Thursday, January 24, 2008

Thresher Shark


Thresher sharks are large lamniform sharks of the family Alopiidae. Found in all temperate and tropical oceans of the world, the family contains three species all within the genus Alopias
Although occasionally sighted in shallow, inshore waters, thresher sharks are primarily pelagic; they prefer the open ocean, staying within the first 500 m of the water column. Common threshers tend to be more common in coastal waters over continental shelves. In the North Pacific, common thresher sharks are found along the continental shelves of North America and Asia. They are rare in the Central and Western Pacific. In the warmer waters of the Central & Western Pacific, bigeye and pelagic thresher sharks are more common.
Thresher sharks are solitary creatures which keep to themselves. It is known that thresher populations of the Indian Ocean are separated by depth and space according to gender. All species are noted for their highly migratory or oceanodromous habits.

Thresher sharks are one of the few shark species known to jump fully out of the water making turns like dolphins, this behaviour is called breaching.
Like all large sharks, threshers are slow growing and are therefore threatened by commercial fisheries. Other than for its meat, the sharks are hunted for their liver oil, skin (for leather), and their fins, for use in shark-fin soup.
They do not appear to be a threat to humans, although some divers have been hit with the upper tail lobe. There is an unconfirmed account of a fisherman being decapitated by a tail swipe as the shark breached.
Thresher sharks are classified as prized gamefish in the United States and South Africa. Common thresher sharks are the target of a popular recreational fishery off Baja Mexico. Thresher sharks are managed in some areas for their value as both a recreational sport fish and commercial species.