New study estimates that commercial fishing kills 100 million sharks annually

Commercial fishing kills roughly 100 million sharks a year, a toll that is pushing many of species of the fish closer to extinction, according to a study published Friday in the journal Marine Policy.

The new estimate by Canadian and American researchers — the most comprehensive analysis yet of global shark mortality — is substantially higher than numbers found in previous studies, in part because it takes into account the impact of illegal catches and discarded sharks. It comes as international negotiators are about to gather in Bangkok starting Sunday to debate whether to impose new trade restrictions on several imperiled shark species.

Sharks are being fished at an average rate that is 30 to 60 percent higher than they can sustain, the scientists conclude, noting that the animals take years to sexually mature and produce their small litters. Sharks are primarily targeted for their fins, which are used in the Asian delicacy shark’s fin soup, though they are also caught accidentally by vessels seeking tuna, swordfish and other species.

The analysis, based on a survey of roughly 100 papers, suggests that despite several efforts to curb shark finning worldwide, the total number of shark deaths has declined only slightly between 2000 to 2010, from 100 million to 97 million.

“It is not sustainable,” said Dalhousie University biology professor Boris Worm, the paper’s lead author, noting that sharks have roamed the seas for more than 400 million years. “Imagine we still had 500 species of dinosaurs around — every form and color from tiny critters to huge, whalelike creatures. Once they were everywhere, but then we started to chop off their tails to make soup from it, and now they are going extinct — not because a meteorite hit the planet, but because we ate their tails.” Elizabeth Wilson, manager of global shark conservation at the Pew Environment Group, said she hoped delegates to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) over the next two weeks would act on the findings and restrict the trade of oceanic whitetip, porbeagle and three types of hammerhead sharks. “The number of sharks being killed is too high,” Wilson said. “There’s an opportunity at CITES to do something to help shark species.”

— Juliet Eilperin