False scad
Encyclopedia
The false scad, Caranx rhonchus (also known as the spotfin scad, ten-finned horse mackerel and yellow horse mackerel), is a species
of medium sized marine
fish
classified in the jack family Carangidae
. The false scad is distributed throughout the tropical and temperate
waters of the eastern Atlantic Ocean
from Namibia
in the south to Spain
and throughout most of the Mediterranean in the north. The species has an atypical body form compared to other species of Caranx
, and can be distinguished from these on its elongate 'scad-like' body shape alone. Distinguishing the species from members of Decapterus
and Trachurus
is more difficult, requiring detailed anatomical analysis. The false scad is known to grow to a length of 60 cm and a weight of 1 kg
. The species lives both pelagically and demersally in continental shelf
waters, ranging from depths of 15 to 200 m. It is a predatory fish, taking small fishes, crustacean
s including euphausiids and shrimp
s, and cephalopod
s as its main prey, with significant dietary shifts as it ages. The false scad reaches sexual maturity
at 2 years of age, with spawning
occurring between April and July in shallow inshore waters, where the juveniles remain. The species is of major importance to fisheries throughout its range, but particularly from Morocco
to Senegal
, with annual catches ranging from 500 to 19000 t
. The species is caught using trawls, seine nets and gill nets and sold fresh, frozen or salted.
, one of a number of groups known as the jacks or trevallies. Caranx itself is part of the larger jack and horse mackerel family Carangidae
, a group of percoid
fishes in the order Perciformes
.
The species was first scientifically described by the French naturalist
Étienne Geoffroy Saint-Hilaire
in 1817 based on a specimen from Alexandria, Egypt which was designated to be the holotype
. He named the species Caranx rhonchus, with the specific epithet of Latin
origin meaning 'snorting' or 'croaking', in reference to the sound the species often makes when pulled from the water. The species placement in Caranx was later revised to Decapterus
, although the revision was not accepted by all authors with the generic status of the species undetermined for many years. It has now been accepted by most taxonomic authorities, that despite the species appearance, the false scad shares more anatomical features with Caranx than Decapterus.
The species was independently renamed once by Henry Weed Fowler
in 1919 under the name of Caranx angolensis, which was similarly shifted to Decapterus before synonymy was recognized and the name sunk into C. rhonchus.
The common name
of 'false scad' refers to the scad like appearance of the fish, despite it not being a member of Decapterus or Trachurus
, the two genera most commonly referred to as 'scads'. Other lesser used names for the species include spotfin scad, ten-finned horse mackerel and yellow horse mackerel.
of the Carangidae was published. Using mitochondrial cytochrome b
sequences, the species (which was labelled Decapterus rhoncus) was found to be strongly related to another member of Decapterus, as well as members of Trachurus, with no close relationships with genus Caranx. The species did place within the same subfamily (or tribe
) as Caranx; Carangini. A study of the pterygiophore insertion patters in the Carangidae also came to the conclusion it should not be placed in Caranx; nor any other currently recognised genus. It was recommended that it be placed in a new genus, however the authors delayed any such action pending publication of a current study into carangid relationships.
, although is more common at lengths of around 35 cm. The species has a much different body profile to most other species of Caranx, possessing an elongate, slightly compressed body in place of the deep, oblong
shaped forms of its larger relatives. The species dorsal profile is approximately as equally convex as the ventral profile. The dorsal fin
is in two distinct parts, the first consisting of 8 spines while the second has 1 spine and 28 to 32 soft rays. The anal fin consists of 2 detached spines anteriorly, followed by 1 spine and 25 to 28 soft rays. The soft rays located at the end of both the dorsal and anal fins are detached and only connected by a basal interradial membrane, forming a partially detached finlet. The pectoral and pelvic fins are both short. The species lateral line
is weakly arched anteriorly, becoming straight after the end of the dorsal fin lobe. The curved section has 45 to 55 scales
present and 0 to 3 scute
s, while the straight section contains 0 to 8 scales and 24 to 32 scutes.The shoulder girdle is smooth, lacking papillae. The false scad has a well-developed adipose eyelid, particularly posteriorly, with the both jaw
s containing irregular narrow bands of fine teeth. The species has 50 to 58 gill raker
s and 24 vertebrae.
