Whitetip Reef Shark.
A small, slender requiem shark. Short, bluntly rounded snout. First dorsal origin midway between pectoral fin free rear tip and pelvic fin origin. Second dorsal fin over anal fin. Dorsal fin apexes rounded. Second dorsal fin large. Anal fin large. Dorsal coloration grey, brownish grey, or blueish grey, with or without scattered dark spots. Ventrum white or light grey. Fins often dusky. Bright white tip on first dorsal fin, upper caudal lobe and sometimes lower caudal lobe.
Maximum length 168cm. Size at birth 52-60cm.
Tropical Reefs and associated sand flats. From the surface to 330m but usually found between 5-40m.
Whitetip reef sharks are extremely common throughout the tropical Indian Ocean and west/central Pacific. They have a limited range in the Eastern Pacific and are absent from the Atlantic although they have been seen in the eastern Mediterranean having entered through the Suez Canal.
Although widespread and relatively abundant, the whitetip reef shark is taken in line and net trawl fisheries operating in shallow reef areas, this shark has been recorded as part of the multi-species shark catch taken by tropical fisheries, e.g. Barnett (1996), Hayes (1996) and Keong (1996). Although its life history pattern suggests a moderate capacity for rebound (Smith et al. 1998), heavy fishing pressure inshore and lack of management plan in most places suggest that this species may be under threat in heavily fished areas, including remote tropical reefs (Anderson et al.1998).
Citations and References
Smale, M.J. 2009. Triaenodon obesus. The IUCN Red List of Threatened Species 2009: e.T39384A10188990. https://dx.doi.org/10.2305/IUCN.UK.2005.RLTS.T39384A10188990.en. Downloaded on 19 October 2020.
A viviparous species with yolk-sac placenta. 1-5 pups per litter. Whitetip reef sharks have been seen in the process of mating numerous times by divers and researchers. While in a stationary position on the sea floor, the male bites the female’s pectoral fin and inserts one clasper.
Whitetip reef sharks predate on numerous small reef fishes, octopuses, and crustaceans.
Active nocturnal hunters. By day, whitetips rest (often in groups) in caves, crevices, on rocky ledges, or on the sand at the bottom of channels. They are non-migratory, often returning to the same resting site each morning.
Reaction to divers
Quite tollerant of a slow non-threatening approach while at rest. They will bolt if approached too closely.
There are an overwhelming number of places where whitetip reef sharks can be encountered throughout the Indo-Pacific.
In the Eastern Pacific, one of the most interesting spots to watch them is at Roca Partida within Mexico’s Revillagigedo Archipelago. RP a small, rocky monolith standing in 70m of water, 60km from any other island. During the day, whitetips rest on a series of ledges between 10-20m. Space is limited so this is a great place to photograph them piled on top of each other.
Another interesting spot is at a dive site named Manuelita at Cocos Island, Costa Rica. During night dives at this spot, scores of whitetips follow divers around, hunting for reef fishes that are lit up by the diver’s lights.
Whitetip reef sharks are very common around the volcanic islands and atolls of French Polynesia. At the south pass of Fakarava Atoll, the show is dominated by hundreds of grey reef sharks but at the bottom of the channel, there are usually groups of whitetips laying on the sand, facing into the current.
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