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如何说服鲸鱼繁殖?

更新时间:2018-10-8 20:14:30 来源:千亿千亿国际娱乐官网 作者:佚名

How do you convince whales to have sex?
如何说服鲸鱼繁殖?

The plight of the North Atlantic right whale, a species with just 450 individuals left in its population, just got even worse.

北大西洋露脊鲸目前仅存450条,而且生存状况还在逐步恶化。

After a disastrous 2017, in which at least 17 North Atlantic right whale deaths were recorded, it has emerged that no newborn calves have been sighted since.

2017年是露脊鲸多灾多难的一年,至少有17头露脊鲸死亡,且至今都没发现新生幼崽。

This lack of offspring has scientists who study these majestic creatures worried. Is there anything that we can do to encourage right whales to reproduce again?

缺少后代令研究这种大型动物的科学家们非常担心,有什么方法能让露脊鲸重新繁殖呢?

It’s a pertinent question for Moira Brown at the New England Aquarium’s Anderson Cabot Center for Ocean Life. Two of the adult females that died last year were just on the cusp of reproductive age, she points out. That leaves a total of around 100 adult females in the North Atlantic right whale population.

美国新英格兰水族馆(New England Aquarium)安德森卡博特海洋生物中心(Anderson Cabot Center for Ocean Life)的布朗(Moira Brown)就在研究这个问题。她指出,去年死亡的露脊鲸中有两头雌性刚刚到达最佳生育年龄。现在北大西洋露脊鲸只剩下大约100头成年雌性。

“That’s what the future of this population is resting on – 100 adult females is not a lot of animals and these things can go bad pretty quickly,” says Brown.

“露脊鲸未来的数量就靠这100头雌性了,100可不算多,情况还可能急速恶化,”布朗说。

Take the example of the critically endangered Vaquita porpoise – a species that had 600 individuals about 20 years ago. Now, it numbers just 30. The fragility of small populations in marine mammal species is well known. This is why some scientists are estimating that the North Atlantic right whale could go extinct in as little as 23 years, unless its fortunes improve.

以极度濒危的小头鼠海豚为例,大约20年前还有600只,现在只剩下30。众所周知,小种群海洋哺乳动物非常脆弱,所以一些科学家估计,北大西洋露脊鲸可能在短短23年内灭绝,除非情况有所改善。

The whales usually breed in waters off the south eastern coast of the US, near Florida and Georgia, however, they feed elsewhere. Their favourite haunts change from time to time, last year for example, more than expected were sighted in Canada’s Gulf of St Lawrence. There were several reports of right whales becoming entangled in fishing gear there and some of those entanglements proved fatal. But even entanglements that didn’t kill could have had a significant impact on the species’ ability to reproduce.

露脊鲸通常在美国靠近佛罗里达州和佐治亚州的东南沿海水域繁殖,但会选择其他地方饲养幼崽。它们出没的水域不时变化,例如,去年在加拿大圣劳伦斯湾出现了异常多的露脊鲸,有几头被渔具缠绕,有些是致命的。但即使不致命,也可能对繁殖能力产生重大影响。

Although a few fishing ropes might not seem like a big deal to some, they are surprisingly heavy, tough pieces of material. And when wrapped around a whale’s body, they cause significant mobility issues and increase drag when swimming through the water.

可能有人觉得几根捕鱼绳而已问题不大,但它们其实异常沉重且坚韧。缠在鲸鱼身上会增加游水的阻力,严重影响游动。

Recently, whale rescuers have been trying to disentangle a well known female North Atlantic right whale, nicknamed Kleenex, that had been entangled for at least four years.

最近,鲸鱼救援人员正试图解开缠在一头著名的雌性北大西洋露脊鲸身上的绳子,它被昵称为舒洁(Kleenex),已经被绳子缠住至少四年了。

Michael Moore at Woods Hole Oceanographic Institution (WHOI) has studied the long-term effects of such episodes.

伍兹霍尔海洋研究所(Woods Hole Oceanographic Institution, 简称WHOI)的摩尔(Michael Moore)研究了鱼绳缠绕的长期影响。

“For a female right whale, what can you give up if you’re running out of energy? The answer is you don’t get pregnant,” he says.

“如果一头雌性露脊鲸精力不够用,它会放弃什么?答案是放弃繁育,”他说道。

Moore and other whale scientists generally agree: the most significant boost we can give to this species is to reduce the likelihood of entanglements, get out of their way, and hope that they have enough energy to breed.