The false scad is a blueish green to olive green-brown above fading to silvery white below, often with a narrow yellow stripe running from the head to the base of the caudal fin. The fins are hyaline
to dusky with the exception of the caudal fin which is yellow. The second dorsal fin's lobe has a black blotch and narrow pale border at the tip. A black blotch is also present on the operculum
.
waters of the eastern Atlantic Ocean
, although the species is more abundant in certain regions of its range. The species has been reported from as far south as Namibia
, but southern Angola
appears to be the furthest south the species normally ventures. It is distributed north along the west Africa
n coastline, reaching as far north as Spain
in Europe, with is range also extending well into the Mediterranean Sea
. Here it is known as far east as Turkey
, Egypt
and Israel
and as far north as Italy
, Greece
and Albania
.
The false scad lives both pelagically, free swimming high in the water column, as well as demersally, hugging the bottom strata. It prefers sandy or muddy substrates over continental shelf
environments, ranging in depths from 15 m to 200 m. Juveniles tend to inhabit shallower inshore waters including estuaries, lagoons, beach
es and marsh
es.
species, forming large protective masses, often mingling with other semi-pelagic fish
es. Like other carangid species, the species is often attracted to human-made fish attracting devices, which are floating buoy
s used to attract fish for research or angling
purposes. The species has had several extensive studies performed on it, due to its high importance in some Atlantic and Mediterranean fisheries.
s which other small species included in the study did take. This lack of copepods in the false scad's diet was also noticed in an earlier similar study, which looked at the diet of slightly smaller fish. A much later study in the same location found similar results, with fish being the most common prey followed by crustaceans including shrimp
s and mysids, molluscs and annelid
s. There is a change in the diet of the species as it grows, with one study finding 23 to 30 cm long fish took Branchiostoma lanceolatum predominantly, 30 to 35 cm fish took euphausiids and mysids, while 35 to 55 cm fish consumed small fishes of the families Maurolicidae
and Carangidae predominantly. A similar pattern has been seen in other studies, with a general pattern of decreasing amounts of crustaceans and increasing amounts of small fish consumed as the fish grows. Season
al variation in prey items is also known, with crustaceans dominating the diet during autumn and winter, while small fish are more frequently taken in summer. The feeding intensity of the species is lowest during the winter months, with the species feeding predominantly around mid day, and not at all during the night.
during its second year of life at a length of around 20 cm in both sexes. The timing of spawning
appears to vary slightly between locations, with a study in the Mediterranean indicating a period from June to August, while a study off Senegal found the period to be more protracted, occurring from April to November. Spawning occurs in shallow inshore waters, with the event occurring at an optimum water temperatures of 18.7 degrees Celsius. Studies on females between 29 and 35 cm in length found each fish releases between 480,000 and 990,000 eggs
, with the species a partial spawner, in which a proportion of the mature oocyte
s are not released from the ovary
and are instead reabsorbed by the female. Larva
e and juveniles remain in the shallow water environment, with growth quite rapid in the species. The newly hatched fish will reach a length of 12.2 cm at age one year, 17.9 cm at two, 22.3 cm at three, and 29.7 at five years old.
, Senegal
and in the Mediterranean taking the highest numbers of fish. They are fished for primarily with trawls, purse seines and gill nets; although juveniles occasionally turn up inshore nets such as beach seines. The species is part of a number of fish that live a similar semi-pelagic lifestyle that make up what is often referred to as a 'small pelagics fishery'. Some of these are the similar Trachurus species, and due to these also being present in the catch, Caranx rhonchus is often not differentiated, leading to lower than accurate catch statistics. Furthermore, vendors are known to fraudulently market C. rhonchus as 'horse mackerel', which is strictly applied to members of Trachurus. To counter this, there has been research into determining fish species later in the marketing process by means of DNA
analysis, a technique which has yielded strong results. FAO
catch statistics indicate a current annual catch of between 1500 and 3700 tonnes per year from both Africa and Europe between 2002 and 2007. Older catch data indicates much more was taken between 1979 and 1992, with these years having catches between 4000 and 19000 tonnes. The species is sold fresh, frozen, smoked, salted
, dried and is used for fish meal
and oil.
