Bludger (fish)
Encyclopedia
The bludger, Carangoides gymnostethus (also known as the bludger trevally, nakedbreast trevally and Bleeker’s jackfish), is a widespread species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of 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...

 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 bludger inhabits the tropical and subtropical regions of the Indo-west Pacific Ocean
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...

, distributed from South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

 in the west to Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 and New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...

 in the east. It is a large fish, growing to a maximum recorded length of 90 cm, and is very similar to the yellowspotted trevally
Yellowspotted trevally
The yellowspotted trevally, Carangoides fulvoguttatus is a widespread species of large inshore marine fish in the jack family Carangidae. The yellowspotted trevally inhabits the tropical and subtropical waters of the Indo-west Pacific region, from South Africa in the west to Japan and Australia in...

, Carangoides fulvoguttatus, but can be separated by the complete absence of breast scales and a number of other anatomical features. The species inhabits moderately deep 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,...

 coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

 and rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

s, where it preys on small 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 fish. The reproductive biology of the species is poorly known, but it appears to move to more tropical waters to spawn
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

. The bludger is of intermediate importance to fisheries throughout its range, taken by hook and line and various netting methods. It is of some value to 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...

 also, considered a good gamefish, but generally regarded as poor eating due to its soft oily flesh, which is used as bait by many anglers. The name ‘bludger’ is said to either refer to the blunt head of the species, or the destination of the fish when caught by professional fishermen who treat the fish as discard.

Taxonomy and naming

The bludger is classified within the genus 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...

, a group of fish commonly known as jacks and trevallies. Carangoides falls into the jack and horse mackerel family Carangidae
Carangidae
Carangidae is a family of fish which includes the jacks, pompanos, jack mackerels, and scads.They are marine fish found in the Atlantic, Indian and Pacific Oceans...

, itself part the order Perciformes
Perciformes
The Perciformes, also called the Percomorphi or Acanthopteri, is one of the largest orders of vertebrates, containing about 40% of all bony fish. Perciformes means perch-like. They belong to the class of ray-finned fish and comprise over 7,000 species found in almost all aquatic environments...

, in the suborder Percoidei
Percoidei
Percoidei is one of eighteen suborders of bony fish in the order Perciformes. Many commercially harvested fish species are contained in this suborder, including the snappers, jacks, whitings, groupers, bass, perches and porgies.-Divisions:...

.

The species was first scientifically described by the famed French naturalist
Naturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...

 Georges Cuvier
Georges Cuvier
Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...

 in 1833 based on the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 specimen taken in the Seychelles
Seychelles
Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....

. Cuvier named his species Caranx gymnostethus, with the specific epithet
Epithet
An epithet or byname is a descriptive term accompanying or occurring in place of a name and having entered common usage. It has various shades of meaning when applied to seemingly real or fictitious people, divinities, objects, and binomial nomenclature. It is also a descriptive title...

 meaning 'naked breast' in reference to its scaleless breast. The species was later reassigned to the genus Carangoides, where it has remained since. In 1851, Pieter Bleeker
Pieter Bleeker
Pieter Bleeker was a Dutch medical doctor and ichthyologist, famous for his work on the fishes of East Asia – Atlas Ichthyologique des Orientales Neerlandaises – which was published 1862–1877....

 named what he believed to be a new species Carangoides gymnostethoides, which literally translates as 'like Carangoides gymnostethus, indicating its similarity to the bludger. This was later found to be the same as Carangoides gymnostethus and became a junior synonym.
Confusion with Carangoides orthogrammus in Hawaiian waters led John Nichols
John Treadwell Nichols
John Treadwell Nichols was an American ichthyologist.-Biography:Nichols was born as son of John White Treadwell Nichols in Jamaica Plain, Boston, Massachusetts. In 1906 he studied vertebrate zoology at Harvard College where he graduated to Bachelor of Arts...

 to propose subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 of Carangoides gymnostethoides due to slight anatomical differences. These taxa
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...

 possibly represent misidentified C. orthogrammus, although Nichols meticulous distinction of the species may indicate a population of the species may exist in Hawaii, although these subspecies have largely been ignored by taxonomic authorities and remained unresolved. The species has the unusual 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 'bludger', which is said to have arisen by one of two ways; either due to the blunt shape of the species snout or a description of the eventual destination of the fish when caught by professional fishermen seeking more desirable catches. In both cases, the word 'bludger' refers to an object used to bludgeon
Bludgeon
Bludgeon may refer to:* Bludgeon , a fictional character* Bludgeon , a club-like weapon* Crabtree's Bludgeon, a foil to Occam's Razor...

.

Description

The bludger is a large fish, growing to at least 90 cm in length and reaching a recorded maximum weight of 14.5 kg.
The bludger has a body shape very similar to the yellowspotted trevally
Yellowspotted trevally
The yellowspotted trevally, Carangoides fulvoguttatus is a widespread species of large inshore marine fish in the jack family Carangidae. The yellowspotted trevally inhabits the tropical and subtropical waters of the Indo-west Pacific region, from South Africa in the west to Japan and Australia in...

