May 29, 2024

Can the Indian Ocean Humpback Dolphin (Sousa plumbea) Survive in Sri Lanka? Occurrence of a Relict Population in Puttalam Lagoon


Ranil P. Nanayakkara, Tharaka Kusuminda, and Thomas A. Jefferson


Abstract: Until the last few years, the only records of Indian Ocean humpback dolphins (Sousa plumbea) in Sri Lanka were a small number of older stranding records and one unconfirmed sighting, but repeated verified sightings have been made since the early 2000s in the Puttalam Lagoon area of northwestern Sri Lanka. To determine dolphin status and distribution patterns, we conducted monthly surveys of the lagoon from July 2010 to June 2011 and sighted humpback dolphins in the lagoon in every month of the year. Repeated sightings of the same six individuals were made; and in March 2011, one of these humpback dolphins was killed by dynamite fishing. It appears that the population is very small, possibly now consisting only of these five individuals, and is resident in the lagoon. Although it is likely the species was more widespread and abundant in the past, it appears that Puttalam Lagoon may be the only location where this species persists in Sri Lanka at present. Additional research is needed to investigate possible mixing with populations in India, and urgent conservation measures are recommended to ensure the long-term survival of this enigmatic species in Sri Lanka.
Key Words: status, extirpation, management, protection, photo-identification, lentiginosa-type
Document Type: Research article
DOI: 10.1578/AM.40.4.2014.398
Page Numbers: 398-406

Info SKU: Vol__40__Iss__4__Nanayakkara Category: