Natural history and conservation of Irrawaddy dolphins, Orcaella brevirostris : with special reference to the Mekong River, Lao P.D.R.
Date
1996
Authors
Stacey, Pam Joyce
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Abstract
Irrawaddy dolphins, (Orcaella brevirostris), are classified as insufficiently known by the World Conservation Union (IUCN). This thesis describes current knowledge and status of Irrawaddy dolphins, guidelines for conservation, and results of a field study in the Mekong River in southern Lao P.D.R. The field study was comprised of habitat description, shore observations and photo- identification. Sighting frequency decreased from dawn to dusk. Foraging was the principal behaviour, often observed at a tributary mouth. Mean group size was 3.02 and ranged from 1-7. Mean divetime increased significantly when boats were within 100m. Difficulty in obtaining good photographs may limit the use of photo-identification as a research tool.
Throughout the range of this species, populations appear to be declining. If problems of habitat degradation and incidental catch are not adequately addressed, long-term survival may be in jeopardy. Conservation hopes lie in habitat protection, a reduction in incidental catch, further research, and education of local people.