中國大鯢保育困境：放生反致野生品種走向滅絕

The Chinese giant salamander, the world’s largest amphibian and a critically endangered species, has quietly slipped toward extinction in nature. Following an exhaustive, yearslong search, researchers recently reported that they were unable to find any wild-born individuals.

作為世界上最大的兩棲動物和極危物種，中國大鯢已經悄然在大自然中走向滅絕。經過長達數(shù)年的徹底搜索，研究人員前不久報告稱，他們無法找到任何野生的大鯢個體。

“When we started the survey, we were sure we’d at least find several salamanders,” said Samuel Turvey, the lead author and a senior research fellow at the Zoological Society of London.

“開始調查時，我們覺得肯定至少能找到幾條大鯢，”該研究的第一作者、倫敦動物學會(Zoological Society of London)的高級研究員塞繆爾·特維(Samuel Turvey)說。

“It’s only now that we’ve finished that we realize the actual severity of the situation.”

“直到現(xiàn)在調查結束了，我們才意識到情況的嚴重性。”

Millions of giant salamanders live on farms scattered throughout China, where the animals are bred for their meat. But another study by Dr. Turvey and his colleagues shows that reintroducing farmed animals is not a simple solution for saving the species in the wild.

數(shù)以百萬計的大鯢生活在中國各地的養(yǎng)殖場里，作為肉類來源被飼養(yǎng)。但特維和同事們的另一項研究表明，往大自然中重新引入飼養(yǎng)的動物并不是拯救野生物種的一個簡單方法。

In the wild, Chinese giant salamanders were not just one species but at least five, and perhaps as many as eight. On farms, they are being muddled into a single hybridized population adapted to no particular environment.

在野外，中國大鯢不是只有一個種，而是至少包括五個物種，甚至可能多達八個。但在養(yǎng)殖場里，它們被混合成了一個雜交品種，不適應任何特定的環(huán)境。

“The farms are driving the extinction of most of the species by homogenizing them,” said Robert Murphy, a co-author and senior curator of herpetology at the Royal Ontario Museum. “We’re losing genetic diversity and adaptations that have been evolving for millions of years.”

“這些養(yǎng)殖場正在通過同質化加速多數(shù)大鯢物種的滅絕，”該研究的聯(lián)合作者、皇家安大略博物館(Royal Ontario Museum)的爬行動物學高級策展人羅伯特·墨菲(Robert Murphy)說，“我們正在失去進化了數(shù)百萬年的基因多樣性和適應性。”

As with so many other protected species in China, poaching is the main threat to giant salamanders, which can weigh up to 140 pounds. Unlike pangolins, tigers and rhinos, however, salamanders were never historically valued as meat, trophies or medicine.

和中國的其他許多受保護物種一樣，偷獵是重量可達140磅的大鯢的主要威脅。不過，與穿山甲、虎和犀牛不同的是，大鯢在歷史上從未被視為珍貴的肉類、狩獵紀念物或藥材。

“Traditional knowledge associated them with bad luck and dead babies,” Dr. Turvey said. “They were animals you didn’t want to go near.”

“傳統(tǒng)觀念將它們與壞運氣和死去的嬰兒聯(lián)系在一起，”特維說，“它們是你不想走近的動物。”

That changed in the mid-20th century when famine forced people to turn to alternative food sources. By the 1990s, giant salamander meat had been rebranded as a luxury food item in China, and government-subsidized salamander farms began popping up around the country.

這種情況在20世紀中期發(fā)生了變化，當時，饑荒迫使人們轉向其他食物來源。到了20世紀90年代，大鯢的肉在中國被重新定義為一種奢侈食品，政府補貼的大鯢養(yǎng)殖場開始在中國遍地開花。

As prices for live animals skyrocketed, captive populations grew and wild ones plummeted. “The development of this industry led to huge amounts of increased pressure on salamanders, which were poached from the wild to stock these farms,” Dr. Turvey said.

隨著活體大鯢的價格飛漲，圈養(yǎng)大鯢的數(shù)量開始增加，野生大鯢的數(shù)量銳減。“這個行業(yè)的發(fā)展給大鯢帶來了巨大的壓力，它們被從野外捕獵來放進養(yǎng)殖場，”特維說。

Realizing the amphibians were disappearing in nature, officials decided to restock wild populations by releasing captive-born salamanders.

官員們意識到這種兩棲動物正在從自然界中消失，決定釋放人工繁殖的大鯢，以增加野生大鯢的數(shù)量。

But what seemed like a good conservation strategy led to a number of new problems, Dr. Turvey said.

