Biology
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Despite being relatively common in many parts of its range, little is known about the biology of the whitecheek shark (3). This species mainly feeds on fish, along with crustaceans and squid (1), which are snared by its numerous rear-angled, serrated-edged teeth (2).
The whitecheek shark breeds throughout the year, with the female giving birth to an average of two live young, which are already almost half the size of the adult (4).
Conservation
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There are no current conservation measures targeted specifically towards the whitecheek shark. As such a common and widely caught bycatch species, effective conservation strategies would need to employ “no-fishing zones” in order to prevent further declines. Unfortunately, given the current lack of information about this species' movement patterns, it is not yet possible to determine how large these zones would have to be and, therefore, if their creation would be practical (1).
Description
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A widespread species, the whitecheek shark is the most common shark in the Arabian Gulf. Possessing the typical shark form, the whitecheek shark has a pointed snout, large front dorsal fin, greyish upperparts, and a white belly (2). The main distinguishing feature is the black spot on the second, smaller dorsal fin towards the shark's rear (2) (3).
Habitat
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The whitecheek shark is found in shallow, coastal waters, to a maximum depth of 170 metres (2) (3).
Range
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The whitecheek shark is distributed over a large range, extending from the Arabian Gulf, through the Indian Ocean and Indonesia, as far east as Taiwan and Japan, and south as far as northern Australia (1).
Status
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Classified as Near Threatened (NT) on the IUCN Red List (1).
Threats
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Large numbers of whitecheek shark are caught throughout its range, both for human consumption, and as bycatch (1) (3). Being a coastal species, the whitecheek shark falls within numerous commercial and local fishing areas, where its small size means that it falls victim to all commonly used fishing techniques, including gillnetting, hook and line, and trawling. Given the low numbers of offspring produced by the whitecheek shark, it is unlikely to be able to reproduce fast enough to cope with current levels of exploitation in certain parts of its range. Consequently, in heavily fished waters this species has suffered population declines, and even local extinctions (1).
Trophic Strategy
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A common but little-known shark found on the continental and insular inshore areas (Ref. 9997). Feeds mainly on fishes but also on cephalopods, and crustaceans (Ref. 6871). A carnivore (Ref. 9137).
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Morphology
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Vertebrae: 113 - 129
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- Estelita Emily Capuli
Diagnostic Description
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This small species is distinguished by the following characters: snout relatively long and narrowly rounded to almost pointed; upper anterior teeth are oblique and blade-like, coarsely serrated, with lateral margin deeply notched and with several large and serrated basal cusplets; lower anterior teeth are narrower, slightly oblique, lateral margins notched and usually without large basal serrae, finely serrated; total tooth row counts 27-29/24-30, or 52-59; interdorsal space often without a ridge, 17.9-20.8% TL; first dorsal fin relatively low and not falcate, origin over middle of pectoral-fin inner margin, length 14.3-16.2% TL, 1.4-1.6 times height, inner margin 2.2-2.5 in base; second dorsal fin is much smaller, broadly triangular, height 32-37% of first dorsal-fin height, origin about opposite anal fin origin; anal fin is slightly falcate, height 1.0-1.2 times second dorsal-fin height, base 0.9-1.1 times second dorsal fin base; body colour pale brownish dorsally, whitish ventrally; second dorsal fin with a black blotch on upper third of fin, not extending onto upper surface of body and very well defined from ground colour, while other fins mostly plain; total vertebral counts 123-138; monospondylous precaudal counts 42-48; diplospondylous precaudal counts 20; diplospondylous caudal counts 59-70; precaudal counts 62-68 (Ref. 89954).
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Life Cycle
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Viviparous, placental (Ref. 50449). With 2 to 4 pups in a litter; 37-38 cm at birth (Ref. 244). Both male and females mature at about 70 cm (Ref. 6871). Distinct pairing with embrace (Ref. 205). No distinct seasonal reproductive cycle apparent, instead continuously breeding with most mature females pregnant or spent at any one time (Ref.58048).
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- Cristina V. Garilao
Biology
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A common but little-known shark found on the continental and insular inshore areas (Ref. 9997). Feeds mainly on fishes but also on cephalopods, and crustaceans (Ref. 6871). Viviparous (Ref. 50449), with a yolk-sac placenta; gives birth to litters of 1-4 (usually 2) pups (Ref. 58048). Pregnant females (79-100.7 cm TL) that were caught contained 2-5 late-term embryos between 32-38.7 cm TL, thus birth size is presumed to be around 37-39 cm TL. From more than 1000 market specimens (in Kuwait, Qatar and Abu Dhabi), size of males and females range from 36-85 cm TL and 36-100.7 cm TL, respectively, with males reaching maturity between 63-80 cm TL (Ref. 89954). Taken in artisanal and small-scale commercial fisheries and marketed for human consumption (Ref. 244). Fins also utilized (Ref. 6871).
