When prehistoric man arrived in new parts of the world, something strange happened to the large animals: they suddenly became extinct. Smaller species survived. The large, slow-growing animals were easy game, and were quickly hunted to extinction. Now something similar could be happening in the oceans. 

　　That the seas are being overfished has been known for years. What researchers such as Ransom Myers and Boris Worm have shown is just how fast things are changing. They have looked at half a century of data from fisheries around the world. 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. 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. In some long-fished areas, it has halved again since then。

　　Dr. Worm acknowledges that these figures are conservative. One reason for this is that fishing technology has improved. Today’s vessels can find their prey using satellites and sonar, which were not available 50 years ago. 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. In the early days, too, longlines would have been more saturated with fish. 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. Furthermore, in the early days of longline fishing, a lot of fish were lost to sharks after they had been hooked. That is no longer a problem, because there are fewer sharks around now。

　　Dr. Myers and Dr. Worm argue that their work gives a correct baseline, which future management efforts must take into account. They believe the data support an idea current among marine biologists, that of the “shifting baseline”. 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. 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. Most fisheries are well below that, which is a bad way to do business。

　　31. The extinction of large prehistoric animals is noted to suggest that

　　[A] large animals were vulnerable to the changing environment。

　　[B] small species survived as large animals disappeared。

　　[C] large sea animals may face the same threat today。

　　[D] slow-growing fish outlive fast-growing ones。

　　32. We can infer from Dr. Myers and Dr. Worm’s paper that

　　[A] the stock of large predators in some old fisheries has reduced by 90%。

　　[B] there are only half as many fisheries as there were 15 years ago。

　　[C] the catch sizes in new fisheries are only 20% of the original amount。

　　[D] the number of larger predators dropped faster in new fisheries than in the old。

　　33. By saying “these figures are conservative” (Line 1, Paragraph 3)， Dr. Worm means that

　　[A] fishing technology has improved rapidly。

　　[B] the catch-sizes are actually smaller then recorded。

　　[C] the marine biomass has suffered a greater loss。

　　[D] the data collected so far are out of date。.

　　34. Dr. Myers and other researchers hold that

　　[A] people should look for a baseline that can work for a longer time。

　　[B] fisheries should keep the yields below 50% of the biomass。

　　[C] the ocean biomass should be restored to its original level。

　　[D] people should adjust the fishing baseline to the changing situation。

　　35. The author seems to be mainly concerned with most fisheries’

　　[A] management efficiency。

　　[B] biomass level。

　　[C] catch-size limits。

　　[D] technological application。

　　名师解析

　　31. The extinction of large prehistoric animals is noted to suggest that

　　提及大型史前动物的灭绝是为了说明

　　[A] large animals were vulnerable to the changing environment。

　　大型动物容易受到环境变化的影响。

　　[B] small species survived as large animals disappeared。

　　当大型动物消失的时候小型物种存活了下来。

　　[C] large sea animals may face the same threat today。

　　大型海洋动物今天面临相同的威胁。

　　[D] slow-growing fish outlive fast-growing ones。

　　成长缓慢的鱼要比成长快速的鱼活得长。

　　【答案】 C

　　【考点】 推断题。

　　【分析】 通过题干关键词“大型史前动物的灭绝”可以定位到第一段。作者提到它们的灭绝是由于人类的捕杀，作者在第一段最后一句提到，“如今类似的事情可能会发生在海洋中”。因此可以得出结论，即，作者是为了引用大型史前动物的灭绝来引出海洋物种同样面临着由于人类过度捕捞而灭绝的这个话题，故正确答案是[C]。[A]、[B]、[D]选项都没有能够表达出作者的这个意图，而只是很浅层去分析表象。

　　32. We can infer from Dr. Myers and Dr. Worm’s paper that

　　从迈尔斯博士和沃尔姆博士的论文中我们可以推断出

　　[A] the stock of large predators in some old fisheries has reduced by 90%。

　　一些老渔场里大型捕食类鱼种的贮存量已经减少了90%。

　　[B] there are only half as many fisheries as there were 15 years ago。

　　现在渔场的数量只有15年前数量的一半。

　　[C] the catch sizes in new fisheries are only 20% of the original amount。

　　新的渔场中的捕捉数量是原来数量的20%。

　　[D] the number of larger predators dropped faster in new fisheries than in the old。

