Finless porpoises are widely distributed in the coastal waters
of Asia, from the Persian Gulf, east and north to Central
Japan and as far south as the northern coast of Java and the
Strait of Sunda (see map). Finless porpoises are described
as a coastal, estuarine or riverine species and they are usually
sighted near the coast.
Finless porpoises are slender and have no dorsal fin. In its
place along the mid-dorsum is a low dorsal ridge which is
covered by thick denticulated skin. Newborn finless porpoises
are mainly black with some grey on the dorsal ridge area.
These young porpoises quickly become lighter and after 4 to
6 months attain the uniform light grey colour of adults. Both
male and female finless porpoises grow to lengths greater
then 1.55 m. Although there is a great deal of variability
between populations of finless porpoises, males become sexually
mature at 4.5 - 9 years and females at 3-7 years. Finless
porpoises are opportunistic feeders, consuming a wide variety
of fishes, shrimps and cephalopods throughout their range.
Finless porpoises are found yearly throughout their entire
range, but in some areas exhibit seasonal movements and changes
in local abundance. These changes in local abundance and distribution
are not well documented for most regions. Finless porpoises
are currently listed in the IUCN Red List of Threatened Species
as a Data Deficient species throughout their range, except
in China where they are currently listed as Endangered.
The greatest threat to finless porpoise populations is incidental
mortality in fishing gear. These animals are taken in a variety
of driftnet, gillnet, trap net and trawl net fisheries throughout
their range. The extent of bycatch in many areas is not well
documented. They are also caught in "rolling hook"
gear (lines of iron hooks set across the flow of the river)
in the Yangtze River, China.
Kasuya, T. 1999. Finless Porpoise Neophocaena phocaenoides.
In S.H. Ridgeway & R. Harrison [eds.], Handbook of Marine
Mammals, Volume 6: The Second Book of Dolphins and Porpoises.
Academic Press. San Diego.
Jefferson, T.A. et al. 1993. Marine Mammals of the World.
FAO Species Identification Guide. United Nations Environment
Perrin, W.F., Donovan, G.P. and Barlow, J. 1994. Gillnets
and Cetaceans. Report of the International Whaling Commission,
Special Issue 15. Cambridge.