Grunion The normal lifespan of the grunion is three to four years, although individuals up to five years old have been found. Their growth rate slows after the first spawning and stops completely during the spawning season. Consequently, adult fish grow only during the fall and winter. This growth rate variation causes annuli to form on the scales, which have been used for determining ages. California grunion spawn on beaches from two to six nights after the full and new moon beginning soon after high tide and continuing for several hours. As a wave breaks on the beach, the grunion swim
Grunion regulations, the resource seems to be maintaining itself at a fairly constant level. The coastal Indians in California harvested grunion during spawning runs. Archeologists have found fossil grunion otoliths (tiny, bonelike particles or stony platelike structures in the internal ear of lower vertebrates) at various Indian campsites. Grunion were mentioned by Spanish explorer Juan Rodríguez Cabrillo in his ship's log dated around 1542. Scientists first identified grunion in San Francisco Bay in 1860. Frank Zappa wrote a song named "Grunion Run" (originally released as a single by The Hollywood Persuaders), as has Jonathan Richman ("Grunion Run" on his album "I,