The kelp bass, Paralabrax clathratus, boasts an elongated and compressed body with a pointed snout and a sizeable mouth. Its remarkable features include teeth covering the roof of its mouth, fine serrations on the margins of the preopercle, and a prominent spine on the gill cover. With 10 dorsal spines and 13-14 soft rays, the kelp bass displays an impressive dorsal fin. Additionally, it exhibits a truncated caudal fin, often with a wavy margin. While juveniles showcase a light brown coloration, adults range from brown to olive-green, fading ventrally. Notably, the dorsal part of the head displays light yellow spots, while the dorsal body features black, white, and/or olive-green blotches. Distinctively, the kelp bass exhibits piebald or multicolored spotting under its belly, earning it the alternative name of calico bass. This magnificent species can reach a maximum length of 72 centimeters (28 inches) and a maximum published weight of 7.0 kilograms (15.4 pounds).
Paralabrax clathratus thrives in the eastern North Pacific Ocean along the western coast of North America. Its habitat spans from central California to the southern tip of Baja California. Although it was once found as far north as the mouth of the Columbia River on the Oregon-Washington State boundary, the kelp bass has become increasingly rare in locations north of Point Conception in California.
The kelp bass, Paralabrax clathratus, primarily inhabits kelp forests in the eastern North Pacific Ocean. Displaying a strong affinity for kelp, this species thrives at depths ranging from 0 to 61 meters (0 to 200 feet). It demonstrates remarkable adaptability by utilizing various micro-habitats within its preferred kelp environment for feeding, shelter, and breeding. Juvenile kelp bass often seek refuge among the kelp blades and other seaweed species in the intertidal zone. In contrast, adults prefer deeper rocky habitats, where their larger size provides some protection against predators.
The kelp bass engages in spawning activities from late spring to early autumn. During this time, adults form aggregations, typically numbering around 50 individuals but occasionally reaching up to 200 fish. These aggregations occur around natural or man-made structures such as the canopy of kelp forests or piers, at depths ranging from 8 to 18 meters (26 to 59 feet). The mating process involves courtship displays by males, who rub against the female's flanks and nibble at her fins. The females change coloration to dark grey or black on the upper body and bright white on their underparts, while the males darken to an overall charcoal color, adorned with black vertical bars and white spots. Spawning takes place at sunset, with both males and females releasing sperm and eggs simultaneously. The eggs hatch within 36 hours, and the resulting pelagic larvae undergo a month-long phase before settling. The kelp bass reaches sexual maturity at different ages, with males maturing between 2 and 4 years old, measuring 22 centimeters (8.7 inches) in length, and females maturing between 2 and 5 years old, measuring 22.6 centimeters (8.9 inches). This remarkable species boasts a maximum recorded lifespan of 34 years.
The kelp bass is primarily a diurnal species, often seeking cover for shade to observe and catch its prey effectively. It exhibits fidelity to specific home ranges, averaging around 3,000 square meters (32,000 square feet), and displays curiosity toward new objects. While younger kelp bass are less site faithful and tend to move greater distances, their diet evolves as they mature. Juveniles focus on small crustaceans, brittle stars, and small fishes, often taking refuge among the kelp during the day. Sub-adults are more active at night and display a more diverse diet, targeting prey that is active during nocturnal hours. As adults, kelp bass predominantly feed on larger fishes, cephalopods, and larger crustaceans. However, all age groups will opportunistically consume zooplankton when it is abundantly available.
Paralabrax clathratus was scientifically described in 1854 by Charles Frédéric Girard, a notable French ichthyologist and herpetologist. Girard assigned the species the name Labrax clathratus, with the type locality specified as San Diego, California. The generic name "Paralabrax" is derived from the Greek words "para," meaning "the side of," and "labrax," referring to a fish similar to the European sea bass (Dicentrarchus labrax). The specific name "clathratus" is of Latin origin, alluding to the intricate patterning observed in this species.
Paralabrax clathratus is highly regarded for its excellent taste, making it a sought-after culinary delight. In Mexico, it supports a significant commercial fishery. In California, however, there is no commercial fishery for this species, and it is exclusively exploited by recreational anglers. The kelp bass, with its renowned fighting ability, has become one of the most coveted game fishes in the region. The fishery faced significant challenges following the Second World War when sports fisheries exerted heavy pressure. To protect the species, size limits and a ban on the sale of kelp bass were introduced in the 1950s, leading to the recovery of the fishery.