摩尔和其他鲸鱼科学家普遍认为:提高露脊鲸的繁育水平,我们所能做的最有用的事情,是减少它们被渔具缠绕,别挡人家的路,希望它们有足够的精力来繁殖。

The Canadian government recently announced special measures in this vein, including opening and closing the snow crab fishing season earlier than usual this year. The traps used to catch snow crabs are often tethered to ropes linking them to buoys floating on the sea surface. That of course creates a long line through the water column in which a whale could get caught.

加拿大政府最近宣布了与此相关的特别措施,包括在今年提前开始和结束雪蟹的捕捞季。通常是将捕捞雪蟹的陷阱系在绳索上,然后连接到漂浮在海面上的浮标。这么做显然会在水中筑起一条长线,很可能会勾到鲸鱼。

One idea is to use ropes adapted to break when a certain amount of pressure is exerted on them, explains Phil Hamilton, also at the New England Aquarium's Anderson Cabot Center.

同在新英格兰水族馆安德森卡博特中心的汉密尔顿(Phil Hamilton)说,一个想法是用受到一定压力时就会断裂的绳索。

“Basically they just cut the [rope] and they put these sleeves over either end that are designed to break at 1,700 lbs [of pressure],” he explains. “The sleeves are like a dollar apiece.”

他解释道:“只需要切断捕鱼绳,然后把这些受到1,700磅压力就会断裂的筒套套在绳子两端,筒套也就一美元一个。”

A study authored by Hamilton’s colleagues estimated that such measures could reduce life-threatening whale entanglements by up to 72%.

汉密尔顿同事撰写的一项研究估计,这个方法可以将威胁鲸鱼生命的鱼绳缠绕减少高达72%。

Another possibility is to use fishing gear that can rise to the surface without having to be dragged up by rope – WHOI and the Anderson Cabot Center have been working on this idea together.

另一种方法是使用无需绳子拖拽就可以上升到海面的渔具,这也是WHOI和安德森卡博特中心正在共同努力的方向。

But is there anything more interventionist humans can do to encourage or induce reproduction in the species? The answer, according to Moore, Hamilton and Brown is a resounding “no”. These are large marine mammals, with huge ranges. There’s no obvious beneficial way in which we could interfere with them. They also have big appetites so even something like trying to boost their food resources artificially would come at a gargantuan cost.

但是,还有什么比鼓励促进物种繁殖更具干预性呢?“没有,”摩尔,汉密尔顿和布朗的回答都很响亮。露脊鲸属于大型海洋哺乳动物,身形庞大,有效干预的显著办法还没有找到。它们胃口也很大,所以人为增加它们的食物资源成本也很高昂。

It would probably be cheaper to buy out the fishing companies and remove ropes from the water in areas where the whales congregate, suggests Moore.

摩尔说,在鲸鱼聚集的地区游说渔业公司把鱼绳从水里拿出来可能还省点钱。

Hamilton does have one other idea, though. He points out that whales are often stressed by excessive noise in the oceans – mainly from shipping or industrial work. If we could lower these noise levels, that might have a positive impact on their propensity to breed, though that’s not a given.

不过,汉密尔顿也有另一个想法。他指出,海洋噪音过大经常会对鲸鱼造成压力,噪音主要来自航运以及工业。如果我们可以降低噪音,可能会对它们的繁殖产生积极影响,但并不能保证。

There is still hope for North Atlantic right whales. The population has, in fact, been lower than it is today and increased, says Brown. In 1990 there were only about 270 known individuals. This rose over the following 20 years – and even endured periods where breeding levels were very low. In 2000 just one calf was sighted. “The very next year we had 31,” says Brown, pointing out how unpredictable the species can be.

北大西洋露脊鲸仍有希望。布朗说,曾有一段时间比现在数量更少,然后又增加了。1990年,所知的北大西洋露脊鲸只有约270头。其后20年有所上升,当中甚至经历了繁殖水平非常低的时期。2000年,只发现了一头新生幼崽。布朗说“第二年发现了31头”,可见这个物种有多难预测。

And Hamilton says there’s an outside chance that one or two calves were born in recent months, perhaps in unusual calving grounds, and we just haven’t detected them yet.

汉密尔顿表示,最近几个月也可能有一两头幼崽出生,也许不在通常的水域,我们只是还没有发现。

“Personally I still hold out hope that one or two calves will be detected this spring and summer,” he says.

“我个人仍然觉得有希望在今年春夏发现一两头幼崽,”他说。

"Given the species’ fluctuating population history, there is plenty of reason to believe that helpful measures we take now can have the intended effect." adds Brown.

“鉴于露脊鲸的数量总是上下波动,我们有充足的理由相信,现在采取的辅助措施可以达到预期效果,”布朗补充道。

“This population has bounced back before,” she says. “So nobody’s giving up on them.”

“露脊鲸的数量之前也反弹过,”她说。“我们一定不会放弃。”

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