Order - Carcharhiniformes
Family - Carcharhinidae
Genus - Carcharhinus
Species - albimarginatus
Taxonomy:
The silvertip shark was originally described as Carcharias albimarginatus by Rüppell, in 1837. This name was changed to the currently valid Carcharhinus
albimarginatus (Rüppell) later that same year. The genus name Carcharhinus is derived from the Greek "karcharos" meaning sharpen and "rhinos" meaning
nose. The species name albimarginatus is from the Latin "albi" meaning white and "marginatus" meaning to enclose with a border. Synonyms referring to
this species in previous scientific literature include Eulamia platyrhynchus Gilbert 1892 and Carcharhinus platyrhynchus Gilbert 1892.
Common Names:
English language common names include silvertip shark, silver-tip shark, and white fin. Common names in other languages include aileron
blanc du récif (French), aso (Samoan), bagea mara (Gela), cazon (Spanish), gursh (Arabic), iho (Surigaonon), ikan yu (Malay), jarjur
(Arabic), kattafulhi miyaru (Maldivian), marracho de pontas (Portuguese), mwoashog (Carolinian), pating (Tagalog), requin pointe blanche
(French), riff-weißspitzenhai (German), silwertiphaai (Afrikaans), te bakoa (Kiribati), tiburón de puntas blancas (Spanish), tsumajiro
(Japanese), and zarlacz srebrnopletwy (Polish),
Geographical Distribution:
In the western Indian Ocean region, the silvertip is found in the Red Sea and off East Africa including Madagascar, Seychelles, Aldabra Group,
Mauritius, and the Chagos Archipelago. Its range in the western Pacific Ocean is from off southern Japan to northern Australia and French Polynesia
and in the eastern central Pacific from southern Baja, California, Mexico to Colombia including the Cocos, Galapagos, and Revillagigedo Islands.
Habitat:
This shark is commonly found both inshore over continental and insular shelves as well as offshore over banks. It is often reef-associated and lives
at depths to 2,625 feet (800 m). Young individuals reside in shallow waters close to shore to minimize risk from predation.
Biology:
Silvertip shark illustration, FAO Species Catalog, Vol. 4 Part 2 Sharks of the World
Distintice Features:
The silvertip shark is slender with a long and broadly rounded snout. The eyes are large and round. An interdorsal ridge is present on this species.
The first dorsal fin is large with a pointed . It originates over or slightly in front of the free tips of the pectoral fins. The second dorsal fin
originates over or just behind the origin of the anal fin. The pectoral fins are large and semifalcate with narrowly rounded or pointed tips. The caudal
fin is asymmetrical in shape with a rather large upper lobe.
Dentition:
Dentition of the silvertip shark consists of 12-14 teeth in each jaw. The upper teeth are broad and strongly serrated.
The cusps are high and triangular and the crown feet have coarse serrations or low cusplets. The lower teeth have erect, broad serrated cusps with
transverse roots.
Coloration:
The body is dark gray or gray-brown with a bronzy sheen, fading to a white ventral side. An inconspicuous white
band is located on the flank region. This shark's common name "silvertip shark" is in reference to the conspicuous white tips and trailing
margins on all of its fins. The silvertip may be confused with grey reef sharks (Carcharhinus amblyrhynchos), however the grey reef shark has
dark tips on the pectoral fins and trailing edge of the caudal fin. Also, the whitetip reef shark (Triaenodon obesus) is similar in appearance
to the silvertip shark. Although both shark species have white markings on the dorsal and caudal fins, the whitetip reef shark lacks this marking
on the tips of the pectoral fins. The whitetip reef shark also has a more square-shaped snout.
Size, Age, and Growth:
The silvertip shark grows to a maximum total length of 9.8 feet (3 m). However, the average length of this species
is 6.6-8.2 feet (2-2.5 m). The maximum published weight of the silvertip shark is 358 pounds (162.2 kg). This species, both males and females, reaches
maturity at lengths of 5.2-6.2 feet (1.6-1.9 m).
Food Habits:
Prey of the silvertip shark includes benthic and midwater fishes such as wahoo, eagle rays, wrasses, and tunas as well as small sharks. This shark
also feeds on octopuses and squid. The silvertip shark has been observed swimming along the edge of a group of other species of feeding sharks,
dashing into the group to swipe some food.
Reproduction:
Mating behavior includes distinct pairing and occurs during the summer months in the southern hemisphere. This is followed by a yearlong gestation
period with the young born in the summer. The mode of reproduction is viviparous which means the embryos are nourished through a yolksac placenta.
Each litter consists of 1-11 pups with each measuring between 24.8 and 26.7 inches (63-68 cm) in length. The pups live among shallow reefs, feeding
on small fishes. They eventually move out to deeper water as they increase in size.
Predators:
Information regarding predators of the silvertip shark is limited. Large piscivorous fishes and other sharks are potential predators of juveniles.
Importance to Humans:
Data on the silvertip fisheries is lacking although it is probably taken throughout its range. The flesh can be utilized fresh or dried-salted for human consumption.
Danger to Humans:
The silvertip shark should be treated with caution, as it is potentially dangerous to humans. It is considered potentially dangerous due to
its large size, abundance around offshore reefs. According to the International Shark Attack File, this species has been responsible for one
unprovoked attack. Although it tends to keep a distance from divers and swimmers, the silvertip shark will become excited and bold when bait is present.
Conservation:
The silvertip shark is listed as "Data Deficient" throughout its range with the exception of Australia where it is assessed as "Least Concern" with the
World Conservation Union (IUCN). The IUCN is a global union of states, governmental agencies, and non-governmental organizations in a partnership that
assesses the conservation status of species. The "Data Deficient" assessment is indicative of the need for furhter information on fisheries and
population status for this species.
