Blue runner
Encyclopedia
The blue runner, Caranx crysos (also known as the bluestripe jack, Egyptian scad, hardtail jack and hardnose), is a common species
of moderately large marine
fish
classified in the jack family, Carangidae
. The blue runner is distributed across the Atlantic Ocean
, ranging from Brazil
to Canada
in the western Atlantic and from Angola
to Great Britain
including the Mediterranean in the east Atlantic. The blue runner is distinguished from similar species by several morphological features, including the extent of the upper jaw
, gill raker
count and lateral line
scale counts. The blue runner is known to reach a maximum length of 70 cm and 5.05 kg
in weight, but is much more common below 35 cm. The species inhabits both inshore and offshore environments, predominantly over reef
s, however it is known to congregate around large man made offshore structures such as oil platform
s. Juveniles tend to inhabit shallower reef
and lagoon
waters, before moving to deeper waters as adults.
The blue runner is a schooling, predatory fish, predominantly taking fish in inshore environments, as well as various crustacean
s and other invertebrates. Fish living offshore feed nearly exclusively on zooplankton
. The species reaches sexual maturity
at between 225 and 280 mm across its range, with spawning
occurring offshore year round, although this peaks during the warmer months. Larva
e and juveniles live pelagically, often under sargassum
mats or jellyfish until they move inshore. The blue runner is of high importance to fisheries, with an annual catch of between 6000 and 7000 tonne
s taken from the Americas in the last five years. The species is also a light tackle gamefish, taking baits lures and flies, but is often used as bait itself being a mediocre table fish. There has been some suggestion that the eastern Pacific species Caranx caballus, the green jack
, may be conspecific with C. crysos, although this currently remains unresolved.
Caranx
, 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 American ichthyologist Samuel L. Mitchill
in 1815, based on a specimen taken from the waters of New York Bay
, USA which was designated to be the holotype
. He named the species Scomber crysos and suggested a common name of 'yellow mackerel', with the specific epithet reflecting this, meaning "gold" in Greek. The taxon has been variably placed in either Caranx, Carangoides
or Paratractus, but is now considered valid as Caranx crysos. The species has been independently redescribed three times, first as Caranx fusus, which is still incorrectly used by some authors (occasionally as Carangoides fusus), and later as Caranx pisquetus and Trachurus squamosus. These names are considered invalid junior synonyms under ICZN
rules. The species has many common name
s, with the most common being 'blue runner'. Other less commonly used names include 'bluestripe jack', 'Egyptian scad', 'hardtail jack', 'hardnose', 'white back cavalli', 'yellow tail cavalli', as well as a variety of broad names such as 'mackerel', 'runner' and 'crevalle'.
There has been suggestions that the blue runner may be conspecific with the eastern Pacific species Caranx caballus (green jack
), although no specific studies have been undertaken to examine this relationship. Both species were included in a recent genetic
analysis of the entire Carangidae family, with results showing both species are very closely related, although the authors did not comment on genetic distance between the two.
in weight, but is more common at lengths less than 35 cm. The blue runner is morphologically
similar to a number of other carangids, having an elongated, moderately compressed body with dorsal and ventral profiles of approximately equal convexity and a slightly pointed snout. The posterior section of the eye is covered by a moderately well developed adipose eyelid, and the posterior extremity of the jaw
is vertically under the center of the eye. The dorsal fin
is in two parts, the first consisting of 8 spines and the second of 1 spine followed by 22 to 25 soft rays. The anal fin consists of 2 anteriorly detached spines followed by 1 spine and 19 to 21 soft rays. The pectoral fins become more falcate with age, having 21 to 23 rays, and are slightly longer than the head. The lateral line
has a pronounced but short anterior arch, with the curved section intersecting the straight section below the spine of the second dorsal fin. The straight section contains 0 to 7 scales followed by 46 to 56 very strong scute
s, with bilateral keels present on the caudal peduncle. There are a total of 86 to 98 scales and scutes over the entire lateral line. The chest is completely scaled. The upper jaw contains an irregular series of outer canine
s with an inner band of small, regularly spaced teeth, while the lower jaw contains a single band of small teeth. The species has 35 to 42 gill raker
s in total; 10 to 14 on the upper limb and 25 to 28 on the lower limb, with this the only feature that differs between C. crysos and C. caballus. There are 25 vertebrae present.
