Photo-identification as a Tool for Studying the Irrawaddy dolphin, Orcaella brevirostris in Coastal and Riverine of Belawai, Sarawak

Kee, Bee Hoon (2022) Photo-identification as a Tool for Studying the Irrawaddy dolphin, Orcaella brevirostris in Coastal and Riverine of Belawai, Sarawak. [Final Year Project Report] (Unpublished)

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Abstract

The conservation status of the Irrawaddy dolphin (Orcaella brevirostris) has been raised from “vulnerable” to “endangered” due to human activities. Populations of the Irrawaddy dolphins in Belawai, Sarawak are facing threats from fishing and port, suggesting that there might be changes to their population number. Secondary data collected in the years 2017, 2018 and 2021 were used in this research. Also, boat-based photoidentification surveys were conducted from 7 to 10 March 2022 during daylight hours in calm water conditions. This study aimed to identify individual Irrawaddy dolphins based on their dorsal fin characteristics and estimate their abundance in that particular region. All the photographs were sorted by quality and distinctiveness. Matching of the relevant photographs to a catalog of previously identified individuals was then executed and new dolphins found were assigned a unique code. A total of 290 dolphins were photographed, with 232 of them were identified as marked individuals. The MARK statistical programme, using a closed population model, produced a total abundance estimate of 207 (95% CI 160-267) dolphins. The population is relatively small, warning the public for immediate action to conserve and preserve the species to prevent species extinction in the future.

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