　　新的渔场里大型捕食类鱼种的数目下降比旧的渔场快。

　　【答案】 A

　　【考点】 推断题。

　　【分析】 根据题干关键词“Dr Myers and Dr. Worm’s paper”可以定位到第二段最后一句，“根据他们发表在《自然》杂志上的最新论文，一个新的渔场在被开发后的15年中大型捕食类鱼种的生物量平均减少了80%。在有些长期捕捞的地区，自那以后，这个数量又减少了一半。”本句的理解难点就是“In some long-fished areas, it has halved again since then。”这句话里面的“since”从什么时间开始计算，影响本题的解答。“since”指的是从15年结束后开始算呢，还是从15年的第一年开始算。如果是前者，则答案是[A]，因为新的平均下降80%，然后又下降了一半，这个意思就是一共下降了90%；如果是后者，则得出旧渔场大型捕食类鱼种的减少速度低于新渔场，而且只有50%。“since”接时间，后面必须是一个时间点。如果“since”后面接的不是一个时间点而是时间段，则从该时间段结束的时候开始算。例句：“It has been 10 years since I lived in Beijing。”这句话的意思不是“我在北京十年了”，而是“我离开北京十年了”。因此本题的正确答案是[A]。“since”接的是15年结束后的那个点；而且这句话里面还有一个很关键的词“again”(再次)，也很明显说明这里指的是“在下降80%之后，又再次减少了一半”，即“余下的20%又减少了一半，只剩下10%”。

　　33. By saying“these figures are conservative”(Line 1, Paragraph 3)， Dr worm means that

　　沃尔姆博士说“these figures are conservative”(第三段第一行)，他的意思是

　　[A] fishing technology has improved rapidly.  捕鱼的技术已经得到快速提高。

　　[B] the catch-sizes are actually smaller than recorded.  捕鱼量比实际记录的少。

　　[C] the marine biomass has suffered a greater loss.  海洋生物量已经蒙受了更大的损失。

　　[D] the data collected so far are out of date.  目前收集的数据已经过时了。

　　【答案】 C

　　【考点】 推断题。

　　【分析】 根据关键词“conservative”的提示定位到第三段第一句。作者说“这个数据是保守的，因为捕鱼的技术已经提高了。卫星和声纳定位仪都用上了。这就意味着现在海里有更高比例的海洋生物被捕捞了。现在和过去的真正差异可能比通过捕捞记录的反映出来的差异更要糟糕。”接下来的一句话的意思是“以前一些抓不住的海洋生物现在都可以抓住了，以前被鲨鱼抢走的，现在由于鲨鱼都不见了，自然被捕捞的就更多了。”作者同时提到，“由于以前的捕捞技术不够先进，所以以前对海里的生物的总量是低估的。”那么我们可以得出这样的结论“以前的海洋生物总量比我们当时估计的要高，而现在只剩下这么一点了”，就是说“海洋物种被捕捞的比例远远超过我们的记录”。因此可以得出[C]的结论。[A]项的错误在于“捕鱼的技术已经得到快速的提高”这种提法仅仅是作者文中提到的一个原因，作者是为了用这个来证明有了这样的科技，更多的海洋生物就被捕捞了，而不是为了说明技术得到提高。[B]试图比较当时的捕捞量与记录的差别。但是原文说的是今天和过去的真实差别比那个记录反映出来的差别要严重的多。[D]的说法是没有根据的。

　　34. Dr. Myers and other researchers hold that

　　迈尔斯博士以及其他一些研究人员坚持认为

　　[A] people should look for a baseline that can work for a longer time。

　　人们应该寻找一种能够更长时间起作用的基准。

　　[B] fisheries should keep the yields below 50% of the biomass。

　　渔场应该将产量保持在生物量的50%以下。

　　[C] the ocean biomass should be restored to its original level。

　　海洋生物的数量应该恢复到原来的水平。

　　[D] people should adjust the fishing baseline to the changing situation。

　　人们应该根据变化的形势调整捕鱼数量的基准。

　　【答案】 D

　　【考点】 事实细节题。

　　【分析】 本题提到“Dr. Myers”和其他一些研究者的主张，题干中用到了“hold”，而其近义词就是“argue”，定位到最后一段第一句。“Dr. Myers”和“Dr. Worm”坚持认为“他们的工作是给出准确的捕捞数量基准，它是未来的管理工作必定要考虑的”，他们相信自己的数据支持了目前海洋生物学家的观点，即“变化的底线”。也就是说，“人们应该根据变化的形势调整捕鱼数量的基准”，所以正确答案是[D]。[A]不正确的原因是文章中没有提到持续时间更长，文章最后一段提到时间太短指的是调查研究的跨度年份很短。和基数没有关系 [B]不是“Dr. Myers”坚持的主张，而是理论状态下的海洋生物生产。[C]与原文的意思也不符合。

