Risso Dolphin

ORDER: CETACEA

SUBORDER: ODONTOCETI

FAMILY: DELPHINIDAE

GENRE: GRAMPUS

SPECIES: Grampus griseus (Cuvier, 1812)

Grampo, Risso's dolphin, calderòn gris, dauphin de Risso, Rundkopfdelphin

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The adult reaches 3.5 meters in length and weight of 400/600 kg. The body is proportioned, the rostrum is absent and the forehead bulging but not globular as in pilot whales. During life the livery loses color and, in older individuals, the head can become completely white. Moreover, adults present clearly visible scuff marks on the skin, especially on the front part of the body, which help the to have a white color appearance. Infants are of dark color, blackish brown.  Risso dolphins form small groups of 5-6 individuals who often get separated during the search for food. It feeds mainly  on cephalopods but also occasionally on small fish. By the stomach contents observed, they feed on neritic species belonging to the Teuthidae family.

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The Risso's cetaceans are abundant in tropical and temperate waters of the oceans around the world and generally live on the slope of the continental shelf. In the Mediterranean, Risso's dolphin is described as a predominantly pelagic species that lives between -500 and -2000 meters with preference for the highest part between -500 and -1000 meters. However it is not uncommon to find him by the coast. It’s quite common in Italian waters especially in the Ligurian Sea and the North of Sicily, but it’s also present in the Tyrrhenian Sea. The Risso's dolphins are hunted regularly in Japan with documented killing in recent years of 250-500 specimens every hunting activities.  Risso’s dolphin are also victim of hunting craft and bycatch in driftnets and other fishing gear in Sri Lanka and the Philippines; The population in these areas have not yet been properly evaluated.