Neophocaena phocaenoides (G. Cuvier, 1829)

Russell A. Mittermeier & Don E. Wilson, 2014, Phocoenidae, Handbook of the Mammals of the World – Volume 4 Sea Mammals, Barcelona: Lynx Edicions, pp. 528-545 : 541

1.

Indo-Pacific Finless Porpoise

Neophocaena phocaenoides

French: Marsouin aptere / German: Glattschweinswal / Spanish: Marsopa sin aleta indopacifica

Other common names: Black Finless Porpoise, Finless Black Porpoise, Finless-backed Black Porpoise, Indian Dolphin, Indian Finless Porpoise, Little Indian Porpoise, Wide-ridged Finless Porpoise

Taxonomy. Delphinus phocenoides G. Cuvier, 1829 ,

“au Cap” (= South Africa, Western Cape Prov., Cape of Good Hope). Almost certainly erroneous; unknown today from the coast of Africa.

This species is monotypic.

Distribution. Shallow, coastal waters of tropical and subtropical S & E Asia, from the Persian Gulf E to the S East China Sea and S to the Sunda Is. There are no records from Oman and the Philippines, although the species is expected eventually to be found in both locations.

Descriptive notes. Total length 135-171 cm; weight 30-55 kg. Of the two species of finless porpoise, the Indo-Pacific Finless Porpoise is the smaller, reaching a known maximum total body length of only 171 cm. There is no dorsal fin, but there is a dorsal structure (often called a “ridge” or “groove” in the literature) that is lower and wider than in the Narrow-ridged Finless Porpoise ( N. asiacorientalis); it is 4.8-12 cm wide, with 10-17 (occasionally as few as nine or up to 25) roughly longitudinal rows of tubercles. Even in young Indo-Pacific Finless Porpoises, the dorsal structure is wider than in adults of the other species of porpoises. The ridge begins posterior to the mid-length of the body. Head of the Indo-Pacific Finless Porpoise is blunt with no beak, and its body is relatively slender. Adult coloration is dark gray to nearly black, although newborns are much paler than adults, often a creamy gray. Adult condylobasal skull length is 181-245 mm. The rostrum is relatively wide and short; its length is 62-92 mm, with a mean of 74-6 mm. Tooth counts in each half of each jaw are 15-22 in the upper row and 16-22 in the lower row.

Habitat. Shallow, warm waters near the coast. The Indo-Pacific Finless Porpoise is often found in high densities in and near estuaries of large rivers. Although it is tropical, there is a record of its occurrence from the Yellow/Bohai Sea area, although thisis considered extralimital. It penetrates into the Indus River for ¢.60 km and into the Brahmaputra River for ¢.40 km from their mouths.

Food and Feeding. Indo-Pacific Finless Porpoises feed on a wide variety of small marine organisms, some of which are pelagic and others benthic or demersal. Its prey includes fish in the families Apogonidae , Carangiade , Clupeidae , Sparidae , and Engraulidae , plus cephalopods (squid and cuttlefish) and crustaceans.

Breeding. Reproduction of the Indo-Pacific Finless Porpoises has been studied more extensively than in most other species of porpoises. The population that has been best studied is from the area around Hong Kong, where reproduction is strongly seasonal, with most births taking place from October (autumn) to January (winter). Sexual maturity of males occurs at 4-5 years of age and lengths of 138-154 cm, and at 5-6 years and 137-150 cm for females. Gestation appears to last c.11 months, and newborns are ¢.70-80 cm in length. Both species of finless porpoises appear to live up to 20 years, but some individuals in waters near Hong Kong have apparently lived to over 30 years of age.

Activity patterns. Indo-Pacific Finless Porpoises are cryptic, and they generally have a low surfacing profile. Although they do not often appear to leap from the water, they can be very active at times and will often chase fish at high speeds, making sharp turns and fast accelerations. They have more mobility of the neck than do other porpoise species. They do not ride bow waves of vessels.

Movements, Home range and Social organization. There is virtually nothing known about individual movements and home ranges of Indo-Pacific Finless Porpoises because no studies have successfully identified or tagged individuals. In some areas, such as around Hong Kong, there are seasonal shifts in abundance, with higher densities near shore in winter and spring, and lower densities in summer and autumn (when individuals are presumed to spend more time farther offshore). As in other porpoise species, Indo-Pacific Finless Porpoises generally occur as singles or in small groups of up to c.6 individuals. Larger aggregations of up to several dozen sometimes form in areas of good feeding opportunities.

Status and Conservation. CITES Appendix I (under N. phocaenoides ). Classified as Vulnerable on The IUCN Red List. The Indo-Pacific Finless Porpoise was recently evaluated separately on The IUCN Red List (previous assessmentslisted all finless porpoises as a single species). Its classification as Vulnerable was due to observed population declines and inferred reductions of at least 30% in the past three generations. Although it has an extensive distribution throughout south-eastern Asia, and there are clearly many thousands of Indo-Pacific Finless Porpoises, no global population assessment has been attempted. A number of threats face the Indo-Pacific Finless Porpoise, including destruction of habitat from coastal development, disturbance from vessel traffic and other coastal activities, vessel strikes, and various forms of pollution. The major threat, however, comes from entanglement in equipment of variousfisheries, especially gillnets, and this may be threatening the viability of some populations. The population that occurs in waters near Hong Kong is one of the only ones for which robust estimates of abundance have been made, and it appears to number at least 220 individuals. About 1400 Indo-Pacific Finless Porpoises occur in waters off Bangladesh.

Bibliography. Amano (2009), Amano et al. (1992), Fajardo-Mellor et al. (2006), Gao Anli & Zhou Kaiya (19953, 1995b, 1995c¢), Goold & Jefferson (2002), Jefferson (2002), Jefferson & Braulik (1999), Jefferson & Hung (2004), Jefferson, Curry & Kinoshita (2002), Jefferson, Hung et al. (2002), Jefferson, Robertson & Wang (2002), Kasuya, (1999b), Parsons (1998), Parsons & Jefferson (2000), Parsons & Wang (1998), Preen (2004), Reeves et al. (1997), Smith & Tun Mya-Than (2008), Wang, J.Y., Frasier et al. (2008), Wang, J.Y., Yang Shihchu et al. (2010), Wang Peilie (1992), Yang Guang, Ren Wenhua et al. (2002), Zhou Kaiya etal. (1993).

Figures

1. Indo-Pacific Finless Porpoise (Neophocaena phocaenoides), 2. Narrow-ridged Finless Porpoise (Neophocaena asiaeorientalis), 3. Spectacled Porpoise (Phocoena dioptrica), 4. Burmeister’s Porpoise (Phocoena spinipinnis), 5. Vaquita (Phocoena sinus), 6. Harbor Porpoise (Phocoena phocoena), 7. Dall’s 9 Porpoise. Phocoenoides. (null)

Distribution. Shallow, coastal waters of tropical and subtropical S & E Asia, from the Persian Gulf E to the S East China Sea and S to the Sunda Is. There are no records from Oman and the Philippines, although the species is expected eventually to be found in both locations.