This is a demersal fish, living primarily in the lower water column as adults.[2] They inhabit near shore regions and are free swimming.[4] This is an unusual fish in that one eye migrates around from one side to the other as it grows from an upright fry or baby fish into an adult fish that lies on its side. This results in the adult fish having two eyes on the up-side as it lies on the ocean floor. Most flatfish are generally either right-eyed or left-eyed dominant, but the California halibut is unusual in having a roughly even number of each type. [5][6]
Like other flatfish, the halibut hides under sand or loose gravel, camouflaging into the sea floor. They are aggressive predators, using this camouflage to effectively ambush prey such as fishes and invertebrates.[7]
Description
California halibut typically weighs 6 to 30 pounds (3 to 23 kg), with the largest reported weighing 72 pounds (32.7 kg). It is rare, but they can grow up to 60 inches (1.52 m),[2] and their average length is 12 to 24 inches (30 to 61 cm).[7] The largest fish of this species are females since they grow faster, and males do not grow as large. The legal catch limit that applies to all commercial and recreational halibut fisheries is 22 inches and around 4 pounds , and this growth takes them about 3 to 5 years to reach.[2]
This is an unusual fish in that one eye has to migrate around from one side to the other as it grows from a baby fish (fry) into an adult fish that lies on its side. The adult has two eyes on the up-side as it lies on the bottom. Differing from most flatfish species, the California halibut does not show a preference for the side of eye development, with roughly equal left and right sided eye development. [6][5]
Their body coloration is grayish brown with darker brown spots. They are known to change color and pattern to mimic substrates,[7] serving as incredible camouflage into benthic mud, gravel, and sand. They use this for avoiding predators and to ambush prey. [8][9][2]
A fish that closely resembles the California halibut is the Pacific halibut (Hippoglossus stenolepis), which is a larger species found in the northern Pacific Ocean. While the Pacific halibut has a similar flat body shape, it is generally larger and can reach 300 pounds (140kg), and can be distinguished by its slightly different coloration and the position of the eyes. Additionally, the Pacific halibut inhabits colder waters than the California halibut.
The geographic range for California halibut extends from the Quillayute River in northern Washington to Cabo Falsa (22°50’N) in southern Baja California, Mexico. [10][2] Halibut have also been reported in the upper Gulf of California. They are most commonly encountered within Bodega Bay, northern California, to Bahía de San Quintín, northern Baja California. In association with warm water events, halibut are occasionally common in Humboldt Bay.[11] Within these regions, adult California halibut reside on the seabed, in shallow water areas.[4] However, they are known to go as deep as 317 m.[2]
Diet and predators
Halibut are carnivorous ambush predators that feed on fishes and invertebrates. They lie camouflaged in sediment and will swim up off the seabed to feed on schooling fish and invertebrates such as northern anchovy and market squid. [7] While common prey items vary with geographic location and life stage, other prey generally include species of shrimps, crabs, croakers, flatfish, gobies, herring, mackerel, midshipman, sand lance, saury, sculpins, silversides, and surfperch. [10]
Larger adult halibut are considered a cryptic top predator in the benthic community since this aggressive and carnivorous predator is often elusive in nature and are at a low risk of predation due to their relatively large adult size.[10] Other than humans, marine mammals and larger shark species have been documented to eat adult halibut. However, during juvenile stages, halibut have more predators and are likely eaten by a wide variety of species such as sharks and rays, osprey, cormorants, and terns, and marine mammals such as seals, sea lions, and dolphins.[2]
Biology and ecology
Growth in standard length of California halibut from hatching to the completion of metamorphosis.
California halibut have a maximum lifespan of around 30 years, although individuals rarely live beyond 15 years, and typically only females reach this older age. [5] Like other flatfish, California halibut undergo a unique metamorphosis during their early life stages, transforming from symmetric larvae to asymmetric juveniles.[6] Initially, as larvae, they inhabit the water column, but as they metamorphose, they develop an eye on one side of their head and become bottom-dwelling flatfish.[10] This adaptation allows them to shift from pelagic to benthic habitats, where they spend most of their lives.
