Dolphin near fishing boat

Irrawaddy dolphins have been spotted worryingly close to the shore. ©Universiti Malaysia Sarawak

Researchers have found that the distribution patterns of Irrawaddy dolphins (Orcaella brevirostris) indicate a worrying outlook for their future.

Between June 2008 and September 2009, small boat surveys were conducted for 56 days off the coast of Sarawak, Malaysia. Researchers recorded the areas in which dolphins were sighted, noting the depth of the water and proximity to the coastline.

110 of 115 Irrawaddy sightings were made in water depths under 10 m. Unlike finless porpoises or Indo-Pacific bottlenose dolphins, which are also found here, the Irrawaddy dolphins showed a statistically significant preference for areas of shallower depth and closer proximity to shore and river.

This preference puts Irrawaddys at risk, as shallow near-shore areas are vulnerable to environmental degradation resulting from developments on the coast. There is also a growing threat from fishing practices, as dolphins in the shallows can easily become tangled in nets and drown. The dolphins also showed a strong presence in the areas of Kuching and Similajau, which does not bode well either given that both these areas are destined for major coastal developments in the near future.

This information highlights the importance of nearshore coastal habitats for these dolphins, and will hopefully help researchers and managers develop effective conservation strategies to ensure their continued survival.
Irrawady dolphin