Whitefin trevally
Encyclopedia
The whitefin trevally, Carangoides equula (also known as the horse trevally) is a species of deep water offshore
fish
in the jack family Carangidae
. The species inhabits the tropical to temperate waters of the Indo-pacific
and Central Pacific
, ranging from South Africa
in the west to Hawaii
in the east. The whitefin trevally is a moderate sized fish, growing to 37 cm, and is distinguished by a number of morphological traits including fin size, gill raker
count and colour. It inhabits the continental shelf
and slope at depths of up to 200 m over sand and mud substrates
where it preys on fish, crustacean
s and cephalopod
s. Studies in Japan
indicate a length at sexual maturity
of 17.4 cm on average, with spawning
occurring between May and October, with each individual spawning multiple times. Whitefin trevally is of high importance to fisheries in Japan where they are taken by trawlers, although the catch numbers have halved since the 1980s. It is of minor importance elsewhere throughout its range, and is considered a good table fish.
, a group of fish commonly known as jacks and trevallies. Carangoides falls into the jack and horse mackerel family Carangidae
, itself part the order Perciformes
, in the suborder Percoidei
.
The species was first scientifically described by Dutch naturalist
s Coenraad Jacob Temminck
and Hermann Schlegel
in 1844 based on a specimen taken from the waters off Japan, which was designated to be the holotype
. They named the species Caranx equula, although the species was later moved to Carangoides, as well as having a new genus created for it; Kaiwarinus. This genus is currently considered invalid, even though a 1988 review of the phylogeny of the Carangidae found it to be valid, and to be the sister genus to Pseudocaranx, not closely related to Carangoides. The species was independently renamed as Carangoides acutus in 1974, but this is rejected as a junior synonym under ICZN
nomenclature rules.
Specimens taken from Hawaii
and Easter Island
in the Pacific Ocean initially had the name Caranx (Carangoides) dasson applied to them by the American ichthyologist David Starr Jordan
and Snyder. This name was eventually synonymised
with Carangoides equula, but uncertainty still remains whether this population actually represents a separate species or subspecies
. The Carangoides dasson population has the same diagnostic features as Carangoides equula, but exhibit more slender bodies and larger eyes, with William Vaniz-Smith indicating more research is required to determine the relationship between these populations. The name Caranx (Carangoides) dasson is still currently considered to be invalid by taxonomic authorities.
in the species are almost straight. There are two separate dorsal fin
s, the first having 7 spines, while the second consists of 1 spine and 23 to 25 soft rays. The first dorsal fin is moderately high, with the longest spine approximately has high as the soft dorsal-fin lobe is long, and is quite distinctive of the species. The anal fin consists of 2 anteriorly detached spines followed by 1 spine and 21 to 24 soft rays, with the pelvic fin having one spine and 18 or 19 soft rays. The lateral line
has a moderately strong anterior arch with the junction of the curved and straight sections occurring vertically below the twelfth to fifteenth soft rays of the second dorsal fin. The curved segment of the lateral line is longer than the straight section, which contains 0 to 6 scales
followed by 22 to 32 scute
s. The breast is entirely scaled, or has a very small naked area anteroventrally. Both jaw
s contain narrow bands of small teeth, with the outer teeth slightly larger. There are 27 to 32 gill raker
s in total and 24 vertebrae.
The whitefin trevally is silver, with a blue to green dorsal surface, becoming silvery white below. The soft dorsal and anal fins are dusky yellow basally, with the anterior rays of both having dark grey-brown median and white distal bands. The caudal fin is dusky yellow, while the pectoral and pelvic fins are white. Juveniles have between 5 and 7 dark bands vertically on their sides.
waters Indo-Pacific
region, although has a very patchily recorded distribution. In the western Indian Ocean
, the species has only been recorded from South Africa
, Somalia
and in the Gulf of Oman
. In the eastern Indian Ocean, the species is known from north western Australia
, and definitely extends its distribution into the Pacific as far as Okinawa, Japan. If Carangoides dasson is synonymous with Carangoides equula, this extends the species distribution well into the Pacific, ranging to Hawaii and Easter Island. Before the species was recorded in Australia in 1988, the whitefin trevally was thought to only have an anti-tropical distribution. The fish probably has a more continuous distribution than currently known, with lack of adequate sampling
contributiong the patchily known distribution.
