Present in the Mediterranean sea, Risso’s dolphin owes its name to the Nice pharmacist and naturalist of the same name: Antoine Risso (1777-1845). It is an oceanic species whose seasonal migrations are very little known.
They live in tropical and temperate waters and prefer roaming deep bottoms and slopes. They are present in the Mediterranean and in the Gulf of Lion more particularly in the canyons, fond of the funds of 1000 m where they make dives of 300 m and apneas of 30 minutes. Their speed of movement is 7 to 8 km/h on average with peaks at 25-30 km/h.
Cetacean Sheet 6: Risso's dolphin
(Grampus Griseus)
3 impressive facts about Risso's dolphin
1 – Risso’s Dolphin has no teeth on the upper jaw but three to seven pairs of teeth line the tip of the lower jaw. Its color changes throughout its lifetime, from pale gray when young, to darker tones and finally turns white over time. This change in color is due to the multiple scars and scarifications streaking their body, accumulating over time and resulting from interactions between individuals. Very round and very dark eyes can then be distinguished on the light mass. The caudal fin, also dark, has pointed tips, receding backwards, and a well-marked central indentation.
2 – Risso’s dolphin often adopts very specific postures. For example: vertical body and head out of the water for several seconds. This posture is called “spywatching” or “spy-hopping”. It is also found vertical with the caudal fin in the air (“lobtailing”).Relatively few jumps with full body out of the water. It swims slowly and calmly, the head and body partially emerging, the large dorsal fin following the movement. He is considered very agile. The maximum speed of this cetacean is around 25-30 km/h (7-8 km/h at cruising speed, speed peaks at 30 km/h being rare). Its breath is rather short and quite difficult to observe from the surface.
3 – Its sexual maturity is reached between 10 and 13 years for both sexes. A young every 2 to 4 years with a gestation period in the female of 13 to 14 months. Newborns have been observed in the Mediterranean in both May and July.
Observation and Interaction tips with Risso's dolphin
The best way to meet Risso’s Dolphins is not to look for them but to navigate observing all the signs on the water and in the water. The encounter can be opportunistic: your paths cross, but these encounters can also be the subject of a different way of SAILING TO OBSERVE and meet all the species that inhabit our Big Blue.
- Rule n°1: you must always head towards a point next to the group rather than heading straight towards the cetaceans.
- Rule n°2: it is better to have your engine running; even if it is not engaged.
- Rule n°3: once you have reached about 300 meters from the cetaceans (distance at which the boat was probably detected), you will adopt a course in slow and constant approach, only 1 to 2 knots of relative speed.
- Rule n°4: we take advantage of the approach to identify the species, the number, the behavior.
- Rule n°5: you must not approach within 100 meters of cetaceans
Observing is an apprenticeship and many associations offer eco-volunteers wildlife observations where you will learn a lot about these MASTERS of the oceans that are Cetaceans.
In the meantime, we will meet you very soon for the next sheet produced in collaboration with The Peoples of the Sea..
See you soon for new discoveries on the marine fauna of the Mediterranean. Find all the cetacean sheets from the Peoples of the Sea by clicking here!
Fair Wind Captain,
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