Priceless Poo: The Global Cooling Effect of Whales
无价的“便便”：我们为什么要保护鲸鱼
The largest animals in the ocean play a critical role in helping our planet function, but remain under threat from a range of human impacts
海洋中最大的动物在辅助地球功能方面发挥关键作用，但仍受到一系列人类影响的威胁。
Saving the whales may be more important than planting trees when it comes to tackling climate change and keeping our oceans healthy. The world’s largest animals play a crucial role, helping fertilise the microscopic plants that absorb 40% of CO2. They also capture vast amounts of carbon in their bodies before sinking to the bottom of the ocean when they die, where it can remain for centuries.
就应对气候变化和维护海洋健康来说，拯救鲸鱼可能比植树造林更加重要。鲸鱼是世界上体型最大的动物，它能为浮游植物提供肥料，而这些浮游植物可以吸收全球40%的二氧化碳。从这一点来看，鲸鱼发挥的作用不可小觑。此外，鲸鱼体内还固存了大量的碳，死亡后，这些碳会随之沉入海底，有时能在那里封存数百年。
Last year, the International Monetary Fund (IMF) valued the role of whales in carbon sequestration and healthy ocean functions at more than US$1 trillion. Based on scientific papers, it estimated a single great whale to be worth more than US$2 million, given its contribution to carbon capture, fisheries enhancement and tourism.
去年，国际货币基金组织（IMF）估计鲸鱼在碳封存和维持海洋功能健康方面的价值超过1万亿美元。基于其对碳捕获、渔业增殖和旅游业的贡献，一头鲸鱼的价值要超过200万美元。
But populations of whales in the world’s oceans have been decimated in the last two centuries, falling from 5 million to 1.5 million today. More than 30 years after commercial whaling was largely banned in a bid to protect them, whales continue to suffer from human impacts in the form of plastic and noise pollution, ship collisions, fishing gear and global warming.
但过去两百年间，全球海洋中鲸鱼的数量已经从500万头下降至今天的150万头。商业捕鲸活动已经基本被禁止了30多年，但它们仍面临着人类带来的各种各样的影响，如塑料和噪音污染，被船只所伤，被渔具缠绕，以及全球变暖导致的海洋变化等。
Whales and carbon capture
鲸鱼和碳捕获
A whale accumulates carbon through feeding and stores it in its body during its long lifetime. Some weigh 200 tonnes and their average lifespan is 70 years. One species, the bowhead whale, is estimated to have a lifespan of 268 years.
在其漫长的一生中，鲸鱼能够通过进食把碳积累并储存在自己体内。有些鲸鱼重达200吨，平均寿命70年，而弓头鲸的寿命据估计更是长达268年。
When a whale dies, it sinks to the bottom of the ocean, where the carbon in its body stays. The IMF estimates that each great whale sequesters 33 tonnes of CO2 on average, and that a tree absorbs only up to 22kg CO2 a year. Tree-planting schemes are being seen as the cheapest and fastest method of taking CO2 out of the atmosphere. The evidence suggests conserving and boosting whale populations also has great carbon-capturing potential.
鲸鱼死亡后，其尸体以及体内封存的碳一并沉入海底。国际货币基金组织估计，每头鲸鱼平均能够封存33吨二氧化碳，而一棵树每年吸收的二氧化碳只有22公斤。植树造林被认为是消除大气中二氧化碳最便宜、最快的方法，但证据表明保护和扩大鲸鱼种群也有很大的碳捕获潜力。
Sunken whale carcasses take decades to decompose, becoming an entire ecosystem in themselves, supporting deep-sea species from large scavengers to microscopic bacteria with a huge and immediate source of food.
沉入海底的鲸尸需要几十年才能分解，其本身就能构成一个完整的生态系统，能够为大到食腐动物、小到细菌的深海物种提供大量的直接食物来源。
Priceless poo
无价的粪便
Whales do more for carbon capture when they are alive, however, thanks to their jumbo-sized poo. These “faecal plumes” contain enormous amounts of nutrients – including phosphorus, iron and nitrogen – that are essential for the growth of phytoplankton. When these microscopic plants photosynthesise, they consume carbon dioxide and produce oxygen. The IMF calculates that phytoplankton are responsible for capturing about 37 billion tonnes of CO2, the same as 1.7 trillion trees, or four Amazon rainforests. They also contribute as much as 50-85% of the oxygen in the Earth’s atmosphere. Sylvia Earle, the famous National Geographic ocean explorer, has estimated that they provide the oxygen for one in every five breaths we take.