The whitefin trevally is thought to primarily inhabit deep waters on the continental shelf
and slope between 90 and 200 m deep over sand
y and mud
dy substrates. There has been at least one record of the species in shallow inshore waters, where an individual was captured off a sandy beach
on Japan, but thought to be stray fish.
s and cephalopod
s, either by foraging
or chasing down its prey using its eyes which are extremely well adapted to the deep, low light waters. Along with the white trevally
, Pseudocaranx dentex, it is the only member of the Carangidae to have the anatomy of its eyes examined, with the study finding excellent dark environment sight due to the presence of a tapetum
.
The maturation and reproduction of the whitefin trevally have been extensively studied off Japan
due to the species economic importance in this region. Sexual maturity
is reached at a minimum length of 15.1 cm, although most individuals reach maturity at around 17.4 cm length and every individual is mature by 24 cm. Although these parameters were calculated for female fish, observational data suggests the male life history is similar. In Japan, the species has a prolonged spawning
season running from May to October, during which females spawn repeatedly, releasing between 13,862 and 79,899 eggs
per batch. The growth of males and females is very similar, and both have a similar lifespan. A length of 7.5 cm is reached after the first year, and lengths of 12.3 cm, 16.0 cm and 18.8 cm after the second, third and fourth years respectively.
species in the waters off Japan, where it is known as , and of minor importance elsewhere throughout its range. For unknown reasons, the Japanese catch has decreased by half since the mid 1980s. It is taken primarily by bottom trawls on the continental shelf and considered to be a good table fish.
Shore
A shore or 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 past and present, while the beach is at the edge of the shore,...
fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
in the jack family Carangidae
Carangidae
Carangidae is a family of fish which includes the jacks, pompanos, jack mackerels, and scads.They are marine fish found in the Atlantic, Indian and Pacific Oceans...
. The species inhabits the tropical to temperate waters of the Indo-pacific
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
and Central Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, ranging from South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
in the west to Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
in the east. The whitefin trevally is a moderate sized fish, growing to 37 cm, and is distinguished by a number of morphological traits including fin size, gill raker
Gill raker
Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch and are involved with filter feeding tiny prey. They are not to be confused with the gill filaments that compose the bony part of the gill. Rakers are usually present in two rows, projecting from both the...
count and colour. It inhabits the continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
and slope at depths of up to 200 m over sand and mud substrates
Substrate (marine biology)
Stream substrate is the material that rests at the bottom of a stream. There are several classification guides. One is:*Mud – silt and clay.*Sand – Particles between 0.06 and 2 mm in diameter.*Granule – Between 2 and 4 mm in diameter....
where it preys on fish, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s. Studies in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
indicate a length at sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
of 17.4 cm on average, with spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
occurring between May and October, with each individual spawning multiple times. Whitefin trevally is of high importance to fisheries in Japan where they are taken by trawlers, although the catch numbers have halved since the 1980s. It is of minor importance elsewhere throughout its range, and is considered a good table fish.
Taxonomy and naming
The whitefin trevally is classified within the genus CarangoidesCarangoides
Carangoides is a genus of tropical to subtropical marine fishes in the jack family, Carangidae. They are small to large sized, deep bodied fish characterised by a certain gill raker and jaw morphology, often appearing very similar to jacks in the genus Caranx...
, a group of fish commonly known as jacks and trevallies. Carangoides falls into the jack and horse mackerel family Carangidae
Carangidae
Carangidae is a family of fish which includes the jacks, pompanos, jack mackerels, and scads.They are marine fish found in the Atlantic, Indian and Pacific Oceans...
, itself part the order Perciformes
Perciformes
The Perciformes, also called the Percomorphi or Acanthopteri, is one of the largest orders of vertebrates, containing about 40% of all bony fish. Perciformes means perch-like. They belong to the class of ray-finned fish and comprise over 7,000 species found in almost all aquatic environments...