The blue runner's colour varies from bluish green to olive green dorsally, becoming silvery grey to brassy below. Juveniles often have 7 dark vertical bands on their body. Fin colour also varies, with all fins ranging from to dusky or hyaline
to olive green. The species also has a dusky spot which may not be distinct on the upper operculum
.
waters of the Atlantic Ocean
, ranging widely along both the eastern American coastline and the western Africa
n and Europe
an coastlines. In the western Atlantic, the species southernmost record comes from Maceio, Brazil, with the species ranging north along the central America
n coastline, and throughout the Caribbean
and the numerous archipelago
s throughout. From the Gulf of Mexico
its distribution extends north along the U.S. coast and as far north as Nova Scotia
in Canada
, also taking in several north-west Atlantic islands. The blue runner is also present on several central Atlantic islands, making its distribution Atlantic-wide.
In the eastern Atlantic the southernmost record is from Angola
, with the blue runner distributed extensively along the west African coast up to Morocco
and into the Mediterranean Sea
. The blue runner is found throughout the Mediterranean, having been recorded from nearly all the countries on its shores. The species is rarely found north of Portugal
in the north east Atlantic, although records do exist of isolated catches from Madeira Island and Galicia, Spain
. The furthest north it has been reported is southern Great Britain
, where two specimens were taken in 1992 and 1993. There has been a trend of having this and other tropical species found further north more often, with publications indicating the blue runner has recently established stable populations in the Canary Islands, where it previously was rarely sighted. Some authors have attributed this northward migration to rising sea surface temperature
s, possibly the result of climate change
.
The blue runner is primarily an inshore fish throughout most of its range, however it is known to live on reefs in water depths greater than 100 m. Throughout much of its Central American range, it is quite rare inshore, instead more commonly sighted on the outer reefs. The blue runner is primarily a semi-pelagic fish, inhabiting both inshore reefs and the outer shelf edges, sill reefs and upper slopes of the deep reef. Those individuals on shallower reefs often move between reef patches over large sand expanses. Juvenile fish are also known to inhabit the shallow waters of inshore lagoon
s, taking refuge around mangrove
s or in seagrass
amongst coral reef
patches. Fishermen have also taken the species in the Mississippi delta
, indicating it can tolerate lower salinities in almost estuarine environments.
Blue runner are easily attracted to any large underwater or floating device, either natural or man made. Several studies have shown the species congregates around floating buoy-like fish aggregating devices (FADs), both in shallower waters, as well as in extremely deep (2500 m) waters, indicating the species may move around pelagically. In these situations, blue runner always form small aggregations at the water surface, while other larger species tend to congregate slightly deeper. A number of investigations around oil and gas platforms
in the Gulf of Mexico have found blue runner congregate in large numbers around these in the warmer months, where they modify their feeding behavior to take advantage of the structure. Purpose built artificial reef
s and marine aquaculture
cage structures are also known to attract the species, with the former having the added benefit of dispersing wayward food scraps.
or as solitary individuals, although large aggregations of up to 10,000 individuals are known in unusual circumstances. Throughout some parts of its range, it is one of the most abundant species; for example statistics from Santa Catarina Island indicate it is the third most abundant species. The biology, particularly reproductive and growth biology has been quite extensively studied in the blue runner due to this high abundance in the Atlantic, and its importance to fisheries and the ecology
of its environment.
study found the species supplements its fish dominated diet with crab
s, shrimp
s, copepod
s and other small crustaceans. More detailed research in Cape Verde
found as well as fish, blue runner take shrimp, prawn
s, lobster
s, jellyfish
and other small invertebrates. The diet of juveniles is more zooplankton
dominated, with young fish predominantly taking cyclopoid and calanoid copepod
s, and gradually moving to a more fish based diet. Adult blue runner living offshore
or aggregating around oil and gas platforms tend to have less fish in their diet, foraging extensively on larger zooplankton during the summer months, with larval decapods
and stomatopods, hyperiid amphipods, pteropods, and larval and juvenile fishes also taken.