, being more elongated and subcylindricall than most of the genus Carangoides. As a juvenile, the fish is ovate, becoming more elongated with age, with the convex dorsal profile of the head and nape
Nape
The nape is the back of the neck. In technical anatomical/medical terminology, the nape is referred to by the word nucha, which also gives the adjective corresponding to "nape" in English, "nuchal"....

 becoming less steep with age also. 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 is composed of 1 spines and 28 to 32 soft rays, with the anterior lobe of this fin being shorter than the head length. The anal fin has two anteriorly detached spines followed by 1 spine attached to 24 to 26 soft rays and the pelvic fin has 1 spine and 18 to 20 soft rays. The lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...

 has a gentle anterior arch which is slightly longer than the straight section of the lateral line, with the intersection below the sixteenth to twentieth soft ray of the dorsal fin. The curved section contains 78 to 80 scales
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...

 while the straight section consists of 15 to 19 scales and 21 to 27 scute
Scute
A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...

s. The breast is scaleless until the origin of the pelvic fins and up to the origin of the pectoral fins. In adults, the mouth cleft is level with the eye, 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 bands of villiform teeth which become wider anteriorly. There are 27 to 31 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 and 25 vertebrae.

The bludger has an overall silver-green body as a juvenile, while adults have green-blue to olive green body above, becoming more silvery below. At all stages of its life, the fish has a few brown or golden spots in a midlateral band, but much less than the yellowspotted trevally, while the dusky opercular
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....

 spot is often inconspicuous. The dorsal, anal and caudal fins are olive green, with the soft dorsal, anal and anal fins having white lobe tips and the anal having white leading and distal edge. The pelvic and pectoral 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 green.

Distribution and habitat

The bludger is distributed throughout the tropical to subtropical regions of the Indian
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and west Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

s, ranging from South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

 in the west, along east Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...

 and north to the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

. Its distribution in the Indian Ocean extends east to India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, South East Asia, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

 and as far south as northern Australia
Northern Australia
The term northern Australia is generally known to include two State and Territories, being Queensland and the Northern Territory . The part of Western Australia north of latitude 26° south—a definition widely used in law and State government policy—is also usually included...

. In the Pacific Ocean, it extends as far north as Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 and out to New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...

, Tonga
Tonga
Tonga, officially the Kingdom of Tonga , is a state and an archipelago in the South Pacific Ocean, comprising 176 islands scattered over of ocean in the South Pacific...

 and the Kapingamarangi Atoll.

The bludger inhabits moderately deep 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,...

 waters on rocky and 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...

 structures, rarely found in inshore waters.

Biology and fishery

The bludger moves in small schools
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...

 as a juvenile, becoming more solitary with age. The species has a rather soft mouth and weak jaws, limiting the types of prey available to it, with studies showing 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, small 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, mantis shrimp
Mantis shrimp
Mantis shrimp or stomatopods are marine crustaceans, the members of the order Stomatopoda. They are neither shrimp nor mantids, but receive their name purely from the physical resemblance to both the terrestrial praying mantis and the shrimp. They may reach in length, although exceptional cases of...

s and small fish are its main prey. Research on the North West Shelf
North West Shelf
The North West Shelf of Western Australia is an extensive oil and gas region off the North West Australia coast in the Pilbara region.It has a considerable number of oil and gas wells, pipelines, production areas and support facilities.- Location :...

 of Australia indicates there is diet partitioning between the bludger and the yellowspotted trevally, with the bludger taking mostly crustaceans while the yellowspotted trevally consumes mostly fish 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. The species itself is known to be prey for sharks including the blacktip shark, Carcharhinus tilstoni. Reproduction and growth in the species is poorly studied, with preliminary observations in South Africa indicating the fish may move from this region to more tropical waters of Mozambique
Mozambique
Mozambique, officially the Republic of Mozambique , is a country in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west and Swaziland and South Africa to the southwest...

 to spawn
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

.

The bludger is of minor importance to fisheries throughout its range, taken by hook and line as well as gill nets and various types of fish trap. Separate catch statistics are not kept for the species, as it is often not distinguished from other trevallies. The blugder is also of some interest to angler
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...

s, although the level of interest differs between countries. In South Africa it is considered a good catch by boat anglers and spearfishermen
Spearfishing
Spearfishing is an ancient method of fishing that has been used throughout the world for millennia. Early civilizations were familiar with the custom of spearing fish from rivers and streams using sharpened sticks....

 and is generally regarded as high quality table fare
Fish (food)
Fish is a food consumed by many species, including humans. The word "fish" refers to both the animal and to the food prepared from it. Fish has been an important source of protein for humans throughout recorded history.-Terminology:...

. In Australia it is still considered a good gamefish, but of a lower caliber than related species such as giant
Giant trevally
The giant trevally, Caranx ignobilis , is a species of large marine fish classified in the jack family, Carangidae...

 and bluefin trevally
Bluefin trevally
The bluefin trevally, Caranx melampygus , is a species of large, widely distributed marine fish classified in the jack family, Carangidae...

, and is regarded as a poor table fish. Its soft, oily flesh is often used for bait when reef fishing. It may be caught using small baits or lures
Fishing lure
A fishing lure is an object attached to the end of a fishing line which is designed to resemble and move like the prey of a fish. The purpose of the lure is to use movement, vibration, and colour to catch the fish's attention so it bites the hook...

.

External links

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