Risso's Dolphins

Scientific Name:   Grampus griseus


When is the best time to view Risso's Dolphins in Monterey Bay and where is the best viewing?

Risso's dolphins are relatively common off California and are seen year-round in Monterey Bay.  They can usually be found in small groups of 10-30 dolphins.  Rissso’s are often encountered in the deeper parts of the Bay where they favorite prey of squid are located.  Therefore the best way to see Risso Dolphins are from one of the many whale watching boats that leave from Monterey or Moss Landing.

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About Risso's Dolphins

Risso's dolphins appear similar to small whales with rounded heads and stocky physiques. Rissos, like many other dolphins often seem to jump for joy as they swim, soaring out of the water and plunging back in every few seconds in a behavior called porpoising. 

 Risso's dolphins are often covered in scars and appear almost entirely white on the front half of their body.  Scientists suspect scars are from interactions with other Risso's (teeth marks) and from squid, a favorite food with sharp hooks on its tentacles that doesn’t go down without a fight.  In fact, while not much is known about the type of squid preferred by a Risso's dolphin, squid beaks from species that grow up to 12-feet have been found in the stomachs of stranded Risso's dolphins. 

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Risso's Dolphin Fun Facts

  • Dive to depths of over 1,000 feet in search of their favorite food – squid
  • Can hold their breath for 30 minutes
  • Have two to seven pairs of peg like teeth in their lower jaw but none in the upper jaw
  • Produce a wide variety of sounds through echolocation, including clicks, squeals, and cries, all used for communication
  • A famous Risso's dolphin named "Pelorus Jack" was known for escorting ships into New Zealand’s Pelorus Sound for 24 years beginning in 1912

Habitat: Prefer off-shore habitats but migration patterns are unknown. While frequently seen all along the coast of California, Risso's dolphins have been seen as far north as the Gulf of Alaska in the North Pacific or Newfoundland in the North Atlantic, and as far south as Cape Horn in South America, the Cape of Good Hope in South Africa, Southern Australia, and New Zealand.

Size: Males are generally larger than females. The average length is 10 feet, but may grow up to 13 feet. Risso's average about 650 pounds with larger individuals weighing up to 1100 pounds.

Diet: fish, octopus and squid

Lifespan: up to 30 years in the wild

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