Abstract: Investigations on the distribution, population size, and habitat characteristics of animal populations provide the baselines for sound conservation management. Southeast Asia is considered an important habitat for the Indo-Pacific humpback dolphin (Sousa chinensis), but information regarding their population size and habitat characteristics is limited. The present study investigated the distribution and habitat characteristics of humpback dolphins off Donsak, Thailand, and estimated the population size based on photo-identification records. Using the POPAN model, the minimum population size of the humpback dolphins off Donsak was estimated to be 193 (167 to 249; 95% confidence interval), with 36 calves, 58 juveniles, 40 subadults, and 59 adults. The progressively ascending cumulative sighting curve implied that the actual hump-back dolphin population size in the investigated area is likely higher than this estimate. Principal components analysis of the environmental characteristics indicated that the adult dolphins tend to occur in deeper and clearer waters relative to the younger age classes. Alterations of the coast environment and coastal anthropogenic activities may be particularly deleterious for younger dolphins. Findings from this study contribute significantly to our understanding of the humpback dolphins in Thailand and provide valuable insight for future conservation management.
Key Words: Indo-Pacific humpback dolphin, Sousa chinensis, distribution tendency, habitat characteristic, photo-ID, population size, Thailand
Document type: Research article
DOI: http://dx.doi.org/10.1578/AM.41.2.2015.129
Page Numbers: 129-142

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