Blue trevally

{{Short description|Species of ray-finned fish}} {{Speciesbox | image = Blue trevally taxobox.png | status = LC | status_system = IUCN3.1 | status_ref = <ref name = iucn>{{cite iucn | author1 = Smith-Vaniz, W.F. | author2 = Williams, I. | name-list-style = amp | year = 2016 | title = ''Carangoides ferdau'' |errata=2017 | volume = 2016 | article-number = e.T20429455A115372940 | doi = 10.2305/IUCN.UK.2016-3.RLTS.T20429455A46664064.en | access-date = 12 November 2022}}</ref> | taxon = Ferdauia ferdau | authority = ([[Peter Forsskal|Forsskål]], 1775) | range_map = Carangoides ferdau distribution.png | range_map_caption = Approximate range of the blue trevally | synonyms = *''Scomber ferdau'' Forsskål, 1775 *''Caranx ferdau'' (Forsskål, 1775) *''Carangoides ferdau'' (Forsskål, 1775) *''Carangoides hemigymnostethus'' [[Pieter Bleeker|Bleeker]], 1851 *''Caranx hemigymnostethus'' (Bleeker, 1851) *''Caranx laticaudis'' [[Haynes Gibbes Alleyne|Alleyne]] & [[William John Macleay|Macleay]], 1877 *''Carangoides laticaudis'' (Alleyne & Macleay, 1877) *''Caranx gilberti'' [[David Starr Jordan|Jordan]] & [[Alvin Seale|Seale]], 1906 *''Ferdauia lindemanensis'' [[Gilbert Percy Whitley|Whitley]], 1951 | synonyms_ref = <ref name = "fishbase"/> }}

The '''blue trevally''' ('''''Ferdauia ferdau'''''), also known as the '''banded trevally''', '''barred trevally''', '''Ferdau's trevally''' or '''Forskaal's jackfish''', is a common, widespread species of [[pelagic]] [[marine fish]] classified in the jack [[Family (taxonomy)|family]], [[Carangidae]]. The blue trevally is distributed throughout the [[tropical]] and subtropical waters of the [[Indo-Pacific]] and [[Pacific Ocean|central Pacific]] regions, ranging from [[South Africa]] in the west to [[Hawaii]] in the east. It is a moderately large fish, growing to a recorded maximum length of 70 cm, with the number of rays in the second [[dorsal fin]] and the colouring serving as diagnostic features of the species. The species inhabits waters to depths of 60 m, generally inhabiting [[reef]]s, [[beach]]es, [[lagoon]]s, and areas with sandy substrates. It is a predatory fish, taking other fish, [[prawn]]s, [[crab]]s, and [[mollusc]]s, and very little is known of the species' [[reproductive biology]]. The blue trevally is of varying importance to [[fisheries]] throughout its range, with some regions having high catches of the fish. It is considered to be a [[gamefish]], and is sought after for its excellent [[table fish|eating qualities]].

==Taxonomy and naming== The blue trevally is classified within the genus ''[[Ferdauia]]''. ''Ferdauia'' falls into the jack and horse mackerel family [[Carangidae]], and Carangidae is part of the [[Order (biology)|order]] [[Carangiformes]].<ref name = Nelson5>{{cite book |title=Fishes of the World |edition=5th |author1=J. S. Nelson |author2=T. C. Grande |author3=M. V. H. Wilson |year=2016 |pages=380–387 |publisher=Wiley |isbn=978-1-118-34233-6 |url=https://sites.google.com/site/fotw5th/ |access-date=2019-11-24 |archive-date=2019-04-08 |archive-url=https://web.archive.org/web/20190408194051/https://sites.google.com/site/fotw5th/ }}</ref>

The species was first described by the Swedish [[naturalist]] [[Peter Forsskål]] in 1775 based on a specimen taken from the [[Red Sea]].<ref name = "Zoocat">{{cite book | last = Hosese | first = D.F. |author2=Bray, D.J. |author3=Paxton, J.R. |author4=Alen, G.R. | title = Zoological Catalogue of Australia Vol. 35 (2) Fishes | publisher = CSIRO | year = 2007 | location = Sydney | page = 1150 | isbn =978-0-643-09334-8 }}</ref> He named the species ''Scomber ferdau'', thus relating it to the [[Scomber|mackerels]] before the family Carangidae was bought into existence with the creation of [[Bernard Germain de Lacépède|Lacépède]]'s genus ''[[Caranx]]''. With the advent of carangid taxonomy, the species was transferred first to ''Caranx'' and later to ''Carangoides'', and is now placed in the genus ''Ferdauia'' together with the [[island trevally]] (''Ferdauia orthogrammus'').<ref name="ECoF species">{{Catalog of Fishes |genus=Carangichthys |list=species |date=12 February 2026}}</ref><ref name = "fishbase">{{FishBase | Ferdauia | ferdau | year = 2026 | month = February}}</ref> The species was independently described and named a number of times after its initial naming, with this and confusion with ''F. orthogrammus'' in the Indo-Pacific giving rise to a complex history of synonymies. These later names were often transferred between genera before being finally sunk into the name ''Ferdauia ferdau'' and as such are considered to be invalid [[junior synonym]]s. The specific [[epithet]] ''ferdau'' refers to a person named Ferdau, probably the collector of the [[holotype]] specimen.<ref name = "SAfrica">{{cite book | last = van der Elst | first = Rudy |author2=Peter Borchert | title =A Guide to the Common Sea Fishes of Southern Africa | publisher = New Holland Publishers | year = 1994 | page = 142 | isbn = 1-86825-394-5 }}</ref>

