Observations on cetaceans in the waters off Manado, northeastern Sulawesi, Indonesia, July 1995*

Between 6 July and 31 July 1995 I conducted a field study in the waters adjacent to the city of Manado, north-eastern Sulawesi, Indonesia. The goal was to study the abundance and distribution of cetaceans in these waters and to assess future research possibilities in this area.

Manado is situated on the north-eastern tip of Sulawesi at 1°29'N 124°50' E and faces the Sulawesi Sea (=Celebes Sea). Water-depth in Manado Bay given by Admirality Chart No. 2638 show depth up to 1800 m. The northern part of Manado Bay is bounded by the Bunaken Menado Tua Marine National Park, which is known as one of the best diving spots in Indonesian waters. The park covers around 89,000 ha including island and mangrove, and 3728 ha coral reefs. There are four main islands in the park. Manado Tua, a steep island in the form of a truncated cone, is in the south-west. Pulau Bunaken to the south of the group, is low, except for a hill rising to 110 m at the west end. Adjacent to the east is the tiny low lying island of Siladen. All three islands are surrounded by narrow fringing reefs. The widest reef (1.5 km) is found off south-west Bunaken. Pulau Mantehage and Pulau Nain are located to the north.

Reports on marine mammals in this area are scarce. Townsend (1935) reported the Celebes Sea as a whaling ground for sperm whales, Physeter macrocephalus. The only other published record of cetaceans in that area is on the incidental catch of a bottlenose dolphin, Tursiops sp., by fishermen near Manado (Tas'an and Leatherwood 1984). Dugongs, Dugong dugong, are reputed to be common towards the west end of the Arakan Wildlife Reserve south-west of Manado at 1°22 N 124°30' E, where there are extensive seagrass beds and an abundance of inlets and bays in which the animals can shelter (UNEP/IUCN 1988).

I conducted vessel surveyes on ten days between 8 July and 30 July 1995 in the waters of Manado Bay, the southern part of Bunaken Menado Tua Marine National Park and Lembeh Strait, Bitung. A total of 45 h and 17 min. was spent at sea, covering some 230 Nm (430 Km) of survey track, with an average of 4 hours and 31min. per survey day.

Nine cetacean species were recorded in 25 sightings (app. 608 individuals) on 10 days of vessel survey. The sighting of 7 (*) species is confirmed by photographs and identification by cetacean specialists. Cetaceans observed included:
Rough-toothed dolphin, Steno bredanensis (1* sighting)
Bottlenose dolphin, Tursiops sp. (1)
Pantropical spotted dolphin, Stenella attenuata (1)
Spinner dolphin, Stenella longirostris (4*)
Fraser's dolphin, Lagenodelphis hosei (1*)
Melon-headed whale, Peponocephala electra (1*)
Killer whale, Orcinus orca (1*)
Short-finned pilot whale, Globicephala macrorhynchus (2*)
Sperm whale, Physeter macrocephalus (9*)
Dwarf sperm whale, Kogia simus (3*) and Kogia sp. (1).

Literature

Tas'an and S. Leatherwood. 1984. Cetaceans live-captured for Jaya Ancol Oceanarium, Djakarta, 1974-1982. Report International Whaling Commission 34 : 485-489.

Townsend, C. H. 1935. The distribution of certain whales as shown by logbook records of American whale ships. Zoologica 19: 1-50.

UNEP / IUCN 1988. Coral Reefs of the World. Vol. 2: Indian Ocean, Red Sea and Gulf. UNEP Regional Seas Directories and Bibliographies. 389 pp., 36 maps. IUCN Gland and Cambridge, UNEP, Nairobi.

*Originally published in SEAMAM (Southeast Asian Marine Mammals) in November 1996

Distributed by the Interdisciplinary Minor in Global Sustainability at the University of California, Irvine.