, in the suborder Percoidei
Percoidei
Percoidei is one of eighteen suborders of bony fish in the order Perciformes. Many commercially harvested fish species are contained in this suborder, including the snappers, jacks, whitings, groupers, bass, perches and porgies.-Divisions:...
.
The species was first scientifically described by Dutch naturalist
Naturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...
s Coenraad Jacob Temminck
Coenraad Jacob Temminck
Coenraad Jacob Temminck was a Dutch aristocrat and zoologist.Temminck was the first director of the National Natural History Museum at Leiden from 1820 until his death. His Manuel d'ornithologie, ou Tableau systematique des oiseaux qui se trouvent en Europe was the standard work on European birds...
and Hermann Schlegel
Hermann Schlegel
Hermann Schlegel was a German ornithologist and herpetologist.-Early life and education:Schlegel was born at Altenburg, the son of a brassfounder. His father collected butterflies, which stimulated Schlegel's interest in natural history...
in 1844 based on a specimen taken from the waters off Japan, which was designated to be the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
. They named the species Caranx equula, although the species was later moved to Carangoides, as well as having a new genus created for it; Kaiwarinus. This genus is currently considered invalid, even though a 1988 review of the phylogeny of the Carangidae found it to be valid, and to be the sister genus to Pseudocaranx, not closely related to Carangoides. The species was independently renamed as Carangoides acutus in 1974, but this is rejected as a junior synonym under ICZN
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
nomenclature rules.
Specimens taken from Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
and Easter Island
Easter Island
Easter Island is a Polynesian island in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian triangle. A special territory of Chile that was annexed in 1888, Easter Island is famous for its 887 extant monumental statues, called moai, created by the early Rapanui people...
in the Pacific Ocean initially had the name Caranx (Carangoides) dasson applied to them by the American ichthyologist David Starr Jordan
David Starr Jordan
David Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...
and Snyder. This name was eventually synonymised
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
with Carangoides equula, but uncertainty still remains whether this population actually represents a separate species or subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
. The Carangoides dasson population has the same diagnostic features as Carangoides equula, but exhibit more slender bodies and larger eyes, with William Vaniz-Smith indicating more research is required to determine the relationship between these populations. The name Caranx (Carangoides) dasson is still currently considered to be invalid by taxonomic authorities.
Description
The whitefin trevally is a relatively small fish, reaching a maximum known length of 37.5 cm. The species has a body shape similar to a number of other jacks, having a compressed almost rhomboidal body, with the dorsal and ventral profiles approximately equally convex. The dorsal profiles of the snout and napeNape
The nape is the back of the neck. In technical anatomical/medical terminology, the nape is referred to by the word nucha, which also gives the adjective corresponding to "nape" in English, "nuchal"....
in the species are almost straight. There are two separate dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
s, the first having 7 spines, while the second consists of 1 spine and 23 to 25 soft rays. The first dorsal fin is moderately high, with the longest spine approximately has high as the soft dorsal-fin lobe is long, and is quite distinctive of the species. The anal fin consists of 2 anteriorly detached spines followed by 1 spine and 21 to 24 soft rays, with the pelvic fin having one spine and 18 or 19 soft rays. The lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
has a moderately strong anterior arch with the junction of the curved and straight sections occurring vertically below the twelfth to fifteenth soft rays of the second dorsal fin. The curved segment of the lateral line is longer than the straight section, which contains 0 to 6 scales
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...
followed by 22 to 32 scute
Scute
A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...
s. The breast is entirely scaled, or has a very small naked area anteroventrally. Both jaw
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...
s contain narrow bands of small teeth, with the outer teeth slightly larger. There are 27 to 32 gill raker
Gill raker
Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch and are involved with filter feeding tiny prey. They are not to be confused with the gill filaments that compose the bony part of the gill. Rakers are usually present in two rows, projecting from both the...
s in total and 24 vertebrae.
