中国大鲵保育困境：放生反致野生品种走向灭绝
作为世界上最大的两栖动物和极危物种，中国大鲵已经悄然在大自然中走向灭绝。经过长达数年的彻底搜索，研究人员前不久报告称，他们无法找到任何野生的大鲵个体。
“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.
“开始调查时，我们觉得肯定至少能找到几条大鲵，”该研究的第一作者、伦敦动物学会(Zoological Society of London)的高级研究员塞缪尔·特维(Samuel Turvey)说。
“It’s only now that we’ve finished that we realize the actual severity of the situation.”
“直到现在调查结束了，我们才意识到情况的严重性。”
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.
数以百万计的大鲵生活在中国各地的养殖场里，作为肉类来源被饲养。但特维和同事们的另一项研究表明，往大自然中重新引入饲养的动物并不是拯救野生物种的一个简单方法。
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，中国大鲵不是只有一个种，而是至少包括五个物种，甚至可能多达八个。但在养殖场里，它们被混合成了一个杂交品种，不适应任何特定的环境。
“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.”
“这些养殖场正在通过同质化加速多数大鲵物种的灭绝，”该研究的联合作者、皇家安大略博物馆(Royal Ontario Museum)的爬行动物学高级策展人罗伯特·墨菲(Robert Murphy)说，“我们正在失去进化了数百万年的基因多样性和适应性。”
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.
和中国的其他许多受保护物种一样，偷猎是重量可达140磅的大鲵的主要威胁。不过，与穿山甲、虎和犀牛不同的是，大鲵在历史上从未被视为珍贵的肉类、狩猎纪念物或药材。
“Traditional knowledge associated them with bad luck and dead babies,” Dr. Turvey said. “They were animals you didn’t want to go near.”
“传统观念将它们与坏运气和死去的婴儿联系在一起，”特维说，“它们是你不想走近的动物。”
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.
这种情况在20世纪中期发生了变化，当时，饥荒迫使人们转向其他食物来源。到了20世纪90年代，大鲵的肉在中国被重新定义为一种奢侈食品，政府补贴的大鲵养殖场开始在中国遍地开花。
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.
随着活体大鲵的价格飞涨，圈养大鲵的数量开始增加，野生大鲵的数量锐减。“这个行业的发展给大鲵带来了巨大的压力，它们被从野外捕猎来放进养殖场，”特维说。
Realizing the amphibians were disappearing in nature, officials decided to restock wild populations by releasing captive-born salamanders.
官员们意识到这种两栖动物正在从自然界中消失，决定释放人工繁殖的大鲵，以增加野生大鲵的数量。
But what seemed like a good conservation strategy led to a number of new problems, Dr. Turvey said.
但特维表示，这个看似很好的保护策略导致了许多新问题。
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.
不知道国内各地区大鲵物种有明显差异的农民，无意间创造出了杂交品种——通过对捕捞的1000多条大鲵进行基因分析，研究人员证实了这一点。
“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.
“当我们观察养殖动物的时候，我们发现了不同基因组成的大量混合，就像一口女巫的大锅，”昆明动物研究所的爬行动物学家、近两个研究的共同作者车静说道。
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.
防止杂交物种放生野外的制度始终没有建立起来，也无法保证重新引入的物种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.
“这些杂交物种通过改变已经适应当地的野生动物的基因组成，可以造成大麻烦，”车静说。2009年，墨菲和他的同事在一个政府会议上提出了这些担忧，但却没人理会。“他们就是认为这不构成问题，”他说。
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7.2万条人工养殖大鲵被放归野外。到目前为止，偷捕、养殖和放归对野外数量的积累效应还并不清楚。
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，特维和同事组织了一场全国性的大鲵搜寻——这应该是在中国进行的最大一次野生动物调查。
They spent three years scanning riverbeds and turning over rocks at 97 sites in 16 provinces. They found giant salamanders at just four sites.
他们花了三年时间搜寻河床，在16个省的97个地点翻找岩石，但只在4处发现了大鲵。
All of the animals had genetic profiles that did not match the places in which they were living, indicating they likely originated on farms.
所有生物的基因档案与他们先前的栖息地点均不匹配，这表明他们可能来自养殖场。
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.
研究人员还对将近3000名当地人进行了采访，其中约有一半人表示他们曾在野外见过大鲵。但在他们回忆中最后一次看见大鲵，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.
“可能多多少少还有一些纯种大鲵的残存，但事实上，现在任何研究人员都不可能找到它们，”特维说。他还说，鉴于这个情况，避免物种在野外灭绝的最好办法，就是拯救养殖场里的纯种大鲵，然后进行谨慎控制的保护育种，重建每个物种的数量。
“If we wait too long, all those wild-caught individuals will be gone,” he said.
“要是我们等待太久，野外捕获的那些个体就都没了，”他说。
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.
车静补充说，应该立即停止向野外放生未知基因组成的大鲵。但若没有中国政府的首肯，这也无法实现。
“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.”
“我们希望与政府合作改善现有的保护计划，”车静说。“我们有责任根据科学知识来进行保护。”