Studies around these platforms has found blue runner feed with equal intensity during both day and night, with larger prey such as fish taken preferentially at night, with smaller crustaceans taken during the day. Blue runner are one of a number of carangids known to forage
in small schools alongside actively feeding Spinner Dolphin
s (Stenella longirostris), taking advantage of any scraps of food left by the feeding mammals, or any organisms displaced while they forage. The species is also known to eat the dolphins excrement. As well as being important predators, they are also important prey to many larger species including fishes, bird
s and dolphins.
The blue runner reaches sexual maturity
at slightly different lengths throughout its range, with all such studies occurring in the west Atlantic. Research in northwest Florida
found a length at maturity of 267 mm, a study in Louisiana showed the species reaches sexual maturity at 247–267 mm in females and 225 mm in males, and in Jamaica lengths of 260 mm for males and 280 for females were estimated. Spawning appears to occur offshore year round, although several peaks in spawning activity have been found in different areas through the species range. Peak spawning season in the Gulf of Mexico occurs from June to August, with a secondary peak in spawning during October in northwest Florida. Elsewhere, peaks in larval abundance indicate spawning in the warmer summer months between January and August. Each female releases between 41,000 and 1,546,000 eggs on average, with larger fish producing more eggs. Both the eggs and larvae are pelagic.
The blue runner's larva
l stage has been extensively described, with distinguishing features including a slightly shallower body than other larval Caranx, and a heavily pigmented head and body. During this early juvenile stage, there are several dark vertical bars clearly present on the side. Larvae and small juveniles remain offshore, living either at depths of around 10 to 20 m, or congregating around floating objects, particularly Sargassum
mats and large jellyfish
. As the fish grow, they often move to more inshore lagoons and reefs, before slowly making their way to deeper outer reefs at the onset of sexual maturity. Absolute growth rates are not well known, but the species has all the adult characteristics by a length of 59.3 mm. In all cases studied, there are more females in the adult population than males, with female to male ratios ranging from 1.15F:1M to 1.91F:1M. Annual mortality rate
s for the population in the Gulf of Mexico range from 0.41 to 0.53. The oldest known individual was 11 years old based on otolith
rings.
for the species is variable throughout its range, with the Americas having separate statistics kept for the species, while in Africa and Europe it is lumped in with other carangids in statistics. In the Americas, recent catch data suggests an increased amount of the species is being taken (or reported), with the 2006 and 2007 catch averaging between 6000 and 7000 tonne
s, while during the 1980s and 1990s, there was rarely an annual catch greater than 1000 tonnes. Research on the fisheries of local regions has shown how important the fish is to certain fisheries. Artisanal fisheries in Santa Catarina Island have shown blue runner to be third most important and abundant species, making up 5.6% of landings, or 4.38 tonnes. Even subsistence fisheries at the edge of its range in Brazil show a catch of 388 kg in two years from beach seines. Throughout its range the blue runner is commercially taken by haul seines, lampara nets, purse seines, gill nets, and hook and line methods. The fish is sold at market either fresh, dried, smoked or as fishmeal, oil or bait.
Blue runner is also of high importance to recreational fisheries, with anglers
often taking the species both for food and to use as bait. The blue runner has a reputation as an excellent gamefish on light tackle, taking both fish baits, as well a variety of lures including hard bodied bibbed lures, spoons, metal jigs and soft plastic jigs. The species is also a target for light tackle saltwater fly
fishermen, and can push 6-weight fly tackle to its limits. The blue runner is used extensively as live bait for larger fish including billfish
, cobia
and amberjack
. It is considered to be a fairly low quality table fish, and larger specimens are known to carry the ciguatera
toxin in their flesh, with several cases reported from the Virgin Islands
.
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 moderately large 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 runner is distributed across the 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...
, ranging from Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
to Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
in the western Atlantic and from 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...
to Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
including the Mediterranean in the east Atlantic. The blue runner is distinguished from similar species by several morphological features, including the extent of the upper 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...
