Blue trevally
Encyclopedia
The blue trevally, Carangoides ferdau (also known as the banded trevally, barred trevally, Ferdau’s trevally and Forskaal’s jackfish) is a common widespread species
of pelagic marine
fish
classified in the jack family, Carangidae
. The blue trevally is distributed throughout the tropical and subtropical waters of the Indo-Pacific
and central Pacific
regions, ranging from South Africa
in the west to Hawaii
in the east. It is a moderately large fish, growing to a recorded maximum length of 70 cm, with the number of rays in the second dorsal fin
and the colouring serving as diagnostic features of the species. The species inhabits waters to depths of 60 m, generally inhabiting reef
s, beach
es, lagoon
s and sandy substrates. The blue trevally is a predatory fish, taking other fish, prawn
s, crab
s and molluscs, although very little is known of the species reproductive biology
. The blue trevally is of varying importance to fisheries throughout its range, with some regions having high catches of the fish. It is considered to be a gamefish, and is sought after for its excellent eating qualities.
, 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 described by the Swedish naturalist
Peter Forsskål
in 1775 based on a specimen taken from the Red Sea
. He named the species Scomber ferdau, thus relating it to the mackerels
before the family Carangidae was bought into existence with the creation of Lacepede
's genus Caranx
. With the advent of carangid taxonomy, the species was transferred first to Caranx and finally to Carangoides where it has remained to this day. Gilbert Percy Whitley
attempted to separate the species into its own genus; Ferdauia, although this classification is not accepted. The species was independently described and named a number of times after its initial naming, with this and confusion with Carangoides orthogrammus in the Indo-Pacific giving rise to a complex history of synonymies. These later names were often transferred between genera before being finally sunk into the name Carangoides ferdau and as such are considered to be invalid junior synonyms. The specific epithet
of ferdau refers to a person of the name 'Ferdau', probably the name of the collector of the holotype
specimen.
body, with the dorsal profile more convex than the ventral profile. Unlike most of the Carangoides however, the blue trevally’s snout is bluntly rounded, resembling the snouts of the pompanos of the genus Trachinotus and the lips of adults are notably fleshy. There are two separate dorsal fin
s, the first having 8 spines, while the second consists of 1 spine and 26 to 34 soft rays; more than any other species in Carangoides. In young adults, the lobe of the second dorsal fin is often falcate, but usually shorter than the head length. The anal fin has 2 anteriorly detached spines followed by a single spine attached to 21 to 26 soft rays, while the pelvic fin has 1 spine attached to 20 or 21 soft rays. The lateral line
has a gentle anterior arch, with the with junction of the curved and straight sections vertically below the fifteenth to twentieth soft rays of the second dorsal fin. The curved section of the lateral line contains 82 to 90 scales
, while the straight section has 12 to 17 scales and 26 to 31 scute
s. The breast is naked ventrally to origin of the pelvic fins and the base of the pectoral fins, but is interrupted laterally by a moderate band of scales. The upper jaw is highly protractile, containing narrow bands of villiform teeth, which become obsolescent with age, as is the case in the lower jaw
. There are a total of 24 to 29 gill raker
s and 24 vertebrae.
The body is a blue green to yellow green colour above, becoming silvery below, with adults having 5 or 6 dusky vertical bands which usually persist after death. There are numerous, inconspicuous golden spots often present on the sides, mostly above the level of the pectoral fins. The soft dorsal and anal fins are pale yellowish green, and the anterior lobes of both often have white to blue tips. The caudal fin is yellow green, having a dark trailing edge and tips, while the pelvic fins are whitish to hyaline
.
, West Pacific and Central Pacific
Oceans. It ranges from South Africa
in the west, north along the east Africa
n coast to the Red Sea and across to India
and South East Asia. The species ranges south to Australia
and Indonesia
, and as far as Japan
, Hawaii
and a number of Pacific island including Micronesia
, New Caledonia
and Tonga
.
The blue trevally prefers coastal waters to a depth of 60 m, where it inhabits reef
s, beach
es, lagoon
s and deeper sandy substrates. The fish is reported to prefer waters adjacent to sandy beaches. The species lives pelagically, allowing movement between islands and atoll
s. The species is rarely found in estuaries, suggesting a poor tolerance to low salinities.
of the blue trevally is poorly known, with the only data on the species relating to its diet. The blue trevally is a fast swimming predator which often forms small schools
, and takes a variety of small fish (specifically mackerel
and filefish
), crustaceans including prawns, crabs and sea lice
, soft molluscs and other soft prey. In Hawaii, they have been observed following foraging bonefish
or goatfish
, consuming any scraps uncovered by the foragers. The species appear to be in constant abundance all year, but ripe individuals have rarely been reported. No information regarding the reproduction and growth of the species is available, although it is known that larva
e of the species appear during February in the waters off Taiwan, suggesting a December spawning
period, and make up a high proportion of the larval abundance. Juveniles are known to sometimes shelter among the tentacles of large pelagic jellyfish
.
