Oceanic Whitetip Shark, Carcharhinus longimanus
Oceanic Whitetip Shark, Carcharhinus longimanus. Underwater photographs taken in coastal waters off Kailua-Kona, Hawaii, October 2015. Length: 2.0 m (6 feet 7 inches). Photographs courtesy of Bob Hillis, Ivins, Utah.
The Oceanic Whitetip Shark, Carcharhinus longimanus, is a member of the Requiem Shark or Carcharhinidae Family, and is known in Mexico as tiburón oceánico. They are one of the three most abundant oceanic sharks, the other two being the Blue Shark, Prionace glauca and the Silky Shark, Carcharhinus falciformis. Historically they have been known as Sea Dogs, due to their tendency to follow ships at sea. Globally, there are thirty-five species in the genus Carcharhinus, of which seventeen are found in Mexican waters, seven in the Atlantic, four in the Pacific, and six in both the Atlantic and Pacific Oceans.
The Oceanic Whitetip Shark is a medium-sized and stocky requiem sharks with a flattened body and a humpback. They are dark gray dorsally and transition to white ventrally. The tips of their first dorsal fin, the lower lobe of their caudal fin, and their pectoral fins are often white; their fins may also be mottled. Juveniles have black marks. They have a dark saddle marking between their first and second dorsal fins. Their first dorsal fin originates just before the rear tips of the pectoral fins; their second dorsal fin originates over the front edge of the anal fin and is long and rounded; and their pectoral fins are wide-tipped and paddle-like. Their fins are significantly bigger than those of most sharks. Their head has a bluntly rounded snout and circular eyes with nictitating membranes. Their mouth is equipped with triangular teeth; the 13 to 15 teeth on their lower jaw are thin and triangular with serrated tips and the 14 or 15 teeth on their upper jaw are much larger and broader with serrated edges. Their skin is smooth to the touch.
The Oceanic Whitetip Shark is a highly migratory oceanic pelagic shark. They are normally found near the surface far out at sea in waters between 18oC (64oF) and 28oC (82oF) and at depths up to 152 m (500 feet). They reach a maximum of 4.0 m (13 feet 1 inches) in length and 167.4 kg (368 lbs) in weight with females being slightly larger than males. They are slow-moving but are active 24 hours a day. They are more abundant further from land but will enter shallower waters near land on occasion. They are normally found as solitary individuals that cruise the surface looking for food, however, they will form groups and become highly aggressive and capable of making bursts of speed to participate in “feeding frenzies” when an abundance of food is available. They are known to be accompanied by dorados, pilot fish, remoras, and sea turtles. They will also follow schools of bait fish, tuna, squid, and cetaceans (dolphins and pilot whales) that have better food detection abilities. They are omnivores that are competitive and opportunistic predators feeding on various fish (barracuda, dorado, marlin, swordfish, and tuna), crustaceans, gastropods, and sea turtles as-well-as seabirds, marine mammals, mammalian carrion, and detritus. They are not subject to extensive predation with the exception that their juveniles are preyed upon by other large sharks. Reproduction is viviparous with a one-year gestation period; embryos have a yolk sac placenta. Females have litter sizes of up to 15 pups with miniature adults being born measuring 60 cm (2 feet 0 inches) to 65 cm (2 feet 2 inches) in length. They have a lifespan of up to 22 years. The Oceanic Whitetip Shark is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Oceanic Whitetip Shark has a wide distribution being found in all global tropical and subtropical waters. In Mexican waters they are a resident of all oceanic waters of both the Atlantic, including the Gulf of Mexico and the Caribbean, and the Pacific Oceans.
The Oceanic Whitetip Shark is easy to recognize and cannot be confused with any other species.
From a conservation perspective the Oceanic Whitetip Shark is currently classified as Vulnerable. In certain parts of their range they are considered Critically Endangered with population declines and documented catch size reduction by up to 98% over the last thirty years. The Oceanic Whitetip Sharks were formerly abundant but have been subject to heavy global fishing pressure throughout their range. They have been caught in large numbers as a by-catch by longliners, gill nets, handlines, and bottom trawls. The fishery is poorly monitored with virtually no historical catch rates available, no conservation programs in place, and a large number of fish continually being finned for shark fin soup and their carcasses being discarded. They are sold fresh, frozen, smoked, and dried-salted for human consumption and are also processed into fishmeal. Their liver oil is used for vitamin production and their skin for leather goods. They are also pursued by recreational anglers as gamefish. They benefit from having fast growth and early maturation rates. They are fearless and will charge humans with numerous documented attacks on divers and following air and sea disasters. Efforts to maintain them in captivity have generally been unsuccessful.