This is a distinctive dolphin, with a stocky body and extremely small appendages. The short dorsal fin is triangular or slightly falcate, and tends to be more erect in adult males. There is a stubby but well-defined beak. The color pattern is striking; the most distinctive feature is a dark band of varying thickness, running from the face to the anus (in some regions, the band is indistinct). This band is scarcely apparent on young animals, appearing to widen and darken with age, especially in adult males. There is also a flipper stripe that starts mid-length along the lower jaw (in some animals the side stripe is so wide that it merges with the flipper stripe, creating a dark face mask).
Otherwise, the back is dark brownish-gray, the lower sides are cream-colored, and the belly is white or pink. Young animals in particular may have pinkish bellies. There are 38-44 pairs of teeth in each jaw. Maximum size is at least 2.7 m (males) and 2.6 m (females). They may reach weights of over 210 kg.
Can be Confused With
The unique body shape of Fraser’s dolphin should rule-out confusion with other species, but striped dolphins, which also have an eye-to-anus stripe, can be confused with Fraser’s at a distance.
Fraser’s dolphin has a pantropical distribution, largely between 30°N and 30°S. It is an oceanic species, but can be seen near shore in some areas where deep water approaches the coast. Strandings in temperate regions (Brittany, Victoria in Australia, and Uruguay) are probably due to temporary oceanographic changes, such as El Nino.
Atlantic Ocean: In the eastern North Atlantic, Fraser’s dolphins have been seen near the Canary Islands and on the coast of Africa near Sierra Leone. In the western North Atlantic, they have been sighted in the lesser Antilles and the Gulf of Mexico.
Pacific Ocean: In the eastern Pacific, Fraser’s dolphins are known to inhabit the eastern Tropical Pacific. In the western Pacific, range includes the waters surrounding Indonesia, the South China Sea, and the coast of Queensland, Australia.
Indian Ocean: Sightings of Fraser’s dolphins have occurred near Sri Lanka, Madagascar, and the Natal coast of South Africa.
Ecology and Behavior
There is little known of this oceanic species. Herds tend to be large, consisting of hundreds or even thousands of dolphins, often mixed with other species, especially melon-headed whales in the eastern tropical Pacific, Japan, and the Philippines; as well as pilot whales and Risso’s, spotted and spinner dolphins in the Philippines. In some areas, it is considered shy and difficult to approach; in others it is a more approachable. It does not bowride in the eastern tropical Pacific, but appears to in most other areas. In the Philippine Sulu Sea, this species is most likely to bowride on slow-moving vessels. Running herds create a great deal of white water. Not much is known of the life history of the Fraser’s dolphin.
Amano et al. (1996) studied 108 specimens taken in a drive fishery in Japan and found that sexual maturity for females was reached between 5 and 8 years, at a length of 210-220 cm, and for males at 7-10 years at a length of 220-230 cm. Gestation was found to last about 12.5 months, with a predicted neonatal length of 110 cm and a calving interval of 2 years. Calving peaks in spring, summer and autumn have been documented in different areas. Newborns are 1.0-1.1 m long.
Feeding and Prey
Fraser’s dolphins seize their prey, which composes of a broad diet dominated by: Fish > cephalopods > crustaceans
Fraser’s dolphins appear to feed on midwater fish, squid, and crustaceans. Physiological studies indicate that Fraser’s are capable of deep diving, but they have been observed to feed near the surface as well.
The IUCN lists Fraser’s dolphin as “data deficient” in that not enough is known about the species to evaluate its conservation status. It is not on the United States endangered species list. Direct killing has occurred in Japan, the Lesser Antilles, Sri Lanka, Indonesia and the Philippines. Incidental catches in purse seines (eastern tropical Pacific and the Philippines), gill and driftnets (South Africa, Japan, the Philippines, and Sri Lanka), and trap nets (Japan) are also known.
Amano, M., N. Miyazaki and F. Yanagisawa. 1996. Life history of Fraser’s dolphin, Lagenodelphis hosei, based on a school captured off the Pacific coast of Japan. Marine Mammal Science 12:199-214.
Dolar, M.L.L. 2002. Fraser’s dolphin Lagenodelphis hosei. pp. 485-487 in W.F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.
Jefferson, T.A. and S. Leatherwood. 1994. Lagenodelphis hosei. Mammalian Species 470:1-5.
Jefferson, T.A., R.L. Pitman, S. Leatherwood and M.L.L. Dolar. 1997. Developmental and sexual variation in the external appearance of Fraser’s dolphins (Lagenodelphis hosei). Aquatic Mammals 23:145-153.
Perrin, W.F., S. Leatherwood and A. Collet. 1994. Fraser’s dolphin Lagenodelphis hosei Fraser, 1956. pp. 225-240 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Volume 5: The first book of dolphins. Academic Press.
Watkins, W.A., M.A. Daher, K.M. Fristrup and G. Notarbartolo di Sciara. 1994. Fishing and acoustic behavior of Fraser’s dolphin (Lagenodelphis hosei) near Dominica, southeast Caribbean. Caribbean Journal of Science 30:76-82.