Carcharhinus amblyrhynchos, Gray Reef Shark [+]
Kingdom Animalia
Phylum Chordata
Class Elasmobranchii
Order Carcharhiniformes
Family Carcharhinidae
Genus Carcharhinus
species: Carcharhinus amblyrhynchos [+ITIS +WoRMS]
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Description & Behavior
The gray reef shark, Carcharhinus amblyrhynchos (Bleeker, 1856), aka grey reef shark, blacktail reef shark, bronze whaler, shortnose blacktail shark, and whaler shark, is dark gray or bronze-gray above (ventral side) and white below (dorsal side); the caudal fin has a conspicuous wide black posterior margin; the undersides of the pectoral and pelvic fins have black tips and posterior margins, but fins otherwise are not conspicuously black or white-tipped except for a pale-tipped first dorsal in some individuals in the Indian Ocean. This is a medium-sized to large shark, with a broadly rounded snout. The origin of the first dorsal fin is usually over or just in front of the rear tips of the pectoral fins. No interdorsal ridge. Maximum size is reported to reach up to 2.55 m; however the largest measured on record was 1.72 m (female). Most are <1.5 m in length. The maximum weight is 34 kg and the maximum reported age is 25 years.
World Range & Habitat
The gray reef shark occurs on continental and insular shelves and the oceanic waters adjacent to them. They are common on coral reefs, often in deeper areas near drop-offs, in atoll passes, and in shallow lagoons adjacent to areas of strong currents. They form schools during daylight hours in aggregations of up to 100 individuals. Although they are active during the day, they are more active at night when individuals spread out over large areas of the reef, often entering shallow lagoons. They spend their time during the day cruising along the shallow forereef and in reef channels, especially in areas with strong current; individuals often move into reef passes with ebb tides. The average home range is 4.2 km2.
They are found throughout the Indo-Pacific: Madagascar and the Mauritius - Seychelles area, possibly India; also in the Red Sea to South Africa where Carcharhinus wheeleri, the blacktail reef shark, is found. In the Pacific, the gray reef shark ranges from southern China to northern Australia and the Tuamotu Archipelago to Hawaii. This is one of the three most common reef sharks in the Indo-Pacific, the two others are the blacktip reef shark, Carcharhinus melanopterus, and the whitetip reef shark, Triaenodon obesus. They are found in depths between 0-800 m. A gray reef shark was photographed at 800 m by a submersible off Hawaii.
Feeding Behavior (Ecology)
Gray reef sharks feed on reef fishes, squids, cephalopods, crabs, lobsters, and shrimps. They have been observed herding fishes against the reef face before attacking. They tend to be aggressive under baited conditions and readily enter into an excited mob feeding pattern (true feeding frenzies are extremely rare), at which time they may become quite dangerous to humans.
Life History
This species is viviparous with a yolk-sac placenta; they give birth to 1-6 pups in a litter following a gestation period of about 12 months. Birth size is between 45-60 cm. Males and females mature at about 7 to 7.5 years, males mature at 1.3-1.45 m, females mature at about 1.2-1.35. The expected life span is at least 25 years.
Conservation Status/Additional Comments
Gray reef sharks are a curious and aggressive species repeatedly indicated in human attacks. They should not be touched, cornered, or approached by divers. They performs a dramatic threat display, featuring a raised snout, stiffly lowered pectoral fins, an arched back, and exaggerated swimming movements. They are fished commercially for human consumption, fishmeal and other shark products. This species is important in dive eco-tourism in French Polynesia, Palau, and the Maldives.
This widespread social species was formerly common in clear tropical coastal waters and oceanic atolls. Its restricted habitat choice, site fidelity, inshore distribution, small litter size, relatively late age at maturity and increasing mismanaged fishing pressure suggests that this species is under threat. Although caught in tropical multi-species fisheries, it has considerably greater value if protected for dive tourism. This species is quickly being depleted, particularly in the Maldives.
The gray reef shark, Carcharhinus amblyrhynchos, is listed as Lower Risk/near threatened (LR/nt) on the IUCN Red List of Threatened Species:
LOWER RISK (LR) - A taxon is Lower Risk when it has been evaluated, does not satisfy the criteria for any of the categories Critically Endangered, Endangered or Vulnerable. Taxa included in the Lower Risk category can be separated into three subcategories:
1. Conservation Dependent (cd). Taxa which are the focus of a continuing taxon-specific or habitat-specific conservation programme targeted towards the taxon in question, the cessation of which would result in the taxon qualifying for one of the threatened categories above within a period of five years.
2. Near Threatened (nt). Taxa which do not qualify for Conservation Dependent, but which are close to qualifying for Vulnerable.
3. Least Concern (lc). Taxa which do not qualify for Conservation Dependent or Near Threatened.
References & Further Research
BioOne ~ CITES ~ Discover Life ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList ~ MarineBio Network ~ NCBI ~ SCIRIS ~ SIRIS ~ Tree of Life Web Project ~ Wikipedia
Gray reef shark (Carcharhinus amblyrhynchos) - Shark Foundation
Description Grey Reef Shark - Carcharhinus amblyrhynchos - Florida Museum of Natural History
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