Kelp bass (Paralabrax clathratus)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Perciformes · Family: Serranidae · Genus: Paralabrax.

Accepted name: Paralabrax clathratus · Authority: (Girard, 1854) · Taxonomic status: accepted · AphiaID: 282054.

Synonyms and superseded combinations recorded for this taxon: Labrax clathratus Girard, 1854.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=282054 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (FishBase)

Measured values published by FishBase for Paralabrax clathratus. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 72 cm · Depth range: 1–61 m · Habitat zone: benthopelagic · Body shape: fusiform / normal · Vulnerability index: 66.7 of 100 · Fishery importance: commercial.

FishBase notes: Usually found in or near kelp beds, shallow water and to about 50 m but mostly from 2.4-21m . Found throughout water column. Large specimens usually occur in deeper water. Juveniles feed on benthic invertebrates (especially crustaceans); adults feed on fishes and cephalopods (Ref.9342). Both juveniles and adults may feed on plankton when abundant (Ref.9342). Pelagic spawners (Ref. 56049). Also caught with troll lines (Ref. 9342). Excellent food fish and an important game fish (Ref. 9342).

Source: FishBase species summary (SpecCode 3335) — https://www.fishbase.se/summary/Paralabrax-clathratus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

235,538 georeferenced occurrence records for Paralabrax clathratus are published through GBIF from 3 countries or marine areas. The map above plots 18 distinct locations from a sample of 3,000 records, omitting 9 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: United States of America (235,259); Mexico (276); United Kingdom of Great Britain and Northern Ireland (3).

The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.

Source: GBIF Occurrence Search (taxonKey 2387731) — https://www.gbif.org/occurrence/search?taxon_key=2387731&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=282054 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Conservation status (IUCN Red List)

The IUCN Red List assesses Paralabrax clathratus (Girard, 1854) as Least Concern (code LC). No trend, population estimate or threat analysis is given here, because none is available from this source without the Red List API; follow the source link for the full assessment, including its date.

Source: IUCN Red List of Threatened Species (taxon 183858) — https://www.iucnredlist.org/species/183858/0; GBIF IUCN Red List category endpoint (taxonKey 2387731) — https://api.gbif.org/v1/species/2387731/iucnRedListCategory. Accessed 2026-09-23.

Description and natural history (Wikipedia)

Paralabrax clathratus has an elongate, relatively deep, compressed body with a pointed snout and a large, downturned mouth. The mouth extends back as far as the centre line of the pupil and the lower mandible protrudes to form part of the snout. There are teeth all over the roof of the mouth. The margins of the preopercle have fine serrations. There is a large spine on the edge of the gill cover. The dorsal fin has 10 spines and 13–14 soft rays, the 3rd and 4th spine are the longest, both being nearly twice the height of the 2nd spine. The anal fin has 3 spines and 7 soft rays. The caudal fin is truncated, although the margin can be wavy. The juvenile fish are light brown in colour, while the adults are brown to olive-green fading ventrally The dorsal part of the head has a mottling of light yellow spots while the dorsal part of the body is patterned with black, white, and/or olive green blotches. Along the back there are rows of white, rectangle shaped spots. All of the fins are yellow at the tips. The males may develop an orange tint on their lower jaw and chin during mating season. Kelp bass can also change color depending on their surroundings. For example, fish moving from the kelp forest to the open ocean can change from being dark green or brown, to being pale green. Similar color changes have occurred when kelp bass were artificially removed from their habitat and placed into pens for study. Due to a lack of sexual dimorphism, it is impossible to tell males and females apart by sight. Paralabrax clathratus may be phenotypically similar to other north American species of bass such as the spotted bass, white bass, or yellow bass. A distinguishing feature of this species from other sea bass is that the kelp bass has piebald or multi coloured spotting under the belly, which is why it is alternatively called calico bass. They are also by far the largest species in their genus. They attain a maximum total length of 72 cm and a maximum published weight of 7.0 kg. Approximately 40% of all kelp bass alive at any given time are 200 to 250 millimeters in length. Size data was collected using entrapment surveys of 38,875 individuals over the course of 39 years.

Paralabrax clathratus is found in the eastern North Pacific Ocean off the western coast of North America. Its range extends from the central California south to the southern tip of Baja California. It was formerly found as far north as the mouth of the Columbia River on the boundary between Oregon and Washington State but it is now rare anywhere north of Point Conception in California.

