Threadfin jack

{{Short description|Species of fish}} {{Speciesbox | image =Threadfin jack 2.jpg | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Smith-Vaniz, B. |author2=Robertson, R. |author3=Dominici-Arosemena, A. |author4= Bussing, W. |author5=Molina, H. |date=2010 |title=''Carangoides otrynter'' |volume=2010 |article-number=e.T183808A8180545 |doi=10.2305/IUCN.UK.2010-3.RLTS.T183808A8180545.en |access-date=19 November 2021}}</ref> | taxon = Euprepocaranx dorsalis | parent_authority = Kimura, Takeuchi & Yadome, 2022 | authority = ([[Theodore Gill|Gill]], 1863) | range_map = Carangoides otrynter distribution.png | range_map_caption = Approximate range of the threadfin jack | synonyms = *''Caranx otrynter'' Jordan & Gilbert, 1883 *''Carangoides dorsalis'' [[Theodore Gill|Gill]], 1863 *''Carangoides otrynter'' (Jordan & Gilbert, 1883) *''Caranx dorsalis'' (Gill, 1863) *''Citula dorsalis'' (Gill, 1863) *''Paraselene otrynter'' (Jordan & Gilbert, 1883) | synonyms_ref = <ref>{{Cof species|genus=Euprepocaranx|species=dorsalis|access-date=5 March 2026}}</ref> }} The '''threadfin jack''' or '''thread pompano''', '''''Euprepocaranx dorsalis''''', is a species of coastal [[marine (ocean)|marine]] [[fish]] in the jack [[Family (taxonomy)|family]] [[Carangidae]]. The species inhabits the tropical waters of the eastern [[Pacific Ocean]] from [[Baja California]] in the north to [[Ecuador]] and the [[Galapagos Islands]] in the south. It is a moderately large fish, growing to {{cvt|60|cm|in}} and may be recognized by its filamentous [[dorsal fin|dorsal]] and [[anal fin]] lobes. The threadfin jack inhabits both deeper [[coastal]] waters and [[inshore]] environments, including [[reef]]s and [[estuaries]], where it preys on minute [[benthic]] and [[pelagic]] organisms, including small fishes and [[crustacean]]s. Very little is known about the ecology and reproductive cycle in the species. The threadfin jack is of importance to [[fisheries]] throughout its distribution, caught by [[fishing hook|hook-and-line]] and [[fishing net|net]] methods and marketed fresh and salted, and is considered a very good [[fish (food)|table fish]]. The species was named ''Carangoides dorsalis'' by [[Theodore Gill]] 20 years before the name ''Caranx otrynter'' was introduced, but confusion with ''Vomer dorsalis'' led to the proposal of the new name to separate the two species.

==Taxonomy and naming== The threadfin jack is currently placed within the [[monotypic taxon|monotypic genus]] ''Euprepocaranx''.<ref name=KTY>Kimura, Seishi, Shun Takeuchi, and Taishi Yadome. "Generic revision of the species formerly belonging to the genus Carangoides and its related genera (Carangiformes: Carangidae)." Ichthyological Research 69.4 (2022): 433-487.</ref> The threadfin jack is a member of the jack and horse mackerel family [[Carangidae]], which are, in turn, within the [[Order (biology)|order]] [[Carangiformes]].<ref name = Nelson5>{{BioRef |fotw5 |pages=380–387}}</ref>

The species was first [[scientific classification|scientifically described]] by the American [[ichthyologist]] [[Theodore Gill]], who named the species ''Carangoides dorsalis'' based on the [[holotype]] taken from the west coast of [[Central America]].<ref>{{cite journal | last = Gill | first = Theodore N. | title = Descriptive enumeration of a collection of fishes from the western coast of Central America, presented to the Smithsonian Institution by Captain John M. Dow | journal = Proceedings of the Academy of Natural Sciences of Philadelphia | volume = 15 | pages = 162–174 | year = 1863 }}</ref> This name and description was published in the ''Proceedings of the Academy of Natural Sciences'' of Philadelphia, in which Gill one year previously described another carangid, ''Vomer dorsalis''.<ref>{{cite journal | last = Gill | first = Theodore N. | title = Synopsis of the carangoids of the eastern coast of North America | journal = Proceedings of the Academy of Natural Sciences of Philadelphia | volume = 14 |issue = 9 | pages = 430–443 | year = 1862 }}</ref> The state of carangid [[Taxonomy (biology)|taxonomy]] at the time was rather confusing, with many synonymous genera and species present in the literature, and ''Vomer dorsalis'' was soon moved to ''Caranx'', as was ''Carangoides dorsalis'', creating a taxonomic [[homonym]]. To address this problem, the American ichthyologists [[David Starr Jordan]] and [[Charles Henry Gilbert]] in 1883 created the name ''Caranx otrynter'' as a replacement for the species originally named ''Carangoides dorsalis'', basing their description on a new holotype specimen taken from [[Mazatlán]], Mexico.<ref name = "proc">{{cite journal | last = Jordan | first = David S. |author2=Charles H. Gilbert | title = A Review of the American Caranginae | journal = Proceedings of the United States National Museum | volume = 6 | pages = 188–207 | year = 1883 | issue = 367 | doi = 10.5479/si.00963801.6-367.188}}</ref> The authors indicated that if ''Vomer'' was found to be a valid genus or subgenus, ''Vomer dorsalis'' could be reinstated and the original combination of ''Caranx dorsalis'' be restored. Despite ''V. dorsalis'' being transferred to ''[[Selene dorsalis]]'', this never occurred and in a 1994 publication, Gerald Allen and D. Ross Robertson placed ''Caranx otrynter'' into the genus ''Carangoides'',<ref>{{cite book | last = Allen | first = Gerald A.|author2=D.R. Robertson | title = Fishes of the tropical eastern Pacific i-xix | publisher = Crawford House Press | year = 1994 | location = Bathurst | pages = 1–332 | isbn = 978-0-8248-1675-9}}</ref> where it has remained until 2022.<ref>{{cite journal|author=Kimura, S.|author2= Takeuchi, S.|author3= Yadome, T. |year=2022|title= Generic revision of the species formerly belonging to the genus ''Carangoides'' and its related genera (Carangiformes: Carangidae)|journal= Ichthyological Research|volume= 69|issue=4|pages= 433-487 |doi=10.1007/s10228-021-00850-1}}</ref> The specific name ''otrynter'' is derived from Latin, and means a driver, in allusion to the [[whip]]-like ray of the second dorsal fin.<ref name = "proc"/> The common names of the species, threadfin jack and thread pompano, also refer to the filamentous, threadlike dorsal fin.{{Cn|date=January 2021}}

