Populations of tiger, bull, dusky and other sea sharks have plummeted by more than 95 per cent since the 1970s as fisherman kill the animals for their fins or when they scoop other fish from the ocean, according to an expert from the World Conservation Union, or IUCN.
At particular risk is the scalloped hammerhead shark, whose young swim mostly in shallow waters along shores all over the world to avoid predators.
The scalloped hammerhead will be listed on the 2008 IUCN Red List as globally "endangered" due to overfishing and high demand for its valuable fins in the shark fin trade, said Julia Baum, a member of the IUCN's shark specialist group.
"As a result of high and mostly unrestricted fishing pressure, many sharks are now considered to be at risk of extinction," Baum said in a statement.
The numbers of many other large shark species have plunged due to increased demand for shark fins and meat, recreational shark fisheries, as well as tuna and swordfish fisheries, where millions of sharks are taken as bycatch each year, said Baum, a fellow at the Scripps Institution of Oceanography in San Diego.
Last year, IUCN put the great hammerhead, the largest of the nine species of hammerhead, on the Red List as "endangered." IUCN said in September that numbers of the shark in the eastern Atlantic may have crashed by 80 per cent in the last 25 years.
Hammerhead meat has a very low value but the sharks are among the most endangered species because their fins are highly prized for the Asian delicacy shark-fin soup. In shark finning, fishermen chop the fins of the animals and dump the sharks back into the sea.
Fishing for sharks in international waters is unrestricted, said Baum, who supports a recently adopted UN resolution calling for immediate shark catch limits and a ban on shark finning.
