Sousa chinensis
There is a wide variety in coloration of this species and
the colors may change with age. The following variations have
been described:
- slate-grey dorsally and pale grey ventrally (Atlantic
dolphins)
- dark plumbeous grey dorsally, gry flanks and off-white
ventrally (South African dolphins). The fin tip and the
fin base may turn white with age.
- uniformly plumbeous or brownish grey (Indian Ocean dolphins)
- plumbeous or brownish grey with dark bluish-black longitudinal
flecks (Indian Ocean, S. lentigenosa form
pinkish white with dark eye patches (Chinese dolphins).
Calves are dark grey, subadults become mottled greyish pink
- pale-grey back and flanks, fading to off-white ventrally
(Queensland, Australia, dolphins). Older animals may develop
a white fin.
- These animals are rather robust. Marked dorsal and ventral
ridges are present on the peduncle. The melon has a distinct
apex, blending indistinctly with the snout.
- There are some regional variations in size, but on average
adult hump-backed dolphins are 210-220 cm long (range: 180-279
cm) (Ross et al, 1994). They weigh 80-100 kg. They have
29-38 pairs of peg-like teeth in each jaw (26-31 for S.
teuszii) (Evans, 1987).
- Hump-backed dolphins are slow swimmers (4.8 km/hr) and
surface briefly at long intervals (40-60 seconds).
- Their characteristic high roll when surfacing probably
gave them their common name.
The Indo-Pacific hump-backed dolphin can be found in the coastal
waters of the Indian Ocean and the Western Pacific Ocean,
from the northern East China Sea to New South Wales, Australia.
This is a distinctly tropical species, associated with warm
waters (15-36°C). They usually live in shallow waters
(less than 20 m deep). In Moreton Bay, Australia, all sightings
of this species occur in waters of 10 m deep or less and within
6 km of the coast.
Neonate calves are about 1 m in length. There appears to be
no seasonality in reproduction. Very little is known about
maturation and mortality in this species.
There is very little data on the abundance of the species
anywhere in its range.
In the Arabian Sea, Red Sea and Persian Gulf, small numbers
have been taken for their meat. They do occassionally get
entangled in shark nets off South Africa (about 8/year) (Klinowska,
1991). Some animals have been captured for live display. One
animal, a female captured in 1966, is still on display at
Sea World, Gold Coast, Australia. The dolphins of Imraguens
de N'memghar, Mauretania, co-operate with local fishermen
in their fisheries for mullet. This co-operation seems to
benifit both humans and dolphins (Klinowska, 1991). As a result,
the local fishermen are very protective of "their"
dolphins, although they will utilize stranded or accidently
killed dolphins.
The hump-backed dolphin feeds mainly on fish species. The
species taken depend on the area, but include clupeids (herring
family) and mullet, as well as small reef fishes.
In Tin Can Bay, Queensland, Australia, a female hump-backed
dolphin appears daily to interact with bathers. In 1996, she
had a calf and took the calf with her on her visits to the
Bay. Her visits probably started when people offered her fish.
Recently feeding her has been discontinued and is actively
discouraged, but she continues to visit the Bay. (see also
the Photo feature on this dolphin)
Evans, P.G.H. (1987)
The natural history of whales and dolphins. Christopher Helm,
London.
International Whaling Commission (1996)
Report of the sub-committee on small cetaceans. Rep. Int.
Whal. Commn. 46:160-179
Klinowska, M. (1991)
Dolphins, Porpoises and Whales of the World. The IUCN Red
Data Book. IUCN, Gland, Switzerland.
Ross, G.J.B., Heinsohn, G.E. and Cockcroft, V.G. (1994)
Humpback dolphins Sousa chinensis (Osbeck, 1765), Sousa plumbea
(G. Cuvier, 1829) and Sousa teuszii (Kukenthal, 1892). In:
S.H. Ridgway and R. Harrison: Handbook of Marine Mammals.
Volume 5: The first book of dolphins, pp. 23-42. Academic
Press, San Diego
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