[Photo] The scalloped hammerhead shark is threatened by shark finning -- the practice of removing only a shark's fins and dumping the still live but now helpless shark into the ocean to die. (Credit: iStockphoto/Ian Scott)

ScienceDaily (Feb. 17, 2008) — Sharks are disappearing from the world's oceans. The numbers of many large shark species have declined by more than half 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.

Now, the global status of large sharks has been assessed by the World Conservation Union (IUCN), which is widely recognized as a highly comprehensive, scientific-based information source on the threat status of plants and animals.

"As a result of high and mostly unrestricted fishing pressure, many sharks are now considered to be at risk of extinction," explained Julia Baum, a member of the IUCN's Shark Specialist Group who will be speaking at the American Association for the Advancement of Science Annual Conference in Boston on February 17.

"Of particular concern is the scalloped hammerhead shark, an iconic coastal species, which 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," added Baum, who is an NSERC Postdoctoral Fellow at Scripps Institution of Oceanography.

Baum pointed out that fishing for sharks in international waters is unrestricted, and she supports a recently adopted United Nations resolution calling for immediate shark catch limits as well as a meaningful ban on shark finning (the practice of removing only a shark's fins and dumping the still live but now helpless shark into the ocean to die).

Research at Dalhousie University over the past five years, conducted by Baum and the late Ransom Myers, demonstrated the magnitude of shark declines in the northwest Atlantic Ocean. All species the team looked at had declined by over 50 per cent since the early 1970s. For many large coastal shark species, the declines were much greater: tiger, scalloped hammerhead, bull and dusky shark populations have all plummeted by more than 95 per cent.

Adapted from materials provided by Natural Sciences and Engineering Research Council.