Silky shark French: Requin soyeux Spanish: Tiburón jaqueton Appearance: Large, slim shark with moderately large eyes. The silky shark is listed on Annex I, Highly Migratory Species, of the United Nations Convention on the Law of the Sea, though this has yet to result in any management schemes. In the Pacific Ocean, the northern extent of its range runs from southern China and Japan to southern Baja California and the Gulf of California, while the southern extent runs from Sydney, Australia, to northern New Zealand to northern Chile. [2] Females give birth after a gestation period of 12 months, either every year or every other year. [6], The specific epithet falciformis is Latin for "sickle-shaped", which refers to the outline of the dorsal and pectoral fins. The spinner shark (Carcharhinus brevipinna) is a type of requiem shark. The silky shark (Carcharhinus falciformis), also known by numerous names such as blackspot shark, grey whaler shark, olive shark, ridgeback shark, sickle shark, sickle-shaped shark and sickle silk shark, is a species of requiem shark, in the family Carcharhinidae, named for the smooth texture of its skin. It is one of the most common shark species of the open ocean, but due to overfishing its status is now vulnerable. [2][4][10] Good feeding opportunities can draw silky sharks in large numbers; one such feeding aggregation in the Pacific has been documented "herding" a school of small fishes into a compact mass (a bait ball) and trapping it against the surface, whereupon the sharks consumed the entire school. [2], The overall growth rate of the silky shark is moderate compared to other shark species and similar for both sexes, though it varies significantly between individuals. It may also take squid, paper nautilus, and swimming crabs, and there is fossil evidence o… [31], Potential predators of the silky shark include larger sharks and killer whales (Orcinus orca). [39], Like other members of its family, the silky shark is viviparous: once the developing embryo exhausts its supply of yolk, the depleted yolk sac is converted into a placental connection through which the mother delivers nourishment. The silky shark is an opportunistic predator feeding mainly on bony fishes from all levels of thewater column, including tuna, mackerel, sardines, mullets, groupers, snappers, mackerel scads,sea chubs, sea catfish, eels, lanternfishes, filefishes, triggerfishes, and porcupinefishes. The silky shark ( Carcharhinus falciformis) is listed on the IUCN Red List of Threatened Species as Near Threatened globally but Vulnerable in some regions due to continued declines in their populations around the world. [29] These groups are generally segregated by size, and in the Pacific perhaps also by sex. In the Central and Eastern Tropical Pacific silky sharks are even more endangered and classified as ’vulnerable.’ Improving the conservation and management of the silky shark, the thresher sharks and mobula rays ALARMED that the IUCN Shark Specialist Group estimates that one-quarter of shark species (sharks, skates, rays, chimaeras) are threatened with extinction, primarily due to overfishing; Unfortunately, like many other shark species, silky sharks are a very low-producing species – only giving birth to litters of up to 16 pups annually or biennially after a lengthy 1-year gestation period. Adult females have a single functional ovary (on the right side) and two functional uteri, which are divided lengthwise into separate compartments for each embryo. (1971). The species was also given greater protection through an Appendix II listing by the Convention on the International Trade in Endangered Species, which … This pelagic shark, formerly abundant in all tropical oceans, has declined by an estimated 85% in the last 20 years, and is now listed as vulnerable and declining by the International Union for the Conservation of Nature (Rice & Harley, 2013; IUCN, 2017). Nevertheless, mounting evidence indicates the silky shark has, in fact, declined substantially worldwide, a consequence of its modest reproductive rate which is unable to sustain such high levels of exploitation. [7] It may also be referred to as blackspot shark (usually used for C. sealei), grey reef shark (usually used for C. amblyrhynchos), grey whaler shark, olive shark, reef shark, ridgeback shark, sickle shark, sickle silk shark, sickle-shaped shark, silk shark, and silky whaler. [12] Carcharhinus elongatus, an earlier representative of its