New Cetacean Records of Occurrence Isabel L. Beasley1 and Peter J. A. Davidson2 1School of Tropical Environment Studies and Geography, James Cook University, Australia; E-mail: [email protected] 2Bird Studies Canada, British Columbia Program, 5421 Robertson Road, Delta, BC, V4L 3N2, Canada Abstract increased interest has been shown in recent years. Perrin et al. (1995, 1996, 2005) provide the most The first dedicated, boat-based marine mammal comprehensive outline on the current status of surveys in Cambodian coastal waters were con- marine mammal research and conservation in ducted over seven discrete survey periods, span- Southeast Asia. ning February to September 2001. These surveys There has been no previously documented covered the majority of Cambodian coastal waters, research on marine mammals along the Cambodian in addition to the main offshore islands. coastline, and the status of marine mammals in the As a result of these surveys, ten marine mammal adjacent waters of Vietnam and Thailand remains species have now been confirmed to occur in poorly known and little studied. Initial records of Cambodian waters. Six of these, the false killer cetaceans from Thai waters were noted in Bonhote whale, a long-beaked form of common dolphin, (1903) and Suvatti (1950). The first detailed pub- pantropical spotted dolphin, dwarf spinner dol- lished accounts were undertaken by Pilleri & phin, Indo-Pacific bottlenose dolphin, and Indo- Gihr (1974), which focused on the examination Pacific humpback dolphin, constitute new country of marine mammal carcasses and skeletal mate- records for Cambodia. Additionally, a short-finned rial. Lekagul & McNeely (1977) also provided pilot whale was found live-stranded, constituting detailed species accounts; however, some iden- a further new country record. These initial results tifications therein were incorrect, despite being indicate that the current status of marine mammals based on the authors’ own photographs. A marine in Cambodian waters is encouraging, both in terms mammal research project was initiated in 1991 of species diversity and abundance. Cambodian through the Phuket Marine Biological Centre in waters appear to support regionally, if not globally, association with the Small Cetaceans in the Gulf significant populations of several of these species. of Thailand and Andaman Sea Project (Andersen The dugong is almost certainly the most highly & Kinze, 1999; Chantrapornsyl et al., 1996, 1999). threatened marine mammal in the region. Interview and boat-based surveys, in addition to Studies to date have provided important baseline morphological and life history studies on coastal knowledge regarding the status, distribution, and species, were undertaken in the Gulf of Thailand important areas of occurrence for marine mam- by Mahakunlayanakul (1996). Boat-based sur- mals in Cambodia. It is now essential that conser- veys were conducted in Songkhla Lake, southern vation and management strategies are developed Thailand, to assess the population of Irrawaddy and implemented. Public education and awareness dolphins (Orcaella brevirostris) (Beasley et al., and community-based management programs, as 2002), and aerial surveys have been conducted on well as stricter laws, regulations, and adequate the Andaman Sea coast to assess dugong (Dugong enforcement will be essential to conserving the dugon) distribution, abundance, and habitat use remaining marine mammal populations and ensur- (Hines, 2005). To date, 20 species are confirmed ing their survival in Cambodian coastal waters. from Thai waters. Although few dedicated sur- veys have been undertaken to assess abundance of Key Words: cetacean, dugong, conservation, marine mammals in Thai waters, indications are management, Cambodia, Indo-China that coastal populations are small and many may be declining. Introduction There have been few field studies of marine mammals along Vietnam’s 3,260 km of coastline. The status of marine mammals in Southeast Asia A series of marine mammal surveys were under- has received very little focused study, although taken in Vietnam that included riverine, coastal, Conservation Status of Cambodian Marine Mammals 369 and offshore waters (Smith et al., 1995, 1997). Koh Kong (near the Thailand border), dugongs Although only two groups of Indo-Pacific hump- were apparently most abundant near Prek Ksach. back dolphins (Sousa chinensis) and one small They were reportedly found in large groups, but unidentified whale were observed during these their numbers declined substantially as a result of field surveys, a number of marine mammals were hunting, fishing, and loss of seagrass (Nay, 1998). confirmed from “whale temples,” with over 100 