Marine Mammal Science & Conservation

Long-beaked spinner dolphin

Long-beaked spinner dolphins (Stenella longirostris)

Group formation: Social fission fusion groups 25-300

Size: 129–235 cm, calf 0.75 m

Weight: 23–79 kg, calf unknown

Age: 20 yrs

Sexual maturity: males 7-10 yrs, females 4-7 yrs

Gestation: 10 mths, 3 yrs in between

Weaning: 1-2 yrs

Diet: they feed mostly at night on mid-water fishes and deep-water squid, such as small mesopelagic fish, squids, shrimps, for which they will dive 200–300 m and then rest for most of the daylight hours

Predators: sharks, killer whales, false killer whales, pygmy killer whales, short-finned pilot whales

Distribution: lives in all tropical and subtropical waters between 40° N and 40° S, with 4 sub species

Raja Ampat: they are very common and often sighted in large groups of 100 or more

Population size: > 1 million

Conservation Status: Data Deficient ver 3.1,Pop. trend: unknown

Threats: Whaling (Japan, Sri Lanka, Indonesia), chemical and plastic pollution, man-made noise impacts (seismic surveys, military sonar), entanglement in fishing gear, as bycatch in yellow tuna fisheries, over fishing, captivity.


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