==Description== [[File:Threadfin jack.jpg|left|thumb|The threadlike dorsal and anal fin tips are characteristic.]] The threadfin jack is a moderately large species, growing to a known maximum length of 60 cm.<ref name = "fishbase">{{FishBase |Euprepocaranx|dorsalis| id=1915| year = 2026 | month = March}}</ref> The species is similar in appearance to a number of jacks in the genera ''Carangoides'' and ''[[Alectis]]'' in its adult form, having a compressed, [[rectangle|oblong]] body, with the [[anatomical terms of location#Dorsal and ventral|dorsal]] and ventral profiles approximately equal in [[wikt:concave|concavity]]. The head profile is quite angular, being most steep immediately above the mouth, and being moderately steep to the [[nape]], becoming more horizontal [[Anatomical terms of location#Anterior and posterior|posteriorly]]. The juveniles have a more oval to diamond shape, looking much like juveniles of the genus ''Alectis''.<ref name = "FAOPCO">{{cite book | last = Fischer | first = W. |author2=Krupp F. |author3=Schneider W. |author4=Sommer C. |author5=Carpenter K.E. |author6=Niem V.H. | title = Guía FAO para la identificación de especies para los fines de la pesca. Pacífico centro-oriental. Volumen II. Vertebrados - Parte 1. | publisher = FAO | year = 1995 | location = Rome | page = 958 | url = http://www.fao.org/fishery/sidp/3,1/en#Ecp | isbn = 92-5-303409-2 }}</ref> The [[dorsal fin]] is in two parts, the first being greatly diminished and consisting of eight [[Fish anatomy#Spines and rays|spines]] entirely embedded in the skin, with the second dorsal fin composed of one spine and 18 or 19 [[Fish anatomy#Spines and rays|soft rays]]. The [[anal fin]] is composed of two [[Anatomical terms of location#Anterior and posterior|anteriorly]] detached spines followed by one spine and 16 or 17 soft rays.<ref name = "FAOPCO"/> Both juveniles and adults have highly elongated second dorsal and anal fin lobes, extended out into long filaments; they are most pronounced in juveniles.<ref>{{cite book | last = Grove | first = Jack S. |author2=Robert J. Lavenberg | title = The Fishes of the Galápagos Islands | publisher = Stanford University Press | year = 1997 | location = California | page = 376 | isbn = 978-0-8047-2289-6 }}</ref> The [[lateral line]] has a moderate, regular arch anteriorly, which is roughly equal in length to the straight posterior section. The straight section has no to 15 [[scale (zoology)|scales]] followed by 40 to 52 small [[scute]]s. The breast is devoid of scales ventrally to behind the [[pelvic fin]] origin and diagonally up to the [[pectoral fin]] base. Both [[jaw]]s contain uniform bands of small, weak teeth becoming wider posteriorly and irregular conical outer teeth in adults. It has 21 to 23 [[gill raker]]s and 24 [[vertebrae]].<ref name = "FAOPCO"/>

In life, the threadfin jack is a silvery-blue above, becoming silvery-white on the underside, with golden to yellow reflections. The first dorsal and pelvic fin is grey, while the second dorsal, anal, pectoral, and [[caudal fin]]s are [[hyaline]] or grey with a yellow tinge. Juveniles have clear, dark, vertical bands, fading with age. Much like the [[shadow trevally]], small black spots occur on the bases of soft dorsal rays and the body immediately below them that increase in size with age, with a small black blotch on the upper [[operculum (fish)|operculum]].<ref name = "FAOPCO"/>

