科學家首次嘗試人工授精拯救稀有巨鱉

Earlier this month, an international team of scientists, veterinarians and zookeepers gathered at the Suzhou Zoo near Shanghai. Their desperate mission: to attempt the first artificial insemination ever of a softshell turtle, saving the species from oblivion.

本月早些時候，一個由多國科學家、獸醫和動物園管理人員組成的小組齊聚在臨近上海的蘇州動物園。他們肩負着一項緊迫的使命：首次嘗試對一種軟殼龜鱉進行人工授精，以防止該物種滅絕。

“Even if we get just one or two hatchlings, I will be very happy,” said Gerald Kuchling, a project leader for the Turtle Survival Alliance, a nonprofit conservation organization. “Even a single one would give hope for the recovery of this magnificent animal. It would be a turn.”

“即使我們只能得到一兩隻小鱉，我也會非常高興，”非營利性保護組織龜鱉生存聯盟(Turtle Survival Alliance)的項目主管傑拉爾德·庫克林(Gerald Kuchling)說。“哪怕只有一隻，也能帶來讓這種奇妙動物的種羣數量恢復的希望。這可能是一個轉折。”

Quite a turn, actually. The Yangtze giant softshell turtle — thought to be the largest freshwater turtle in the world — was once common in the Yangtze and Red Rivers. But by the late 1990s, pollution, hunting, dams and development had driven it to the brink of extinction.

實際上，的確出現過較大的轉折。被認爲是全世界最大淡水龜的斑鱉，一度在長江和紅河頗爲常見。但到了上世紀90年代末，污染、獵殺、水壩和開發，使其陷入了滅絕的邊緣。

There are only four known specimens remaining, and only one female — an 85-year-old resident of the Suzhou Zoo. For years, biologists have been trying to coax her and her 100-year-old mate to produce hatchlings. So far the pair have disappointed scientists, with the female laying clutch after clutch of unfertilized eggs.

據研究人員所知，目前世界上僅剩四隻斑鱉，其中僅有一隻雌性斑鱉，也就是蘇州動物園中85歲的這一隻。多年來，生物學家一直試圖引誘它和100歲的配偶繁衍後代。但迄今爲止，這一對斑鱉一直未能讓科學家們遂願。雌斑鱉產下了一窩又一窩未受精的卵。

She was discovered only in 2007, three years after the sole other known female died at the Beijing Zoo. Desperate to find another, Dr. Kuchling and Lu Shunqing, a turtle specialist from the Wildlife Conservation Society’s China branch, had asked every zoo in the country to send them photographs of any large softshell turtles in their possession.

這隻雌性斑鱉2007年才被發現。它被發現的三年前，之前那隻被認爲全世界獨一的雌性斑鱉，已在北京動物園死亡。庫克林和國際野生生物保護學會(Wildlife Conservation Society)中國分會的龜鱉專家呂順清渴望再找到一隻雌性斑鱉，於是讓全國所有動物園都把各自的大型軟殼龜鱉的照片寄給他們。

One image, taken at the Changsha Zoo in Hunan, caught their eye, and days later, they arrived to examine the turtle. It was indeed a Yangtze giant softshell turtle and, crucially, a female. She had once been part of a traveling animal exhibition, they learned, and became a permanent resident of the zoo shortly after the end of the Chinese Revolution in 1949.

湖南省長沙動物園拍攝的一幅照片引起了他們的注意。幾天後，他們去該動物園對照片上的那隻鱉進行了檢查。那的確是一隻斑鱉，而且關鍵還是一隻雌性斑鱉。他們瞭解到，那隻斑鱉曾經參加過巡迴動物展覽，在中國革命於1949年結束後不久，它就永久性地留在了該動物園。

Dr. Kuchling and Dr. Lu arranged for her transport to the Suzhou Zoo, where they hoped she and the zoo’s male specimen would begin producing more of their kind. To their delight, the animals did appear to mate, and that summer, the female laid around 180 eggs.

庫克林和呂順清安排將它轉移到了蘇州動物園，希望它能和那裏的一隻雄性斑鱉開始繁殖出更多同類。令他們高興的是，這兩隻斑鱉似乎的確交配了。那年夏天，雌斑鱉產下了大約180枚蛋。

But none proved fertile, a disappointment that would repeat itself for six years. “The conservation world was holding its breath,” said Rick Hudson, the president of the Turtle Survival Alliance. “It’s been a lot of frustration since.”

但沒有一枚受精。這個令人失望的現象重複了六年。“整個野生動物保護界都屏住了呼吸，”龜鱉生存聯盟的會長裏克·赫德森(Rick Hudson)說，“從那以後就一直失望。”

Scientists decided to intervene. On May 6, Dr. Kuchling and Dr. Lu, with a team that included turtle experts from the United States, drained the male’s pond and used a cargo net to wrangle the 140-pound turtle onto a stack of car tires that served as a makeshift examination stand. Putting him under anesthesia, the scientists used an electrical probe to induce a partial penile erection.

