American Samoa Mammal
Fraser's Dolphin (common name)
Lagenodelphis hosei (scientific name)
Charles Hose, a British zoologist and colonial administrator, was the first person to take notice of Fraser’s dolphin. He found a skull on the beach in Sarawak, Borneo in 1895, which he gave to the British Museum. No one else took note of the skull until 1956, when Francis Fraser studied the skull and found it similar to Lagenorhynchus and Delphinus, but distinct from both. The dolphin’s scientific name honors Hose, while its common name honors Fraser. Fraser’s dolphin prefers deep tropical waters and is found around the world, but is especially common in the Pacific Ocean, including in the waters around American Samoa.
ALSO KNOWN AS
Sarawak Dolphin, short-snouted whitebelly dolphin
Fraser’s dolphin has a sturdy body with a small but well-defined beak, which is usually deep gray at the tip. The dolphin’s triangular dorsal fin is also smaller than in many other species, and sits halfway down its back. Its flippers and flukes are also noticeably smaller. Another distinguishing feature of the Fraser's dolphin is a clear black or gray horizontal stripe that runs along its body. Above the stripe, these dolphins are bluish or brownish gray, while below the stripe they are usually white or slightly pinkish. Color changes with age. Young dolphins don’t have very distinct colors or patterns. There is also some variation in color and pattern between individual dolphins.
Up to 18 years
Warm ocean waters in temperate, subtropical, and tropical areas, normally below 3,300 feet (1000 m).
Range: Deep, warm waters from 30° South to 30° North, worldwide.
Conservation Status: Least Concern (LC). Fraser's dolphins are sometimes accidentally caught in driftnets, trap nets, and gillnets used by fisheries to catch other ocean fish.
Fraser's dolphins prefer to swim in groups and are difficult to separate from their schools. Most groups consist of about 10 to 100 dolphins, but Fraser’s dolphins will sometimes swim in much larger groups of up to 1,000. Occasionally they swim with whales as part of their group, especially false killer whales, melon-headed whales, and short-finned pilot whales. Risso's dolphins may also join Fraser’s dolphin groups.
As Fraser’s dolphins swim, they usually create a turbulent wake because of their strong, splashy strokes. Groups sometimes swim in a long line. Female Fraser’s dolphins start breeding when they are between five and eight years old, and males when they are seven to 10. Single calves are born after 10 to 12.5 months.
Top land speed recorded: 35 mph (56 kph)
The species feeds on pelagic fish, squid, and shrimp found some distance below the surface of the water (200–500 metres). Virtually no sunlight penetrates this depth, so feeding is carried out using echolocation alone.
Breeding interval: Biennial
Birthing period: Year-round
Average litter size: 1 calf
Size at birth: 42 lb (20 kg)
Click to enlarge an image
Data Source: U.S. Fish and Wildlife Service
Author: World Trade Press