一
1—When prehistoric man arrived in new parts of the world, something strange happened to the large animals: they suddenly became extinct.
2—Smaller species survived.
3—The large, slow-growing animals were easy game, and were quickly hunted to extinction. Now something similar could be happening in the oceans.
译文：
当史前人类到达世界的新区域时，某些奇怪的事情发生在大型动物身上：它们突然灭绝了。体型较小的物种幸存了下来。生长缓慢的大型动物容易被捕获，且迅速被猎杀直至灭绝。现在类似的事情可能正在各大洋中发生。
二
1—That the seas are being overfished has been known for years.
2—What researchers such as Ransom Myers and Boris Worm have shown is just how fast things are changing.
3—They have looked at half a century of data from fisheries around the world.
4—Their methods do not attempt to estimate the actual biomass (the amount of living biological matter) of fish species in particular parts of the ocean, but rather changes in that biomass over time.
5—According to their latest paper published in Nature, the biomass of large predators (animals that kill and eat other animals) in a new fishery is reduced on average by 80% within 15 years of the start of exploitation.
6—In some long-fished areas, it has halved again since then.
译文：
人们多年来早已经知晓海洋正在遭受过度捕捞。而诸如兰森姆·迈尔斯和鲍里斯·沃尔姆这样的研究者所揭示的只是情势恶化到底有多快。他们研究了全世界渔场半个世纪的数据。其研究方法不是试图估算特定海域中鱼类的实际生物量(活体生物的数量)，而是(估算)随着时间推移这些生物量的变化。据他们在《自然》杂志上发表的最新论文可知，一个新渔场在开发之初的15年中大型食肉鱼类(猎食其他动物的鱼类)的生物量平均减少了80%。在一些长期捕鱼的地区，生物量自那之后又减少了一半。
三
1—Dr. Worm acknowledges that these figures are conservative. One reason for this is that fishing technology has improved.
2—Today’s vessels can find their prey using satellites and sonar, which were not available 50 years ago.
3—That means a higher proportion of what is in the sea is being caught, so the real difference between present and past is likely to be worse than the one recorded by changes in catch sizes.
4—In the early days, too, longlines would have been more saturated with fish.
5—Some individuals would therefore not have been caught, since no baited hooks would have been available to trap them, leading to an underestimate of fish stocks in the past.
6—Furthermore, in the early days of longline fishing, a lot of fish were lost to sharks after they had been hooked.
7—That is no longer a problem, because there are fewer sharks around now.
译文：
沃尔姆博士承认这些数据是保守的。其原因之一是捕鱼技术已经改进。当今的船只可以使用50年前还没有的卫星和声呐技术来寻找猎物。这就意味着更高比例的海洋生物正在被捕获，因此现在和过去之间的真正差异很可能比捕捞量变化所显示出的差异更大。而且，在早期，多钩长线上本可以挂满更多的鱼。有些鱼之所以没有被捕捉，是因为没有可利用的带饵鱼钩来诱捕它们，进而导致过去的鱼类资源量被低估。此外，在使用多钩长线捕鱼的初期，许多鱼被钩住后又被鲨鱼夺走。而现在这不再是一个问题，因为鲨鱼很少出现了。
四
1—Dr. Myers and Dr. Worm argue that their work gives a correct baseline, which future management efforts must take into account.
2—They believe the data support an idea current among marine biologists, that of the “shifting baseline”.
3—The notion is that people have failed to detect the massive changes which have happened in the ocean because they have been looking back only a relatively short time into the past.
4—That matters because theory suggests that the maximum sustainable yield that can be cropped from a fishery comes when the biomass of a target species is about 50% of its original levels.
5—Most fisheries are well below that, which is a bad way to do business.
译文：
迈尔斯博士和沃尔姆博士认为他们的研究成果将提供一个未来管理活动必须考虑的正确基线。他们认为其数据验证了海洋生物学家就“变化基线”的一种普遍看法。这种看法就是人们未能发觉海洋中发生的巨大变化是因为他们一直只回顾过去一段相对较短时间内的情况。而这事关重大，因为理论认为当目标物种的生物量大约为其原始水平的50%时，从渔场能够获得最大持续渔获量。大部分渔场都远低于这个水平，这是一种有害的经营方式。
