Blackfin scad
Encyclopedia
The blackfin scad, Alepes melanoptera, (also known as the shortfinned trevally and Chinese trevally) is a species of tropical marine
fish
of the jack family Carangidae
. The species inhabits inshore waters throughout the Indo-Pacific
region, although is rare in the western Indian Ocean. It is not a large species, with the largest reported capture being 25 cm, and it is distinguished readily from similar species by the prominent black dorsal fin
. It is a predator which feeds on plankton
ic crustacean
s, but little else is known of its biology. The blackfin scad is a minor food fish throughout its range, and is highly valued in Cambodia
and Thailand
.
. The Carangidae are perciform fish in the suborder Percoidei
.
The species was first scientifically described by the English naturalist
William John Swainson under the name of Trachinus melanoptera, placing the species in a new genus which was found to be already in use by an unrelated species of fish. The species was therefore subsequently placed in the new combination of Alepes melanoptera, becoming the type species
of the new genus Alepes. After Swainson's initial description, Pieter Bleeker
unknowingly redescribed the species as Selar malam, a name which was revised three times before it too was assigned to Alepes. The species was redescribed twice more by Day in 1876 and Chu and Chen in 1958. Being Swainson is the first author to correctly describe the fish, even though he initially ascribed it to the wrong genus, the ICZN
recognises Alepes melanoptera as the correct name, and the rest as invalid junior synonyms. Such synonymy is common in the genus Alepes due to the abundance of similar genera. The specific name 'melanoptera' literally means 'black wing' in Greek; a reference to its distinctive colouration.
. The species has a tendency, like other carangids, to become more elongated with age, thus changing their body proportions slightly. It has an oblong, compressed body with dorsal and ventral profiles that are nearly equally convex in shape. The nose somewhat blunter than others in the genus, and has a mouth full of numerous comb like teeth. Like other members of Alepes, it has an adipose eyelid which is well developed only on the posterior section of the eye. The dorsal fin is split into two sections like in all of the Carangidae, the first with 7 or 8 spines and the second with one spine followed by 23 to 26 soft rays. The anal fin consists of two detached spines followed by a single spine and 18 to 21 soft rays, with both the anal and dorsal fins have a low profile. The pectoral fin is falcate and extends to beyond the junction of the curved and straight sections of the lateral line
. The lateral line itself is strongly arched anteriorally, with the curved and straight sections of the line intersecting just after the commencement of the spinous dorsal fin. The curved section of the lateral line holds 31 to 50 scales
and up to 2 scute
s, while the straight section holds up to 4 scales and 49 to 69 scutes. The gill raker
s number 24 to 30 and the species has 24 vertebrae. The blackfin scad has a maximum known length of 25 cm.
The upper body of the fish is silvery blue above grading to a silvery white below with a diffuse black spot. The membranes of the first, spinous dorsal fin are black, giving the species its common name. All other fins are pale to hyaline
with the exception of the caudal fin which is a dusky yellow with darker edges.
region. The species has been recorded as far west as the Persian Gulf
(Kuwait) and has a seemingly sparse distribution in the western Indian Ocean
up to India
and Sri Lanka
. It is common around the Asia
n coast, Malaysia, Thailand
, Philippines and as far south as Indonesia
. The northernmost captures have been made in Okinawa, Japan and a specimen has also been collected off Taiwan
. The species frequents inshore habitats, not found in the open ocean.
predator, consuming a variety of pelagic shrimp
s, prawn
s and copepod
s.
The species is caught mainly by hook and line methods but is not considered a major commercial species
in any regions. Despite this, the fish is highly esteemed in Cambodia
and Thailand, where it is fried
, steamed
or baked
. It may also be salted
or dried
.
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
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...
of 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 inshore waters throughout 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...
region, although is rare in the western Indian Ocean. It is not a large species, with the largest reported capture being 25 cm, and it is distinguished readily from similar species by the prominent black 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...
. It is a predator which feeds on plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
ic 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, but little else is known of its biology. The blackfin scad is a minor food fish throughout its range, and is highly valued in Cambodia
Cambodia
Cambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...
and Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
.
Taxonomy and naming
The blackfin scad is one of five species in the scad genus Alepes, which is one of 33 genera of the jack family, CarangidaeCarangidae
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 Carangidae are perciform fish 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 the English naturalist
Naturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...