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 medium sized 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 false scad is distributed throughout the tropical and temperate
Temperate
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 of the eastern Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
from Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
in the south to Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
and throughout most of the Mediterranean in the north. The species has an atypical body form compared to other species of 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...
, and can be distinguished from these on its elongate 'scad-like' body shape alone. Distinguishing the species from members of 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 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"...
is more difficult, requiring detailed anatomical analysis. The false scad is known to grow to a length of 60 cm and a weight of 1 kg
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
. The species lives both pelagically and demersally in 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,...
waters, ranging from depths of 15 to 200 m. It is a predatory fish, taking small fishes, 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 including euphausiids 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...
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 as its main prey, with significant dietary shifts as it ages. The false scad reaches 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...
at 2 years of age, 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 April and July in shallow inshore waters, where the juveniles remain. The species is of major importance to fisheries throughout its range, but particularly from Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
to Senegal
Senegal
Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...
, with annual catches ranging from 500 to 19000 t
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
. The species is caught using trawls, seine nets and gill nets and sold fresh, frozen or salted.
Taxonomy and naming
The false scad is classified within the genus CaranxCaranx
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...
, one of a number of groups known as the jacks or trevallies. Caranx itself is part of the larger 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...
, a group of percoid
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:...
fishes in 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...
.
The species was first scientifically described by the French naturalist
Naturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...
Étienne Geoffroy Saint-Hilaire
Étienne Geoffroy Saint-Hilaire
Étienne Geoffroy Saint-Hilaire was a French naturalist who established the principle of "unity of composition". He was a colleague of Jean-Baptiste Lamarck and expanded and defended Lamarck's evolutionary theories...
in 1817 based on a specimen from Alexandria, Egypt 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...
. He named the species Caranx rhonchus, with the specific epithet of Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
origin meaning 'snorting' or 'croaking', in reference to the sound the species often makes when pulled from the water. The species placement in Caranx was later revised to 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....
, although the revision was not accepted by all authors with the generic status of the species undetermined for many years. It has now been accepted by most taxonomic authorities, that despite the species appearance, the false scad shares more anatomical features with Caranx than Decapterus.
The species was independently renamed once by Henry Weed Fowler
Henry Weed Fowler
Henry Weed Fowler was an American zoologist born in Holmesburg, Pennsylvania.He studied at Stanford University under David Starr Jordan...
in 1919 under the name of Caranx angolensis, which was similarly shifted to Decapterus before synonymy was recognized and the name sunk into C. rhonchus.
The common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
of 'false scad' refers to the scad like appearance of the fish, despite it not being a member of Decapterus or 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"...
, the two genera most commonly referred to as 'scads'. Other lesser used names for the species include spotfin scad, ten-finned horse mackerel and yellow horse mackerel.
Phylogeny
Despite being classified in Caranx based on anatomical features, the generic affinities of the false scad have been questioned after a molecular phylogenyMolecular phylogeny
Molecular phylogenetics is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree...
of the Carangidae was published. Using mitochondrial cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
sequences, the species (which was labelled Decapterus rhoncus) was found to be strongly related to another member of Decapterus, as well as members of Trachurus, with no close relationships with genus Caranx. The species did place within the same subfamily (or tribe
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...
) as Caranx; Carangini. A study of the pterygiophore insertion patters in the Carangidae also came to the conclusion it should not be placed in Caranx; nor any other currently recognised genus. It was recommended that it be placed in a new genus, however the authors delayed any such action pending publication of a current study into carangid relationships.