, gill raker
Gill raker
Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch and are involved with filter feeding tiny prey. They are not to be confused with the gill filaments that compose the bony part of the gill. Rakers are usually present in two rows, projecting from both the...
count and 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...
scale counts. The blue runner is known to reach a maximum length of 70 cm and 5.05 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...
in weight, but is much more common below 35 cm. The species inhabits both inshore and offshore environments, predominantly over reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s, however it is known to congregate around large man made offshore structures such as oil platform
Oil platform
An oil platform, also referred to as an offshore platform or, somewhat incorrectly, oil rig, is a lаrge structure with facilities to drill wells, to extract and process oil and natural gas, and to temporarily store product until it can be brought to shore for refining and marketing...
s. Juveniles tend to inhabit shallower reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
and 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,...
waters, before moving to deeper waters as adults.
The blue runner is a schooling, predatory fish, predominantly taking fish in inshore environments, as well as various crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and other invertebrates. Fish living offshore feed nearly exclusively on zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
. The species 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 between 225 and 280 mm across its range, 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 offshore year round, although this peaks during the warmer months. 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 live pelagically, often under sargassum
Sargassum
Sargassum is a genus of brown macroalga in the order Fucales. Numerous species are distributed throughout the temperate and tropical oceans of the world, where they generally inhabit shallow water and coral reefs. However, the genus may be best known for its planktonic species...
mats or jellyfish until they move inshore. The blue runner is of high importance to fisheries, with an annual catch of between 6000 and 7000 tonne
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...
s taken from the Americas in the last five years. The species is also a light tackle gamefish, taking baits lures and flies, but is often used as bait itself being a mediocre table fish. There has been some suggestion that the eastern Pacific species Caranx caballus, the green jack
Green jack
The green jack, Caranx caballus , is an abundant species of coastal marine fish in the jack family Carangidae. The species is distributed in the eastern Pacific Ocean along the American coastline from Santa Cruz Island off California in the north to Peru in the south, as well as a number of islands...
, may be conspecific with C. crysos, although this currently remains unresolved.
Taxonomy and naming
The blue runner is classified within the genusGenus
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...
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...
, 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 American ichthyologist Samuel L. Mitchill
Samuel Latham Mitchill
Samuel Latham Mitchill was an American physician, naturalist, and politician from New York. He was born in Hempstead, New York...
in 1815, based on a specimen taken from the waters of New York Bay
New York Bay
New York Bay is the collective term for the marine areas surrounding the entrance of the Hudson River into the Atlantic Ocean. Its two largest components are Upper New York Bay and Lower New York Bay, which are connected by The Narrows...
, USA 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 Scomber crysos and suggested a common name of 'yellow mackerel', with the specific epithet reflecting this, meaning "gold" in Greek. The taxon has been variably placed in either Caranx, Carangoides
Carangoides
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...
or Paratractus, but is now considered valid as Caranx crysos. The species has been independently redescribed three times, first as Caranx fusus, which is still incorrectly used by some authors (occasionally as Carangoides fusus), and later as Caranx pisquetus and Trachurus squamosus. These names are considered invalid junior synonyms under ICZN
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
rules. The species has many 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...
s, with the most common being 'blue runner'. Other less commonly used names include 'bluestripe jack', 'Egyptian scad', 'hardtail jack', 'hardnose', 'white back cavalli', 'yellow tail cavalli', as well as a variety of broad names such as 'mackerel', 'runner' and 'crevalle'.
There has been suggestions that the blue runner may be conspecific with the eastern Pacific species Caranx caballus (green jack
Green jack
The green jack, Caranx caballus , is an abundant species of coastal marine fish in the jack family Carangidae. The species is distributed in the eastern Pacific Ocean along the American coastline from Santa Cruz Island off California in the north to Peru in the south, as well as a number of islands...
), although no specific studies have been undertaken to examine this relationship. Both species were included in a recent genetic
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
analysis of the entire Carangidae family, with results showing both species are very closely related, although the authors did not comment on genetic distance between the two.