==Description== [[File:Carangoides ferdau.jpg|thumb|left|240px|A darker-pigmented individual]]

The blue trevally is a moderately large fish, growing to a recorded maximum length of 70 cm and a weight of 8 kg.<ref name = "fishbase"/> The species has a compressed, oblong body, with the [[anatomical terms of location#Dorsal and ventral|dorsal]] profile more convex than the ventral profile. The snout is bluntly rounded, resembling the snouts of the pompanos of the genus ''[[Trachinotus]]'' and the lips of adults are notably fleshy.<ref name = "FAO">{{cite book |editor-last=Carpenter |editor-first=Kent E. |editor2=Volker H. Niem | title = FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Volume 4: Bony fishes part 2 (Mugilidae to Carangidae) | website=fao.org | year = 2001 | location = Rome |page= 2694 | url = ftp://ftp.fao.org/docrep/fao/009/x2400e/x2400e52.pdf | isbn = 92-5-104587-9 | publisher = Food and Agriculture Organization of the United Nations}}</ref> Two separate [[dorsal fin]]s are found, the first having eight [[Fish anatomy#Spines and rays|spines]], while the second consists of one spine and 26 to 34 [[Fish anatomy#Spines and rays|soft rays]]. In young adults, the lobe of the second dorsal fin is often falcate, but usually shorter than the head length. The anal fin has two [[Anatomical terms of location#Anterior and posterior|anteriorly]] detached spines followed by a single spine attached to 21 to 26 soft rays, while the [[pelvic fin]] has one spine attached to 20 or 21 soft rays.<ref name = "Lin1999">{{cite journal | last = Lin | first = Pai-Lei | author2 = Shao, Kwang-Tsao | title = A Review of the Carangid Fishes (Family Carangidae) From Taiwan with Descriptions of Four New Records | journal = Zoological Studies | volume = 38 | issue = 1 | pages = 33–68 | year = 1999 | url = http://cat.inist.fr/?aModele=afficheN&cpsidt=10055944 | access-date = 2008-10-24 | archive-date = 2012-02-29 | archive-url = https://web.archive.org/web/20120229173915/http://cat.inist.fr/?aModele=afficheN&cpsidt=10055944 }}</ref> The [[lateral line]] has a gentle anterior arch, with the junction of the curved and straight sections vertically below the 15th to 20th soft rays of the second dorsal fin. The curved section of the lateral line contains 82 to 90 [[scale (zoology)|scales]], while the straight section has 12 to 17 scales and 26 to 31 [[scute]]s.<ref name = "Lin1999"/> The breast is naked ventrally to origin of the pelvic fins and the base of the [[pectoral fin]]s, but is interrupted laterally by a moderate band of scales. The upper jaw is highly protractile, containing narrow bands of [[Ichthyology terms#V|villiform]] teeth, which become [[obsolescent]] with age, as is the case in the lower [[jaw]].<ref name = "FAO"/> It has a total of 24 to 29 [[gill raker]]s and 24 [[vertebrae]].<ref name = "Barrier">{{cite book | last = Randall | first = John Ernest |author2=Roger C. Steene|author3=Gerald R. Allen | title = Fishes of the Great Barrier Reef and Coral Sea | publisher = University of Hawaii Press | year = 1997 | page = 161 | isbn = 0-8248-1895-4 }}</ref>

The body is a blue-green to yellow-green above, becoming silvery below, with adults having five or six dusky vertical bands which usually persist after death.<ref name = "Barrier"/> Numerous, inconspicuous golden spots often are present on the sides, mostly above the level of the pectoral fins. The soft dorsal and anal fins are pale yellowish-green, and the anterior lobes of both often have white to blue tips. The [[caudal fin]] is yellow green, having a dark trailing edge and tips, while the pelvic fins are whitish to [[hyaline]].<ref name = "Gunn">{{cite journal | doi = 10.3853/j.0812-7387.12.1990.92 | last = Gunn | first = John S. | title = A revision of selected genera of the family Carangidae (Pisces) from Australian waters | journal = Records of the Australian Museum Supplement| volume = 12 | pages =1–78 | year = 1990 | doi-access = free }}</ref>

==Distribution and habitat== [[File:Blue trevally, Micronesia.jpg|thumb|240px|A blue trevally patrolling a Micronesian reef]] The blue trevally has a wide distribution, inhabiting the [[tropical]] and subtropical waters of the [[Indian Ocean|Indian]], [[West Pacific]] and [[Central Pacific Area|Central Pacific]] Oceans.<ref name = "Gunn"/> It ranges from [[South Africa]] in the west, north along the [[East Africa]]n coast to the Red Sea and across to [[India]] and [[Southeast Asia]]. The species ranges south to [[Australia]] and [[Indonesia]], and as far as [[Japan]], [[Hawaii]], and a number of Pacific islands, including [[Micronesia]], [[New Caledonia]], and [[Tonga]].<ref name = "fishbase"/>

