Bottlenose Dolphin Facts: 

  • Scientific nameTursiops truncatus
  • Length: 8 - 11 ft
  • Weight: 300-500 lbs, males larger than females
  • Lifespan: up to 50 yrs
  • Calves: single calves can be born anytime after a gestation of 12 months, are nursed for up to 18 months and may remain with the mother for 3 or 4 years 
  • Diet: wide variety of fish, squid, crustaceans
  • Range: Warm and temperate waters worldwide. In California the coastal stock occurs in shallow water  north to San Francisco, Marin and Sonoma Counties  
  • Population: 500-600 in California 
  • Conservation status: vulnerable, but not endangered

Illustration by Uko Gorter

Prior to the El Nino that brought warm water to California in 1982-83, bottlenose dolphins were primarily residents of the Southern California coast. When water temperatures returned to normal, some of the dolphins stayed north, expanding the species' range.

We are working in collaboration with a marine mammal research group in Monterey Bay, Okeanis, and researchers farther south along the entire California coast to compare their dolphin observations with ours. Based on photographs of individuals, most of the animals we see in San Francisco Bay have also   been sighted in Monterey, and a few are known from Southern California.

This research is authorized by NOAA Letter of Confirmation #15477.

Project Leader:  Izzy Szczepaniak
Dolphin with prominent scars
A trio of bottlenose dolphins, including a calf

Photo-Identification: Similar to the Harbor Porpoise Project, we are compiling a catalog of bottlenose dolphins in the San Francisco Bay Area. Photographs will help us track animals over time — individuals are recognized by notches or scars on the dorsal fin. 

Bottlenose Dolphin Project

Bottlenose Dolphins are recent visitors to San Francisco Bay. The northern limit of their regular range is currently the Pacific coast off San Francisco and Marin County, and they occasionally enter the Bay, sometimes foraging for fish in Fort Point Cove, just east of the Golden Gate Bridge.  


Field Studies of Porpoises, Dolphins & Whales
in San Francisco Bay and on the Coast of Northern California

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  • Bottlenose Dolphin near Oyster Point in SF Bay:        Please see our "News & Events" tab for an update.

  • SF Bay Area: look for small groups along our coastal beaches, especially Ocean Beach in San Francisco. They are also seen occasionally at Rodeo Beach in Marin County.