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
USS Grunion Maru". Her first torpedo ran low, but despite its magnetic pistol it failed to detonate. Two more bounced harmlessly off the "Kano Maru" without exploding. However, the remaining torpedo missed its target and circled back, striking the periscope supports on the submerged submarine without exploding. The damage the torpedo inflicted, combined with a jammed rear dive plane, triggered a sequence of events that caused the loss of depth control. The "Grunion" lunged below her maximum operational depth, and at about 1000 feet would have imploded. What remained of the ship struck the seabed, breaking off about 50 feet of her