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- Kent E. Carpenter
Importance
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fisheries: commercial
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分布
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分布於印度-西太平洋區，西起阿拉伯灣及阿拉伯海，東至菲律賓海域，北至日本，南至澳洲、阿拉夫拉海等。臺灣分布於澎湖海域。
利用
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主要以底拖網、流刺網及延繩釣捕獲，經濟價值高。肉質佳，可加工成各種肉製品，處理過後之殘骸製成魚粉。
描述
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體呈紡錘型，軀幹較修長。頭寬扁。尾基上下方具一凹窪。吻尖突。眼圓，瞬膜發達。前鼻瓣延長呈三角形；無口鼻溝或觸鬚。口裂弧形，口閉時上下頜緊合，不露齒；上頜齒側扁，三角形，邊緣具鋸齒，齒尖明顯外斜，齒根小齒尖亦顯著；下頜齒較窄而直立或略傾斜，邊緣亦具鋸齒，基底寬。噴水孔缺如。背鰭2個，背鰭間存在隆脊，第一背鰭中大，起點與胸鰭內角相對，後緣幾平直，下角尖突；第二背鰭小，起點稍後於臀鰭起點，後緣斜直，後角尖突；胸鰭大型，鐮刀形，後緣凹入，外角鈍尖，內角亦鈍尖，鰭端伸達第一背鰭基底後端；尾鰭寬長，尾椎軸上揚，下葉前部顯著三角形突出，中部低平延長，與後部間有一深缺刻，後部小三角形突出，尾端鈍尖。體背側灰色或灰褐色，腹側灰白；僅第二背鰭具明顯之黑色鰭尖，餘鰭與體同色。
棲地
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棲息於大陸棚、島嶼斜坡的中小型鯊類。主要以魚類、頭足類及甲殼類為食。胎生，一胎可產下1-4尾幼鯊，剛出生之幼鯊體長可達31-40公分。
Whitecheek shark
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The whitecheek shark or widemouth blackspot shark (Carcharhinus dussumieri) is a requiem shark of the family Carcharhinidae, found in the Indo-West Pacific Ocean between latitudes 34°N and 25°S. It can reach a length of 1 m. It feeds mainly on fish, cephalopods, and crustaceans. It is a viviparous species, with the female giving birth to up to four live young.
The specific name honours the French explorer and trader Jean-Jacques Dussumier (1792–1883).
Description
The whitecheek shark grows to a length around 100 cm (39 in). It has a slender body and long head with a rounded snout. The eyes are oval and both jaws have multiple rows of backward-pointing, serrated teeth. The pectoral fins are long, narrow, and curved and have narrow, pointed tips. The first dorsal fin is triangular, uncurved, and moderately sized, and the second dorsal fin is much smaller than the first and bears a large black patch at its apex. The whitecheek shark's dorsal (upper) surface is grey or brownish-grey, while its ventral (under) surface is pale.[2][3]
Distribution
The whitecheek shark is native to the Indo-Pacific Ocean, where it is found on continental shelves and inshore slopes around islands down to about 170 m (560 ft). Its range extends from the Arabian Sea and Persian Gulf to Java, Indonesia, Japan, and Australia.[2]
Behaviour
The whitecheek shark mostly feeds on fish, but also eats octopus, squid, and various crustaceans including crabs. It sometimes picks off molluscs and worms from the seabed.[2]
It is a common species, but not well known, and it is sometimes confused with the blackspot shark (Carcharhinus sealei). Both males and females mature when they are about 70 cm (28 in) long. Females are viviparous and breeding takes place throughout the year, with females normally being either pregnant or having recently given birth. One to four, but usually two, pups are retained in the uterus, where they feed from a yolk sac.[2] They are about 38 cm (15 in) at the time of birth.[2][3]
Status
The IUCN lists the whitecheek shark as near threatened in its Red List of Threatened Species because it is often caught in shallow-water fisheries by rod and line, gillnetting, and trawling. Its population trend seems to be decreasing and it is facing local extinction in some parts of its range. It is usually caught as bycatch rather than as the target species, and in Australian waters, makes up around 2 to 3% of the total biomass caught.[1] It is not harmful to man and its flesh is marketed for human consumption.[3]
References
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Whitecheek shark: Brief Summary
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The whitecheek shark or widemouth blackspot shark (Carcharhinus dussumieri) is a requiem shark of the family Carcharhinidae, found in the Indo-West Pacific Ocean between latitudes 34°N and 25°S. It can reach a length of 1 m. It feeds mainly on fish, cephalopods, and crustaceans. It is a viviparous species, with the female giving birth to up to four live young.
The specific name honours the French explorer and trader Jean-Jacques Dussumier (1792–1883).
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Description
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Found on the continental and insular shelves, more commonly on inshore areas. Probably feeds on small fishes, cephalopods, and crustaceans. Viviparous; 2 to 4 pups litter size; 38 to 39 cm at birth. Taken in artisanal and smallscale fisheries and marketed for human consumption.
Froese, R. & D. Pauly (Editors). (2023). FishBase. World Wide Web electronic publication. version (02/2023).
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