These halibut are broadcast spawners with high fecundity, meaning they produce thousands of offspring in each spawning cycle. [7] Spawning occurs primarily from spring to summer, with males and females gathering in offshore waters to release their eggs and sperm into the open water, allowing fertilization to happen externally.[13][11] This strategy disperses fertilized eggs widely, increasing the chances of larval survival. The spawning season’s peak varies by latitude, occurring earliest in Mexican waters and progressing northward through southern and central California. Though spawning occurs outside estuaries, bays like San Francisco Bay serve as essential nursery habitats for juvenile growth and maturation. [7]
Temperature-dependent sex determination is observed in California halibut. When raised at 15°C, they develop into an equal amount of females and males, but at higher temperatures (19°C and 23°C), more males are produced.[14][10] Additionally, while most flatfish species have a set eye preference, California halibut can develop as either left- or right-eyed, a trait that occurs during metamorphosis around 42 days post-hatching, where one of their eyes migrate over their head to join the same side as their other eye.[13] Juveniles that survive this stage are resilient, particularly to changes in salinity, though older juveniles may have reduced tolerance.
Recruitment success, or survival into adulthood, varies significantly by region, with central California exhibiting higher variability due to factors like upwelling and sea surface temperature, which can impact larval survival rates.[13] This recruitment variability, influenced by abiotic factors, is critical for maintaining healthy population levels, as insufficient recruitment to adulthood can threaten population stability.[10][15]
Industry and recreation
Flatfish aquaculture production by country (FAO 2006)
On the Pacific coast, the California halibut supports important recreational and commercial fisheries throughout its range from the Oregon–Washington border in the United States to the southern part of Baja California in Mexico.[16][10]
Fishing for both recreational and commercial purposes is open year-round, except that trawling is prohibited from March 15 to June 15 within the California halibut Trawl Grounds in Southern California . Commercial hook-and-line fishing and recreational fishing are permitted throughout the state, except in designated protected areas.[2] The gill net fishing is limited to Southern California, specifically south of Point Arguello. While the trawl fishing is allowed statewide, it must occur outside of state waters. Halibut fishing is commonly conducted from ports ranging from Bodega Bay to San Diego, occasionally extending further north to the port of Eureka. In 2019, halibut fishing activities were reported from all major port complexes across the state.[2]
Various institutions in California, including the University of California – Davis, the California halibut Hatchery in Redondo Beach, and the Hubbs-SeaWorld Research Institute in San Diego, have partnered with organizations in Mexico, such as CICESE in Ensenada and CIBNOR in La Paz, Baja California Sur. [10] Together, they aim to establish the biological groundwork needed to advance the aquaculture of this species, focusing on both juvenile production for stock enhancement and the cultivation of market-sized individuals.[10][12]
Halibut is a highly valued flatfish and a significant commodity in California. Although available year-round, it is especially abundant in the summer and is commonly found in California's restaurants, grocery stores, and farmers' markets. It can also be purchased directly at the dock, either whole or live. Halibut is rarely frozen, as freezing negatively affects its texture, which contributes to the artisanal nature of this fishery and keeps much of the product local within California.[7][2]
Related Research Articles
Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world; some species will also enter estuaries.
A flatfish is a member of the ray-finned demersal fish order Pleuronectiformes, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through or around the head during development. Some species face their left sides upward, some face their right sides upward, and others face either side upward.
Halibut is the common name for three species of flatfish in the family of right-eye flounders. In some regions, and less commonly, other species of large flatfish are also referred to as halibut.
The California spiny lobster is a species of spiny lobster found in the eastern Pacific Ocean from Monterey Bay, California, to the Gulf of Tehuantepec, Mexico. It typically grows to a length of 30 cm (12 in) and is a reddish-brown color with stripes along the legs, and has a pair of enlarged antennae but no claws. The interrupted grooves across the tail are characteristic for the species.