Dugongs are now considered extirpated from skulls observed at 18 whale temples throughout the Koh Kong area (Nelson, 1999; Marsh et al., the country (Smith, 1996). Ho & Nghi (1999) 2002). present a review on the status of marine mammals Extensive research has recently been conducted in Vietnamese waters. Interviews and direct obser- by the first author on the Irrawaddy dolphin pop- vations have confirmed that the dugong inhabits ulation that inhabits the lower Mekong River of the waters surrounding Con Dao National Park, southern Lao PDR, Cambodia, and Vietnam. Vietnam (Cox, 2000). This may be one of the last This population now primarily inhabits a 190 km remaining populations of dugongs in Vietnamese stretch of river from Khone Falls (just north of waters; however, there is a strong possibility that the Lao PDR/Cambodian border), south to Kratie dugongs are moving between this and other sea- Township, Cambodia. Based on a combination grass habitats in adjacent Cambodia. Resulting of line-transect and photo-identification survey primarily from skeletal specimens, 17 marine methodologies from 2001 to 2005, the total popu- mammal species have been documented from lation was thought to only number between 127 Vietnamese waters. The small number of sight- to 161 individuals (95% CL = 89 to 289) as of ings during boat-based surveys indicates that the April 2005 (Beasley, 2007). The Irrawaddy dol- abundance of cetaceans in Vietnamese waters may phin population inhabiting the Mekong River is be alarmingly small. not discussed further in this paper. The first known records of marine mammals along Cambodian coastal waters are noted by Materials and Methods Lloze (1973) who describes records by Krempf (1924-1925) and Gruvel (1925) (both not viewed) Study Area who recorded (old nomenclature) Delphinus Cambodia’s coastline measures 435 km in delphis, Steno (sotalia) sinensis Flower, Steno length. The seaward boundary of the coastal (sotalia) plumbea Dussumier, Steno rostratus, zone has been delimited as the outer limit of the Neophocoena (Neomeris) phocoenoides, and Exclusive Economic Zone (seemingly referring to Orcaella brevirostris. Additionally, an Irrawaddy Cambodian territorial waters) and covers a total dolphin skull was described by Monsieur H. area of 55,600 km2 (Nelson, 1999). The coastal Argod (Lloze, 1973) as being found on one of zone is wholly encompassed within the Provinces the seven Pirate Isles, 6 km south of Kep (now of Koh Kong and Kampot, and the Municipalities in Vietnamese waters). The only previous infor- of Kompong Som (Sihanoukville) and Kep mation on marine mammals in Cambodia was (Nelson, 1999). outlined by Tana et al. (1995) and Perrin et al. Despite its relatively short length, the Cambodian (1996). During coastal surveys for coral and sea- coastline supports quite a variety of habitats. The grass, Nelson (1999) observed finless porpoise seas are generally shallow, seldom exceeding (Neophocaena phoceanoides) and Irrawaddy dol- 60 m even in the most remote offshore waters. phins. These are the only known confirmed records The seabed is generally of very gentle gradient, of cetaceans in the coastal waters of Cambodia. A lacking any marked “shelfing” or other prominent Workshop on Marine Mammals and Sea Turtles underwater features. There are substantial areas of of Cambodian, Thai and Vietnamese Waters was mangrove, most notably around Koh Kong Bay held at the Nha Trang Institute of Oceanography and the Peam Krasaop Wildlife Sanctuary imme- (8-13 February 1999) and is outlined in Andersen diately to the north (both in the northern coastal & Kinze (2000). This paper mentions evidence for section of Koh Kong Province), around the west- two new cetacean species records from Cambodia: ern and northern shores of Kompong Som Bay the bottlenose dolphin and finless porpoise (citing (southern Koh Kong Province), in Ream National the unpublished Andersen & Kinze 1996 work- Park (Kompong Som Municipality), and between shop report); these reports are regarded as uncon- Kampot and Kep (southern Kampot Province). firmed, however, as details on the locations and Sandy beaches are found along much of the specifics of the sightings were not provided, and country’s coastline, particularly in Kompong the Andersen & Kinze 1996 workshop report Som Municipality, but also in Koh Kong and remains unpublished. Dugongs were reported to Kampot Provinces, and the numerous bays around be abundant along parts of the Cambodian coast offshore islands. There are at least 52 islands until approximately 1975 (Nelson, 1999). In off the Cambodian mainland, many of which 370 Beasley and Davidson are uninhabited, varying in size from tiny rocky These distance