然而，活着的鲸鱼能为碳捕获做出更多的贡献，这要归功于它们的巨型粪便。它们的粪便含中有磷、铁、氮等大量营养物质，这些都是浮游植物这种微生物生长所必须的。浮游植物光合作用时会消耗二氧化碳并产生氧气。国际货币基金组织估计，浮游植物可捕获约370亿吨二氧化碳，相当于1.7万亿棵树，也就是4个亚马逊雨林。它们还为地球大气贡献了50%到85%的氧气。《国家地理》杂志著名海洋探险家西尔维亚·厄尔（Sylvia Earle）估计，人类每呼吸五次，其中就有一次的氧气来自浮游生物。
Scientific research shows that whales have a “multiplier effect”, increasing phytoplankton production wherever they are found. As well as bringing nutrients from the ocean’s depths to the surface through their vertical movement, known as the “whale pump”, they also distribute them laterally, the “whale conveyor belt”, on their vast migrations.
科学研究表明鲸鱼可以带来“乘数效应”，它们无论到哪里都会增加那里浮游植物的产量。除了通过垂直运动将海洋深处的营养物质运送到海面，即所谓的“鲸鱼泵”作用之外，鲸鱼还通过大范围的迁徙运动带动这些营养物质的横向扩散，即“鲸鱼传送带”现象。
Whale behaviour
鲸鱼行为
Humans have always found the behaviour of whales intriguing and endearing, perhaps because we have so much in common. Whales and dolphins live in tightly knit groups known as pods, have complex relationships and talk to each other. A 2017 study compiled a list of behaviours that are similar to humans and primates including: working together for mutual benefit; teaching young how to hunt and use tools; using regional “dialects”; identifying individuals with unique sounds; looking after young not their own; and social play.
人类总是认为鲸鱼的行为既有趣又可爱，大概是因为彼此之间存在很多共同点。鲸鱼和海豚以群落的形式生活在一起，成员间关系紧密、复杂，并且它们相互之间能够交流。2017年的一项研究总结了鲸鱼与人类和灵长类动物相似的一系列行为，包括：为了共同利益达成合作；教授年轻一代如何捕食和使用工具；使用“方言”；通过独特的声音识别个体；照顾其它鲸鱼的幼崽；以及社交游戏。
Ship strikes and entanglement
船只撞击和缠绕
Many of the world’s busiest cargo and ferry lanes and ports directly overlap with areas where whales feed and breed or travel along migratory routes. Ship strikes have become a leading cause of death, with whales often simply unable to get out of the way in time. Noise from boats also interferes with their ability to navigate and communicate.
世界上许多最繁忙的货物和渡轮航道及港口与鲸鱼迁徙途中觅食、繁殖或游憩的海域重叠。鲸鱼往往无法及时躲避船只而与其相撞，因此撞击已经成为导致其死亡的主要原因之一。另外，船只发出的噪音也会对鲸鱼导航和交流的能力造成干扰。
As fisheries respond to a growing global appetite for seafood, entanglement in fishing gear is also an increasing threat. Particularly affected is the North Atlantic right whale, found along the east coast of North America from Florida to Canada, a region also home to lucrative lobster and crab fisheries. The long vertical ropes or “lines” used to connect traps on the ocean floor to floats on the water’s surface can be lethal to right whales. The ropes can constrict body parts and cut into flesh and bone, causing abrasion, infection and sometimes severance. Often whales can drag the heavy gear around for months, struggling to eat, swim, dive, breathe and reproduce. They lose energy and weight gradually, sometimes taking years to die.
随着全球海产品需求的增长，渔业活动也日益繁忙，被渔具缠绕更是逐渐成为很多鲸鱼物种面临的一大威胁，尤其是北大西洋露脊鲸。这种鲸常见于北美洲东海岸弗罗里达州到加拿大一带海域，这里还有利润丰厚的龙虾和螃蟹渔业。放置在海底的捕虾笼与海面的浮标之间通过一根长长的绳索或“线”相连。这根垂直的“长线”便成了露脊鲸面临的一大致命威胁。一旦被它们缠住，这些绳索就会对鲸鱼身体构成压迫，甚至伤其筋骨，造成擦伤、感染，有时甚至断肢。通常鲸鱼可以拖着沉重的渔具生活数月，挣扎着进食、游泳、潜水和繁殖，最终逐渐消瘦，失去力量，有时要挣扎数年才能死去。
Studies show that nearly three-quarters (72%) of diagnosed right whale deaths between 2010-18 occurred because of entanglements, and that 85% have been caught in fishing gear at least once. There are now just 409 remaining individuals, with less than 100 females of breeding age. Without intervention, they may be functionally extinct by 2040.
