The king threadfin (''Polydactylus macrochir''), also known as the blind salmon, blink tassel-fish, burnett salmon, gold threadfin, king salmon, kingfish, Sheridan threadfin, triped tassel fish, or threadfin salmon, is a species of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

, a

threadfin Threadfins are silvery grey perciform fish of the family Polynemidae. Found in tropical to subtropical waters throughout the world, the threadfin family contains eight genera and about 40 species. An unrelated species sometimes known by the name ...

from the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Polynemidae Threadfins are silvery grey perciform fish of the family Polynemidae. Found in tropical to subtropical waters throughout the world, the threadfin family contains eight genera and about 40 species. An unrelated species sometimes known by the name ...

which is found in southern

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

and northern Australia.

Description

The king threadfin is a large threadfin which can attain a maximum

total length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

of and a maximum published weight of , although the more common total length is . It has a pointed snout and the dorsal profile of the head is almost flat in young fish and concave in adults. There are two separate

dorsal fins A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

, the first dorsal fin has 8 spines and the second spine is thicker than others. The second dorsal fin has a single spine and 11 to 13 soft rays. The

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

has 3 spines and 10 to 12 soft rays, the base of the anal fin base is roughly equal in length to the base of the second dorsal fin base. The

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

has 14 or 15 unbranched rays, and has a length equivalent to roughly a quarter of the

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

with its tip just falling short or just reaching the tip of the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

. There are 5 pectoral filaments with first filament being the shortest, reaching past the level of origin of the pelvic fin. The second pectoral filament extends to past the tip of the pelvic fin. The third and fifth pectoral filaments extend past the level of the origin of the anal fin. The fourth pectoral filament is the longest, having a length equivalent to 40 to 53% of the standard length and this filament extends far beyond the level of the origin of the anal fin. The

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

is deeply forked with neither of its lobes being filamentous. There are 60-76 pored scales on its

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

which is simple In form and extends from the upper end of the gill slit to the upper end of lower caudal fin lobe. The ppper sides of head and the flanks are tinged golden silver, becoming silvery on the lower flanks. Both dorsal fins are pale brown, the pectoral and pelvic fins are vivid yellow. The front portion of the anal fin is yellow, the remainder being yellowish white. The pectoral filaments are white or yellowish white. The tail is greyish with a greyish black rear margin.

Distribution

The king threadfin is found in the eastern Indian Ocean and the western Pacific Ocean. It is found in southern New Guinea and northern Australia. In Australia its range extends from

Eighty Mile Beach Eighty Mile Beach, also spelled Eighty-mile Beach or 80-mile Beach, lies along the north-west coast of Western Australia about half-way between the towns of Broome, Western Australia, Broome and Port Hedland, Western Australia, Port Hedland. I ...

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

to the

Brisbane River The Brisbane River is the longest river in South East Queensland, Australia, and flows through the city of Brisbane, before emptying into Moreton Bay on the Coral Sea. John Oxley, the first European to explore the river, named it after the Go ...

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

. In New Guinea its range extends along the southern coast from

Western New Guinea Western New Guinea, also known as Papua, Indonesian New Guinea, or Indonesian Papua, is the western half of the Melanesian island of New Guinea which is administered by Indonesia. Since the island is alternatively named as Papua, the region ...

, Indonesia, to the Gulf of Papua in Papua New Guinea.

Habitat and biology

King threadfin occur in shallow, turbid waters such as coastal waters, estuaries, mangrove creeks, and mangrove-lined rivers, over sandbanks and mud substrates. It normally aggregates into loose schools, however, the larger individuals are more frequently recorded as pairs or as individuals. This is a carnivorous species which feeds on prawns and fish. It is a

protandrous Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, ...

hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...

and fish between fork lengths of appear to be transitional hermaphrodites in that they have mature male and immature female reproductive organs, and they function reproductively as males. King threadfins in the process of transitioning are most frequently recorded from June to September. The females

spawn Spawn or spawning may refer to: * Spawn (biology), the eggs and sperm of aquatic animals Arts, entertainment, and media * Spawn (character), a fictional character in the comic series of the same name and in the associated franchise ** '' Spawn: Ar ...

pelagic eggs but little is known about the larvae although the nursery areas are inshore, shallow and of low salinity.

Fisheries

The king threadfin is one of the most important species in the fisheries in the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...

and

and it is caught mostly using coastal set gillnets, and also using fixed tidal traps, beach seines, ring nets and handlines. The fishery in the southern part of the

Gulf of Carpentaria The Gulf of Carpentaria (, ) is a large, shallow sea enclosed on three sides by northern Australia and bounded on the north by the eastern Arafura Sea (the body of water that lies between Australia and New Guinea). The northern boundary is ...

is dominated by males in the age range 3-6 years old. In the Gulf of Carpentaria between 1980 and 1987 the gillnet fishery landings of this species equalled an average 30% by weight of total landings. It is a popular sport fishing quarry too and in Queensland and Western Australia there are minimum sizes which can be taken and a bag limit.

Species description

''Polydactylus macrochir'' was first formally described as ''Polynemus macrochir'' in 1867 by Albert Günther who gave the type locality as

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

, thought to be an error for Queensland.

References

{{Taxonbar, from=Q2593321

King threadfin The king threadfin (''Polydactylus macrochir''), also known as the blind salmon, blink tassel-fish, burnett salmon, gold threadfin, king salmon, kingfish, Sheridan threadfin, triped tassel fish, or threadfin salmon, is a species of marine ray-fin ...

Fish described in 1867 Taxa named by Albert Günther