Risso’s Dolphin

Risso's Dolphin, courtesy NOAA

SPECIES FACTS

Scientific Name
Grampus griseus
Life Expectancy
35 years

BIRTH FACTS

Weight
45 lbs (20 kg)
Length
3.5-5.5 ft (1.1-1.7 m)

ADULT FEMALE FACTS

Weight
660-1,100 lbs (300-500 kg)
Length
12 ft (3.7m)

ADULT MALE FACTS

Weight
660-1,100 lbs (300-500 kg)
Length
13 ft (4m)

Adult Risso’s dolphins are gray with extensive white scaring. As the dolphins mature they can almost appear to be completely white. Calves are gray in color as they don’t have the extensive rake marks. Risso’s dolphins also have a white anchor-shaped patch, on their ventral/chest area (from throat to belly).

They tend to grow up to 3 meters in length. They are stocky in stature with a rounded head. The dorsal fin is curved to the back. The flippers are long and thin. The overall shape of this dolphin is similar to a pilot whale.

HOW TO SPOT

Look for surface activity and gray/ white dorsal fins. Adults can even be seen underwater close to the surface due to their white color from scaring.

WHEN AND WHERE TO SEE

You can see this species frequently in the waters of Monterey Bay and off the coast of British Columbia.

RANGE

Risso’s prefer offshore waters worldwide in the warm temperate, subtropical and tropical waters of both the northern and southern hemispheres. They can be seen frequently around Monterey Bay, California.

Risso's Dolphin, courtesy NOAA

BIOLOGY

This species tends to feed primarily on squid, though they can feed on several different species of fish.

SOCIAL STRUCTURE AND BEHAVIOR

Groups of Risso’s are usually small, around 3-40 animals. However, “super-pods” can be seen with upwards of several thousand animals. This species can also be seen mixed with other species of dolphin (such as Pacific White-Sided and Northern Right Whale Dolphins).

These dolphins can be a very “surface’ active species. They can be seen breaching, pec-slapping, lobtailing and spyhopping and even porpoising (when chased by predators).

CURRENT AND HISTORICAL THREATS

In some parts of the world, Risso’s are hunted for human consumption. They can also be susceptible to accidental fishing gear entanglement and toxins.