Apreliminary study of population size of Irrawaddy Dolphins (Orcaella brevirostris) in Cowie Bay, Sabah, Malaysia

Abstract

A population of Irrawaddy dolphins (Orcaella brevirostris) occurs in Cowie Bay, southwest of Sabah. Boat-based photo-identification surveys were conducted over a period of 12 months, from October 2009 to September 2010. Photographs were first sorted according to quality and according to physical appearance of Irrawaddy dolphins’ dorsal fin. They were then assigned a unique code. A total of 27 Irrawaddy dolphins were identified and all were adults. The data obtained from this survey was used to estimate the population size via mark-recapture method. The total population size was estimated to be 31 individuals (SE = 1.8508).