Fish Facts » Thresher Shark
The thresher shark can be easily identified by the long upper lobe of the caudal fin. The lobe can be as long as the body and gives the tail a slender "whiplike" appearance. It has a moderate size eye and a first dorsal fin free rear tip located ahead of the pelvic fins. The pectoral fins are falcate and narrow tipped. The sides above the pectoral-fin bases are marked with a white patch that extends forward from the abdominal area. Threshers are usually dark brown and slate gray but can be almost completely black. They are white on their underside, but have dark spots near the pelvic fin and the caudal peduncle. The white color can extend above the pectoral fins onto the head.
The thresher shark is a pelagic species inhabiting both coastal and oceanic waters. It is most commonly observed far from shore, although it wanders close to the coast in search of food. Adults are common over the continental shelf, while juveniles reside in coastal bays and near shore waters. It's mostly seen on the surface but it inhabits waters to 1,800 feet (550 m) in depth. Thresher sharks are observed infrequently jumping out of the water. Threshers are considered a highly migratory species in the U.S. by the National Marine Fisheries Service for fishery management purposes.
Bony fish make up 97% of the thresher's diet. They feed mostly on small schooling fish such as menhaden, herring, Atlantic saury, sand lance, and mackerel. Bluefish and butterfish are the most common meal. They also feed on bonito and squid. Thresher sharks encircle schools of fish and then stun the prey with their tails. This is often done in groups and/or pairs. They have also been known to kill sea birds with their tails.
The meat and the fins have good commercial value. Their hides are used for leather and their liver oil can be processed for vitamins. When found in groups, threshers are a nuisance to mackerel fisherman because they become tangled in their nets. Threshers have been widely caught in offshore longlines by the former USSR, Japan, Taiwan, Spain, Brazil, Uruguay, USA and other countries. The northwestern Indian ocean and eastern Pacific are especially important fishing areas. A drift net fishery for the shark developed in southern California; however, the stock was rapidly overfished. It is classed as a game fish and sportsmen in the USA and South Africa fish them. They are often hooked on the upper lobe of the caudal fin. This occurs when the sharks try to stun live bait with their caudal fin. Threshers put up an energetic resistance and often succeed in freeing themselves.
Male thresher sharks mature at about 10.5 feet (330 cm ) and females at around 8.5 - 14.8 feet (260 - 450cm). They are about 5 feet (150 cm) long at birth and grow 1.6 feet (50 cm) a year as juveniles. Adults grow about 0.3 feet (10 cm) a year. The maximum reported length of the thresher shark is 24.9 feet (760 cm), and the maximum weight recorded is over 750 lbs (340 kg).
The thresher shark, an oceanic and coastal species, inhabits tropical and cold -temperate waters worldwide. It is most common in temperate waters. In the Atlantic Ocean, it ranges from Newfoundland to Cuba and southern Brazil to Argentina, and from Norway and British Isles to Ghana and Ivory Coast, including the Mediterranean Sea. Although it is found along the entire U.S. Atlantic coast, it is rare south of New England. In the Indo-Pacific region, it is found off South Africa, Tanzania, Somalia, Maldives, Chagos Archipelago, Gulf of Aden , Pakistan, India, Sri Lanka, Sumatra, Japan , Republic of Korea, Australia, New Zealand, and New Caledonia. The thresher shark is also found in the Society Islands, Fanning Islands, and Hawaiian Islands. In the eastern Pacific Ocean it occurs off the coast of British Columbia to central Baja California, Panama south to Chile.
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