Risso’s dolphin (Grampus griseus)
Group formation: Social groups 5-50
Size: 2.6-4 m (male and female same size), calf 1.1-1.7 m
Weight: 300-500 kg, calf 20 kg
Age: 40 yrs
Sexual maturity: males 10-12 yrs, females 8-10 yrs
Gestation: 13-14 mths, with 2-4 yrs in between
Weaning: unknown (probably 1-3 yrs)
Diet: mostly squid, nocturnal feeders.
Distribution: Cosmopolitan species that lives in deep water preferably close to continental shelves, close to land (400-1000m) prefer temperate, subtropical and tropical waters but the range is 60° N to 60° S.
Raja Ampat: they have been sighted rarely in small groups (25), but nothing is known about them.
Population size: unknown
Conservation Status: Least Concern ver 3.1, Pop. trend: unknown
Threats: Whaling (Faeroe Islands, Japan, Sri Lanka, Indonesia, West Indies), chemical and plastic pollution, man-made noise impacts (seismic surveys, military sonar), entanglement in fishing gear, over fishing, captivity.