UNDERWATER WORLD SHARK'S PAGE

Extinction has become a real possibility for our oceans’ top predator. A bowl of sharkfin soup used to be the food of emperors, a refined delicacy taken in small quantities and on special occasions only. Affluence has changed all that dramatically. Conservative estimates now speak of an annual worldwide consumption of over 350 tons of sharkfin. This translates into more than half a million sharks killed every year for their fins, often under exceptionally brutal circumstances.

Dead finned shark

Stocks have been depleted so severely that sharkfin is now imported into South East Asia from as far away as Scandinavia and South America. All shark species are affected, even the rare Basking Shark and the legendary Great White. And demand is increasing.

At issue is not culture, but sustainability. A balanced approach is needed in this emerging conflict between old cultural habits and the need for conservation of all our marine resources. The problem is global, but the solution may be right in your own hands.

morphology	unlikely to reach much over 3 m
distribution	it is widespread in warm tropical and sub-tropical water from the Galapagos and Revill Gigedos Islands in the Eastern Pacific, through French Polynesia and the Marshall Islands to South Africa and the Natal Coast. In the Indian Ocean, it is the most abundant shark around Mauritius and the Seychelles. It is conspicuously absent in Hawaii and does not occur in the Atlantic.
habitat	it is generally a deeper inshore shark, inhabiting the waters from 30 to 400 m along drop-offs and banks. Small individuals are sometimes found in atoll lagoons of the Tuamotus. Although generally bottom oriented, the silvertip has been found far out at sea, and it is not infrequently found near the surface - usually as a result of attractive stimulus conditions. They also occur at sea in depths approaching the above maximum, where the bottom is much deeper.
feeding	one study shows stomach contents as being 70% smallfish, 10% eagle ray, 10% octopus and the balance indigestible material. This indicates that the silvertip possesses a fairly generalized feeding pattern, being able to feed from flat fish on the bottom to mid-water and surface fish. When feeding in the presence of an observer, the silvertip usually watches from a distance, grabbing the prey in a rapid dash at an opportune moment after which it glides away. Occasionally, especially in younger specimens, this species is curious and closely approaches divers.
disposition	the silvertip has been said to attack man, and its large size, strong dentition and inquisitive and persistent nature make it a potentially dangerous species. To a degree it is a nervous shark, remaining at the edge of any disturbance, but if attracted, it becomes persistent, gradually moving closer. This species shows a strong attraction to certain artificially produced, low-frequency, pulsed sounds during acoustic experiments, which may relate to their reported attraction to ships at sea.

morphology	its maximum recorded size is 2.33 m, however individuals over 1.9 m are rare.
distribution	the gray reef shark occurs in tropical and sub-tropical waters from the Hawaiian chain and Easter Island westward to the western Indian Ocean. It is reported from as far north as Midway (28° N) southward to Easter Island (28°S).
habitat	the gray reef shark generally seems to prefer rugged terrain such as that on the drop-off of outer reefs and in lagoons around patch reefs in or arising from deeper water. It often shows a preference for areas adjacent to strong currents, e.g., the ocean and lagoon sides of atoll passes. This species shows a definite orientation towards the bottom, although it not infrequently rises to the surface. Telemetry tagging data exists which indicates it may swim kilometers off shore at a depth of less than 100 m , while the bottom may be a thousand meters below. In the central Pacific it is the most common deeper, inshore shark, and is found from the surface to a little over 100 m. Where the reef blackfin shark is absent, e.g., Johnston and Marcus Islands, the gray reef shark is found commonly by day over the shallow reef normally reserved for the blackfin reef shark. However, at Toau in the Tuamotus where the blackfin reef shark is abundant, the gray reef shark is occasionally found by day in 1 m of water. The gray reef shark is usually restricted to small islands, where it shows a preference for the leeward side. In keeping with the above generalization , the gray reef shark is uncommon around the major Society and Hawaiian Islands, but is abundant in the Tuamotu Islands and leeward Hawaiian chain.
feeding	one report, which is probably a good average, indicates that the gray reef shark feeds 53 % of the time on small fish, 25 % on larger fish, 18 % on cephalopods and 4 % on crustaceans. This species is only very rarely cannibalistic, although it will eat the flesh of closely related species. The gray reef shark, although capable of feeding off the bottom, is most successful in feeding on organisms in the water column near the bottom. It can rapidly follow odors to their source for substantial distances (at least hundreds of meters), and it is capable of directly determining the source of sounds for a distance of about 200 m.
disposition

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