lineage with smooth-edged teeth, is known from Oligocene (34–23 Mya) deposits in the Old Church formation of Virginia, and the Ashley formation of South Carolina. Since 2017, the silky shark has been classified as a vulnerable species by the International Union for Conservation of Nature (IUCN). The Silky shark feeds on bony fish such as tuna, mackerel, sardines, and … Carcharhinus falciformis. Distinctive features of the silky shark include its small first dorsal fin and large pectoral fins. Its sense of hearing is extremely acute, allowing it to localize the low-frequency noises generated by other feeding animals, and, by extension, sources of food. The significance of these behaviors is unknown. The total annual catch reported to the Food and Agriculture Organization fell steadily from 11,680 tons in 2000 to 4,358 tons in 2004. "Sharks of the genus, Hoffmayer, E. R., Franks, J. S., Driggers, W. B. [35][36] Silky sharks frequently intermingle with schools of scalloped hammerheads (Sphyrna lewini), and have been known to follow marine mammals. [9] Mine Dosay-Abkulut's 2008 ribosomal DNA analysis, which included the silky, blue, and bignose sharks, confirmed the closeness of those three species. Females give birth to litters of up to 16 pups annually or biennially. It has a rounded apex, an "S"-shaped rear margin, and a free rear tip about half as long as the fin is tall. However, Japanese fisheries in the Pacific and Indian Oceans have recorded no change in catch rate between the 1970s and the 1990s,[1] and the validity of the methodologies used to assess declines in the Gulf of Mexico and the northwestern Atlantic have come under much debate. Garrick, J. IUCN Status: Near Threatened . [24] One of the largest members of its genus, the silky shark commonly reaches a length of 2.5 m (8.2 ft), with a maximum recorded length and weight of 3.5 m (11 ft) and 346 kg (763 lb), respectively. Targeted fisheries likewise appear to exist in Tanzania and Kenya for pelagic sharks, including vulnerable silky sharks, endangered mako and thresher sharks, and critically endangered oceanic whitetip sharks — all of which are CITES-listed and heavily affected by industrial fisheries. Carcharhinus falciformis. Interdorsal ridge present. & Simpfendorfer, C. 2017. [28], Studies conducted off the Florida coast and the Bahamas have shown that silky sharks are highly sensitive to sound, in particular low-frequency (10–20 Hz), irregular pulses. The silky shark is mainly valued for its fins, popular on the Hong Kong shark fin market. Although slow-reproducing like most other sharks, the wide distribution and large population size of the silky shark was once thought to buffer the species against these fishing pressures. Significant geographical variation is seen in its life history details. Tagging data have recorded individual sharks moving up to 60 km (37 mi) per day, and covering distances up to 1,339 km (832 mi). A set of poorly described, Eocene (56–34 Mya) teeth resembling those of this species are known from Egypt. [2] However, given the highly migratory nature of the silky shark and its association with tuna, no simple way is known to reduce bycatch without also affecting the economics of the fishery.[21]. [2], Primarily an inhabitant of the open ocean, the silky shark is most common from the surface to a depth of 200 m (660 ft), but may dive to 500 m (1,600 ft) or more. The circular, medium-sized eyes are equipped with nictitating membranes (protective third eyelids). [1] The litter size ranges from one to 16 and increases with female size, with six to 12 being typical. The fins (except for the first dorsal) darken at the tips; this is more obvious in young sharks. The anal fin originates slightly ahead of the second dorsal fin and has a deep notch in the posterior margin. [18] The highest reported growth rates are from sharks in the northern Gulf of Mexico, and the lowest from sharks off northeastern Taiwan. [11], Initial efforts to resolve the evolutionary relationships of the silky shark were inconclusive; based on morphology, Jack Garrick in 1982 suggested the blackspot shark (C. sealei) as its closest relative. (2009). ... Sickle Shark, Sickle-shaped Shark, Sickle Silk Shark, Net-eater Shark. "Movements and Habitat Preferences of Dusky (. It is one of the most abundant sharks in the pelagic zone, and can be found around the world in tropical waters. Bonfil, R., Mena R. and de Anda, D. (September 1993). [25] Fishery data on