Product Code Database
The golden trevally ( Gnathanodon speciosus), also known as the golden kingfish, banded trevally or king trevally, is a species of large ocean fish classified in the jack and horse mackerel family Carangidae, and the only member of the monospecific genus Gnathanodon. The golden trevally is widely distributed throughout the tropical and subtropical waters of the Indian Ocean and , ranging from South Africa in the west to Central America in the east, extending to Japan in the north and Australia in the south. The species predominantly occupies inshore waters where it inhabits both reef and sandy substrates. The golden trevally is easily distinguished from its relatives by its fleshy, rubbery lips and unique colouration, which ranges from bright yellow with black bars as a juvenile to a golden-silvery colour as an adult. It is known to grow to in length and in weight. The golden trevally schools as a juvenile, often closely following larger objects including and jellyfish. The species uses its protractile jaws to suck out prey from the sand or reef, and consumes a variety of fish, and . Spawning aggregations gather at night at different times of the year throughout its range. The golden trevally is a considerable constituent of several Middle Eastern fisheries and being of minor importance to many others, with a worldwide annual catch of to recorded between 2000 and 2010. The golden trevally is a popular gamefish, taken by bait, fishing lure, fly fishing and also spear throughout its range. Several Asian countries currently farm the fish in caged aquaculture. Due to their brilliant colouration, juveniles are popular in marine aquaria.
The species was scientifically described for the first time by the Swedish people naturalist Peter Forsskål in 1775. Forsskål referred the species to the genus Scomber, where many jacks were placed before the recognition of the family Carangidae. The species is initially referred with two epithets; Scomber rim, speciosus in this publication; however the following page names it as Scomber speciosus with 'rim' given as a transcription of the species' Arabic name. Consequently, authorities regard Scomber rim as a junior synonym. Forsskål's description was based on an individual from the Red Sea off Jeddah, Saudi Arabia. The holotype has since been lost and a neotype was invalidly designated by Ronald Fricke in 1999. The specific epithet speciosus is Latin language for beautiful. The species was transferred to Caranx before the Dutch people ichthyologist Pieter Bleeker placed it in its own genus Gnathanodon, with this name derived from the Latin for 'toothless jaws'. In addition to Forsskål's naming, seven other later names have been ascribed to the fish, with all of these now recognised as invalid junior synonyms under ICZN rules. The species common names generally refer to its appearance with 'golden trevally' (or kingfish), 'banded trevally' and 'king trevally' used. In Hawaii the species is referred to as 'ulua paʻopaʻo' or 'papio' when small.
A study on the phylogeny of the Carangidae-based primarily on osteology by Soko Gushiken found that Gnathanodon is closely related to and forms a monophyletic group with Caranx. The species has yet to be included in any molecular phylogeny study of the family.
The golden trevally predominantly occupies inshore waters of varying substrate, although is known to occur on deeper continental shelf in Australia. In coastal areas the species inhabits rocky and as well as open where it forages for food. A systematic study in northern Australia indicated it to be one of the only species to be approximately equally distributed in both reef and soft-bottom habitats. Golden trevally appear to prefer clear water to turbid waters, and thus is only encountered rarely in low turbidity estuarine environments. One known exception to this was the capture of several individuals in a shallow mangrove swamp in Baja California which appeared to be foraging for prey.
The golden trevally's colour is the species most prominent distinguishing feature, and for which it acquired its common names. Juveniles are a bright golden yellow colour over their entire body and all fins, with 7 to 11 black vertical crossbars all over their body. These bars generally alternate between broad and narrow. The caudal fin lobes have dark tips and there is a prominent black edge to the operculum. As the fish grows, the body becomes more silver to silvery golden and the cross bars fade or disappear, often replaced by dark blotches. The fins remain yellow, often with greenish tinges. The dark edge of the operculum also fades with age.
The golden trevally is a Diurnality foraging carnivore which, unlike other carangids, does not normally seek out individual prey items. The highly protractile mouth possessed by the species is used to form a tube to suck prey out of both reef- and algae-dominated habitats, as well as filtering organisms out of sandy substrates. In the latter case, both sand and any prey items are taken into the mouth and filtered through the gill rakers; sand is expelled, while small organisms are trapped and swallowed. The species takes a variety of prey including such as shrimp, , and , as well as and small fish. Golden trevally found inhabiting a mangrove swamp were found to have fed exclusively on fish ( Mugil curema), suggesting the species also actively hunts down fleeing prey. A laboratory study using only four individuals being fed found that one fish will take the 'lead' position in this situation while another will attack the other fish in the school, apparently in competition for food.
A variety of have been recorded from the species, including , , and a nematode which inhabits the fish's swimbladder.
Reproduction in the golden trevally has been studied in both the Indian and Pacific Oceans. In Hawaii, spawning occurred from late February to early October, with a peak from late April to early September. Five distinct peaks during this time were correlated with the first and third quarters of the moon. Spawning occurred from the early evening into the night. In the Indian Ocean, in the southern Persian Gulf, spawning occurred in April and May, with defined peaks in recruitment of juveniles into the local fishery during September and October. The male:female sex ratio in this population was 1:1.01, close to parity. Growth rates were also studied using in this population, with an increase in growth rate during the winter (November to April). Von Bertalanffy growth curves were also calculated for the species.
The golden trevally is commonly targeted by both angling and spearfishing, and is considered to be a gamefish. Golden trevally will take a variety of fishing bait and fishing lure and may be caught from both the shore and boats, making it a highly accessible species. Baits commonly employed for golden trevally include prawns and a variety of small fish or cut baits. The fish are known to follow a chumming stream right up to the back of a boat, allowing for easy capture on unweighted baits. A variety of lures may be employed when targeting the species, including jigging, Fishing popper, spoon lures, slices, and minnows, with large minnows trolled around reefs often accounting for larger specimens. The use of saltwater fly fishing to specifically target golden trevally has developed in recent years, especially over shallow, sandy flats. In these cases, a sinking line and leader is employed to not spook the fish in these shallow waters. Once hooked, golden trevally are known for fast runs and hard fights, especially when reef or other structures are present. Golden trevally are considered one of the best members of the trevally family for eating, with bleeding recommended. The fish has slightly translucent, dark-pink flesh while fresh, becoming white and juicy during cooking, although has a tendency to become dry, flaky, and fibrous. A rich, tangy fish flavour is noted.
Juvenile golden trevally are often used in marine aquaria due to their vivid yellow colour and black banding, with larger individuals also kept in larger tanks. The development of laboratory culturing specifically for the aquarium trade has been achieved in Singapore.
External links
|
|