==Distribution and habitat== The threadfin jack is distributed throughout the [[tropical]] regions of the eastern [[Pacific Ocean]], inhabiting the western coast of the [[Americas]]. The northern limit to the species range is southern [[Baja California]], with its range extending south to [[Mexico]] and [[Central America]] to a southern limit of [[Ecuador]], with the species also recorded from the [[Galapagos Islands]].<ref name = "fishbase"/> It is one of only two species of the genus ''Carangoides'' found on the western coastline of the Americas, with the other species being the widely distributed [[island trevally]], ''Carangoides orthogrammus''.<ref name = "FAOPCO"/>

The species appears to undergo a major transition in lifestyle after its juvenile phase, with young individuals leading a [[pelagic]] lifestyle, able to be transported to [[Shore|offshore]] islands such as the Galapagos by currents. Older individuals are more [[benthic]] in nature, inhabiting the bottom of the water column in mostly [[coastal]] waters on [[reef]]s.<ref>{{cite journal | last = Dominici-Arosemena | first = Arturo |author2=Matthias Wolff | title = Reef fish community structure in the Tropical Eastern Pacific (Panama): living on a relatively stable rocky reef environment | journal = Helgoland Marine Research | volume = 60 | issue = 4 | pages = 287–305 | year = 2006 | doi = 10.1007/s10152-006-0045-4 | doi-access = free | bibcode = 2006HMR....60..287D }}</ref> Smaller fish have been recorded from [[estuaries]], [[mangrove]]-lined creeks, shallow [[bay]]s, and [[lagoon]]s,<ref name = "ns">{{cite journal | last = Cooke | first = Richard | title = Prehistoric Nearshore and Littoral Fishing in the Eastern Tropical Pacific: An Ichthyological Evaluation | journal = Journal of World Prehistory | volume = 6 | issue = 1 | pages = 1–49 | year = 1992 | doi = 10.1007/BF00997584 | s2cid = 161134586 }}</ref> although larger fish live in much deeper waters up to {{convert|50|m|ft|abbr=on}} in depth.<ref name = "Mexfish">{{cite web | publisher = Mexfish.com | title = Threadfin Jack, Thread Pompano | work = Fish Identification | year = 2007 | url = http://www.mexfish.com/fish/thrjck/thrjck.htm | access-date = 2007-09-27 }}</ref>

==Biology and fishery== Much of biology and ecology of the threadfin jack is unknown, with the species' diet the only studied aspect of its biology. A study in fishes of the continental shelf of [[Colombia]] found the species takes predominantly small, benthic fishes of the families [[Triglidae]], [[Synodontidae]], and [[Batrachoididae]]. Other common prey included benthic [[crustaceans]], including various [[crab]]s and [[shrimp]].<ref>{{cite journal | last = López-Peraltaand | first = R.H. |author2=C.A.T. Arcila | title = Diet Composition of Fish Species from the Southern Continental Shelf of Colombia | journal = Naga, WorldFish Center Quarterly | volume = 25 | issue = 3–4 | pages = 23–29 | year = 2002 | url = http://www.worldfishcenter.org/naga/Naga25-3&4/pdf/NAGA_25no3n4_features_e.pdf | access-date = 2007-09-27 }}</ref> Nothing is known of its reproductive cycle.{{Cn|date=January 2021}}

The threadfin jack is of some importance to [[fisheries]] throughout its range, although individual catch statistics for the species are not kept. It is often caught by hook-and-line methods or by [[gill net]]s and various artisanal traps. It is considered to be good to excellent [[fish (food)|table fare]], and is marketed both fresh and [[salting (food)|salted]].<ref name = "FAOPCO"/> The species has also been found at a number of [[archaeological]] sites in both [[Panama]] and Ecuador, indicating it has been caught by humans for food for at least 3450 years.<ref name = "ns"/><ref>{{cite book | last = Stahl | first = Peter W. | editor = Raymond, J.S. & Burger R.L. | title = Archaeology of Formative Ecuador | publisher = Dumbarton Oaks Research Library and Collection | year = 2003 | location = Washington D.C | page = 198 | chapter = The Zooarchaeological Record from Formative Ecuador | isbn = 978-0-88402-292-3 }}</ref> The threadfin jack is also of interest to [[angling|angler]]s who catch the species occasionally, and is considered a minor [[gamefish]]. Juveniles are occasionally caught from shore, such as [[pier]]s and [[Breakwater (structure)|breakwater]]s, while larger individuals are caught over deeper reefs. The species takes a variety of [[bait (fishing)|bait]], including fish and prawns, but they also take [[fishing lure|lures]], including hard and small, fly-like Sabiki lures.<ref name = "Mexfish"/>

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

==External links== *[http://www.mexfish.com/fish/thrjck/thrjck.htm Mexfish fact sheet and photographs]

[[Category:Fish of Mexican Pacific coast]] [[Category:Fish of the Gulf of California]] [[Category:Western Central American coastal fauna]] [[Category:Galápagos Islands coastal fauna]] [[Category:Fish described in 1883|threadfin jack]] [[Category:Taxa named by David Starr Jordan]] [[Category:Taxa named by Charles Henry Gilbert]]