Risso’s dolphin

Grampus griseus
Risso’s dolphin

Appearance

Size: max 2.6-4.1m

Key features:
- White scarring across the body
- Tall dark coloured dorsal fin

Up close Risso’s dolphins are hard to be mistaken for anything else. Risso’s dolphins are born dark grey but over time they obtain scarring due to interactions with other Risso’s dolphins. These scars stay white so overtime the scars can accumulate to the point where the animal can appear completely white.
Risso’s dolphins have a tall, sickle-shaped fin which is dark and rarely scarred. The dorsal fin can easily be mistaken for that of a killer whale if seen from a distance due to its height and colour. They have a bulbous forehead and an indistinctive beak.


Behaviour

Risso’s dolphins typically feed at night so they spend much of the day travelling slowly and logging at the surface. They are highly inquisitive animals that frequently breach, spy-hop and tail slap. They are highly sociable and are commonly seen with other cetacean species.

Distribution

Risso’s dolphins have a worldwide distribution from the tropics to temperate waters. They are more commonly seen around the continental shelf and in deep water. It is believed there is seasonal movement of Risso’s dolphins from offshore to inshore in some areas, although it is unknown if this occurs in European waters.

Threats

Like many other dolphins, Risso’s dolphins are subject to threats such as entanglement in fishing gear, pollution, collisions with vessels, decreasing availability of prey, anthropogenic sound and habitat degradation.

Sightings Map

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