Description
The blue runner is moderately large in size, growing to a maximum confirmed length of 70 cm and 5.05 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...
in weight, but is more common at lengths less than 35 cm. The blue runner is morphologically
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
similar to a number of other carangids, having an elongated, moderately compressed body with dorsal and ventral profiles of approximately equal convexity and a slightly pointed snout. The posterior section of the eye is covered by a moderately well developed adipose eyelid, and the posterior extremity of the 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...
is vertically under the center of the eye. 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 parts, the first consisting of 8 spines and the second of 1 spine followed by 22 to 25 soft rays. The anal fin consists of 2 anteriorly detached spines followed by 1 spine and 19 to 21 soft rays. The pectoral fins become more falcate with age, having 21 to 23 rays, and are slightly longer than the head. 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 pronounced but short anterior arch, with the curved section intersecting the straight section below the spine of the second dorsal fin. The straight section contains 0 to 7 scales followed by 46 to 56 very strong 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, with bilateral keels present on the caudal peduncle. There are a total of 86 to 98 scales and scutes over the entire lateral line. The chest is completely scaled. The upper jaw contains an irregular series of outer canine
Canine tooth
In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, fangs, or eye teeth, are relatively long, pointed teeth...
s with an inner band of small, regularly spaced teeth, while the lower jaw contains a single band of small teeth. The species has 35 to 42 gill raker
Gill raker
Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch and are involved with filter feeding tiny prey. They are not to be confused with the gill filaments that compose the bony part of the gill. Rakers are usually present in two rows, projecting from both the...
s in total; 10 to 14 on the upper limb and 25 to 28 on the lower limb, with this the only feature that differs between C. crysos and C. caballus. There are 25 vertebrae present.
The blue runner's colour varies from bluish green to olive green dorsally, becoming silvery grey to brassy below. Juveniles often have 7 dark vertical bands on their body. Fin colour also varies, with all fins ranging from to dusky or 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 olive green. The species also has a dusky spot which may not be distinct on the upper 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
The blue runner is extensively 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 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...
, ranging widely along both the eastern American coastline and the western Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n and 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...
an coastlines. In the western Atlantic, the species southernmost record comes from Maceio, Brazil, with the species ranging north along the central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
n coastline, and throughout the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
and the numerous archipelago
Archipelago
An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...
s throughout. From the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
its distribution extends north along the U.S. coast and as far north as Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, also taking in several north-west Atlantic islands. The blue runner is also present on several central Atlantic islands, making its distribution Atlantic-wide.
In the eastern Atlantic the southernmost record is from 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...
, with the blue runner distributed extensively along the west African coast up to 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...
and 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...
. The blue runner is found throughout the Mediterranean, having been recorded from nearly all the countries on its shores. The species is rarely found north of Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
in the north east Atlantic, although records do exist of isolated catches from Madeira Island and Galicia, 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...
. The furthest north it has been reported is southern Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
, where two specimens were taken in 1992 and 1993. There has been a trend of having this and other tropical species found further north more often, with publications indicating the blue runner has recently established stable populations in the Canary Islands, where it previously was rarely sighted. Some authors have attributed this northward migration to rising sea surface temperature
Sea surface temperature
Sea surface temperature is the water temperature close to the oceans surface. The exact meaning of surface varies according to the measurement method used, but it is between and below the sea surface. Air masses in the Earth's atmosphere are highly modified by sea surface temperatures within a...
s, possibly the result of climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
.
Habitat
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, taking refuge around mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
s or in seagrass
Seagrass
Seagrasses are flowering plants from one of four plant families , all in the order Alismatales , which grow in marine, fully saline environments.-Ecology:...
amongst coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
patches. Fishermen have also taken the species in the Mississippi delta
Mississippi Delta
The Mississippi Delta is the distinctive northwest section of the U.S. state of Mississippi that lies between the Mississippi and Yazoo Rivers. The region has been called "The Most Southern Place on Earth" because of its unique racial, cultural, and economic history...
, indicating it can tolerate lower salinities in almost estuarine environments.
