Sharks use the Earth’s magnetic field as a sort of natural GPS to navigate journeys that take them great distances across the world’s oceans, scientists have found.
科学家发现，鲨鱼可以利用地球磁场作为一种天然的全球定位系统(GPS)来进行穿越世界海洋的长途旅行。
Researchers said their marine laboratory experiments with a small species of shark confirm long-held speculation that sharks use magnetic fields as aids to navigation — behavior observed in other marine animals such as sea turtles.
研究人员说，他们在海洋实验室对一种小型鲨鱼进行的实验证实了长期以来的猜测，即鲨鱼利用磁场作为导航辅助手段，同时在海龟等其他海洋动物身上也观察到了这种行为。
Their study, published this month in the journal Current Biology, also sheds light on why sharks are able to traverse seas and find their way back to feed, breed and give birth, said marine policy specialist Bryan Keller, one of the study authors.
这项研究的作者之一、海洋政策专家布赖恩·凯勒表示，他们的研究成果发表在本月的《当代生物学》杂志上，也揭示了为什么鲨鱼能够穿越海洋，还能找到回去觅食、繁殖和生产的路。
“We know that sharks can respond to magnetic fields,” Keller said. “We didn’t know that they detected it to use as an aid in navigation ... You have sharks that can travel 20,000 kilometers and end up in the same spot.”
“我们知道鲨鱼能对磁场做出反应，”凯勒说，“我们不知道他们是如何来导航的，无法想象鲨鱼可以游两万公里，还能回到最初的起点。”
The question of how sharks travel long distance has long intrigued researchers.
鲨鱼是如何长途旅行的问题一直吸引着研究人员。
Looking for answers, Florida State University scientists decided to study bonnethead sharks — a hammerhead that lives on both American coasts and returns to the same estuaries every year.
为了寻找答案，佛罗里达州立大学的科学家们决定研究大白鲨——一种生活在美国海岸和每年返回同一河口的锤头鲨。
Researchers exposed 20 bonnetheads to magnetic conditions that simulated locations hundreds of kilometers away from where they were caught off Florida.
研究人员将20条大鱼暴露在磁场条件下，这些磁场条件模拟了它们在佛罗里达州附近数百公里外被捕获的地点。
They found that the sharks began to swim north when the magnetic cues made them think they were south of where they should be.
他们发现，当磁信号让鲨鱼以为自己在的南方时，它们开始向北游去。
That finding is compelling, said Robert Hueter, senior scientist emeritus at Mote Marine Laboratory & Aquarium, who was not involved in the study. Hueter said further study is needed to find how the sharks use the magnetic fields to determine their location and whether larger, long-distance migrating sharks use a similar system to find their way.
莫特海洋实验室和水族馆的退休高级科学家罗伯特·休特(Robert Hueter)说，这一发现令人信服，他没有参与这项研究。休特说，还需要进一步的研究来发现鲨鱼是如何利用磁场来确定自己的位置的，以及大型、远距离迁徙的鲨鱼是否使用类似的系统来确认方向。
