Risso’s Dolphins in San Diego

Grampus griseus

Risso’s dolphins are a deep diving species that can be found in all of the worlds tropical and temperate oceans. They are one of the less frequently encountered species of dolphin we can observe on our San Diego whale watching tours. Typically we encounter them near the drop off where depths reach over 1,000 feet and they can deep dive for squid.

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Risso’s Dolphin Info

Description – Risso’s dolphins are members of the ‘Blackfish’ family of cetaceans. They have a robust body reaching 13 feet, weight over 1,000 pounds and a slender tail stock. They are born dark grey in color with a tall sickle shaped dorsal fin. Their skin appearance turns white as they age, which can help determine their relative age. But this change is not due to age, instead the white appearance is actually scarring from teeth raking during social interactions within groups of Risso’s dolphins.

Range – Risso’s dolphins can be found in all the worlds tropical and temperate oceans. They frequent areas of deep water where they can find their preferred food source, squid. There are many unique populations that are known to have distinct home ranges. These residents are frequently seen over their lifetime, which makes researching Risso’s dolphins much easier than migratory species.

Behavior – Often considered a timid species, Risso’s dolphins can also become very active when socializing. They are known for their jumps, ‘spy hopping’, tail slapping and pectoral slapping. There are 2 types of groups within Risso’s dolphins society; males together or nursery pods of cows and calves. We usually see pods of 6-10 male Risso’s dolphins in San Diego.

While they have been recorded diving as long as 30 minutes to over 1,000 feet, they usually make short feeding dives of less than 6 minutes. They hunt during the night, taking advantage of the nocturnal abundance of prey in shallower waters.


The most recent population estimate of Risso’s dolphins along California’s coast is over 6,000 individuals. They are protected under the MMPA although not considered as threatened of extinction. The health of their population can be linked to their habitat (deep water away from most human activity) and because they do not typically interact with fisheries while feeding.