　　35. The author seems to be mainly concerned with most fisheries’

　　作者看上去主要关注大多数渔场的

　　[A] management efficiency.  经营效率。

　　[B] biomass level.  生物量水平。

　　[C] catch-size limits.  捕捞量的限制。

　　[D] technological application.  技术应用。

　　【答案】 B

　　【考点】 文章主旨题。

　　【分析】 本题问的是作者最关注的是渔场的哪一个方面，这个问题实际上考的是文章的主旨。从前到后，作者一直在提过度捕捞对海洋生物量的影响。[A]显然不是本文的重点。[D]在文章中只是被作者引用来表示现在的海洋生物被过度捕捞。[C]在文中最后一段有提及，但是显然不是文章的主题。作者最关心的是海洋生物量的变化，因此正确答案选[B]项。

　　难句解析：

　　1. 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。

　　【结构分析】 本句是一个并列句，连接词是“so”。前一个分句中，“that means” 后面省略了宾语从句连接词“that”，在这个宾语从句中，“a higher proportion of what is in the sea”是主语，“is being caught”是谓语部分。这个主语里面又包含了一个由“what”引导的从句，做介词“of”的宾语。后一个分句是一个比较级结构，主语是“the real difference”，“the one”代替“the difference”，“recorded”是过去分词做后置定语。

　　2. In the early days, too, longlines would have been more saturated with fish. 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。

　　【结构分析】 这里是两个句子。之所以把第一句拿来一起分析，是因为这句话的理解对第二句的理解很重要。第一句话中的“would have been more saturated”是虚拟语气的一种，是对过去未能发生的事情的一种假设。随后一句，仍然是虚拟语气。我们来分析一下这个结构。“since”指的是原因，即，“当时怎么就没有这样的可以装诱饵的鱼钩”，其实际意思是“如果当初有这样的鱼钩，一些海洋生物个体就不会被抓不住”。“leading”是现在分词引导结果状语。

　　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。

　　【结构分析】 本句的主句是“The notion is that…”，“that”引导表语从句。在这个表语从句中，“people have failed to detect the massive changes”是句子的主谓宾，“which”引导一个定语从句，指代“changes”。“because”引导一个原因状语从句，在表语从句中表示原因。

　　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。

　　【结构分析】 本句的主句是“that matters”，“because”引导一个原因状语从句。在这个从句中，“theory suggests”是主句，“suggest”后面的“that”引导一个宾语从句。

　　全文翻译：

　　当史前人类来到世界的各个新区域时，一些奇怪的事情也会发生在当地的大型动物身上。它们突然就灭绝了，较小的物种存活了下来。生长缓慢的大型的动物很容易成为猎物，很快被猎杀而灭绝。现在类似的情形也可能正在海洋中发生。

　　人们知道海洋被过度捕捞这个事实已经很多年了。迈尔斯博士和沃尔姆博士这样的研究人员所展示的情况说明了变化有多快。他们研究了全世界渔场半个世纪的数据。他们的方法不是试图确切估计在具体某地方的海洋中鱼类的量，而是估计该地区生物量随着时间推移的变化。根据他们发表在《自然》杂志上的最新论文，一个新的渔场在被开发后的头15年中大型捕食类鱼种的生物量平均减少了80%。在有些长期捕捞的地区这个数量随后又减少了一半。

　　沃尔姆博士承认这些数据是保守的。其中一个原因是捕鱼技术已经得到发展，今天的船只可以使用卫星和声纳定位仪来寻找猎物，这些在50年前都还没有。这意味着更高比例的海洋生物正在被捕捞，因此现在和过去的真正差异可能比捕捞量记录反映的差异更要糟糕。以前，多钩长线本可以抓更多的鱼，但是因为当时没有可用来捕捉它们的带鱼饵的钩，个别的鱼在当时就没有被捉住，这导致了过去对鱼的贮存量的低估。而且，在用多钩长线捕捞的初期，许多鱼被钩住后又被鲨鱼夺走。而现在这不再是问题，因为附近的鲨鱼更少了。

　　迈尔斯博士和沃尔姆博士认为他们的工作给出了准确的捕捞数量基准，它是未来的管理工作必须要考虑在内的。他们认为这些数据支持了现在海洋学家的一种观点，即“变化的底线”。这种观点认为人们没有检测出海洋中已经发生的巨大变化，因为他们只回顾了过去相当短的一段时期。这有很大的影响，因为理论显示，渔场中要获得最大可持续产量，目标物种的生物量需要维持在原来水平的约50%。但是大部分渔场低于这个水平，这可不是好的商业做法。

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