Newcomer Lurks Amid the Kelp
The warmer than usual ocean water we have been experiencing in Laguna is forcing marine life observers to get out their reference books to look up some of the unusual marine life being seen lately.
One of the visitors present in our local waters is the finescale triggerfish (Balistes polylepis). Although they have a range from Northern California to Chile, they are native to warmer tropical and subtropical waters and rarely found north of Baja California. Inhabiting both caves and crevasses of the rocky reefs and also the sandy bottoms close to shore, they can be found up to depths of over 1,600 feet. Named for the three spines in their dorsal fin that lock erect and are held in position by a ”trigger” mechanism when threatened, they are formidable and aggressive opponents and their only predators are apex predators such as sharks, California sea lions, several species of marlin and large moray eels.
Reaching a length of up to 30 inches, the finescale triggerfish is an odd looking fish with a deep, compressed, almost diamond shaped body with prominent triangular dorsal and anal fins. The skin of the triggerfish is thick and leathery with fine scales. Colored shades of gray with brownish or bluish speckles on the head, it has a lighter gray underside. With eyes set far back on the body, the fish has a small, powerful mouth with strong, protruding teeth that resemble human incisors. The placement of its eyes and sharp teeth enable the carnivorous finescale triggerfish to feed on crustaceans, mollusks, sea urchins and other marine animals that are covered with protective spines or shells by crushing them. Considered one of the more intelligent fishes, they utilize the technique of blowing jets of water into the sand uncovering invertebrates or turning over sea urchins which they consume. It is thought that their lifespan is around seven years.
Finescale triggerfish aggregate seasonally to spawn. Timed to the lunar cycle and tides, they gather during July and August and perform their mating rituals of touching and blowing sand to form a concave nest surrounded by pebbles. After laying her eggs, the female becomes fiercely protective of not only the nest area, but a conical shaped area that expands toward the surface of the ocean. They have been known to attack humans to protect their nests. The larvae are pelagic and drift with the currents.
Most of the recent sightings of the finescale triggerfish in Laguna have been over the outer edge of the rocky points and within the kelp beds in deeper water. Notoriously skittish, to view them, small movements may allow for a closer approach. Although bites in our area are almost unheard of, if one approaches you aggressively, the recommended defense is to kick your fins in its face until removing yourself from its territory.
Local residents Mia Davidson and artist Jan Sattler are year round ocean swimmers who believe a better-educated public will contribute to preservation of the marine habitat and its organisms.