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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 Fisheries
Letter of Confirmation #20386.

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. Currently, we have 97 adult dolphins in our photo-ID catalog. 

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
Dolphin with prominent scars
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.  
  • 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 and Stinson Beach in Marin County, and near Bodega Bay in Sonoma County. One dolphin has been sighted repeatedly in San Francisco Bay off Alameda since July 2016. 

Illustration by Uko Gorter

A trio of bottlenose dolphins, including a calf


Field Studies of Porpoises, Dolphins & Whales