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Monterey Bay


California Grunion Spawn in Monterey (Summer 2013)

August, 2013

Measuring grunion in Monterey July 2013. Credit: Erica Burton (MBNMS/NOAA)

California Grunion (Leuresthes tenuis) was observed spawning on Del Monte Beach (east of commercial wharf #2) during the summer of 2013 on June 8, June 23, July 8, July 23, August 6, and August 20.  California Grunion spawn on sandy beaches during spring and summer months, on the first four nights of the full and new moons (centered around high tide). Grunion are more commonly found in southern California and northern Baja California, but occasionally are observed in Monterey and as far north as Tomales Bay.

As waves break on sandy beaches, Grunion swim as far up on the beach as possible. Spawning females use their tail to dig in to the moist sand to lay their eggs. Males then curl around the female and release milt.  In 10-14 days, during the next high tide series, the grunion hatch and enter the water to continue their development.

Grunion are small, slender fish with greenish backs, silver-blue stripe on sides, and silver bellies.  They can reach a maximum total length of 8 inches. Grunion are only taken by recreational fishers.  During open season a state fishing license is required, and fish can only be collected by hand.

 

FACTS

  • California Grunion (Leuresthes tenuis) is a marine fish related to Jacksmelt and Topsmelt, all members of the family Atherinopsidae (New World silversides)
  • Grunion are small, slender fish, reaching 8 inches total length; few live to be more than three years old
  • Grunion have been observed from Tomales Bay, California, USA to San Juanico Bay, Baja California, Mexico; but typically range from Point Conception, California to Point Abreojos, Baja California
  • Grunion spawn on sandy beaches during spring and summer months, on the first four nights of the full and new moons (centered around high tide)
  • Eggs hatch after 10-14 days, during the next high tide series

 

Spawning grunion. Credit: Adam Obaza (SWR/NMFS/NOAA)

Helpful Links:

The Amazing Grunion (CDFW)

California Grunion Facts and Runs (including schedule)

Video of California Grunion spawning in southern California

Report your observations

 

 

 

 

Additional Information:

Love, M.S. Certainly more than you want to know about the fishes of the Pacific coast: A postmodern experience. Really Big Press, Santa Barbara, California. 650 pp.

Miller, D.J. and R.N. Lea. 1972. Guide to the coastal marine fishes of California. California Department Fish and Game, Fish Bull. 157. 249 pp.

Roberts, D., R.N. Lea, K.M Martin. 2007. First record of the occurrence of the California Grunion, Leuresthes tenuis, in Tomales Bay, California: A northern extension of the species.