Island trevally
| Island trevally | |
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| Species: | C. orthogrammus
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| Binomial name | |
| Carangoides orthogrammus | |
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The island trevally, Carangoides orthogrammus (also known as the island jack, thicklip trevally and false bluefin trevally), is a widespread species of offshore marine fish classified in the jack family Carangidae. The island trevally is common through the tropical regions of the Indian and Pacific Oceans, ranging from Mozambique and the Seychelles in the west to Hawaii and the Revillagigedo Islands in the central and eastern Pacific. The species is almost completely absent from the continental shelves, instead inhabiting offshore islands where it is found in lagoons and on reef systems. It is a moderately large fish, growing to a maximum recorded length of 75 cm and 6.6 kg in weight, and is distinguishable by its angular snout and yellow spots, as well as more detailed anatomical features. The island trevally often moves in small schools, preying on a variety of small fishes and crustaceans. It is of moderate importance to fisheries throughout its range, often taken by trawls, hook and line and various inshore netting methods, and is sold fresh or salted at market.
Taxonomy and naming
The island trevally is classified within the genus Carangoides, a group of fish commonly called jacks and trevallies. Carangoides falls into the jack and horse mackerel family Carangidae, itself part the order Perciformes, in the suborder Percoidei.[1]
The species was first scientifically described by the American ichthyologists Jordan and Gilbert in 1881 based on a specimen taken from the Revillagigedo Islands, which was designated to be the holotype.[2] They named this new species Caranx orthogrammus, placing the species in a closely related genus of jacks, but this was later changed to Carangoides after further revision of the family had occurred. The species was independently redescribed a named a number of times, with the fish placed in subspecies status twice. John Treadwell Nichols considered his C. ferdau jordani to be separate to C. orthogrammus, or possibly a subspecies of the blue trevally, Carangoides ferdau, and was later treansferred to Carangoides jordani.[3] It was also considered a subspecies of a synonym the bludger, Carangoides gymnostethoides, and was also renamed as Carangoides nitidus. The fish is now considered a separate species, with the subspecies names and the later names rendered invalid under the ICZN naming rules. The species is commonly known as 'island trevally' in reference to its preferred offshore habitat, with the names 'thicklip trevally' and 'false bluefin trevally'[4] also used as descriptive names. The specific epithet means "straight lined" in Greek.[2]
Description
The island trevally is a moderately large fish, growing to a maximum recorded length of 75 cm and 6.61 kg in weight.[5] The species is quite similar to Carangoides ferdau, although the prominent yellow spots serve as a quick identifying feature.[6] The island trevally has a compressed oblong shaped body with the dorsal profile more convex than the ventral profile and the snout usually being slightly rounded.[7] The dorsal fin is in two sections, the first consisting of 8 spines and the second of 1 spine and 28 to 31 soft rays, with the lobe of the second dorsal fin being slightly falcate in younger individuals, but is always shorter than the head length. The anal fin has 2 detached spines followed by 1 spine attached to 24 to 26 soft rays, while the pelvic fin has 1 spine attached to 21 or 22 soft rays.[8] The lateral line has a very slight anterior arch, with the intersection of the straight and curved sections between the 15th to 19th soft ray of the dorsal fin. The curved section contains 96 to 106 scales, while the straight section contains 20 to 30 scales and 21 to 28 scutes.[8] The breast is scaleless ventrally until the origin of pelvic fins, often with a small patch of pre-pelvic scales. Laterally, this naked area of the breast is separated from the naked base of the pectoral fins by a moderate band of scales. The lips are notably fleshy in adults, with both jaws containing narrow bands of villiform teeth which become obsolescent with age. There are 28 to 32 gill rakers in total and 24 vertebrae.[7]
The island trevally is a pale blue green above, becoming more silvery below, with adults having several quite large elliptical yellow to brassy spots scattered on their body close to the midline. There may be 9 or 10 dark vertical bars on the body from the head to the peduncle. The soft dorsal, anal and caudal fins are a pale brownish to brilliant blue, with all other fins being pale green to hyaline in colour.[9]
Distribution and habitat
The island trevally is distributed throughout the offshore waters of the tropical and subtropical regions of the Indian and Pacific Oceans. In the Indian Ocean, it ranges from Mozambique on the east coast of Africa north to the Gulf of Aden, but has not been recorded further north until India and Sri Lanka.[5] Its range extends throughout South East Asia, Indonesia and northern Australia in the eastern Indian Ocean. In the Pacific Ocean, the species has been recorded from Taiwan, Japan, Hawaii and the Revillagigedo Islands off Mexico in the eastern Pacific, as well as many Pacific islands.[5]
As the species common name partly suggests, the island trevally very rarely is found on the continental shelves, instead living around offshore islands formed by volcanic activity or isolated slivers of continental material remaining from continental rifting. These islands are often quite large, and have most of the geographical features of the continental environment including beaches, reefs, lagoons and even estuaries. The island trevally is known from all of these habitats, as well as slightly deeper seaward reefs up to 50 m deep.[10] In Hawaii, the species is less frequently found inside protected bays, and more often slightly further offshore presumably due to competition with other species.[11] The island trevally is one of a number of carangid species known to be attracted to man made fish attracting devices, which are installed to aggregate fish for anglers.[12]
Biology and fishery
The island trevally moves both as a solitary individual or in small schools through its habitat, with the species often accounting for large proportions of an areas immediate biomass when moving in schools.[13] The species diet consisting of small fish species and crustaceans, with studies on the species exact diet composition has finding the fish takes different species and different ratios of prey throughout its range. A study conducted in New Caledonia found the species consumed 98% fish, with only 1 percent crabs and shrimps,[14] while a large study in Hawaii found it took 64.7% crustaceans including crabs, shrimps and stomatopods while taking only 32.3% fish consisting of gobies and benthic fishes of the order scorpaeniformes, as well as 2% cephalopods.[11] In this setting, it appears that the major carangid species in the region alter their diet to reduce interspecific competition, but change this partitioning elsewhere in their range where they co-occur.[11] Reproduction and growth are poorly studied in the species, with only a general estimate of spawning timing of March in the Solomon Islands.[15]
The island trevally is of moderate importance to fisheries throughout its range, often taken by hook and line, trawls and various types of artisanal gear.[7] The species is generally only caught as bycatch, with catch numbers often very small in comparison to the target species of the fishery.[16] Throughout most of its range, catch statistics are not kept. The species is marketed fresh, dry or salted, and is considered a good table fish.[5]
References
- ^ "Carangoides orthogrammus". Integrated Taxonomic Information System. October.
