Author: (Poey, 1861)
An unmistakable requiem shark, with stocky build, short blunt snout, and long, broad, paddleshaped pectoral fins and a high first dorsal fin, plus white tips and sometimes black markings on fins.
A large, stocky species (up to about 3 m or more). Snout short and broadly rounded; internarial width 1 to 1.1 times in preoral length; eyes circular and small, their length 0.9 to 2.5% of total length; anterior nasal flaps low and broadly angular, not expanded; upper labial furrows short and inconspicuous; hyomandibular line of pores just behind mouth corners not conspicuously enlarged; gill slits moderately long, third 3.1 to 4.1% of total length and less than a third of first dorsal base; usually 14/ 14 rows of anteroposterior teeth in each jaw half but varying from 13 to 14/13 to 15; upper teeth with very broad, triangular, strongly serrated, erect to slightly oblique cusps that merge into crown feet with slightly coarser serrations but no cusplets; lower teeth with erect to slightly oblique, stout serrated cusps and transverse or moderately arched roots. A low interdorsal ridge usually present. First dorsal fin very large and distally expanded, not falcate, with a broadly rounded apex and posterior margin curving anteroventrally and posteroventrally from fin apex; origin of first dorsal fin just anterior to the pectoral free rear tips; inner margin of first dorsal moderately long, half dorsal base or somewhat less; second dorsal fin large and high, its height 2.7 to 3.9% of total length, its inner margin short and 1 to 1.1 times its height; origin of second dorsal over or slightly anterior to anal origin; pectoral fins very large, elongated, nearly straight and distally expanded, with broadly rounded apices, length of anterior margins about 19 to 29% of total length; 228 to 244 total vertebral centra, 123 to 131 precaudal centra. Colour grey-bronze above, white below; white mottling usually present on fins, particularly pectorals, first dorsal, pelvics, and caudal tips; but young additionally with black blotches or tips on most fins, especially the pelvic, second dorsal, anal, and ventral caudal lobe, as well as black saddles at second dorsal insertion, upper caudal origin, and sometimes between the dorsal fins, that fade in adults; an inconspicuous white band on flank.
Primarily oceanic in tropical and warm-temperate waters. Western Atlantic: Maine to Argentina, including Caribbean and Gulf of Mexico. Central Atlantic. Eastern Atlantic: Madeira, Portugal south to the Gulf of Guinea, possibly Mediterranean Sea. Western Indian Ocean: South Africa, Madagascar, Mozambique, Mauritius and Scychelles, Red Sea, India. Western Pacific: China (including Taiwan Island), the Philippines, New Caledonia, Australia (southern Australian coast). Central Pacific: Hawaiian Islands south to Samoa Islands, Tahiti and Tuamotu Archipelago and west to Galapagos Islands. Eastern Pacific: Southern California to Peru, including Gulf of California and Clipperton Island.
Habitat and Biolony:
A common, oceanic-epipelagic, but occasionally coastal, tropical and warmtemperate shark, usually found far offshore in the open sea. It sometimes occurs in water as shallow as 37 m inshore, particularly off oceanic islands or in continental areaswhere the shelf is very narrow, but is generally found in water with the bottom below 184 m, from the surface to at least 152 m deep. Temperatures of waters in which it reaularly occurs are 18° to 28°C and normally prefers water above 20°C, although one was caught in water of 15 C; it tends to withdraw from waters that are cooling below this, as in the Gulf of Mexico in winter.
Population dynamics and structure are little-known. Apparently size and sexual segregation occurs in this shark as in many other species. Longline catches in the Central Pacific show it definitely increases in abundance as a function of increasing distance from land, and, unlike the silky shark (Carcharhinus falciformis) but as in the blue shark (Prionace glauca), it does not congregate around land masses. The oceanic whitetip is mpst abundant in the tropics from 20 N to 20°S, but with appropriate movements of warm-water masses can occur far beyond its normal range. At the time of writing (November, 1983), a warm-water incursion along the California coast in the USA has, among other species, brought the oceanic whitetip far north, to off of Catalina Island in southern California and possibly to northern California (B. Lea, pers. comm.). This is one of the three most abundant oceanic sharks (the other two being the silky and blue sharks), and one of the more abundant of large marine organisms. It apparently does not form polarized schools, though it may aggregate in numbers around a food source.
