26 Décembre 2012
The grey shark (Carcharhinus amblyrhynchos), also referred as the dagsit shark, is a reef species that lives in the tropical and subtropical zones of the world.
This species can be identified by its bronze tint and its white underside. It can also be distinguished by a broad black band on the edge of the tail and black markings on the tips of the pectoral fins. Its first dorsal fin is either grey or white tipped. It has a powerful and massive body that can measure up to 6,6ft and 66lbs. It presents an extended and rounded muzzle. Its long and sharp pectoral fins give it some relative elegance and stream-lined form.
This species must not be confused with the other species of grey shark – Carcharhinus Plumbeus. This species, on the other hand, is bigger and has a higher and straighter dorsal fin. It is often found in open ocean habitats.
The Grey Reef shark is a common species of French Polynesia that can live up to 25 years. It frequents areas near strong current like passes or oceanic slopes in external reefs at depths of up to 900 ft. The grey reef shark moves in groups during the day and hunts alone at night. Large schools have been observed to group hundreds of grey reef sharks that cruise the reef area. Of a curious nature, this shark does not hesitate to approach divers. Once their curiosity is satisfied, they usually go on their way and leave well enough alone.
Like a lot of other shark species, the grey reef shark feeds on fish, octopi and sometimes crustaceans. To hunt its prey, this shark has an effective arsenal: a keen sense of smell to track a scent over long distances, a keen sense of hearing that enables it to zero in on the origin of a sound over 200 meters away and a strong swimming capability that allows it to reach speeds of up to 50km/h. The grey shark can be dangerous when it hunts in groups because it has been known to get into an unstable frenzy.
The grey reef shark is a viviparous fish becoming sexually mature after 7 years old. It gives birth to around 6 live baby sharks per litter of about 60cm in length. During the mating season, males abandon their traditional territories to enlarge their mating zone. Females have a long gestation period of 12 months.
During the day, sharks naturally define a precise meeting place. A classic example is the Tumakohua pass of Fakarava, where these huge congregations of sharks have been observed. It is known among divers as the "grey shark wall" - one of the most impressive sights a diver can behold. An experience of a lifetime !
© photos - V.Truchet