Physical Description

  • Large fish with compressed, tuna-shaped body and a pointed, conical head with downward-slanting mouth.
  • Blue to violet coloration on back, with ten or eleven silver-blue stripes on back running obliquely from the back fin forward.
  • Short, long, black dorsal (tail) fin that runs almost whole length of fish.
  • Can be up to 40 inches long, and weighing up to 25 pounds.


  • From Alaska to tip of Baja California, Mexico.
  • Not common north of Point Conception.


  • Found anywhere from inshore to about 100 miles offshore.
  • Can be in depths of 300-600 feet.


  • They reach sexual maturity at age 2.
  • Spawning generally from late January to May.
  • Eggs float freely in top 300 feet of water.
  • Eggs usually hatch within 4-5 days after spawning.


  • Small schooling fishes, such as sardines and anchovies, squid, shrimp.


  • Larger fish such as tuna, as well as other bonito.
  • Humans (fished for sport and for seafood).

Interesting Facts

  • Bonito populations heavily fluctuate with warm and cold water, which often fluctuates with atmospheric fluctuations like the Pacific Decadal Oscillation.
  • Unlike most fishes, they have no swim bladder.
  • They often swim in large schools.

Sources: California Sea Grant; FishBase; California Department of Fish and Wildlife

Photo: Paula Selby