Description
The false scad is a moderately large species, growing to a known maximum length of 60 cm and a weight of 1 kgKilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
, although is more common at lengths of around 35 cm. The species has a much different body profile to most other species of Caranx, possessing an elongate, slightly compressed body in place of the deep, oblong
Rectangle
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 forms of its larger relatives. The species dorsal profile is approximately as equally convex as the ventral profile. The 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...
is in two distinct parts, the first consisting of 8 spines while the second has 1 spine and 28 to 32 soft rays. The anal fin consists of 2 detached spines anteriorly, followed by 1 spine and 25 to 28 soft rays. The soft rays located at the end of both the dorsal and anal fins are detached and only connected by a basal interradial membrane, forming a partially detached finlet. The pectoral and pelvic fins are both short. The species 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...
is weakly arched anteriorly, becoming straight after the end of the dorsal fin lobe. The curved section has 45 to 55 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...
present and 0 to 3 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 contains 0 to 8 scales and 24 to 32 scutes.The shoulder girdle is smooth, lacking papillae. The false scad has a well-developed adipose eyelid, particularly posteriorly, with the 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 containing irregular narrow bands of fine teeth. The species has 50 to 58 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 false scad is a blueish green to olive green-brown above fading to silvery white below, often with a narrow yellow stripe running from the head to the base of the caudal fin. The fins are 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...
to dusky with the exception of the caudal fin which is yellow. The second dorsal fin's lobe has a black blotch and narrow pale border at the tip. A black blotch is also present on the operculum
Operculum (fish)
The operculum of a bony fish is the hard bony flap covering and protecting the gills. In most fish, the rear edge of the operculum roughly marks the division between the head and the body....
.
Distribution and habitat
The false scad 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 of the eastern Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, although the species is more abundant in certain regions of its range. The species has been reported from as far south as Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
, but southern Angola
Angola
Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, the Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city...
appears to be the furthest south the species normally ventures. It is distributed north along the west Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...
n coastline, reaching as far north as Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
in Europe, with is range also extending well 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...
. Here it is known as far east as Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...
, Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
and Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...
and as far north as Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
, Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....
and Albania
Albania
Albania , officially known as the Republic of Albania , is a country in Southeastern Europe, in the Balkans region. It is bordered by Montenegro to the northwest, Kosovo to the northeast, the Republic of Macedonia to the east and Greece to the south and southeast. It has a coast on the Adriatic Sea...
.
The false scad lives both pelagically, free swimming high in the water column, as well as demersally, hugging the bottom strata. It prefers sandy or muddy substrates over 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,...
environments, ranging in depths from 15 m to 200 m. Juveniles tend to inhabit shallower inshore waters including estuaries, lagoons, 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 and marsh
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....
es.
Biology
The false scad is a schoolingShoaling 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...
species, forming large protective masses, often mingling with other semi-pelagic fish
Pelagic fish
Pelagic fish live near the surface or in the water column of coastal, ocean and lake waters, but not on the bottom of the sea or the lake. They can be contrasted with demersal fish, which do live on or near the bottom, and reef fish which are associated with coral reefs.The marine pelagic...
es. Like other carangid species, the species is often attracted to human-made fish attracting devices, which are floating buoy
Buoy
A buoy is a floating device that can have many different purposes. It can be anchored or allowed to drift. The word, of Old French or Middle Dutch origin, is now most commonly in UK English, although some orthoepists have traditionally prescribed the pronunciation...
s used to attract fish for research or angling
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...
purposes. The species has had several extensive studies performed on it, due to its high importance in some Atlantic and Mediterranean fisheries.
