美研究報告指香港市場販售瀕臨絕種魚翅

更新日期:2009/12/02 02:20 張曉雯

（法新社華盛頓1日電） 一項新研究今天指出，高科技鑑識方法證實，香港市場販售的部分鯊魚鰭，來自瀕臨絕種的鯊魚，研究結果證明確有必要採取更加嚴厲貿易管制措施。

美國科學家表示，他們使用一種DNA鑑識方法，能夠追蹤到香港所售鯊魚鰭的地理根源，以及證明某些瀕臨絕種鯊魚，已成業者的捕殺目標。

研究團隊正敦促預定2010年3月召開的「瀕臨絕種野生動植物國際貿易公約」（CITES）會議，盡快擬定貿易管制規範，藉以保護雙髻鯊與其他鯊魚種類。

研究主要作者柴普曼（Demian Chapman）說：「這種交易已在黑暗勢力的保護下進行多年。」柴普曼任教於紐約附近的「石溪大學」（Stony Brook University）海洋保育科學研究所。

研究結果今天發布於「瀕危物種研究」（Endangered Species Research）期刊，內容描述團隊如何分析指甲大小的DNA樣本，這些樣是62片從香港市場購得的路氏雙髻鯊魚鰭。

他們發現，21%的香港鯊魚鰭屬於瀕臨絕種的路氏雙髻鯊，這些鯊魚來自西大西洋。

石溪大學海洋保育科學研究所長皮克西（ EllenPikitch）說：「保護措施不足加上無節制的捕殺活動，導致許多鯊魚種類面臨嚴峻危險。」（譯者：中央社張曉雯）

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港1/5斧頭鯊魚翅屬瀕危

2009-12-02

【明報專訊】本港去年魚翅入口量達9950噸，總值22.39億元，美國科學家首次以DNA分析取自本港市面的62個斧頭鯊魚翅樣本，發現多達21％取自大西洋西部的瀕危斧頭鯊，研究人員促《瀕危野生動植物種國際貿易公約》（CITES）締約國，將此鯊魚品種納入限制售賣類別，以免令斧頭鯊因過度捕獵而面臨絕種。

研究人員促限制售賣

目前被列入CITES受保護瀕危鯊魚品種共有4種，其中所有品種的野生鋸鯊均屬「高度瀕危物種」，全面禁止商業貿易；姥鯊、大白鯊、 鯨鯊品種則屬受許可證制度管制的限制貿易品種。

根據漁護署紀錄，今年截至10月共接獲119公斤姥鯊的入口申請。斧頭鯊因不屬限制貿易品種，署方無入口數量資料。

美國Stony Brook大學海洋保育科學中心將於國際學術期刊《瀕危物種研究雜誌》發表報告，研究人員首次引用辨識海龜、海洋哺乳類動物的DNA鑑證技術，追索從本港市面抽取的62個斧頭鯊魚翅樣本，了解被殺取翅的斧頭鯊來自何方。結果多達21％魚翅取自大西洋西部的斧頭鯊魚，此種鯊魚已被國際環保組織（IUCN）列為瀕危物種。CITES締約國明年3月舉行會議，研究人員期望這項研究促使CITES將斧頭鯊和其餘5種鯊魚品種納入限制貿易種類。國際愛護動物基金會早前指全球每年捕殺1億條鯊魚，本港屬最大魚翅消費市場之一，年售2000萬條。

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Researchers Track Hammerhead Shark Fins To Source Using DNA Barcodes

December 01, 2009

By Andrea Anderson

NEW YORK (GenomeWeb News) – In a paper appearing online today in the journal Endangered Species Research, scientists used DNA barcoding to determine the geographic origin of scalloped hammerhead shark fins being sold by vendors in Hong Kong and to identify genetic subgroups within living sharks in the western Atlantic.

A trio of researchers from Florida's Nova Southeastern University used DNA barcodes based on about 500 base pairs of mitochondrial DNA sequence to determine the haplotype for dozens of scalloped hammerhead shark fins in a Hong Kong market. Their results suggest that the fins came from scalloped hammerheads throughout the Indo-Pacific and Atlantic oceans — including the western Atlantic, where the scalloped hammerhead shark populations are thought to have all but collapsed.

"We found sequence from everywhere, basically," lead author Demian Chapman, formerly at Nova Southeastern University's Guy Harvey Research Institute and now a researcher at Stony Brook University's Institute for Ocean Conservation Science, told GenomeWeb Daily News. "It just attests to the fact that the [fin] trade is sourced from everywhere."

Chapman and his colleagues also improved on existing mitochondrial haplotype classification schemes for western Atlantic scalloped hammerheads, sampling almost 200 living sharks.

An estimated 26 million to 73 million sharks are killed for their fins each year, including between one million and three million hammerheads. Much of the shark fishing that supplies the shark fin markets is unregulated, the team noted, and conservationists are concerned that over-fishing could take a toll on shark populations.

"Inadequate protection, combined with inexorable pursuit, has placed many shark species at grave risk," Ellen Pikitch, a marine science researcher at Stony Brook University and executive director of its Institute for Ocean Conservation Science, who was not directly involved in the research, said in a statement.

For the current study, Chapman and his co-workers used DNA barcodes based on 547 bases of mitochondrial DNA as part of their "genetic stock identification" to track the origin of scalloped hammerhead fins back to their source.

They focused on the scalloped hammerhead because it is in particularly high demand in due to its large fins and ample fin needles, part of the fin used as a thickening agent in shark fin soup.

Past studies suggest scalloped shark populations have already collapsed in parts of the North Atlantic and Gulf of Mexico and the shark has been classified as endangered by the International Union for the Conservation of Nature.

When the researchers sequenced mtDNA from 62 scalloped hammerhead shark fin samples collected from 11 fin traders in a Hong Kong market, they found 18 different mitochondrial haplotypes with some 21 percent of the fins corresponding to haplogroups in the endangered western Atlantic region.

Of the 62 samples tested, 57 belonged to haplogroups identified in previous studies while three resembled Indo-Pacific haplogroups, one was similar to haplogroups in West Africa and another grouped with sharks from the Caribbean. The five new haplotypes clustered very deep within the Atlantic and Pacific groups, Chapman explained, making the classification unambiguous.

To get a better handle on the genetic patterns in the western Atlantic, the team also assessed data for 140 live scalloped hammerheads sampled in the region, incorporating data for 37 samples collected as part of previous studies. In so doing, they identified three distinct groups: a northern group in the US Atlantic and the Gulf of Mexico, a central group found near Belize and Panama, and a southern group near Brazil.

"The fact that scalloped hammerhead shark DNA shows strong population DNA signatures means that we can trace the geographic origin of most of their fins sold at markets," senior author Mahmood Shivji, director of the Guy Harvey Research Institute, said in a statement. "From a broader perspective, this type of DNA forensic testing of fins will be an incredibly useful tool to prioritize areas for conservation and ensure sharks aren't wiped out in particular regions by excessive fishing."

In particular, the researchers would like to see changes to the Convention on International Trade in Endangered Species, or CITES, oversight of scalloped hammerhead and other sharks. Chapman and Pikitch plan to attend next year's CITES meeting in Qatar in March to push for so-called Appendix II designation for six shark species, including the scalloped hammerhead. Such a classification would require permits for international trade of the species.

In the future, the researchers hope to further refine their understanding of genetic patterns in the scalloped hammerhead and other shark populations. And along with mitochondrial patterns, Chapman is also looking at parts of the hammerhead genome that contain evidence of location-specific selection pressures.

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