The blue trevally inhabits [[coastal]] waters to a depth of 60 m, over [[reef]]s, [[beach]]es,<ref>{{cite journal | last = Lin | first = H.J. |author2=Shao, K.T. | title = Seasonal and diel changes in a subtropical mangrove fish community | journal = Bulletin of Marine Science| volume = 65 | issue = 3 | pages = 775–794 | year = 1999 }}</ref> [[lagoon]]s, and areas with sandy substrates. The species lives [[pelagic]]ally, allowing movement between islands and [[atoll]]s.<ref name = "Gunn"/> It is rarely found in [[estuaries]], suggesting a poor tolerance to low salinities.<ref name = "SAfrica"/>

==Biology and fishery== [[File:Carangoides ferdau, avec sa méduse Thysanostoma loriferum.jpg|thumb|240px|A young blue trevally with its jellyfish ''[[Thysanostoma loriferum]]''.]] Like many Indo-Pacific carangids, the biology and [[ecology]] of the blue trevally is poorly known, with the only data on the species relating to its diet. It is a fast-swimming [[predator]] which often forms small [[Shoaling and schooling|schools]], and takes a variety of small fish (specifically [[mackerel]] and [[filefish]]),<ref>{{cite journal | last = Bachok | first = Z. | author2 = M.I. Mansor | author3 = R.M. Noordin | title = Diet composition and food habits of demersal and pelagic marine fishes from Terengganu waters, east coast of Peninsular Malaysia | journal = NAGA, WorldFish Center Quarterly | volume = 27 | issue = 3/4 | pages = 41–47 | year = 2004 | url = http://www.worldfishcenter.org/naga/naga27-3n4/pdf/article08.pdf | access-date = 2008-10-05 | archive-url = https://web.archive.org/web/20060927181740/http://www.worldfishcenter.org/naga/naga27-3n4/pdf/article08.pdf | archive-date = 2006-09-27 }}</ref> [[crustaceans]] including [[prawns]], [[crabs]], and [[sea lice]], soft [[mollusc]]s, and other soft prey.<ref name = "SAfrica"/> In Hawaii, they have been observed following foraging [[bonefish]] or [[goatfish]], consuming any scraps uncovered by the foragers.<ref name = "Hawaii">{{cite web | last = hawaiisfishes.com | title = Barred Jack | work = Fish Identification | year = 2005 | url = http://www.hawaiisfishes.com/fishes/neatfish/carangoides_ferdau.htm | access-date =2008-10-06 }}</ref> The species appears to be in constant abundance all year, but ripe individuals have rarely been reported. No information regarding the [[reproduction]] and growth of the species is available, although [[larva]]e of the species are known to appear during February in the waters off Taiwan, suggesting a December [[spawn (biology)|spawning]] period, and make up a high proportion of the larval abundance.<ref>{{cite journal | last = Hsieh | first = H.Y. |author2=Wen-Tseng Lo |author3=Don-Chung Liu |author4=Pei-Kai Hsu |author5=Wei-Cheng Su | title = Winter spatial distribution of fish larvae assemblages relative to the hydrography of the waters surrounding Taiwan | journal = Environmental Biology of Fishes | volume = 78 | issue = 4| pages = 333–346 | year = 2007 | doi = 10.1007/s10641-006-9101-9 | s2cid = 26056620 }}</ref> Juveniles are known to sometimes shelter among the tentacles of large pelagic [[jellyfish]].<ref name = "Hawaii"/>

The species is of [[fishery|commercial importance]] in a number of areas due to its high abundance, or more often taken as bycatch in other major fisheries. Catch statistics for the individual species are rarely kept, though, and it is generally grouped with other trevallies. It is caught mainly on hook and line and with [[gill net]]s and various traps.<ref name = "FAO"/> In South Africa, it is considered a popular [[gamefish]], and is often taken by anglers using various small baits, with the best catches had at dawn and dusk.<ref name = "SAfrica"/> It is considered to be an excellent [[table fish]], although [[ciguatera]] poisoning attributed to this fish has been reported rarely.<ref name = "fishbase"/>

==References== {{Reflist|2}}

==External links== *[https://web.archive.org/web/20080819172721/http://australianmuseum.net.au//fishes/fishfacts/fish/cferdau.htm Information page at Australian Museum Online] *[http://www.hawaiisfishes.com/fishes/neatfish/carangoides_ferdau.htm Description at Hawaiian fishes.com] *[http://www.fishbase.org/summary/Speciessummary.php?id=1921 Blue trevally at Fishbase] * {{SealifePhotos|218395}}

[[Category:Caranginae]] [[Category:Marine fish of East Africa]] [[Category:Fish of Micronesia]] [[Category:Fish described in 1775|blue trevally]]