Blue runner are easily attracted to any large underwater or floating device, either natural or man made. Several studies have shown the species congregates around floating buoy-like fish aggregating devices (FADs), both in shallower waters, as well as in extremely deep (2500 m) waters, indicating the species may move around pelagically. In these situations, blue runner always form small aggregations at the water surface, while other larger species tend to congregate slightly deeper. A number of investigations around oil and gas platforms
Oil platform
An oil platform, also referred to as an offshore platform or, somewhat incorrectly, oil rig, is a lаrge structure with facilities to drill wells, to extract and process oil and natural gas, and to temporarily store product until it can be brought to shore for refining and marketing...
in the Gulf of Mexico have found blue runner congregate in large numbers around these in the warmer months, where they modify their feeding behavior to take advantage of the structure. Purpose built artificial reef
Artificial reef
An artificial reef is a human-made underwater structure, typically built to promote marine life in areas with a generally featureless bottom, control erosion, block ship passage, or improve surfing....
s and marine aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
cage structures are also known to attract the species, with the former having the added benefit of dispersing wayward food scraps.
Biology
The blue runner normally moves either in small schoolsShoaling 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...
or as solitary individuals, although large aggregations of up to 10,000 individuals are known in unusual circumstances. Throughout some parts of its range, it is one of the most abundant species; for example statistics from Santa Catarina Island indicate it is the third most abundant species. The biology, particularly reproductive and growth biology has been quite extensively studied in the blue runner due to this high abundance in the Atlantic, and its importance to fisheries and the ecology
Ecology
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 its environment.
Diet and feeding
The blue runner is a fast swimming predator which primarily takes small benthic fishes as prey in inshore waters. Studies on the species diet on both side of the Atlantic have shown similar results. A Puerto RicanPuerto Rican people
A Puerto Rican is a person who was born in Puerto Rico.Puerto Ricans born and raised in the continental United States are also sometimes referred to as Puerto Ricans, although they were not born in Puerto Rico...
study found the species supplements its fish dominated diet with 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, 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, 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 and other small crustaceans. More detailed research in Cape Verde
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...
found as well as fish, blue runner take shrimp, 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, lobster
Lobster
Clawed lobsters comprise a family of large marine crustaceans. Highly prized as seafood, lobsters are economically important, and are often one of the most profitable commodities in coastal areas they populate.Though several groups of crustaceans are known as lobsters, the clawed lobsters are most...
s, 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...
and other small invertebrates. The diet of juveniles is more zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
dominated, with young fish predominantly taking cyclopoid and calanoid 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, and gradually moving to a more fish based diet. Adult blue runner living offshore
Shore
A shore or shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In Physical Oceanography a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of the shore,...
or aggregating around oil and gas platforms tend to have less fish in their diet, foraging extensively on larger zooplankton during the summer months, with larval 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...
and stomatopods, hyperiid amphipods, pteropods, and larval and juvenile fishes also taken.
Studies around these platforms has found blue runner feed with equal intensity during both day and night, with larger prey such as fish taken preferentially at night, with smaller crustaceans taken during the day. Blue runner are one of a number of carangids known to forage
Forage
Forage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...
in small schools alongside actively feeding Spinner Dolphin
Spinner Dolphin
The Spinner Dolphin is a small dolphin found in off-shore tropical waters around the world. It is famous for its acrobatic displays in which they spin longitudinally along their axis as they leap through the air.-Taxonomy:...
s (Stenella longirostris), taking advantage of any scraps of food left by the feeding mammals, or any organisms displaced while they forage. The species is also known to eat the dolphins excrement. As well as being important predators, they are also important prey to many larger species including fishes, bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s and dolphins.
Reproduction and growth
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 slightly different lengths throughout its range, with all such studies occurring in the west Atlantic. Research in northwest Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
found a length at maturity of 267 mm, a study in Louisiana showed the species reaches sexual maturity at 247–267 mm in females and 225 mm in males, and in Jamaica lengths of 260 mm for males and 280 for females were estimated. Spawning appears to occur offshore year round, although several peaks in spawning activity have been found in different areas through the species range. Peak spawning season in the Gulf of Mexico occurs from June to August, with a secondary peak in spawning during October in northwest Florida. Elsewhere, peaks in larval abundance indicate spawning in the warmer summer months between January and August. Each female releases between 41,000 and 1,546,000 eggs on average, with larger fish producing more eggs. Both the eggs and larvae are pelagic.