The species is of commercial importance
in a number of areas due to its high abundance, or more often taken as bycatch in other major fisheries. Catch statistics for the individual species are rarely kept though, and it is generally grouped with other trevallies. It is caught mainly on hook and line, as well as with gill nets and various traps. In South Africa, it is considered a popular gamefish, and is often taken by anglers using various small baits, with the best catches had at dawn and dusk. It is considered to be an excellent table fish, although there have been rare reports of ciguatera
poisoning attributed to this fish.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of pelagic marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
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...
classified 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 blue trevally is distributed throughout the tropical and subtropical 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...
regions, 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. It is a moderately large fish, growing to a recorded maximum length of 70 cm, with the number of rays in the second 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...
and the colouring serving as diagnostic features of the species. The species inhabits waters to depths of 60 m, generally inhabiting reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s, 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...
es, lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
s and sandy substrates. The blue trevally is a predatory fish, taking other fish, prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
s, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s and molluscs, although very little is known of the species reproductive biology
Reproductive biology
Reproductive biology is a study mainly involving the reproductive system and sex organs. It is closely related to reproductive endocrinology and infertility. also is miotosis and miosis...
. The blue trevally is of varying importance to fisheries throughout its range, with some regions having high catches of the fish. It is considered to be a gamefish, and is sought after for its excellent eating qualities.
Taxonomy and naming
The blue 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 described by the Swedish naturalist
Naturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...
Peter Forsskål
Peter Forsskål
Peter Forsskål, sometimes spelled Pehr Forsskål, Peter Forskaol, Petrus Forskål or Pehr Forsskåhl, was a Swedish explorer, orientalist, naturalist and an apostle of Carl Linnaeus.-Early life:...
in 1775 based on a specimen taken from the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
. He named the species Scomber ferdau, thus relating it to the mackerels
Scomber
Scomber is a genus of ocean-dwelling mackerels in the family Scombridae.-Species:FishBase lists four species:* Blue mackerel, Scomber australasicus Cuvier, 1832.* Atlantic Chub Mackerel, Scomber colias Gmelin, 1789....
before the family Carangidae was bought into existence with the creation of Lacepede
Lacepede
Lacepede can refer to:* Bernard Germain Étienne de la Ville, Comte de Lacépède , French naturalist and politician.* Jean de La Ceppède , French poet.* Rue Lacépède, a street in Paris...
's genus Caranx
Caranx
Caranx is a genus of tropical to subtropical marine fish 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 genera by specific gill raker, fin ray and dentition...
. With the advent of carangid taxonomy, the species was transferred first to Caranx and finally to Carangoides where it has remained to this day. Gilbert Percy Whitley
Gilbert Percy Whitley
Gilbert Percy Whitley was a British-born Australian ichthyologist and malacologist who was Curator of Fishes at the Australian Museum in Sydney for about 40 years. He was born at Swaythling, Southampton, England, and was educated at King Edward VI School, Southampton and Osborne House...
attempted to separate the species into its own genus; Ferdauia, although this classification is not accepted. The species was independently described and named a number of times after its initial naming, with this and confusion with Carangoides orthogrammus in the Indo-Pacific giving rise to a complex history of synonymies. These later names were often transferred between genera before being finally sunk into the name Carangoides ferdau and as such are considered to be invalid junior synonyms. The specific epithet
Epithet
An epithet or byname is a descriptive term accompanying or occurring in place of a name and having entered common usage. It has various shades of meaning when applied to seemingly real or fictitious people, divinities, objects, and binomial nomenclature. It is also a descriptive title...
of ferdau refers to a person of the name 'Ferdau', probably the name of the collector of 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...
specimen.
Description
The blue trevally is a moderately large fish, growing to a recorded maximum length of 70 cm and a weight of 8 kg. The species is similar in general morphology to a number of other trevallies in the genus Carangoides, having a compressed, oblongRectangle
In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles. The term "oblong" is occasionally used to refer to a non-square rectangle...
body, with the dorsal profile more convex than the ventral profile. Unlike most of the Carangoides however, the blue trevally’s snout is bluntly rounded, resembling the snouts of the pompanos of the genus Trachinotus and the lips of adults are notably fleshy. 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 8 spines, while the second consists of 1 spine and 26 to 34 soft rays; more than any other species in Carangoides. In young adults, the lobe of the second dorsal fin is often falcate, but usually shorter than the head length. The anal fin has 2 anteriorly detached spines followed by a single spine attached to 21 to 26 soft rays, while the pelvic fin has 1 spine attached to 20 or 21 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 gentle anterior arch, with the with junction of the curved and straight sections vertically below the fifteenth to twentieth soft rays of the second dorsal fin. The curved section of the lateral line contains 82 to 90 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...
