Alepes
Encyclopedia
Alepes is a genus
containing five extant species
of tropical marine
fish
es in the jack family, Carangidae
. They are commonly known as scads, a term applied to many genera of carangid fishes. Their body form, however, differs from these other scads by being much more ovate in shape, more similar to the larger jacks taken as game fish
, although scads are generally much smaller. They are found in coastal waters throughout the Indo
-West Pacific region.
. Recent phylogenetic studies using molecular information have placed Alepes in the subfamily Caranginae (or the tribe Carangini). The most comprehensive study suggests the genus is basal to all other 'scads' and 'horse mackerels' of the genera Trachurus
, Decapterus
, and Selar, whilst still being closely affiliated with larger members of Caranginae such as Caranx
.
Alepes was first created in 1839 by the English naturalist
William John Swainson, after he initially proposed it to be a subgenus
of Trachinus, which he had created to accommodate Trachinus melanoptera, a species he had just described. Trachinus was invalid, however, as it was already in use for a genus of weever
s. This makes A. melanoptera the type species
of the genus. The other species currently placed in Alepes were not directly classified in the genus, but were transferred from other, often distantly related genera. Many of these species have numerous junior synonyms. "Alepes" comes from the Greek word alepis, 'without scales'.
A single species has been identified from the fossil record; Alepes pin, described from the Lower Miocene in eastern Crimean Oblast
. This area was once part of the Indian Ocean which extended well into Europe
at the time.
shaped bodies, with fin arrangements much like the rest of the Carangidae. They have two dorsal fin
s, the first consisting of weak spines and the second of a single spine followed by a number of soft rays. The anal fin has two detached spines anterior to the main section which consists of one spine and a number of soft rays. Their lateral line
s have a moderate to strong anterior curve, with scute
s present on the straight section of the lateral line. They are all a blue-green-grey above, fading to silvery white below. Only one, A. kleinni has bands or markings.
The fish in Alepes are all predators, taking a range of crustaceans including copepod
s, decapods
, prawn
s and shrimp
, as well as small fish. At least one species shows a change in feeding intensity over the period of a year. The reproduction of most species is unstudied, except for A. kleinii. This species spawn
s on a single event over a period of a few months, releasing small transparent, pelagic eggs. Natural spawning behavior in the genus is unknown.
-West Pacific region. Their ranges overlap along the India
n, Asia
n and Indonesia
n coastlines, although some are distributed as far south as South Africa
and northern Australia
, while others extend as far north as Japan
. Two species, A. djedaba and A. kleinii are known to inhabit the Red Sea
, and have passed into the Mediterranean Sea
through the Suez canal
as part of the Lessepsian migration. They are all coastal species, not found in the open ocean.
, although Alepes kleinii appears to be taken in substantial enough numbers in India to warrant extensive research. They are taken by a variety of fishing methods including hook and line, trawls and a variety of netting methods. Their flesh is of good quality, and some regions regard various species as high quality and market them fresh, or dried and salted. They are of no interest to recreational fishermen
, although occasionally taken as bait or bycatch.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
containing five extant species
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 tropical marine
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...
es 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...
. They are commonly known as scads, a term applied to many genera of carangid fishes. Their body form, however, differs from these other scads by being much more ovate in shape, more similar to the larger jacks taken as game fish
Game fish
Game fish are fish pursued for sport by recreational anglers. They can be freshwater or marine fish. Game fish can be eaten after being caught, though increasingly anglers practise catch and release to improve fish populations. Some game fish are also targeted commercially, particularly...
, although scads are generally much smaller. They are found in coastal waters throughout the Indo
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...
-West Pacific region.
Taxonomy and phylogeny
Alepes is a genus containing five extant and one extinct species. It is part of the jack family, Carangidae, a group of perciform fish in the suborder PercoideiPercoidei
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:...
. Recent phylogenetic studies using molecular information have placed Alepes in the subfamily Caranginae (or the tribe Carangini). The most comprehensive study suggests the genus is basal to all other 'scads' and 'horse mackerels' of the genera Trachurus
Trachurus
Jack mackerels are marine fishes in the Trachurus genus of the Carangidae family. The type species of the genus is the Atlantic horse mackerel, Trachurus trachurus. The name of the genus is derived from the Greek word trachys, meaning "rough", and the Greek word oura, meaning "tail"...
, Decapterus
Decapterus
Decapterus is a genus of marine fishes in the family in the jack family, Carangidae. They are commonly known as mackerel scads, and round scads. They are found throughout the world....
, and Selar, whilst still being closely affiliated with larger members of Caranginae such as 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...
.
Alepes was first created in 1839 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, after he initially proposed it to be a subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...
of Trachinus, which he had created to accommodate Trachinus melanoptera, a species he had just described. Trachinus was invalid, however, as it was already in use for a genus of weever
Weever
Weevers are nine species of fish of family Trachinidae, order Perciformes. They are long , mainly brown and have poisonous spines on their first dorsal fin and gills. During the day, weevers bury themselves in sand, just showing their eyes, and snatch prey as it comes past, which consists of...
s. This makes A. melanoptera 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 genus. The other species currently placed in Alepes were not directly classified in the genus, but were transferred from other, often distantly related genera. Many of these species have numerous junior synonyms. "Alepes" comes from the Greek word alepis, 'without scales'.
