CETACEAN SPECIES RICHNESS AND RELATIVE ABUNDANCE AROUND THE BAR REEF MARINE SANCTUARY, SRI LANKA

摘要

The Bar Reef Marine Sanctuary, off north-western Sri Lanka, and its adjacent waters were suspected to be an important Cetacean habitat, but a dedicated Survey had never been undertaken. Therefore, a one-year survey was carried out from April 2004 to May 2005 to fill the vacuum of knowledge on Cetacean species of the area, and to gather baseline data for management and conservation. Surveys were carried out twice every month. Thirty three sightings of eight cetacean species were documented. The species recorded were Balaenoptera acutorostrata, Balaenoptera musculus, Physeter macrocephalus, Kogia sima, Peponocephala electra, Stenella longirostris, Tursiops truncatus and Sousa chinensis. The first confirmed sighting of S. chinensis in Sri Lanka's waters was recorded while K. sima and P. electra were sighted off the west coast for the first time. The northern and central parts of the Sanctuary can be termed as 'cetacean hotspots' due to high species richness and year-round abundance. Baseline data from this survey can be used immediately for management purpose, though further research is recommended. S. chinensis needs special consideration as the newly discovered population is heavily dependent on the Puttalam Lagoon which is under intense human use, making these dolphins vulnerable to a multiplicity of anthropogenic threats.