- Razorbelly scad
name = Razorbelly scad
image_width = 240px
phylum = Chordata
genus = "
species = "A. kleinii"
binomial = "Alepes kleinii"
binomial_authority = (Bloch, 1793)
(De Vis, 1884)
range_map_width = 240px
range_map_caption = Approximate range of the razorbelly scad
The razorbelly scad, "Alepes kleinii" (also known as the banded scad, golden scad and goggle-eye scad) is a small species of
tropicalmarine fishin the Jack family, Carangidae. The species inhabits coastalwaters in the Indo-Pacific, from Pakistanin the west to Japanand Australiain the east, often found over reefs. The razorbelly scad has a complex taxonomic history, and even recently has had its position in the genus "Alepes" challenged, but appears to be stable after a molecular phylogenystudy supported the placement in "Alepes". It is very similar to other scads in the same genus, but is readily identified by its unique teeth. Razorbelly scad are predatory fish, taking a variety of crustaceans and shrimps, and show a change in feeding intensity over the year. Reproduction and development has been extensively studied in India, where spawning occurs in a single event from January to September. The species is commonly taken in tropical fisherieswhere it is marketed fresh or dried.
Taxonomy and naming
The razorbelly scad is classified in the scad genus "
Alepes", which is part of the jack family, Carangidae. The Carangidae are perciform fishes in the suborder Percoidei. [ITIS | ID = 641975 | taxon = "Alepes kleinii" | year = 2008 | date = 2 January]
Like a number of other members of "Alepes", the razorbelly scad suffers from a complicated taxonomic history, in which the species has been described and named no less than seven times, and has had three of those names reassigned to different genera.FishBase species | genus = Alepes | species = kleiniis | year = 2008 | month = January] The first person to describe and name the species was the German
naturalist Marcus Elieser Blochin 1793, assigning the name "Scomber kleinii" putting the species in a genus of mackerel. This was later transferred to the jack genus " Caranx" and finally to the genus "Alepes", which Swainsonhad created in 1839. This is the currently accepted name, as Bloch was the first to describe the fish, even though he put it in the wrong genus. In a marathon effort of synonymy, Georges Cuvierdescribed the species under three separate names in 1833, of which two were reclassified into "Alepes", forming the commonly used junior synonyms of "Alepes para" and "Alepes kalla". The razorbelly scad was described and named three times after Cuvier's efforts by Bleeker, De Vis and Wakiya. In a 1942 review of "Caranx kalla", Nichols tried to separate and rationalise a number of synonyms, even suggesting a subspecies of De Vis' "Caranx queenslandiae" be created. [cite journal | last = Nichols | first = J.T. | title = On Fishes Confused with Caranx kalla Cuvier and Valenciennes | journal = Copeia | volume = 1942 | issue = 4 | pages = 226–229 | date = 1942 | id = | accessdate = 2008-01-03 | doi = 10.2307/1438009 ] The type specimenof "A. kleinii" was collected from the Malabarcoast off India.cite journal | last = Lin | first = Pai-Lei | coauthors = 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 | date = 1999 | url = http://cat.inist.fr/?aModele=afficheN&cpsidt=10055944 | accessdate = ] Although commonly called razorbelly scad, and recognised as such by fishbase, the species also is known as banded scad, goggle-eye scad and golden scad.
Although the species, including many of its synonyms, has been placed in the genus "Alepes" for some time, the nature of its teeth has made this placement controversial. Two authors have argued that the species should be reassigned to a new
monotypicgenus due to it having short conical teeth in comparison to the rest of "Alepes"' comblike teeth.cite journal | 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 | date = 1990 | accessdate =2007-11-01 ] This problem was addressed in a molecular phylogenetic study of the Carangidae in which "A. kleinii" and "A. djedaba" (Shrimp scad) were included. The results confirmed the placement of "A. kleinii" in "Alepes", with the authors arguing the two species were too closely related to warrant placement in a new genus. [cite journal | last = Zhu | first = Shi-Hua | coauthors = Wen-Juan Zing, Ji-Xing Zou, Yin-Chung Yang & Xi-Quan Shen | title = Molecular phylogenetic relationship of Carangidae based on the sequences of complete mitochondrial cytochrome b gene | journal = Acta Zoologica Sinica | volume = 53 | issue = 4 | pages = 641–650 | date = 2007 | url = http://www.actazool.org/paperdetail.asp?id=6630&volume=53&number=4&bgpage=641&=endpage650&year=2007&month=8 | accessdate = 2008-01-03 ]
The razorbelly scad is similar in body shape and profile to the rest of "Alepes", possessing a strongly compressed ovate body. The dorsal profile of the body is definitively less than the ventral profile, giving the upper and lower parts of the body an
asymmetrywhich is further heightened by the different sized lobes of the caudal fin.cite book | last = Carpenter | first = Kent E. | coauthors = Volker H. Niem (eds.) | title = 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) | publisher = FAO | date = 2001 | location = Rome | pages = 2684 | url = http://ftp://ftp.fao.org/docrep/fao/009/y4160e/y4160e00.pdf | isbn = 92-5-104587-9 ] The head of the fish tapers to a pointed snout, with the large eye having a well developed posterior adiposeeyelid. The teeth of the fish are a major diagnostic feature of the species, with the upper jawhaving two irregular rows of small conical teeth at the front of the mouth, transitioning to a paving of blunt teeth at the back. The lower jaw is similar, having two rows of short conical teeth in the front of the jaw changing to one row of blunter teeth further back. There are two separate dorsal fins, the first containing eight weak spines while the second consists of a single spine followed by 23 to 26 soft rays. The anal finhas two detached spines anterior to the main section, which consists of a single spine followed by 19 to 22 soft rays.cite book | last = Randall | first = John Ernest | coauthors = Roger C. Steene, Gerald R. Allen | title = Fishes of the Great Barrier Reef and Coral Sea | publisher = University of Hawaii Press | date = 1997 | pages = 161 | isbn = 0824818954 ] The upper caudal fin lobe is larger than the lower lobe, whilst the pelvic finis quite small in comparison to those of other carangids. The lateral lineis strongly arched anteriorally, with the arched and straight sections of the line intersecting below the fourth to sixth soft dorsal rays. The curved section of the line contains 32 to 46 scales and up to 2 scutes, while the straight section consists of 35 to 45 scutes and up to 2 scales. The species has 24 vertebraeand a total of 38 to 44 gill rakers.cite book | last = Randall | first = John E. | title = Coastal Fishes of Oman | publisher = University of Hawaii Press | date = 1995 | location = Honolulu | pages = 183 | isbn = 0824818083 ] It is a fairly small fish compared to most carangids, only known to reach 16 cm in length.