A single species has been identified from the fossil record; Alepes pin, described from the Lower Miocene in eastern Crimean Oblast
Crimean Oblast
The Crimean Oblast was an oblast of the former Russian SFSR and Ukrainian SSR , which was at the time part of the Soviet Union. Its capital was the city of Simferopol....
. This area was once part of the Indian Ocean which extended well into Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
at the time.
Species
- Smallmouth scadSmallmouth scadThe smallmouth scad, Alepes apercna , is a species of tropical marine fish in the jack family Carangidae. The species is endemic to northern Australia, inhabiting primarily inshore waters...
, Alepes apercna (Grant, 1987) - Shrimp scadShrimp scadThe shrimp scad, Alepes djedaba , is a species of widespread tropical marine fish of the jack family, Carangidae...
, Alepes djedaba (ForsskålPeter ForsskålPeter 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:...
, 1775) - Razorbelly scadRazorbelly scadThe razorbelly scad, Alepes kleinii is a small species of tropical marine fish in the Jack family, Carangidae. The species inhabits coastal waters in the Indo-Pacific, from Pakistan in the west to Japan and Australia in the east, often found over reefs...
, Alepes kleinii (BlochMarcus Elieser BlochMarcus Elieser Bloch was a German medical doctor and naturalist. He is generally considered one of the most important ichthyologists of the 18th century.- Life :...
, 1793) - Blackfin scadBlackfin scadThe blackfin scad, Alepes melanoptera, 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...
, Alepes melanoptera (Swainson, 1839) - Herring scadHerring scadThe herring scad, Alepes vari , is a common species of tropical marine fish in the jack family Carangidae. The species inhabits the surface waters of coastal regions throughout the Indo-West Pacific region, feeding on a variety of crustaceans and small fishes...
, Alepes vari (CuvierGeorges CuvierGeorges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...
, 1833) - Alepes pin, (Bannikov, 1985) Extinct
Biology
The species in Alepes are all relatively small fish, with the largest, A. vari, growing to 56 centimetres (22 in). The other species are much more often encountered at sizes below 20 centimetres (8 in). They have strongly compressed ovate to 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...
shaped bodies, with fin arrangements much like the rest of the Carangidae. They have two 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 consisting of weak spines and the second of a single spine followed by a number of soft rays. The anal fin has two detached spines anterior to the main section which consists of one spine and a number of soft rays. Their 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...
s have a moderate to strong anterior curve, with 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 present on the straight section of the lateral line. They are all a blue-green-grey above, fading to silvery white below. Only one, A. kleinni has bands or markings.
The fish in Alepes are all predators, taking a range of crustaceans including 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, decapods
Decapoda
The decapods or Decapoda are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crayfish, crabs, lobsters, prawns and shrimp. Most decapods are scavengers. It is estimated that the order contains nearly 15,000 species in around 2,700 genera, with...
, 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 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...
, as well as small fish. At least one species shows a change in feeding intensity over the period of a year. The reproduction of most species is unstudied, except for A. kleinii. This species spawn
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...
s on a single event over a period of a few months, releasing small transparent, pelagic eggs. Natural spawning behavior in the genus is unknown.
Distribution and habitat
The members of Alepes are all distributed in the tropical to subtropical regions of the IndoIndo
Indo or Indo-European people is a term, used since the 19th century, to describe a Eurasian people of mixed European and indigenous Indonesian ancestry...
-West Pacific region. Their ranges overlap along the 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...
n, 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 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...
n coastlines, although some are distributed as far south as 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...
and northern Australia
Northern Australia
The term northern Australia is generally known to include two State and Territories, being Queensland and the Northern Territory . The part of Western Australia north of latitude 26° south—a definition widely used in law and State government policy—is also usually included...
, while others extend as far north 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...
. Two species, A. djedaba and A. kleinii are known to inhabit 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...
, and have passed into the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
through the Suez canal
Suez Canal
The Suez Canal , also known by the nickname "The Highway to India", is an artificial sea-level waterway in Egypt, connecting the Mediterranean Sea and the Red Sea. Opened in November 1869 after 10 years of construction work, it allows water transportation between Europe and Asia without navigation...
as part of the Lessepsian migration. They are all coastal species, not found in the open ocean.
Relationship to humans
The species of Alepes are not of major commercial interestFishery
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,...
, although Alepes kleinii appears to be taken in substantial enough numbers in India to warrant extensive research. They are taken by a variety of fishing methods including hook and line, trawls and a variety of netting methods. Their flesh is of good quality, and some regions regard various species as high quality and market them fresh, or dried and salted. They are of no interest to recreational fishermen
Angling
Angling is a method of fishing by means of an "angle" . The hook is usually attached to a fishing line and the line is often attached to a fishing rod. Fishing rods are usually fitted with a fishing reel that functions as a mechanism for storing, retrieving and paying out the line. The hook itself...
, although occasionally taken as bait or bycatch.