‘Superpredator’ humans are hunting other animals out of existence


A new study drives home the destructive power of our species. Not only do we kill other animals at much higher rates than other predators, but our ability to bring down larger adults can make it very difficult for some prey populations to recover. This superpredator status may fill our bellies, but it has darker implications. “Any predator capable of exerting such impact will eventually drive its prey to extinction,” warns Gerardo Ceballos, an ecologist at the National Autonomous University of Mexico in Mexico City.

一项新研究清楚揭示了我们人类的破坏力。不仅是因为我们猎杀动物的速度比其他种类的捕食者更快,还在于我们能够捕杀成年个体,这使得猎物的种群更加难以恢复。这种超级猎手的身份可以满足我们的口腹之欲,但它有很消极的影响。Gerardo Ceballos是位于墨西哥城的墨西哥国立自治大学的一位生态学家,他警告说:“任何有能力施加这种影响的捕食者,最终都将导致它的猎物走向灭绝。”

It’s happened before. About 14,000 years ago, humans entering North America caused many large species, such as the mammoth, to disappear. And our hunting technologies have only improved since then, particularly when it comes to catching fish. Overfishing is a severe problem in some parts of the world, and a recent report concludes that because of human activity, more than 90 fish species are at risk of extinction.


The new study originated in a casual observation. Thomas Reimchen, an evolutionary ecologist at the University of Victoria in Canada, has spent years studying how predators impact the stickleback fish on an island 130 kilometers off the Canadian Pacific coast. Over the decades he determined that each species never kills more than 2% of the sticklebacks per year and usually attacks juveniles.

这项新研究源于一个偶然的观察。加拿大维多利亚大学的进化生态学家Thomas Reimchen常年在距加拿大太平洋海岸130千米的一个海岛上研究捕食者如何影响棘鱼。数十年的研究之后,他发现每个捕食物种每年捕食的棘鱼不会超过2% ,并且捕杀的通常是幼体。

Yet off that same island, fishermen seemed to be taking a far higher percentage of salmon, mostly adults. The contrast bothered him, so Reimchen and a few former students searched the scientific literature for data on the rate at which humans and other animals were killing other species.

然而,在同一海岛附近,渔民捕捞的三文鱼远远超过这个比例,而且捕捞的都是成年个体。这种对比让他很困扰,所以Reimchen 和他之前的几个学生查阅了很多科学文献,来查找人类和其它动物捕杀其他生物的速度。

After a decade compiling and analyzing about 300 studies, the team came to some grim conclusions, says Chris Darimont, a conservation scientist also at the University of Victoria who helped lead the study. Humans and other predators—like lions, wolves, and grizzly bears—kill wild herbivores at about the same rate, but humans kill large carnivores at nine times the rate of other predators, Darimont, Reimchen, and their colleagues report today in Science.

同样来自维多利亚大学的环境保护科学家Chris Darimont说,在经过了十年时间对大约三百项研究的汇编和分析之后,他领导的团队得到了一些残酷的结论。人类和其他捕食者如狮子、狼和灰熊捕杀野生食草动物的速度差不多,但人类捕杀大型食肉动物的速度是其他捕食者的九倍。Darimont与 Reimchen以及他们的同事现已将这一结果发表在《科学》杂志上(8月21日号)。

We kill those carnivores not for food, but for trophies and—sometimes—to eliminate them as competitors, Darimont says. Because they naturally don’t face much predation, they have not evolved ways to successfully avoid humans or reproduce fast enough to make up for human-induced losses.


But the toll on fish is even greater. The researchers report that people catch adult fish at a rate up to 14 times other predators. Thanks to mechanized fishing, the annual human toll on marine fish may exceed 100 million tons. What’s worse, by focusing on catching large adults, fishing removes individuals in their reproductive prime that are needed to replenish diminishing populations. Already,?this fishing pressure has caused species to evolve new growth patterns and behaviors.


Marine ecologist Nicholas Dulvy from Simon Fraser University in Burnaby, Canada, is pleased with the work. Hunting and fishing have “not captured the public attention necessary to change the status quo,” says Dulvy, who was not involved with the study. “The disparity between human and animal predation rates is a useful way of illustrating how ecologically out-of-whack many exploitation rates and management policies are.” Darimont thinks people need to take a lesson from other predators, switching the focus to catching juveniles and lowering catch rates.

加拿大本那比市西蒙·弗雷泽大学的海洋生态学家Nicholas Dulvy对这项工作很满意。他并没有参与这项研究,但他说,“猎杀和捕捞并没能在公众眼中引起足以改变现状的关注度。人类和动物捕杀速度的不同,是说明开采速度和管理政策如何造成生态紊乱的一个有效途径。”Darimont 认为人类应该向其他捕食者学习,转而捕杀幼体并降低捕杀速度。

But others take issue with the study’s approach and conclusions. “I think it’s total rubbish,” says Ray Hilborn, an ecologist at the University of Washington, Seattle. An expert on sustainable exploitation, he says that even though humans may take more fish than any one predator, their haul makes up only 40% of total natural predation on fish.

但有人对该项研究的方法以及结论持有异议。华盛顿大学西雅图分校的生态学家Ray Hilborn说:“我认为那项研究完全就是垃圾”。Ray Hilborn是可持续发展方面的专家,他说尽管人类捕捞的鱼远超过其他捕食者,但他们的捕捞量也只及被自然捕食的鱼类数量的40%。

Hilborn says this is a reasonable amount given the need to provide food for the human population, and the new work is “fuzzing up what we mean by sustainability.” He says he doesn’t think that people can fish less and still provide enough food for the world.


Even so, people should take a really hard look at management practices that go after the largest individuals, says Blaire Van Valkenburgh, a paleoecologist at the University of California, Los Angeles, who was not involved with the work. “Getting that attitude to change is going to be very difficult, but at least [with this paper] we will be able to get some people to talk about it.”

加利福尼亚大学洛杉矶分校的古生态学家Blaire Van Valkenburgh(他并没有参与这项研究工作)认为,即便如此,人类也应该仔细审视自己专门捕捞大型个体的做法。“让人们改变目前的态度是非常困难的,但至少(这篇论文)会让一些人来讨论这个问题。”



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