The blue runner's 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...
l stage has been extensively described, with distinguishing features including a slightly shallower body than other larval Caranx, and a heavily pigmented head and body. During this early juvenile stage, there are several dark vertical bars clearly present on the side. Larvae and small juveniles remain offshore, living either at depths of around 10 to 20 m, or congregating around floating objects, particularly Sargassum
Sargassum
Sargassum is a genus of brown macroalga in the order Fucales. Numerous species are distributed throughout the temperate and tropical oceans of the world, where they generally inhabit shallow water and coral reefs. However, the genus may be best known for its planktonic species...
mats and large 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...
. As the fish grow, they often move to more inshore lagoons and reefs, before slowly making their way to deeper outer reefs at the onset of sexual maturity. Absolute growth rates are not well known, but the species has all the adult characteristics by a length of 59.3 mm. In all cases studied, there are more females in the adult population than males, with female to male ratios ranging from 1.15F:1M to 1.91F:1M. Annual mortality rate
Mortality rate
Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...
s for the population in the Gulf of Mexico range from 0.41 to 0.53. The oldest known individual was 11 years old based on otolith
Otolith
An otolith, , also called statoconium or otoconium is a structure in the saccule or utricle of the inner ear, specifically in the vestibular labyrinth of vertebrates. The saccule and utricle, in turn, together make the otolith organs. They are sensitive to gravity and linear acceleration...
rings.
Relationship to humans
The blue runner is a highly important species to commercial fisheries throughout parts of its range. Due to its abundance, it may be one of the primary species in a fishery. The availability of fisheries statisticsStatistics
Statistics is the study of the collection, organization, analysis, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments....
for the species is variable throughout its range, with the Americas having separate statistics kept for the species, while in Africa and Europe it is lumped in with other carangids in statistics. In the Americas, recent catch data suggests an increased amount of the species is being taken (or reported), with the 2006 and 2007 catch averaging between 6000 and 7000 tonne
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...
s, while during the 1980s and 1990s, there was rarely an annual catch greater than 1000 tonnes. Research on the fisheries of local regions has shown how important the fish is to certain fisheries. Artisanal fisheries in Santa Catarina Island have shown blue runner to be third most important and abundant species, making up 5.6% of landings, or 4.38 tonnes. Even subsistence fisheries at the edge of its range in Brazil show a catch of 388 kg in two years from beach seines. Throughout its range the blue runner is commercially taken by haul seines, lampara nets, purse seines, gill nets, and hook and line methods. The fish is sold at market either fresh, dried, smoked or as fishmeal, oil or bait.
Blue runner is also of high importance to recreational fisheries, with anglers
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...
often taking the species both for food and to use as bait. The blue runner has a reputation as an excellent gamefish on light tackle, taking both fish baits, as well a variety of lures including hard bodied bibbed lures, spoons, metal jigs and soft plastic jigs. The species is also a target for light tackle saltwater fly
Saltwater fly fishing
Saltwater fly fishing is the practice of fly fishing in saltwater, especially in coastal areas.- Sources :* Herd, Andrew. A Fly Fishing History. http://www.flyfishinghistory.com/salt_water_fly_fishing.htm...
fishermen, and can push 6-weight fly tackle to its limits. The blue runner is used extensively as live bait for larger fish including billfish
Billfish
The term billfish is applied to a number of different large, predatory fish characterised by their large size and their long, sword-like bill. Billfish include the sailfish and marlin, which make up the family Istiophoridae, and the swordfish, sole member of the family Xiphiidae...
, cobia
Cobia
Cobia —also known as black kingfish, black salmon, ling, lemonfish, crabeaters, aruan tasek, etc.—are perciform marine fish, the sole representative of their family, the Rachycentridae.-Description:...
and amberjack
Amberjack
Amberjack refers to 3 species of Atlantic fish of the Carangidae family , which includes the jacks and the pompanos.Greater amberjacks, Seriola dumerili, are the largest of the jacks. They usually have dark stripes extending from nose to in front of their dorsal fins...
. It is considered to be a fairly low quality table fish, and larger specimens are known to carry the 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...
toxin in their flesh, with several cases reported from the Virgin Islands
Virgin Islands
The Virgin Islands are the western island group of the Leeward Islands, which are the northern part of the Lesser Antilles, which form the border between the Caribbean Sea and the Atlantic Ocean...
.