William John Swainson under the name of Trachinus melanoptera, placing the species in a new genus which was found to be already in use by an unrelated species of fish. The species was therefore subsequently placed in the new combination of Alepes melanoptera, becoming the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the new genus Alepes. After Swainson's initial description, Pieter Bleeker
Pieter Bleeker
Pieter Bleeker was a Dutch medical doctor and ichthyologist, famous for his work on the fishes of East Asia – Atlas Ichthyologique des Orientales Neerlandaises – which was published 1862–1877....
unknowingly redescribed the species as Selar malam, a name which was revised three times before it too was assigned to Alepes. The species was redescribed twice more by Day in 1876 and Chu and Chen in 1958. Being Swainson is the first author to correctly describe the fish, even though he initially ascribed it to the wrong genus, the 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...
recognises Alepes melanoptera as the correct name, and the rest as invalid junior synonyms. Such synonymy is common in the genus Alepes due to the abundance of similar genera. The specific name 'melanoptera' literally means 'black wing' in Greek; a reference to its distinctive colouration.
Description
The blackfin scad has a body profile very similar to that of the other round scads of the genus Alepes, in particular to Alepes apercna, but can be distinguished quite easily by the prominent black colouration of the dorsal finDorsal 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...
. The species has a tendency, like other carangids, to become more elongated with age, thus changing their body proportions slightly. It has an oblong, compressed body with dorsal and ventral profiles that are nearly equally convex in shape. The nose somewhat blunter than others in the genus, and has a mouth full of numerous comb like teeth. Like other members of Alepes, it has an adipose eyelid which is well developed only on the posterior section of the eye. The dorsal fin is split into two sections like in all of the Carangidae, the first with 7 or 8 spines and the second with one spine followed by 23 to 26 soft rays. The anal fin consists of two detached spines followed by a single spine and 18 to 21 soft rays, with both the anal and dorsal fins have a low profile. The pectoral fin is falcate and extends to beyond the junction of the curved and straight sections of 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...
. The lateral line itself is strongly arched anteriorally, with the curved and straight sections of the line intersecting just after the commencement of the spinous dorsal fin. The curved section of the lateral line holds 31 to 50 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...
and up to 2 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, while the straight section holds up to 4 scales and 49 to 69 scutes. The 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 number 24 to 30 and the species has 24 vertebrae. The blackfin scad has a maximum known length of 25 cm.
The upper body of the fish is silvery blue above grading to a silvery white below with a diffuse black spot. The membranes of the first, spinous dorsal fin are black, giving the species its common name. All other fins are pale 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...
with the exception of the caudal fin which is a dusky yellow with darker edges.
Distribution and habitat
The blackfin scad is distributed throughout parts of the tropical and subtropical Indo-PacificIndo-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. The species has been recorded as far west as the Persian Gulf
Persian Gulf
The Persian Gulf, in Southwest Asia, is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.The Persian Gulf was the focus of the 1980–1988 Iran-Iraq War, in which each side attacked the other's oil tankers...
(Kuwait) and has a seemingly sparse 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...
up 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 Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
. It is common around the Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
n coast, Malaysia, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
, Philippines and as far south as 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...
. The northernmost captures have been made in Okinawa, Japan and a specimen has also been collected off Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
. The species frequents inshore habitats, not found in the open ocean.
Biology and fisheries
The biology and ecology of the blackfin scad are poorly studied, although the diet of the species is known. The species is a planktivorousPlankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
predator, consuming a variety of pelagic shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
s, 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 and copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
s.
The species is caught mainly by hook and line methods but is not considered a major commercial species
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 any regions. Despite this, the fish is highly esteemed in Cambodia
Cambodia
Cambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...
and Thailand, where it is fried
Frying
Frying is the cooking of food in oil or another fat, a technique that originated in ancient Egypt around 2500 BC. Chemically, oils and fats are the same, differing only in melting point, but the distinction is only made when needed. In commerce, many fats are called oils by custom, e.g...
, steamed
Steaming
Steaming is a method of cooking using steam. Steaming is considered a healthy cooking technique and capable of cooking almost all kinds of food.-Method:...
or baked
Baking
Baking is the technique of prolonged cooking of food by dry heat acting by convection, and not by radiation, normally in an oven, but also in hot ashes, or on hot stones. It is primarily used for the preparation of bread, cakes, pastries and pies, tarts, quiches, cookies and crackers. Such items...
. It may also be salted
Curing (food preservation)
Curing refers to various food preservation and flavoring processes, especially of meat or fish, by the addition of a combination of salt, nitrates, nitrite or sugar. Many curing processes also involve smoking, the process of flavoring, or cooking...
or dried
Drying (food)
Drying is a method of food preservation that works by removing water from the food, which inhibits the growth of microorganisms and hinders quality decay. Drying food using sun and wind to prevent spoilage has been practised since ancient times, and was the earliest form of food curing...
.