this shark are often confounded by under-reporting, lack of species-level separation, and problematic identification. Their underside… This protects key habitat for six species of sharks (Silvertip Shark, Whitetip reef shark, Tiger shark, Silky shark, Galapagos Shark, and Scalloped Hammerhead) . However, it only rarely comes into contact with people due to its oceanic habits. [50][51][52], As of 2017, the silky shark is classified by the International Union for Conservation of Nature as a vulnerable species. Its range extends farther north and south along continental margins than in oceanic waters. The Silky shark is a type of shark of the genus Carcharhinus, family Carcharhinidae. A .F. [4][22] Fourteen to 16 and 13–17 tooth rows are found on either side of the upper and lower jaws, respectively (typically 15 for both). They pri­mar­ily in­habit con­ti­nen­tal and in­su­lar shelves, but have also been found over deep water reefs and in open ocean, slope, and shal­low, coastal water habi­tats. Long rounded snout. A narrow dorsal ridge runs between the dorsal fins. The silky shark is an active, inquisitive, and aggressive predator, though it will defer to the slower but more powerful oceanic whitetip shark in competitive situations. Silky sharks are classified as ‘near threatened’ by the International Union for Conservation of Nature (IUCN). [28][37], The silky shark is an opportunistic predator, feeding mainly on bony fishes from all levels of the water column, including tuna, mackerel, sardines, mullets, groupers, snappers, mackerel scads, sea chubs, sea catfish, eels, lanternfishes, filefishes, triggerfishes, and porcupinefishes. The five pairs of gill slits are moderate in length. [4] When approaching something of interest, it may seem inattentive, sedately circling and sometimes swinging its head from side to side. Froese, Rainer and Pauly, Daniel, eds. Over repeated exposures, silky sharks habituate to the sound change and stop withdrawing, though it takes them much longer to do so compared to the bolder oceanic whitetip shark. Considering that the scalloped hammerhead shark is categorized as “critically endangered” by the IUCN Redlist of Threatened Species, these new … [15], The silky shark has a cosmopolitan distribution in marine waters warmer than 23 °C (73 °F). ), along with 25 grey reef sharks (C. amblyrhynchos) and a lone silvertip shark (C. albimarginatus). Carcharhinus falciformis. Furthermore, their association with tuna results in many sharks being taken as bycatch in tuna fisheries. Downloaded on 09 June 2015. One central Pacific study has found females growing much slower than males, but the results may have been skewed by missing data from large females. The Silky shark gets its name from the fact that it has a smooth, "silky" texture. [19] Larger sharks generally move longer distances than smaller ones. [4] Tracking studies in the tropical eastern Pacific and northern Gulf of Mexico have found that cruising silky sharks spend 99% of their time within 50 m (160 ft) of the surface, and 80–85% of their time in water with a temperature of 26–30 °C (79–86 °F); the pattern was constant regardless of day or night. The lower teeth are narrow, erect, and smooth-edged. In the Atlantic Ocean, it is found from the U.S. state of Massachusetts to Spain in the north, and from southern Brazil to northern Angola in the south, including the Mediterranean Sea, Gulf of Mexico, and Caribbean Sea. [4][7] The coloration quickly fades to a dull gray after death. [18] Silky sharks are highly mobile and migratory, though the details of their movements are little-known. The shark then proceeds to swim in tight loops with a stiff, jerky motion, often turning broadside towards the perceived threat. signatus). Regardless of which one dominates, the two predators do not engage in any overtly aggressive behavior against each other. The Silky Shark get its name for its smooth skin. [2][28][30], The life history characteristics of the silky shark differ across its range (see table). [19] In the Gulf of Aden, it is most common in late spring and summer. [4][22], The skin is densely covered by minute, overlapping dermal denticles. On occasion, sharks have also been seen suddenly charging straight up, veering away just before reaching the surface and gliding back down to deeper water. [32], The bite force of a 2-m-long silky shark has been measured at 890 newtons (200 lbf). 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