美國湯碗驚現瀕危鯊魚魚翅

Genetic testing of shark fin soup from cities across the United States found DNA from eight endangered and threatened shark species.

In the first nationwide analysis of shark fin soup, bowls of the Asian delicacy served in 13 out the 14 U.S. cities tested were found to contain species at risk of extinction.

A bowl of soup sampled in Boston contained fin meat of a scalloped hammerhead shark, which is listed as Endangered on the IUCN Red List of Threatened Species.

To arrive at their conclusions, scientists analyzed DNA from shark fin soup samples gathered in Albuquerque, Atlanta, Boston, Chicago, Denver, Fort Lauderdale, Houston, Las Vegas, Los Angeles, New York, Orlando, San Francisco, Seattle, and Washington, DC.

Denver was the only city where the soup samples did not contain fins from species listed as Endangered, Vulnerable or Near Threatened by the IUCN.

Shark attack survivors who have become global advocates for conservation of their attackers helped collect some of the samples for the study. The survivors, as well as the soup study, will be featured during Discovery’s show “Shark Fight” at 9 pm EDT Wednesday, August 15.

Dr. Demian Chapman, who co-led the research team, said, “The DNA testing again confirms that a wide variety of sharks are being killed for the fin trade, including seriously threatened species.”

“U.S. consumers of shark fin soup cannot be certain of what’s in their soup. They could be eating a species that is in serious trouble,” he said.

The soup samples were analyzed at the Institute for Ocean Conservation Science at Stony Brook University in New York, where Dr. Chapman is assistant science director.

Dr. Chapman worked with the Pritzker Laboratory at the Field Museum in Chicago to modify existing DNA-barcoding techniques to identify shark DNA fragments that had deteriorated in the fin treatment and cooking process.

In addition to the scalloped hammerhead, the research team found that the 32 samples identified as sharks included smooth hammerheads, school sharks, and spiny dogfish, which are all listed as Vulnerable to extinction on the IUCN Red List.

“This is further proof that shark fin soup here in the United States – not just in Asia – is contributing to the global decline of sharks,” said Liz Karan, manager of global shark conservation at the Pew Environment Group, which financially supported the research.

The Pew Environment Group’s shark conservation campaign is a worldwide effort focused on saving sharks. Since the start of the campaign in 2009, six countries have created national shark sanctuaries: Palau, the Maldives, Honduras, the Bahamas, Tokelau, and the Marshall Islands, covering a total of 1.8 million square miles.

Karan said, “Sharks must be protected from overfishing and any international trade in these vulnerable and endangered species must be tightly regulated.”

Dr. Chapman’s research combines DNA analysis with ecological data to better understand the population biology, evolution, and ecology of large marine vertebrates, particularly sharks.

In addition to the scalloped hammerhead, other at-risk shark species found in U.S. soup bowls include: the smooth hammerhead, the shortfin mako, the spiny dogfish, the school shark – all listed as Vulnerable to extinction; as well as the blue shark, the copper shark and the bull shark – all listed as Near Threatened.

In June, Costa Rica and Honduras announced plans to propose new trade rules for hammerhead sharks under the Convention on the International Trade in Endangered Species, which meets next in March 2013.

Shark fins are obtained by slicing the fins off of sharks caught at sea; the bodies of the living sharks often are thrown back. Unable to move normally, the damaged sharks die of suffocation or are eaten by predators.

The IUCN’s Shark Specialist Group says shark finning is widespread, “largely unmanaged and unmonitored” and that “the rapidly expanding and largely unregulated shark fin trade represents one of the most serious threats to shark populations worldwide.”

“We consider, therefore, that a ban on shark finning is justified throughout the world’s oceans and high seas,” the 160 experts of the Shark Specialist Group say in a joint statement on their website.

“Finning causes the death of tens of millions of sharks. This potentially threatens the survival of rare and vulnerable species and, by removing large numbers of top predators from the oceanic ecosystem, may have dramatic and undesirable ecological impacts that could potentially threaten yields of other commercial species,” warns the Shark Specialist Group.

Shark fins are among the most expensive seafood products anywhere in the world, commonly retailing at $400 per kilogram. Because the shark fin trade is largely unreported, estimates of the global value of the shark fin trade can only be rough, ranging from US$540 million to $1.2 billion. Studies estimate that between 26 to 73 million sharks are harvested annually for their fins.

Shark fin soup is popular as a banquet food at Chinese celebrations. In the United States, where shark finning is prohibited, a bowl of the gelatinous soup can cost between $70 and $150.