{{cite web}}: Check date values in:|date=and|year=/|date=mismatch (help) - ^ a b Hosese, D.F. (2007). Zoological Catalogue of Australia Vol. 35 (2) Fishes. Sydney: CSIRO. p. 1150. ISBN 978-0-643-09334-8.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Nichols, John T. (1922). "Carangoides jordani from the Hawaiian Islands with notes on related fishes". American Museum Novitates. 50: 1–4. Retrieved 2008-10-28.
- ^ Hutchins, B. (1986). Sea Fishes of Southern Australia: Complete Field Guide for Anglers and Divers. Melbourne: Swainston Publishing. pp. 1–187. ISBN 1-86252-661-3.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b c d Froese, Rainer; Pauly, Daniel (eds.) (2008). "Carangoides orthogrammus" in FishBase. October 2008 version.
- ^ Randall, John Ernest (1997). Fishes of the Great Barrier Reef and Coral Sea. University of Hawaii Press. p. 161. ISBN 0824818954.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b c Carpenter, Kent E. (2001). FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Volume 5. Bony fishes part 3 (Menidae to Pomacentridae) (PDF). Rome: FAO. p. 2684. ISBN 92-5-104587-9.
{{cite book}}: Check|url=value (help); Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b Lin, Pai-Lei (1999). "A Review of the Carangid Fishes (Family Carangidae) From Taiwan with Descriptions of Four New Records". Zoological Studies. 38 (1): 33–68.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Gunn, John S. (1990). "A revision of selected genera of the family Carangidae (Pisces) from Australian waters". Records of the Australian Museum Supplement. 12: 1–78.
{{cite journal}}:|access-date=requires|url=(help) - ^ Robertson, D.R. (1996). "Zoogeography of the shorefish fauna of Clipperton Atoll". Coral Reefs. 15 (2): 121–131.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b c Meyer, Carl G. (2001). "Diet, resource partitioning and gear vulnerability of Hawaiian jacks captured in fishing tournaments". Fisheries Research. 53 (2): 105–113. doi:10.1016/S0165-7836(00)00285-X.
{{cite journal}}:|access-date=requires|url=(help); Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Gaertner, J.C. (2008). "Visual censuses around drifting fish aggregating devices (FADs): a new approach for assessing the diversity of fish in open-ocean waters". Marine Ecology Progress Series. 366 (3): 175–186. doi:10.3354/meps07554.
{{cite journal}}:|access-date=requires|url=(help); Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Brock, R.E. (1998). "Community Structure of Fishand Macrobenthosat Selected Sites Fronting Sand Island, O'Ahu, Hawaii, in Relation to the Sand Isalnd Ocean Outfall, Year 9 - 1998" (PDF). Water Resources Research Centre Project Report. PR-99-07: 1–49. Retrieved 2008-10-28.
- ^ Kulbicki, Michel (2005). "Diet composition of carnivorous fishes from coral reef lagoons of New Caledonia". Aquatic Living Resources. 18 (3): 231–250. doi:10.1051/alr:2005029.
{{cite journal}}:|access-date=requires|url=(help); Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Rhodes, K.L. (2004). "Solomon Islands Spawning Aggregation Monitoring Training Workshop Report Gizo, Western Province, Solomon Islands 13-21 March 2004" (PDF). TNC Pacific Island Countries Report. 2 (04). The Nature Conservancy: 1–15. Retrieved 2008-10-28.
- ^ Hardman, E.R. (2006). "Annual Report on the Status of the Artisanal Seine Net Fishery of Rodrigues 2006" (PDF). Shoals Rodrigues, Pointe Monier, Rodrigues: 1–67. Retrieved 2008-10-29.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help)