Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Carcharhinus
Species: amblyrhynchos
Taxonomy:
The grey reef shark was originally described as Carcharias amblyrhynchos by Bleeker in 1856. He later changed this name to the currently valid
name of Carcharhinus amblyrhynchos. The genus name Carcharhinus is derived from the Greek "karcharos" meaning sharpen and "rhinos" meaning nose.
Synonyms used in previous scientific literature that refer to the grey reef shark include Carcharias nesiotes Snyder 1904, Carcharhinus menisorrah
Whitley 1944, Galeolamna fowleri Whitely 1944, Galeolamna turfiensis Whitely 1949, Galeolamna coongoola Whitely 1964, and Carcharhinus wheeleri Garrick 1982.
Common Names:
English language common names include grey reef shark, blacktail reef shark, black-vee whaler, bronze whaler, gray reef shark,
gray shark, gray whaler shark, longnose blacktail shark, shark, and whaler shark. Other common names from across the world include 'anga (Tongan),
bagea totoho (Gela), grijze rifhaai (Dutch), grys rifhaai (Afrikaans), ikan yu (Malay), jarjur (Arabic), kortneus-swartsterthaai (Afrikaans), mago
(Niuean), malie-aloalo (Samoan), marracho enlutado (Portuguese), nga-man-nee (Burmese), pako mej (Marshallese), pating (Tagalog), qio dravu
(Fijian), raira (Tahitian), requin ŕ queue noire (French), requin bar (French), requin blanc (French), requin dagsit (French), requin gris
(French), te alava (Tuvaluan), te bakoanimarawa (Kiribati), tiburón coralero rabinegro (Spanish), and tiburón de arrecifes (Spanish).
Geographical Distribution:
The grey reef shark is limited to the Pacific and Indian Oceans. In the Indo-Pacific, it is found in the waters off Madagascar and in the
Mauritius-Seychelles region. In the western Pacific Ocean, this shark ranges from southern China to northern Australia and the Tuamoto
Archipelago. It is one of the most common reef sharks in the Pacific Ocean, along with the blacktip reef shark (Carcharhinus melanopterus)
and the whitetip reef shark (Triaenodon obesus). It is also found in the Indian Ocean, off the coast of India to South Africa, including the
Red Sea. In this region it is often referred to as Carcharhinus wheeleri.
Habitat:
Primarily distributed in shallow tropical and subtropical waters, the grey reef shark is often found near coral atolls and lagoons adjacent to reef
habitats. It is often observed swimming along the outer edges of coral reefs. Its depth ranges from 0-920 feet (0-280 m). However, this species has
been observed in waters down to 3,280 feet (1,000 m). Although more active during the night, grey reef sharks sometimes form schools during the day.
These schools swim close to the bottom, over flat habitats. Grey reef sharks also form loose aggregations that lurk close to reef drop-offs. Lone
individuals may be seen over shallow reefs either lying motionless on the bottom of the sea floor for long periods of time or swimming. Tagging
studies show that sharks living near ocean reefs are nomadic and travel long distances along the reef habitat each day. Sharks residing in lagoon
areas tend to return day after day to the same site.
Biology: Distintice Features:
This is a large shark with a slender, fusiform body and low inter-dorsal ridge between the first and second dorsal fins. The tall and nearly straight
first dorsal fin originates over the posterior third of the pectoral fin inner margin. The long pelvic fins are straight, each with a pointed tip. The
snout of the Galapagos shark is broadly rounded.
Resembling the grey reef shark (C. amblyrhyncos), the Galapagos shark can be distinguished with a more slender body and a slightly rounded tip on
the first dorsal fin. The Galapagos shark very closely resembles the dusky shark (C. obscurus). The Galapagos shark has a much more erect first
dorsal fin and larger teeth than the dusky shark, however this can be difficult without direct comparison of two specimens. The easiest method to
distinguish these two species is by the number of precaudal vertebrae - there are 103-109 in the Galapagos shark and 86-97 in the dusky shark. To
determine the number of vertebrae, the backbone must be exposed from the back of the skull to the base of the tail.
Dentition: The serrated upper teeth are relatively long and broadly triangular in shape. The very finely serrated lower teeth are
symmetrical and erect. Typically there are 14 teeth on either side of the symphysis in each jaw with one tooth located at the symphysis.
Galapagos shark line drawing FAO Species Catalog, Vol. 4 Part 2 Sharks of the World
Size, Age, and Growth: The Galapagos shark reaches a maximum length of 12.1 feet (3.7 m). Male individuals mature at lengths
of 6.9-7.5 feet (2.1-2.3 m) while females mature at 7.2-8.2 feet (2.2-2.5 m) in length. Age of Galapagos sharks at first reproductive effort is
approximately 10 years. Maximum known lifespan is approximately 24 years.
Food Habits: This shark feeds primarily on bottom-dwelling fishes as well as on squid and octopus. These fish include eels,
flatheads, groupers, flatfish, and triggerfish. As Galapagos sharks reach large sizes, they also feed on other elasmobranchs. In the Galapagos
Islands off the coast of Ecuador, it has been observed preying on sea lions and marine iguanas. The Galapagos shark displays threat gestures
to warn competitors in the search for food.
Reproduction: Galapagos sharks are "viviparous", or livebearing, with embryos nourished by a yolksac-placenta during gestation. Mating
and birth occurs early in the year within Hawaiian waters. Female individuals often have mating scars from males biting the gills, fins, and body.
After gestation during which the embryos develop inside the mother, live birth results in a litter size of 4-16 pups. Each pup measures 24-31 inches
(60-80 cm) in length. The pups stay in shallow water nursery areas to avoid predation and cannibalism from members of their own species, eventually
moving out to deeper waters as they mature.
Predators:
Large sharks are potential predators of the Galapagos shark. Cannibalism is also reported within this species.
Importance to Humans:
Due to its somewhat remote habitat and patchy distribution, the Galapagos shark is of little economic importance. There is little information
available regarding utilization of this shark, however it has flesh of excellent quality for human consumption.
Danger to Humans:
According to the International Shark Attack File, the Galapagos shark has been responsible for one fatal attack on a swimmer in the Virgin Islands.
In locations where this shark is abundant, they often are attracted to divers, sometimes even becoming a hindrance. When divers took aggressive
actions, these sharks were not deterred but instead became more excited. Prior to attack, the Galapagos shark has been reported to display threat
behaviors including arching of the back, raising the head, and lowering the caudal and pectoral fins while swimming in a twisted, rolling motion.
This species is considered potentially dangerous and may attack if a food source is present such as during spearfishing activities. If there are large
numbers of Galapagos sharks present, it would be wise to limit one's activities in the water.
Conservation:
The Galapagos shark is currently considered "Near Threatened" by the World Conservation Union (IUCN). A taxon is assessed as "Near Threatened" when it has
been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is
likely to qualify for a threatened category in the near future. The IUCN is a global union of states, governmental agencies, and non-governmental
organizations in a partnership that assesses the conservation status of species. In Australia and Ocean (western Pacific Ocean), the Galapagos shark
is considered "Data Deficient" due to a lack of information on populations in this region. However, there is a marine reserve that encompasses this
species' range off Lord Howe Island (AUS) and the Kermadec Islands (New Zealand) where it is not considered to be under threat.