Diet and feeding
It is a predatory species, with several studies conducted to determine its diet and feeding habits. A study in the Cape Blanc region found Branchiostoma lanceolatum (a cephalochordate), euphausiids, small fish and other small crustaceans were the predominantly taken food items, with a surprising absence of copepodCopepod
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 which other small species included in the study did take. This lack of copepods in the false scad's diet was also noticed in an earlier similar study, which looked at the diet of slightly smaller fish. A much later study in the same location found similar results, with fish being the most common prey followed by crustaceans including 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 and mysids, molluscs and annelid
Annelid
The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...
s. There is a change in the diet of the species as it grows, with one study finding 23 to 30 cm long fish took Branchiostoma lanceolatum predominantly, 30 to 35 cm fish took euphausiids and mysids, while 35 to 55 cm fish consumed small fishes of the families Maurolicidae
Pearlsides
Mueller's pearlside or Mueller's bristle-mouth fish, Maurolicus muelleri, a marine hatchetfish of the genus Maurolicus, is found in deep tropical and subtropical waters of all oceans, from the surface to depths of 1,500 m...
and Carangidae predominantly. A similar pattern has been seen in other studies, with a general pattern of decreasing amounts of crustaceans and increasing amounts of small fish consumed as the fish grows. Season
Season
A season is a division of the year, marked by changes in weather, ecology, and hours of daylight.Seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earth's axis relative to the plane of revolution...
al variation in prey items is also known, with crustaceans dominating the diet during autumn and winter, while small fish are more frequently taken in summer. The feeding intensity of the species is lowest during the winter months, with the species feeding predominantly around mid day, and not at all during the night.
Reproduction and growth
The false scad reaches sexual maturitySexual 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...
during its second year of life at a length of around 20 cm in both sexes. The timing of 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...
appears to vary slightly between locations, with a study in the Mediterranean indicating a period from June to August, while a study off Senegal found the period to be more protracted, occurring from April to November. Spawning occurs in shallow inshore waters, with the event occurring at an optimum water temperatures of 18.7 degrees Celsius. Studies on females between 29 and 35 cm in length found each fish releases between 480,000 and 990,000 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...
, with the species a partial spawner, in which a proportion of the mature oocyte
Oocyte
An oocyte, ovocyte, or rarely ocyte, is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in the ovary during female gametogenesis. The female germ cells produce a primordial germ cell which undergoes a mitotic...
s are not released from the ovary
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
and are instead reabsorbed by the female. 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 and juveniles remain in the shallow water environment, with growth quite rapid in the species. The newly hatched fish will reach a length of 12.2 cm at age one year, 17.9 cm at two, 22.3 cm at three, and 29.7 at five years old.
Relationship to humans
The false scad is of major importance to commercial fisheries throughout its range, with fisheries off MoroccoMorocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
, Senegal
Senegal
Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...
and in the Mediterranean taking the highest numbers of fish. They are fished for primarily with trawls, purse seines and gill nets; although juveniles occasionally turn up inshore nets such as beach seines. The species is part of a number of fish that live a similar semi-pelagic lifestyle that make up what is often referred to as a 'small pelagics fishery'. Some of these are the similar Trachurus species, and due to these also being present in the catch, Caranx rhonchus is often not differentiated, leading to lower than accurate catch statistics. Furthermore, vendors are known to fraudulently market C. rhonchus as 'horse mackerel', which is strictly applied to members of Trachurus. To counter this, there has been research into determining fish species later in the marketing process by means of DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
analysis, a technique which has yielded strong results. FAO
Fão
Fão is a town in Esposende Municipality in Portugal....
catch statistics indicate a current annual catch of between 1500 and 3700 tonnes per year from both Africa and Europe between 2002 and 2007. Older catch data indicates much more was taken between 1979 and 1992, with these years having catches between 4000 and 19000 tonnes. The species is sold fresh, frozen, smoked, salted
Salting (food)
Salting is the preservation of food with dry edible salt. It is related to pickling . It is one of the oldest methods of preserving food, and two historically significant salt-cured foods are dried and salted cod and salt-cured meat.Salting is used because most bacteria, fungi and other potentially...
, dried and is used for fish meal
Fish meal
Fish meal, or fishmeal, is a commercial product made from both whole fish and the bones and offal from processed fish. It is a brown powder or cake obtained by rendering pressing the cooked whole fish or fish trimmings to remove most of the fish oil and water, and then ground...
and oil.