Whilst alive, the razorbelly scad is a bluish grey to greenish grey on the upper body, becoming lighter and more silvery ventrally. Dark vertical bands are sometimes present on the body above the lateral line, and a large black spot is present on the upper operculum and surrounding shoulder region. The fins are pale to
hyalinewith the exception of the caudal fin which is yellow to dusky in colour, with the upper lobe generally brighter and having a narrow dusky edge.
Distribution and habitat
The razorbelly scad is broadly distributed over the tropical Eastern Indo-
West Pacificregion, not as widely distributed as most of the genus "Alepes". The species has been recorded from the Red Seain the west,cite journal | last = Adam | first = B.T. | title = Red Sea Fishes Recently Found in the Mediterranean | journal = Copeia | volume = 1966 | issue = 2 | pages = 254–275 | date = 1966 | id = | accessdate = 2008-01-03 | doi = 10.2307/1441133 ] but is rarely found west of Pakistan. It is common along the Indian, Sri Lankan and South East Asian coasts, extending throughout Indonesia, Philippines, Taiwan, reaching as far north as Japanand as far south as northern Australia. As "Caranx kalla", the species was recorded at least once in the Mediterranean Sea, passing through the Suez Canalfrom the Red Sea as part of the Lessepsian migration. The species inhabits inshore coastalenvironments, especially reefhabitats.
Biology and fishery
The razorbelly scad is a
predatory fish, whose feeding activity changes, at least in some regions, over the course of a year. A 1988 study in Indian waters found that the species is an active feeder during February and March, showing only moderate activity for the rest of the year.cite journal | last = Kalita | first = Binod | coauthors = Jayabalan, N. | title = Food and feeding habits of the golden scad "Caranx kalla" (Cuv. & Val.) along Mangalore coast | journal = Environment and Ecology | volume = 18 | issue = 4 | pages = 869–873 | location = | date = 2000 | id = ISSN 0970-0420 | accessdate = 2008-01-03 ] Their main prey items were small crustaceans, particularly copepods and small or larval fish, with smaller amounts of Lucifer, prawns, amphipods and fish eggs taken.
Reproduction and spawning in the species has been studied only in Indian waters, where razorbelly scad spawn in a single event from January to September, with peaks in February and in June to August.cite journal | last = Venkataramani | first = V.K. | coauthors = Natarajan, R. | title = Breeding biology of carangid fishes "Carangoides malabaricus" (Bloch and Schn.) and "Alepes kalla" (Cuv. and Val.) along Porto Novo Coast | journal = Indian Journal of Marine Sciences | volume = 13 | issue = 1 | pages = 14–18 | location = New Delhi | date = 1984 | id = ISSN 0379-5136 | accessdate =2007-11-30 ] The eggs are
pelagic, spherical and transparent, measuring 0.58 to 0.61 mm in diameter. Newly hatched larvae are 1.13 mm in diameter, and the developmental biologyof the larvae has been well studied. [cite journal | last = Subrahmanyam | first = C.B. | title = Eggs and early development of two more carangids from Madras | journal = Journal of the Marine Biology Association of India | volume = 8 | issue = 1 | pages = 188–192 | date = 1968 | id = | accessdate = 2008-01-03 ] The fecundityof the species has been shown to be correlated with total length and body weight.The growth of razorbelly scad was also studied off the Indian coast near Mangalore. It was found the species grows to 83-84 mm in its first year, 131 mm in the second and 143 mm in the third year of its life.cite journal | last = Kalita | first = B. | coauthors = Jayabalan, N. | title = Age and growth of the carangid "Alepes para" (Class: Osteichthyes) from Mangalore coast, west coast of India | journal = Indian Journal of Marine Sciences | volume = 26 | issue = 1 | pages = 107–108 | date = 1997 | id = ISSN 0379-5136 | accessdate = 2008-01-03 ] From the data collected, the growth curve predicts a maximum size of 17.1 cm, although it would require a long lifespan. Each sex reaches sexual maturityat a different size, in males it is 128.5 mm and 126.5 mm in females.
The species is commonly taken as part of a number of
fisheries, although catch data is not available. It is taken by methods including hook and line, gill nets as well as other subsistencefishing gear. Razorbelly scad is marketed fresh and dried salted.
* [http://www.fishbase.org/Summary/SpeciesSummary.php?id=1903 Razorbelly scad at fishbase]
* [http://research.kahaku.go.jp/zoology/Fishes_of_Libong/data/p032_01b.html Brief profile]
* [http://nio.org/Biology/fish/Fishe_larvae_51.pdf Detailed developmental biology (PDF)]
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