Paralabrax clathratus is found at depths between 0 and 61 m, though they typically remain between 2.7 and 21.3 meters below the surface. They show a strong association with kelp and are almost always found inhabiting kelp forests and estuaries. They can also reside in nearshore rocky-reefs. They utilize a variety of micro-habitats within this habitat for feeding, shelter and breeding, for example the juveniles will hide among the blades of kelp and among seaweed in the intertidal zone. The adults prefer deeper water, venturing into rocky habitats where their larger size gives them some protection against predation. The kelp bass spawns in the late spring to the early autumn, with spawning season peaking in the summer. When spawning the adults form aggregations of up to 200 fish, but more commonly numbering around 50 individuals. Because of these aggregations, Kelp bass are most commonly fished during the months of June, July, and August. Virtually none are caught from October through April, when spawning aggregations cease. The aggregations are normally formed around a natural or man-made structure such as the canopy of the kelp forest or piers and occur at depths of 8 to 18 m. The mating fish break off into smaller groups in which a gravid female will swim to the substrate and males will perform courtship displays by rubbing themselves against her flanks and nibbling at her fins. While they are mating, the females change colour to dark grey or black on the upper body, and bright white on their underparts, while males also darken to an overall charcoal colour, broken by black vertical bars and white spots. Additionally, about 75% of males develop an orange snout during mating season. The males and females release the sperm and eggs at the same time, normally spawning between 32 minutes before sunset and 120 minutes after sunset. They are capable of releasing eggs and sperm multiple times in a single evening. There is no known correlation between male size and participation in spawning aggregations. Interestingly, spawning activity tends to peak each month around the time of the full moon. The reason for this remains a mystery, though it has been suggested that spawning during the high tides that are associated with the full moon may increase fertilization success. After spawning the eggs hatch within 36 hours. There is then a pelagic larval phase which lasts for 25–36 days, before the fish "settle", or transition out of the larval phase and develop into juveniles. Juveniles stay in the kelp forest to protect themselves from predators. As they mature, they venture father into the open ocean. They grow an average of 0.59 millimeters per day for the first 90 days of their lives. Most of the kelp bass's growth takes place during the first few years of life, but they have indeterminate growth. Males are sexually mature at between 2 and 4 years old and half of them are mature when they have attained 22 cm in length. Females are mature at 2 to 5 years old and half of them are mature at 22.6 cm. Male and female kelp bass grow in length at the same rate. Their maximum recorded lifespan is 34 years, but most do not live for anywhere near this long. Using this maximum age as a reference, studies found that, on average, about 17.6 percent of kelp bass die from natural causes each year. This does not include death by fishing. They rarely live past age 15 in the wild. In order to collect data on the growth and life history of Paralabrax clathratus, scientists dove along transects and recorded the number of fish that they saw within a 3-meter radius and their sizes. Fish that were between 1.5 and 2 centimeters in length were considered to be newly recruited, fish from 2.1 cm to 10 cm in length were considered to be juveniles, and fish from 10.1 cm to 15 cm were considered to be subadults. Any fish that was longer than 15 cm was assumed to be a fully grown adult.

This species is largely diurnal, but can remain active both day and night. Individuals are faithful to their home ranges, which average around 3000 m2, but can be anywhere from 33 to 11,224 square meters in size. They may remain in the same area for up to 3 years. Barron sand channels can act as a barrier for their movement. Data on the movement and range of Paralabrax clathratus is collected using acoustic tracking. Essentially, individuals are caught and given anesthesia. An acoustic transmitter is then inserted between the pelvic fins and vent. The fish are then weighed, measured, and tagged for external identification. After the fish are released, tracking is carried out on a small boat equipped with a hydrophone and receiver. The location of each fish is recorded every 15 minutes for up to 1 month. The younger fish are less site faithful than the older individuals and will move greater distances. This may be because their diet changes as they mature. The juveniles are more diurnal as zooplankton is more abundant during the day and their small size means they are subjected to greater predation so they take sanctuary among the kelp. Sub-adults are more active at night and have a more diverse diet with their preferred prey being more active at night. As adults, kelp bass feed on small fish, crustaceans, mollusks, and other small primary consumers. In winter, their feeding options are far more limited than in summer, and many Kelp Bass go hungry. When meat is unavailable, they are sometimes forced to rely on kelp and algae. The primary predator of adult kelp bass is the giant sea bass (Stereolepis gigas), whose population has increased significantly in recent years.

Source: Wikipedia: Paralabrax clathratus — https://en.wikipedia.org/wiki/Paralabrax_clathratus (CC BY-SA 4.0). Accessed 2026-09-23.