研究表明，2010至2018年间死亡的北大西洋露脊鲸有近四分之三（72%）是由渔具缠绕造成的，有85%曾至少被渔具缠绕过一次。目前全球北大西洋露脊鲸仅存409头，处于育龄的雌性不到100头。如果不采取干预措施，它们可能在2040年功能性灭绝。
As well as live fishing gear, whales are also being killed in their thousands by “ghost gear”: abandoned, lost or discarded plastic fishing nets, ropes and lines in which they become trapped.
除了正在使用的渔具，“幽灵渔具”也是导致成千上万头鲸鱼死去的罪魁祸首：这些被遗弃、丢失或抛弃的塑料渔网、绳索和渔线会困住鲸鱼。
Climate change
气候变化
Warmer ocean temperatures and melting sea ice pose serious threats to the survival of the world’s great whales. The reduction of sea ice cover is likely to impact belugas, narwhal and bowhead species for whom the Arctic provides habitat and feeding grounds. In the Antarctic, sea ice is also decreasing in certain areas, resulting in massive declines in krill, a primary food source for many species including whales.
海洋温度升高和海冰融化对鲸鱼这种庞然大物的生存构成了严重威胁。海冰覆盖的减少可能会影响白鲸、独角鲸和弓头鲸，因为北极是它们的栖息地和觅食地。南极一些地区的海冰也在减少，导致磷虾大量减少，而磷虾是包括鲸鱼在内许多物种的主要食物来源。
The krill and plankton that form the foundation of the marine ecosystem are also being affected by the increasing acidification of the ocean as it absorbs more CO2. Some species will be unable to form and maintain their protective calcium carbonate shells, threatening animals further up the food chain. Studies show that plankton populations could decrease by as much as 40% by 2050. Coral reefs and polar regions are on the frontline of the acidification crisis, with North Pacific salmon, mackerel, herring, cod and baleen whales among the species under the most immediate threat.
构成海洋生态系统基础的磷虾和浮游生物也受到海洋酸化加剧的影响。海洋吸收的二氧化碳越多，海水酸化也就越严重，这就意味着其中一些物种将无法形成和维持自身的保护性碳酸钙外壳，从而进一步威胁食物链上游的关键物种。研究表明到2050年，浮游生物的数量可能减少40%。珊瑚礁和极地地区是酸化危机的前沿，北太平洋鲑鱼、鲭鱼、鲱鱼、鳕鱼和须鲸都是面临最直接威胁的物种。
Warmer seas will also affect the distribution of whales. If their prey moves as a result of climate change, they will likely follow. Mass movement of species to different habitats will result in increased competition for diminishing amounts of prey.
海洋变暖也会影响鲸鱼分布。如果猎物因气候变化而迁移，鲸鱼很可能会随之而去。物种向不同的生境大规模迁移，再加上猎物数量的不断减少，导致竞争加剧。
Pollution
污染
Toxic chemicals banned decades ago could kill off more than half of the world’s killer whale population in 30-50 years, scientists believe. PCBs (polychlorinated biphenyls) are manmade organic compounds once used in electrical equipment, flame retardants and paints until they were found to be so dangerous to human health that they were banned in the US in the 1970s and Europe in 1987. Resistant to heat, chemicals and natural degradation, the same things that made PCBs so attractive also makes them hard to destroy, and so they remain in the ecosystem decades later. Some were improperly stored or disposed of, or even directly discharged into soils, rivers, wetlands and the ocean. Entering the food chain, they have worked their way up to concentrate in top predators, causing cancers, altering behaviour, damaging immune systems and harming reproduction. European killer whale populations, along with dolphins and porpoises, are the most contaminated in the world, and sadly some of the most heavily exposed populations are not expected to survive the next few decades.
科学家认为，几十年前就被禁止使用的有毒化学物质可能在30至50年内杀死全球一半以上的虎鲸种群。多氯联苯属于人造有机化合物，曾用于电气设备、阻燃剂和油漆，后被发现对人体健康有重大危害，因而美国和欧洲分别于上世纪70年代和1987年禁用这种化合物。耐热、化学性状稳定、不易自然降解，这些曾经让多氯联苯极具吸引力的性质也让它难以分解，因此能够在生态系统中存在数十年。有的是因为储存或处置不当，有的甚至会被直接排入土壤、河流、湿地和海洋。多氯联苯进入食物链后一路向上，在顶端食肉动物体内积聚，引发癌症，导致行为改变，免疫系统受到破坏，生殖力受损。欧洲的虎鲸种群、海豚和鼠海豚是世界上受污染影响最严重的物种，一些污染暴露最严重的种群预计活不过未来几十年。
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