但特維表示，這個看似很好的保護策略導致了許多新問題。

Not recognizing that salamanders from different parts of the country were distinct species, farmers had inadvertently created hybrids — a fact that the researchers confirmed through genetic analysis of over 1,000 captive amphibians.

不知道國內各地區(qū)大鯢物種有明顯差異的農民，無意間創(chuàng)造出了雜交品種——通過對捕撈的1000多條大鯢進行基因分析，研究人員證實了這一點。

“When we looked at farmed animals, we found a large mixture of different genetic components, like a witch’s caldron,” said Jing Che, a herpetologist at the Kunming Institute of Zoology and co-author of both recent studies.

“當我們觀察養(yǎng)殖動物的時候，我們發(fā)現(xiàn)了不同基因組成的大量混合，就像一口女巫的大鍋，”昆明動物研究所的爬行動物學家、近兩個研究的共同作者車靜說道。

No system was ever put in place to prevent hybrids from release into the wild, nor to ensure that reintroduced animals were matched with their geographic origins.

防止雜交物種放生野外的制度始終沒有建立起來，也無法保證重新引入的物種可以匹配它的地域出身。

“These hybrids may create a big mess by changing the genetic makeup of locally adapted wild animals,” Dr. Che said.In 2009, Dr. Murphy and his colleagues raised these concerns at a government meeting but were dismissed. “They just said it wasn’t an issue,” he said.

“這些雜交物種通過改變已經適應當?shù)氐囊吧鷦游锏幕蚪M成，可以造成大麻煩，”車靜說。2009年，墨菲和他的同事在一個政府會議上提出了這些擔憂，但卻沒人理會。“他們就是認為這不構成問題，”他說。

At least 72,000 captive-bred salamanders have been released since then. Until now, the cumulative effect of poaching, farming and release on wild populations was unknown.

此后，至少有7.2萬條人工養(yǎng)殖大鯢被放歸野外。到目前為止，偷捕、養(yǎng)殖和放歸對野外數(shù)量的積累效應還并不清楚。

So in 2013, Dr. Turvey and his colleagues organized a nationwide giant salamander search — apparently the largest wildlife survey ever conducted in China.

因此，在2013年，特維和同事組織了一場全國性的大鯢搜尋——這應該是在中國進行的最大一次野生動物調查。

They spent three years scanning riverbeds and turning over rocks at 97 sites in 16 provinces. They found giant salamanders at just four sites.

他們花了三年時間搜尋河床，在16個省的97個地點翻找?guī)r石，但只在4處發(fā)現(xiàn)了大鯢。

All of the animals had genetic profiles that did not match the places in which they were living, indicating they likely originated on farms.

所有生物的基因檔案與他們先前的棲息地點均不匹配，這表明他們可能來自養(yǎng)殖場。

The researchers also interviewed nearly 3,000 local people, about half of whom said they had seen giant salamanders in the wild. But the most recent sightings they could recall took place, on average, 18 years ago.

研究人員還對將近3000名當?shù)厝诉M行了采訪，其中約有一半人表示他們曾在野外見過大鯢。但在他們回憶中最后一次看見大鯢，平均都是在18年前。

“There could be remnant populations of genuine salamanders scattered here and there, but they are effectively impossible for any researchers to find now,” Dr. Turvey said.Given that, the best strategy for preventing extinction in the wild, he added, is to rescue genetically pure animals from farms, and then undertake carefully controlled conservation breeding to rebuild each species’ numbers.

“可能多多少少還有一些純種大鯢的殘存，但事實上，現(xiàn)在任何研究人員都不可能找到它們，”特維說。他還說，鑒于這個情況，避免物種在野外滅絕的最好辦法，就是拯救養(yǎng)殖場里的純種大鯢，然后進行謹慎控制的保護育種，重建每個物種的數(shù)量。

“If we wait too long, all those wild-caught individuals will be gone,” he said.

“要是我們等待太久，野外捕獲的那些個體就都沒了，”他說。

Releases of giant salamanders without knowing their genetic makeup should stop immediately, Dr. Che added. But that can’t happen without buy-in from Chinese authorities.

車靜補充說，應該立即停止向野外放生未知基因組成的大鯢。但若沒有中國政府的首肯，這也無法實現(xiàn)。

“We hope to work with the government to improve the existing conservation plan,” Dr. Che said. “We have a responsibility to do conservation based on scientific knowledge.”

“我們希望與政府合作改善現(xiàn)有的保護計劃，”車靜說。“我們有責任根據(jù)科學知識來進行保護。”