, while the straight section has 12 to 17 scales and 26 to 31 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 naked ventrally to origin of the pelvic fins and the base of the pectoral fins, but is interrupted laterally by a moderate band of scales. The upper jaw is highly protractile, containing narrow bands of villiform teeth, which become obsolescent with age, as is the case in the lower 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...
. There are a total of 24 to 29 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 and 24 vertebrae.
The body is a blue green to yellow green colour above, becoming silvery below, with adults having 5 or 6 dusky vertical bands which usually persist after death. There are numerous, inconspicuous golden spots often present on the sides, mostly above the level of the pectoral fins. The soft dorsal and anal fins are pale yellowish green, and the anterior lobes of both often have white to blue tips. The caudal fin is yellow green, having a dark trailing edge and tips, while the pelvic fins are whitish to hyaline
Hyaline
The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...
.
Distribution and habitat
The blue trevally has a wide distribution, inhabiting the tropical and subtropical waters of the IndianIndian 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...
, West Pacific and Central Pacific
Central Pacific
Central Pacific can refer to:* The Central Pacific Railroad, the western part of the Transcontinental Railroad in the United States* The Central Pacific Area, a subdivision of the Pacific Ocean Areas in World War II...
Oceans. It ranges 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, north along the east Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
n coast to the Red Sea and across to India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and South East Asia. The species ranges south to 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 Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, and as far as 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...
, 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 a number of Pacific island including Micronesia
Micronesia
Micronesia is a subregion of Oceania, comprising thousands of small islands in the western Pacific Ocean. It is distinct from Melanesia to the south, and Polynesia to the east. The Philippines lie to the west, and Indonesia to the southwest....
, New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
and Tonga
Tonga
Tonga, officially the Kingdom of Tonga , is a state and an archipelago in the South Pacific Ocean, comprising 176 islands scattered over of ocean in the South Pacific...
.
The blue trevally prefers coastal waters to a depth of 60 m, where it inhabits reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s, 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...
es, lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
s and deeper sandy substrates. The fish is reported to prefer waters adjacent to sandy beaches. The species lives pelagically, allowing movement between islands and atoll
Atoll
An atoll is a coral island that encircles a lagoon partially or completely.- Usage :The word atoll comes from the Dhivehi word atholhu OED...
s. The species is rarely found in estuaries, suggesting a poor tolerance to low salinities.
Biology and fishery
Like many Indo-Pacific carangids, the biology and ecologyEcology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
of the blue trevally is poorly known, with the only data on the species relating to its diet. The blue trevally is a fast swimming predator which often forms small schools
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
, and takes a variety of small fish (specifically mackerel
Mackerel
Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. They may be found in all tropical and temperate seas. Most live offshore in the oceanic environment but a few, like the Spanish mackerel , enter bays and can be...
and filefish
Filefish
Filefish are tropical to subtropical tetraodontiform marine fish of the diverse family Monacanthidae. Found in the Atlantic, Pacific and Indian Oceans, the filefish family contains approximately 107 species in 26 genera...
), crustaceans including prawns, crabs and sea lice
Sea lice
The sea louse is a copepod within the order Siphonostomatoida, family Caligidae. There are 36 genera within this family which include approximately 42 Lepeophtheirus and 300 Caligus species...
, soft molluscs and other soft prey. In Hawaii, they have been observed following foraging bonefish
Bonefish
The bonefish is the type species of the Albulidae family, or bonefishes in order Albuliformes. It is amphidromous, living in inshore tropical waters, moving onto shallow mudflats to feed with the incoming tide, and retreating to deeper water as the tide ebbs...
or goatfish
Goatfish
Goatfishes are tropical marine perciform fish of the family Mullidae. Seldom found in brackish waters, goatfish are most associated with the reefs of the Atlantic, Indian, and Pacific Oceans...
, consuming any scraps uncovered by the foragers. The species appear to be in constant abundance all year, but ripe individuals have rarely been reported. No information regarding the reproduction and growth of the species is available, although it is known that larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e of the species appear during February in the waters off Taiwan, suggesting a December 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...
period, and make up a high proportion of the larval abundance. Juveniles are known to sometimes shelter among the tentacles of large pelagic jellyfish
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
.
The species is of commercial importance
Fishery
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,...
in a number of areas due to its high abundance, or more often taken as bycatch in other major fisheries. Catch statistics for the individual species are rarely kept though, and it is generally grouped with other trevallies. It is caught mainly on hook and line, as well as with gill nets and various traps. In South Africa, it is considered a popular gamefish, and is often taken by anglers using various small baits, with the best catches had at dawn and dusk. It is considered to be an excellent table fish, although there have been rare reports of ciguatera
Ciguatera
Ciguatera is a foodborne illness caused by eating certain reef fishes whose flesh is contaminated with toxins originally produced by dinoflagellates such as Gambierdiscus toxicus which lives in tropical and subtropical waters. These dinoflagellates adhere to coral, algae and seaweed, where they are...
poisoning attributed to this fish.