Physical Description

  • A small, silver, schooling fish.
  • Maximum length is up to 16 inches, normally about 12 inches long.
  • Blue-green coloration on back and white coloration on the sides and belly, with one to three sets of dark spots along the side.


  • Southeastern Alaska to Baja California, Mexico.
  • Found worldwide, in the subtropical and temperate waters of the Pacific and Indian Oceans, and in the Atlantic Ocean by South Africa.


  • Primarily a pelagic species, found in the temperate open ocean.
  • Normally in schools in the top 165 feet of the open ocean.


  • They reproduce at 1 or 2 years old, depending on conditions.
  • They can spawn multiple times per season.
  • Eggs and sperm are released externally for fertilization.
  • Eggs hatch within 3 days.


  • Filter feeders that feed on plankton.
  • Juveniles feed on zooplankton, such as copepods, and adults feed on phytoplankton.


  • Bluefin tuna, Pacific bonito, Panga fish, blackbelly rosefish, gurnard, herring, Pacific jack mackerel, copper shark, blacktip shark, dusky shark, bottlenose dolphin, Thornback ray, catshark, houndshark, sharks, and fish.
  • Minke whale, Bryde’s whale, seagulls, Dusky dolphin, fur seals, Dall’s porpoise, mutton birds, little penguin.
  • People catch thousands of metric tons per year of sardines for food, fishing bait, and even pet food.

Interesting Facts

  • Sardines can form huge schools of up to 10 million fish! 
  • The Pacific sardine fishery fluctuates naturally with oceanic fluctuations of warm and cold water, and can lead to years of “booms and busts” of the sardine fishery.
  • The sardine fishery is currently closed because the population level is too low.
  • At times sardines are the most abundant fish in the California Current.

Sources: FishBase; NOAA Fisheries; California Sea Grant

Photo: Paula Selby

See the sardines’ schooling behavior in person at Birch Aquarium!

The Pacific sardine was the largest fishery on the North American Pacific coast in the 1930s and 1940s, but in 1949 it collapsed. The California Cooperative Oceanic Fisheries Investigations (CalCOFI) was created to help determine the cause of the collapse. Since then, CalCOFI has become so much more than just about sardines. A collaboration between Scripps, the California Department of Fish and Wildlife, NOAA Southwest Fisheries Science Centers, and CCE-LTER, CalCOFI now goes on quarterly cruises where they sample hydrographic and biological data from up to 113 stations. These cruises help us learn about climate change, the state of fisheries, invasive species, plastic pollution, and countless other scientific questions we couldn’t have imagined back in 1949!