The whitefin trevally is silver, with a blue to green dorsal surface, becoming silvery white below. The soft dorsal and anal fins are dusky yellow basally, with the anterior rays of both having dark grey-brown median and white distal bands. The caudal fin is dusky yellow, while the pectoral and pelvic fins are white. Juveniles have between 5 and 7 dark bands vertically on their sides.
Distribution and habitat
The whitefin trevally is distributed throughout the tropical and temperateTemperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
waters Indo-Pacific
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
region, although has a very patchily recorded distribution. In the western Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
, the species has only been recorded from South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, Somalia
Somalia
Somalia , officially the Somali Republic and formerly known as the Somali Democratic Republic under Socialist rule, is a country located in the Horn of Africa. Since the outbreak of the Somali Civil War in 1991 there has been no central government control over most of the country's territory...
and in the Gulf of Oman
Gulf of Oman
The Gulf of Oman or Sea of Oman is a strait that connects the Arabian Sea with the Strait of Hormuz, which then runs to the Persian Gulf. It is generally included as a branch of the Persian Gulf, not as an arm of the Arabian Sea. On the north coast is Pakistan and Iran...
. In the eastern Indian Ocean, the species is known from north western Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, and definitely extends its distribution into the Pacific as far as Okinawa, Japan. If Carangoides dasson is synonymous with Carangoides equula, this extends the species distribution well into the Pacific, ranging to Hawaii and Easter Island. Before the species was recorded in Australia in 1988, the whitefin trevally was thought to only have an anti-tropical distribution. The fish probably has a more continuous distribution than currently known, with lack of adequate sampling
Sample (statistics)
In statistics, a sample is a subset of a population. Typically, the population is very large, making a census or a complete enumeration of all the values in the population impractical or impossible. The sample represents a subset of manageable size...
contributiong the patchily known distribution.
The whitefin trevally is thought to primarily inhabit deep waters on the continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
and slope between 90 and 200 m deep over sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
y and mud
Mud
Mud is a mixture of water and some combination of soil, silt, and clay. Ancient mud deposits harden over geological time to form sedimentary rock such as shale or mudstone . When geological deposits of mud are formed in estuaries the resultant layers are termed bay muds...
dy substrates. There has been at least one record of the species in shallow inshore waters, where an individual was captured off a sandy beach
Beach
A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...
on Japan, but thought to be stray fish.
Biology
The whitefin trevally is a benthic predator, taking a variety of small fish, crustaceanCrustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s, either by foraging
Foraging
- Definitions and significance of foraging behavior :Foraging is the act of searching for and exploiting food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce...
or chasing down its prey using its eyes which are extremely well adapted to the deep, low light waters. Along with the white trevally
White trevally
White trevally, Pseudocaranx dentex, is a jack of the family Carangidae widespread in tropical and warm temperate areas between 40°N and 47°S, in the Atlantic, Mediterranean, Indian and Pacific Oceans. It has a deep body, and a greenish colour with metallic overtones and a dark spot above the...
, Pseudocaranx dentex, it is the only member of the Carangidae to have the anatomy of its eyes examined, with the study finding excellent dark environment sight due to the presence of a tapetum
Tapetum lucidum
The tapetum lucidum is a layer of tissue in the eye of many vertebrate animals....
.
The maturation and reproduction of the whitefin trevally have been extensively studied off Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
due to the species economic importance in this region. Sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
is reached at a minimum length of 15.1 cm, although most individuals reach maturity at around 17.4 cm length and every individual is mature by 24 cm. Although these parameters were calculated for female fish, observational data suggests the male life history is similar. In Japan, the species has a prolonged spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
season running from May to October, during which females spawn repeatedly, releasing between 13,862 and 79,899 eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
per batch. The growth of males and females is very similar, and both have a similar lifespan. A length of 7.5 cm is reached after the first year, and lengths of 12.3 cm, 16.0 cm and 18.8 cm after the second, third and fourth years respectively.
Relationship to humans
The whitefin trevally is a commercially importantFishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
species in the waters off Japan, where it is known as , and of minor importance elsewhere throughout its range. For unknown reasons, the Japanese catch has decreased by half since the mid 1980s. It is taken primarily by bottom trawls on the continental shelf and considered to be a good table fish.