The Scophthalmidae are a family of flatfish found in the North Atlantic Ocean, Baltic Sea, Mediterranean Sea, and Black Sea. Fish of this family are known commonly as turbots, though this name can refer specifically to Scophthalmus maximus, as well. Some common names found in species of this family are turbots, windowpanes, and brills.
The European plaice, commonly referred to as simply plaice, is a species of marine flatfish in the genus Pleuronectes of the family Pleuronectidae.
Hippoglossus stenolepis, the Pacific halibut, is a species of righteye flounder. This very large species of flatfish is native to the North Pacific and is fished by commercial fisheries, sport fishers, and subsistence fishers.
The yellowbelly flounder is a flatfish of the genus Rhombosolea, found around New Zealand. A different species from the genus Rhombosolea is found in Australia and also goes by the name yellow-belly flounder. The Māori people have commonly fished for R. leporina, and many other species of flatfish, throughout New Zealand's coastal waters for hundreds of years. The Māori name for this species is pātiki tōtara.
The New Zealand sand flounder is a righteye flounder of the genus Rhombosolea, found around New Zealand in shallow waters down to depths of 100 m.
The Pacific sanddab, also known as the soft flounder, mottle sanddab, or megrim, is a fish species in the order Pleuronectiformes, or flatfish. It is by far the most common sanddab, and it shares its habitat with the longfin sanddab and the speckled sanddab. The adult Pacific sanddab is bilaterally asymmetrical and ‘left-eyed’, meaning both eyes are located on the left side of its body.
The gray smooth-hound is a houndshark of the family Triakidae. It is spotless and smooth with a narrow head and long blunted snout. This shark is found on continental shelves of the subtropical eastern Pacific. Its range extends from northern California to the Gulf of California, usually residing in waters less than 80 meters deep. Adults are between 0.5 and 1.6 meters long. Furthermore, this shark is viviparous with an egg yolk placenta. Reproduction occurs annually and inland estuaries are common nursery grounds. Although there is little data on the shark’s population trends and catch quantities, the gray smooth-hound is not considered as vulnerable to overfishing. Additionally, there have been three reported sightings of albinism in this species, which is rare for elasmobranchs.
The Pacific angelshark is a species of angelshark, family Squatinidae, found in the eastern Pacific Ocean from Alaska to the Gulf of California, and from Ecuador to Chile, although those in the Gulf of California and southeastern Pacific may in fact be separate species. The Pacific angelshark inhabits shallow, coastal waters on sandy flats, usually near rocky reefs, kelp forests, or other underwater features. This species resembles other angel sharks in appearance, with a flattened body and greatly enlarged pectoral and pelvic fins. Characteristic features of this shark include a pair of cone-shaped barbels on its snout, angular pectoral fins, and a brown or gray dorsal coloration with many small dark markings. It attains a maximum length of 1.5 m (4.9 ft).
Citharichthys stigmaeus, the speckled sanddab, is a species of lefteye Blothid flounder in the genus Citharichthys. It is native to the eastern Pacific Ocean, ranging from Alaska in the north to Baja California, Mexico in the south. It is usually found in benthic habitats, in both bays and coastal areas. It varies temporarily both seasonally and annually. It is often found highest in abundance during the spring and summer, but are found in much lower densities in the winter.
The Greenland halibut or Greenland turbot belongs to the family Pleuronectidae, and is the only species of the genus Reinhardtius. It is a predatory fish that mostly ranges at depths between 500 and 1,000 m (1,600–3,300 ft), and is found in the cold northern Atlantic, northern Pacific, and Arctic Oceans.
The olive flounder, bastard halibut or Korean halibut is a temperate marine species of large-tooth flounder native to the North-western Pacific Ocean. It is the highest valued finfish in the world, known to be excellent for aquaculture due to a rapid growth rate and popularity in Korea.
Samaridae is a family of crested flounders, small flatfishes native to the Indo-Pacific. The family contains four genera with a total of 29 species.
The summer flounder or fluke is a marine flatfish that is found in the Atlantic Ocean off the East Coast of the United States and Canada. It is especially abundant in waters from North Carolina to Massachusetts.
