(Related: "Asian Shark-Fin Trade May Be Larger Than Expected" [April 28, 2003].)
The new report appears in this month's issue of the journal Ecology Letters.
"The global demand for shark fins has increased dramatically in the last few decades, and this has created incentives for fishermen to go after sharks and retain shark fins," McAllister said.
According to Peter Knights, executive director of the conservation nonprofit WildAid, demand for shark-fin meat is the biggest problem facing the fishes.
That demand, Knights says, is especially strong among China's growing middle class. Newly flush Chinese may be buying shark-fin meat simply to prove they can, he adds, since the delicacy has little nutritional value and hardly any flavor.
Even so, the meat isn't limited to Asian menus.
A cup of shark-fin soup at the China Max seafood restaurant in San Diego, California, for example, can be had for $18. Braised whole shark fin runs $40.
"We make it all the time," said a man who answered the phone at the restaurant.
Russell H. Hudson is a spokesperson for the Seafood Coalition, an umbrella group of fishing-industry organizations. He agrees that the world trade in sharks is huge, but he says that the new report doesn't tell a complete and accurate story.
"More samples are needed to be collected at all life and marketing stages for this analysis to keep going forward," Hudson said.
"Maybe they should work with some fishing interests to help verify their conversions. The same species in different oceans tend to grow and mature at different lengths"—a contention that lead study author Shelley Clarke says has no scientific basis.
Knights, of WildAid, agrees that the new findings are imperfect.
The new data is "useful," he said. "But to be really useful it should be done by species and by individual areas," Knights said.
"[Shark data is] not recorded anywhere in that way. That's the biggest problem in getting sharks listed as endangered."
Lead study author Clarke adds that there is currently no way to trace fins at market to their home waters, at least not through genetic testing.
The Convention on International Trade in Endangered Species now lists only three shark species—basking, whale, and great white—as endangered. (See great white shark photos, facts, wallpapers, and more.)
Knights says studies of fishing rates may be more helpful, and these have indicated precipitous declines in shark populations.
"Sharks are the tigers and lions and cheetahs and leopards of the sea. And if we lose them—these top predators—there will be long-term damage," he said.
"They're slow reproducing, late to mature, more like mammals than fish in their biology—and we're completely trashing them.
"There's virtually no management of shark fisheries around the world. We're playing with fire," Knights said.
Study co-author McAllister is hopeful that it's not too late.
"Some progress is being made," he said. "In at least a few instances decision-makers at high levels are taking the results of recent studies like ours seriously and taking more stringent and immediate actions to address current threats to shark populations.
"For example," McAllister said, "based partly on our study, just last week the European Parliament voted to reduce the tolerance level for the maximum permissible percentage of shark landings that can be made up of fins from 5 percent down to 2 percent."
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