[6] They are located worldwide in cold to temperate waters, but most typically found along continental shelves due to their eating habits.

[10] The holotype referred to a specimen at the Muséum National d'Histoire Naturelle, an exhibit using preserved skin and skull obtained at Brest, France.

In older calves, the nonwhite areas darken to nearly black, and then lighten (except for the always dark dorsal fin).

The pronounced appearance of these scars results from the lack of repigmentation, which may be advantageous as a display that reduces further challenges from other males.

There have been several documented sightings in Roskilde Fjord, in the waters of Lejre Vig, just off of the coast of Skjoldungernes Land National Park, Denmark.

[18] In the Pacific, they range from French Polynesia west to Samoa, north to the Hawaiian Islands, as far as the Gulf of Alaska.

They are quite common along the western coasts of British Columbia, the United States and Mexico, continuing their range to the southern tip of Tierra Del Fuego.

In the eastern Atlantic, they have been sighted as far south as the offshore waters of Liberia, Guinea and Western Africa north through the Canary Islands and the Azores to southern Greenland.

On the western Atlantic side, Risso’s dolphins have been seen as far south as Guyana and Martinique; they can be found throughout much of the Caribbean Sea and the Gulf of Mexico to Florida and the Bahamas, and all along the American Eastern Seaboard and the Canadian Maritime Provinces.

[7] Since at least 2017, Risso's dolphins have begun to appear off of the subarctic Norwegian coast, as far north as Bleik's Canyon, off of Andøya.

Possible explanations for this movement are a changing climate or varying water currents, as well as a northward migration of prey species or competition with other cetaceans, such as pilot whales.

[13] Analysis carried out on the stomach contents of stranded specimens in Scotland showed that the most important species preyed on in Scottish waters is the curled octopus (Eledone cirrhosa).

Tagging of a population in the Azores revealed that Grampus griseus plan whether to make a shallow or deep dive, with different strategies that create profitable foraging for the considerable expenditure in time and energy.

Risso's can achieve depths over 600 m (2,000 ft) by exhausting their lungs and using several spins to rapidly descend, almost vertically, and increase the time spent foraging.

This allows the species to exploit a deep and dispersed layer of prey such as squid, those taking refuge during daylight when they become more vulnerable to predation.

[29] A famed individual named Pelorus Jack was widely reported between 1888 and 1912, travelling with ships navigating the Cook Strait in New Zealand.

A law protecting the animal was passed after a public outcry, renewed twice more, but suggested be invalid by its reference to Fisheries acts that did not concern marine mammals.

[23] At least one case report of strandings in Japan's Goto Islands has been associated with parasitic neuropathy of the eighth cranial nerve by a trematode in the genus Nasitrema.

[37] There was a recent reporting of a juvenile male Risso's dolphin that was stranded alive on the coast of Gran Canaria on 26 April 2019.

This was the first documented case of capture myopathy and stress cardiomyopathy in a male juvenile Risso's dolphin that has received rehabilitation.