Paralichthys lethostigma, the southern flounder, is a species of large-tooth flounder native to the East Coast of the United States and the northern Gulf of Mexico. It is a popular sport fish and is the largest and most commercially valuable flounder in the western North Atlantic Ocean and Gulf of Mexico. It is a "left-eyed flounder", meaning the left side is pigmented and is the "up side".
The Gulf flounder is a species of saltwater flounder.
Atherinopsis californiensis, the jack silverside or jacksmelt, is a species of neotropical silverside native to the Pacific coast of North America from Oregon, United States to southern Baja California, Mexico. This species grows to 45 cm (18 in) in total length, silver throughout the body, grey dorsal pattern, light silver ventral-lateral. Yellow spot present behind the eye, on operculum. and is important commercially as a source of human food. It is the only known member of its genus.
↑ MacNamara, R., Mankiewicz, J. L., Salger, S. A., Stuart, K., Borski, R. J., Godwin, J., & Drawbridge, M. (2024). Temperature regulates sex determination and growth in the paralichthid flatfish California halibut. Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, 341(7), 811–821. https://doi.org/10.1002/jez.2823
1 2 Alvarez-González, C.A., Cervantes-Trujano, M., Tovar-Ramírez, D. et al. Development of Digestive Enzymes in California Halibut Paralichthys californicus Larvae. Fish Physiol Biochem 31, 83–93 (2005). https://doi.org/10.1007/s10695-006-0003-8
1 2 3 Allen, L. (1985). Recruitment, Distribution, and Feeding Habits of Young-of-the-Year California Halibut (Paralichthys californicus) in the Vicinity of Alamitos Bay-Long Beach Harbor, California, 1983-1985. Department of Biology, California State University. External links
1 2 3 4 5 6 7 8 9 MacNamara, R., Mankiewicz, J. L., Salger, S. A., Stuart, K., Borski, R. J., Godwin, J., & Drawbridge, M. (2024). Temperature regulates sex determination and growth in the paralichthid flatfish California halibut. Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, 341(7), 811–821. https://doi.org/10.1002/jez.2823
1 2 Allen, L. (1985). Recruitment, Distribution, and Feeding Habits of Young-of-the-Year California Halibut (Paralichthys californicus) in the Vicinity of Alamitos Bay-Long Beach Harbor, California, 1983-1985. Department of Biology, California State University. External links
1 2 Conklin, D. E., Piedrahita, R. H., Merino, G. E., Muguet, J. B., Bush, D. E., Gisbert, E., … Cervantes-Trujano, M. (2004). Development of California Halibut, Paralichthys californicus, Culture. Journal of Applied Aquaculture, 14(3–4), 143–154. https://doi.org/10.1300/J028v14n03_11
1 2 3 Power, D., Einarsdottir, I., Pittman, K., Sweeney, G., & Hildahl, J. (2008). The Molecular and Endocrine Basis of Flatfish Metamorphosis.
↑ Madon, S. (2002). Ecophysiology of juvenile California halibut paralichthys californicus in relation to body size, water temperature and salinity. Marine Ecology Progress Series, 243, 235–249. https://doi.org/10.3354/meps243235
↑ Barnes, C. L., Starr, R., & Rielly, P. (2015). Growth, Mortality, and Reproductive Potential of California Halibut (Paralichthys Californicus) off Central California. https://doi.org/10.31979/etd.wd2a-vj4j
↑ Allen, M.J. 1990. The biological environment of the California halibut, Paralichthys californicus. Fish Bulletin (California Department of Fish and Game)
Miller, D.L. and R.N. Lea. 1972. Guide to the coastal marine fishes of California. Calif. Dept. Fish and Game, Fish Bull. 157. 299 p
Oda, D. 1991. Development of eggs and larvae of California halibut Paralichthys californicus and fantail sole Xystreurys liolepis (Pisces: Paralichthyidae). Fishery Bulletin, U.S. 89:387-402.
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