The Pacific jack mackerel (''Trachurus symmetricus''), also known as the Californian jack mackerel or simply jack mackerel, is an abundant

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military ...

fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...

in the jack family,

Carangidae The Carangidae are a family of ray-finned fish which includes the jacks, pompanos, jack mackerels, runners, and scads. It is the largest of the six families included within the order Carangiformes. Some authorities classify it as the only family ...

. It is distributed along the western coast of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

, ranging from

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...

in the north to the

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...

in the south, inhabiting both offshore and inshore environments. The Pacific jack mackerel is a moderately large fish, growing to a maximum recorded length of 81 cm, although commonly seen below 55 cm. It is very similar in appearance to other members of its genus, ''

Trachurus Jack mackerels or saurels are marine fish in the genus ''Trachurus'' of the family Carangidae. The name of the genus derives from the Greek words ''trachys'' ("rough") and ''oura'' ("tail"). Some species, such as ''T. murphyi'', are harvested in ...

'', especially '' T. murphyi'', which was once thought to be a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics ( morphology), but that can successfully interbreed. Not all specie ...

of ''T. symmetricus'', and inhabits waters further south. Pacific jack mackerel travel in large

schools A school is an educational institution designed to provide learning spaces and learning environments for the teaching of students under the direction of teachers. Most countries have systems of formal education, which is sometimes compulsor ...

, ranging up to 600 miles offshore and to depths of 400 m, generally moving through the upper part of the

water column A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...

Distribution and habitat

The Pacific jack mackerel is distributed through the eastern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the conti ...

from

in the north, south to the western North American seaboard to the Baja California peninsula in the

. It has been reported as far south as the

Galápagos Islands The Galápagos Islands ( Spanish: , , ) are an archipelago of volcanic islands. They are distributed on each side of the equator in the Pacific Ocean, surrounding the centre of the Western Hemisphere, and are part of the Republic of Ecuad ...

, but at these latitudes it would be sympatric with ''T. murphyi'', possibly resulting in confusion of the two species. Pacific jack mackerel occur in both

and

inshore A shore or a shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In physical oceanography, a shore is the wider fringe that is geologically modified by the action of the body of water pas ...

environments, often venturing up to 600 miles offshore and to known depths of 400 m. In more coastal environments, they are known to inhabit bays and very shallow waters.

Description

The Pacific jack mackerel is very similar to all other members of ''Trachurus'' and a number of other carangid genera, having an elongated, slightly compressed body with both the dorsal and ventral profiles of the body having the same degree of curvature. It is a medium-to-large-sized fish, growing to a maximum known length of 81 cm (32 in), although more commonly below 55 cm. The two separate

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

s are composed of eight spines and one spine followed by 31 to 35

soft rays Fish anatomy is the study of the form or morphology of fish. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish. In practice, fish anatomy and fish physiology ...

, respectively. The

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

is composed of two spines

anteriorly Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

detached followed by one spine connected to 26 to 30 soft rays. In some larger individuals, the last few rays at the posterior of the soft dorsal and anal fins are almost entirely separate from the rest of the fin, forming finlets. The

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

is strongly forked, typical amongst Carangidae, while the

ventral fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two ...

consists of one spine and five soft rays. The

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

terminates before the front of the anal fin, having 22 to 24 rays in total. The

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

dips strongly after the pectoral fin, having 50 to 53

scales Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number w ...

on the upper section and 43 to 52 keeled

scute A scute or scutum (Latin: ''scutum''; plural: ''scuta'' "shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of birds. The term is also used to describe the anterior po ...

s posteriorly. The species'

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, ...

are minute, with a patch of teeth on the

tongue The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by taste ...

in a narrow club-shaped strip. There are 24

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

in total. Pacific jack mackerel are metallic blue to olive-green dorsally, becoming more silvery ventrally, before transitioning to a white

belly Belly may refer to: Anatomy * The abdomen, the part of the body between the pelvis and the thorax; or the stomach ** A beer belly, an overhang of fat above the waist, presumed to be caused by regular beer drinking ** Belly dance * The fleshy, cent ...

. The top of the head and area near eye is quite dark with a dark spot on the upper rear of the gill cover. The fins are mostly

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

to dusky, although caudal fin may be yellow to reddish.

Relationship to humans

Pacific jack mackerel are fished commercially as well as for sport. They are often caught on baited hook from piers and boats, and also while salmon trolling. Commercial fishing occurs along the coast. Large individuals often move inshore and north in the summer. Pacific jack mackerel is canned in the same manner as salmon. Fish are cleaned, gutted and finned, then packed into cans with salt and water.

