Cuvier first described Risso’s Dolphin in 1812. The species’ common name is for Mr. Risso who described a specimen to Cuvier on which Cuvier made his first description. Another common name for Risso’s Dolphin is the Grampus (also the species genus) – although as a common name was historically used to describe the Orca.
Population and distribution
It is found worldwide in temperate and tropical waters, usually in deep waters rather than close to land. As well as the tropical parts of the Indian, Pacific and Atlantic Oceans, Risso’s are also found in the Mediterranean and Red Seas, though are absent from the Black Sea. Their preferred environment is just off the continental shelf on steep banks (with water depths varying from 1200 to 3000 ft) with water temperature at least 50Â°F and preferably in excess of 60Â° F.
The population around the continental shelf of the United States has been recorded to be in excess of 60,000. In the Pacific a census recorded 175,000 individuals in eastern tropical waters and 85,000 in the west. No global estimate of population exists.