This shark is slow-movingbut quite active and apparently equally so at daytime or night. It often cruises slowly at or near the surface with its huge pectoral fins conspicuously outspread, but can suddenly dash for a short distance when greatly disturbed. It is much more leisured in its movements than the silky shark (which is often found along with it), but compensates for it by being far more aggressive, especially when competing for food with silky sharks. Similar-sized whitetips generally dominate silky sharks when the two are closely contesting the same piece of food, but if the food drifts much beyond the reach of the whitetip the silky shark generally grabs it and flees because of its greater speed and agility. The oceanic whitetip is cautious in investigating hooked baits but very bold and incredibly persistant in attending potential sources of food.
Viviparous, with a yolk-sac placenta; litter sizes 1 to 15, with larger females having larger litters. This shark apparently mates and gives birth in the early summer in the western North Atlantic and southwestern Indian Ocean, and has a gestation period of about a year. In the central Pacific, females with small embryos have been found throughout the years, suggesting a less tight seasonality of birth (and presumably mating) than the western Atlantic. Also, non-breeding adult females have been found to outnumber gravid females in the equatorial central Pacific.
Feeds primarily on oceanic bony fishes and cephalopods, including lancetfish, oarfish, threadfins, barracuda, jacks, dolphinfish, tuna, skipjack and other scombrids, marlin, squid and occasionally stingrays (probably Dasyatis violacea, the unique pelagic stingray), sea birds, turtles, marine gastropods, crustaceans, carrion from marine mammals, and garbage. It was seen feeding on a tight school of threadfins like a person eating an apple, by slowly taking bites out of the school. Whitetips have been observed feeding in a remarkable way on denseschools of small tuna that were in turn frenziedly feeding on sardines at the surface. Quite a number of whitetip cruised erratically at the surface in the middle of the tuna with mouths wide open; they did not attempt to snap or chase any of the tunas during the course of a half hour's observation. As several of the whitetips captured had these tuna in their stomachs, it was suggested that the sharks merely wait for the tuna to dash into their open mouths before biting them! The oceanic whitetip is a pest to longline fisheries for tuna and other pelagic fishes because it persistantly accompanies the boats and damages or totally devours the catches. When warm-water whale fisheries were operated, such as the sperm-whale fishery out of Durban, South Africa, this shark was often responsible for most of the damage to floating carcasses. They have powerful jaws and large teeth, albeit less so than the bull and pigeye sharks (C. leucas and C. amboinensis). Divers have filmed them removing huge chunks out of dead whales and dolphins, which they readily do by biting and shaking to drive the teeth through the meat.
This is a dangerous species, responsible for a few verified and unverified attacks on swimmers and boats. Divers have encountered it in the open ocean, and it has shown extreme persistence in investigating and circling them both in baited and unbaited situations, possibly as a prelude to an attack. The whitetips were fended off before they might bite; however, they often would return to circle and approach again. Various actions to frighten off these sharks usually have limited or no effects, unlike many other species, including the great white, that often flee when aggressively confronted. In the film 'Blue water, white death' these sharks were filmed feeding on a sperm whale carcass off Durban, South Africa. Few sharks were actively feeding although many were present and seemed bloated from previous meals; but the diving team involved were slowly but persistently approached by apparently sated whitetips, and had to deter them from approaching too close and possibly attacking by bumping them on the snout. This shark was thought by Bass, D'Aubrey and Kistnasamy (1973) to have been chiefly responsible for the deaths of many people in the water after the ship "Nova Scotia" was torpedoed and sunk by a German submarine during the second world war off northern Natal, South Africa. Because of its opportunistic feeding habits, heavy build, strong jaws and teeth, and stubbornaggressiveness, this shark should be treated with extreme care. Fortunately some potential attacks on divers have been averted by prompt action on their part and by the slowness of the approaching whitetips.
Maximum possibly 350 to 395 cm for gigantic individuals, but most are below 300 cm; males maturing at 175 to 198 cm and reaching at least 245 cm, females maturing at about 180 to 200 cm and reaching at least 270 cm; size at birth 60 to 65 cm.
A length-weight curve for Cuban sharks is:
WT = 0.7272 x 10 4TL2 678(Guitart Manday, 1975).
Interest to Fisheries:
This is a wide-ranging, common oceanic shark that is regularly caught with pelagic longlines, also handlines and occasionally pelagic and even bottom trawls. It is utilized fresh, smoked and dried salted for human consumption, for hides, for fins (processed into the ingredients for shark-fin soup), and for liver oil (extracted for vitamins) and fishmeal.
The earliest available name for this species is apparently Squalus (Carcharias) maou Lesson, 1830, but due to the wider usage and placement on the Official List of Specific Names in Zoology of Squalus longimanus Poey, 1861 Garrick (1982) decided to use it instead of S. maou; this action is followed here.
Holotype: Male of 1640 mm, extant? Type Locality: Cuba.