History

Before 1947, the pacific jack mackerel was of minor importance. It was referred to as the horse mackerel, and had little market appeal. However, in 1948, the

US Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

decided to allow the use of "jack mackerel" on all labeling, and that affected its appeal. The new label, combined with low catches of

Pacific sardine ''Sardinops'' is a monotypic genus of sardines of the family Clupeidae. The only member of the genus is ''Sardinops sagax''. It is found in the Indo-Pacific and East Pacific oceans. Its length is up to . It has numerous common or vernacular names ...

in 1947-48 and increased catches of pacific jack mackerel during the same time, resulted in the fish gaining importance. In the past, mackerel consumption was considered a sign of low income. In the segregated

American South The Southern United States (sometimes Dixie, also referred to as the Southern States, the American South, the Southland, or simply the South) is a geographic and cultural region of the United States of America. It is between the Atlantic Ocean ...

, it was often associated with African Americans. Today, most of these stereotypes are gone.

As food

Pacific jack mackerel tastes similar to

canned sardines Sardines ("pilchards") are a nutrient-rich, small, oily fish widely consumed by humans and as forage fish by larger fish species, seabirds and marine mammals. Sardines are a source of omega-3 fatty acids. Sardines are often served in cans, but c ...

. It may be used interchangeably with salmon or tuna in recipes. Jack mackerel is considered safer to consume than tuna because it is a smaller fish, and not a top predator, thus avoiding accumulation of heavy metals such as mercury.

Taxonomy and naming

The Pacific jack mackerel is classified within the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Trachurus'', commonly known as the horse mackerels or jack mackerels. ''Trachurus'' is part of the jack family Carangidae, which is classified within the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

Carangiformes Carangiformes is an order of the ray-finned fishes. The order is part of a clade which is a sister clade to the Ovalentaria, the other orders in the clade being Synbranchiformes, Anabantiformes, Istiophoriformes and Pleuronectiformes. The Carangi ...

. Recent

genetic studies Genetic analysis is the overall process of studying and researching in fields of science that involve genetics and molecular biology. There are a number of applications that are developed from this research, and these are also considered parts of ...

have divided the Carangidae into four subfamilies, with the genus ''Trachurus'' falling into

Caranginae Caranginae is a subfamily of ray-finned fish from the family Carangidae which consists of twenty genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In th ...

(or

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confl ...

Carangini), being most closely related to the 'scads' of the genera ''

Decapterus ''Decapterus'' is a genus of marine fishes of jack family, Carangidae, commonly known as mackerel scads, round scads, or horse mackerel. They are found throughout the world. Species Currently, 10 or 12 recognized species are found in this genus: ...

'' and '' Selar''. The species was first

scientifically described A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

William Orville Ayres William Orville Ayres (September 11, 1817 – April 30, 1887) was an American physician and ichthyologist. Born in Connecticut, he studied to become a doctor at Yale University School of Medicine. Life and career Ayers, the son of Jared an ...

in 1855 based on the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

specimen taken from

San Francisco Bay San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland. San Francisco Bay drains water f ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. He named the species ''

Caranx ''Caranx'' is a genus of tropical to subtropical marine fishes in the jack family Carangidae, commonly known as jacks, trevallies and kingfishes. They are moderate- to large-sized, deep-bodied fishes which are distinguished from other carangid g ...

symmetricus'', correctly identifying its relationship to the jacks, but incorporating it into what was later found to be the wrong genus. The fish was redescribed in 1944 under a different name, ''

polyaspis'', from a specimen caught in

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

, which under the ICZN rules classifies as a

junior synonym The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linn ...

, and it is therefore discarded. In 1983, ''C. symmetricus'' was transferred to ''Trachurus symmetricus'' by William N. Eschmeyer and Earl Herald. The species has twice been treated as a

; once as ''Trachurus picturatus symmetricus'' (a subspecies of the blue jack mackerel), and the second more commonly used subspecies of ''Trachurus symmetricus symmetricus''. For many years, the latter was accepted as a valid combination, with ''Trachurus symmetricus murphyi'' considered to be a southern subspecies

population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction usi ...

Mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

analysis has now confirmed these subspecies to be separate species, with ''T. s. murphyi'' now simply '' Trachurus murphyi'', the Inca scad. The

divergence In vector calculus, divergence is a vector operator that operates on a vector field, producing a scalar field giving the quantity of the vector field's source at each point. More technically, the divergence represents the volume density of ...

time of these two species was deemed relatively recent, at around 250,000 years ago. ''T. symmetricus'' is known commonly as the 'Pacific jack mackerel' in reference to its

distribution Distribution may refer to: Mathematics * Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations *Probability distribution, the probability of a particular value or value range of a vari ...

, with the species often called simply 'jack mackerel' or 'mackereljack'

References

External links

* {{Taxonbar, from=Q2626960 Pacific jack mackerel Western North American coastal fauna Fish of Mexican Pacific coast Taxa named by William Orville Ayres Pacific jack mackerel