科學家決定插手。5月6日，庫克林和呂順清，以及一個包括來自美國的龜鱉專家在內的小組，抽走了雄斑鱉所在池塘的水，用一個網兜將140磅（約合64公斤）重的它打撈起來，放在堆疊起來充當臨時體檢臺的汽車輪胎之上。將雄龜麻醉後，科學家用一根電探針刺激，讓它的生殖器部分勃起。

Normally, the penis of the Yangtze giant softshell turtle looks a bit like a medieval weapon. Equipped with fleshy spikes, protuberances and lobes, it is designed to navigate the female’s equally complex reproductive organ, located inside a byzantine chamber called the cloaca.

斑鱉的陰莖通常看起來有點像一種中世紀的武器。它的陰莖具有肉質刺頭、突起和裂片，以便進入雌性斑鱉同樣複雜的生殖器官，位於被稱爲泄殖腔的複雜腔體中。

The problem became immediately clear to the scientists: This turtle’s penis was mangled.

在科學家看來，問題立即變得非常清楚：這隻斑鱉的陰莖損壞了。

Two decades earlier, another Yangtze giant softshell turtle had been added to the male’s pond in an attempt to mate the animals. The second turtle turned out to be male, as well, and the two fought. The second male was killed, and the victor suffered serious damage to his shell and, it now appears, to his reproductive organ.

20年前爲了促使斑鱉交配，另一隻斑鱉被放入了這隻雄性斑鱉所在的池塘。結果那隻斑鱉也是雄性，兩隻雄性斑鱉展開爭鬥。第二隻雄性斑鱉死亡，勝者的殼嚴重受損，現在看來，它的生殖器官當時似乎也受到了損害。

The team also examined the male’s sperm — extracted using electrical stimuli — and finally discovered good news. While motility was low, the sperm were viable. The scientists decided to proceed with artificial insemination of the female.

該小組還通過電刺激提取了這隻雄性斑鱉的精子，並對精子進行了檢測。最終他們發現了好消息，雖然活性較低，但這些精子具有繁衍能力。科學家決定繼續對雌性斑鱉進行人工授精。

With no case studies to go on, the team had to improvise. Dr. Kuchling examined the sedated female’s cloaca with a fiber-optic endoscope to locate the compartment leading to her oviducts. Then Barbara Durrant, the director of reproductive physiology at the San Diego Zoo’s Institute for Conservation Research, deposited the semen.

由於沒有案例進行研究，該小組只好隨機應變。庫克林利用光纖內窺鏡對已經麻醉的雌性斑鱉的泄殖腔進行了檢查，確定了通往其輸卵管的區域所在的位置。聖迭戈動物園(San Diego Zoo)保護研究所(Institute for Conservation Research)生殖生理部門主任芭芭拉·達蘭特(Barbara Durrant)注入了這些精子。

“It was just a matter of delivering the semen through a small plastic tube into what we think is the correct place,” she said. “Unfortunately, there just hasn’t been that much basic reproductive physiology work done in turtles and tortoises.”

“就是通過一根小塑料管，將精子送入我們認爲正確的地方，”她說。“遺憾的是，龜鱉的基本生殖生理工作以前做得不多。”

Even if it’s guesswork, artificial insemination may be the only chance to save the species. Two other male Yangtze giant softshell turtles are believed to be in Vietnam — one in Hoan Kiem Lake, in the center of Hanoi. But those animals “are pretty much off limits for any non-Vietnamese,” Dr. Kuchling said, and so a collaborative breeding program seems unlikely.

即便只是摸着石頭過河，人工受精可能也是拯救這個物種的唯一途徑。據信，其他兩隻雄性斑鱉在越南——其中一隻在河內市中心的劍湖。但庫克林表示，“非越南人恐怕無法接觸到”那些斑鱉，因此不太可能開展合作，實施繁殖計劃。

A handful of Yangtze giant softshell turtles may remain in the wild; tentative sightings have been reported in a dam reservoir on the Red River in Yunnan Province. Conservationists, however, are not betting that another male will be captured anytime soon.

還有少量斑鱉可能生活在野外：有人稱在雲南紅河大壩看到過斑鱉。然而保育人士並不確定很快能發現另外一隻雄性斑鱉。

Now the wait begins. When the female lays her first clutch of eggs, probably by late June, the scientists will know if this first effort was fruitful.

現在，等待開始了。當雌性斑鱉產出第一批蛋的時候——可能要到6月底，科學家才能知道這第一次的努力是否有效。

“Nobody has ever done this before, and it’s probably a long shot,” Dr. Kuchling said. “But we are all hopeful, and if it doesn’t work this time, we’ll definitely try again. Despair is not an option.”

“以前沒人這麼做過，成功的希望可能不大，”庫克林說。“但我們都充滿希望，如果這次不成功，我們肯定會再試一次。我們不會絕望。”