Conservation Status (IUCN)
Vulnerable (high risk of endangerment in the wild)
Only recently separated from the Narrow-Ridged Finless Porpoise in classification (2008), with there likely being no interbreeding between the two species since the last glacial maximum even though both species share a reasonably large area of habitat in east Asia. This species is sometimes confused with dugongs (order Sirenia) on first glance because of the dark body and rounded flippers that sometimes break the surface of the water. Dugongs and the Indo-Pacific Finless Porpoise overlap in range in some parts of the tropics.
Western edge of the range is the Persian Gulf, hugging the coast of Asia the range extends east along northern edge of the Indian ocean, Sumatra, Java, Borneo, Cambodia, Vietnam and southern China.
Physical Description and Identifying Features
No dorsal fin, with a wide dorsal ridge (3.5cm – 12.0 cm wide) that is lined with 10-25 rows of tubercles. The function of the tubercles is currently unknown. Adult animals are gray in color with lighter patches on their undersides. Geographical variation exists in the darkness of the grey colouration, as well as some variation with age.
Behavior and Ecology
Shy of boats and similarly to other porpoise species lacks showy or splashy behaviors. Seen as individuals, pairs or in groups of up about 20 animals. Tend to stay in shallow (less than 200m deep) coastal waters, with estuaries and mangrove swamps being preferred habitats. There seems to be a strong habitat preference for areas with soft or sandy bottoms. This species has been noted to spend up to 60% of their time at or near the surface of the water.
Sexual maturity between age 3-6 years
Thought to range between 18-25 years.
Small fish, crustaceans (demersal species, i.e: species that live close to the seabed), and cephalopods (squids, octopuses and cuttlefish).
The Indo-Pacific Finless porpoise is seen in lower densities than the related Narrow-Ridged Finless porpoise, though most studies have occurred in regions where the Narrow-Ridged species dominates or exists outside of the shared range of the two species. The waters surrounding Hong Kong are thought to be home to roughly 217 Indo-Pacific Finless Porpoises. The general population trend is decreasing, according to the IUCN.
Further Reading and References
[zotpress items=”HHRKAVS2,K42RTVRX,25XRCHBF” style=”apa”]