Question

    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 the figures are conservative. One reason for this is that fishing technology has improved. Today's vessels (船)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 (多钩长线) would have been more filled with fish. Some individuals would therefore not have been caught, since no baited hooks (带饵钩)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 idea 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 （产量）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.

1.The extinction of large prehistoric animals is noted to suggest that____.

A.large animals were easily hurt in 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

2.By saying these figures are conservative , Dr. Worm means that____ .

A.fishing technology has improved rapidly

B.the catch-sizes are actually smaller than recorded

C.the marine biomass has suffered a greater loss

D.the data collected so far are out of date

3.Dr. Myers and other researchers hold that____ .

A.people should look for a baseline that can't work for a longer time

B.fisheries should keep the yield below 50% of the biomass

C.the ocean biomass should restore its original level

D.people should adjust the fishing baseline to changing situation

4.The writer seems to be mainly concerned with most fisheries’____ .

A.biomass level B.management efficiency

C.catch-size limits D.technological application

Answer

1.C

2.C

3.D

4.A

【解析】

本文是一篇说明文，介绍了大型海洋动物也面临着像史前大型动物一样灭绝的危险，人们应该根据情况的变化调整捕鱼基线以保持海洋渔业的最大生物量。

1.推理判断题。根据第一段中的“The large, slow-growing animals were easy game, and were quickly hunted to extinction. Now something similar could be happening in the oceans.”可知，这种生长缓慢的大型动物很容易被猎杀，很快就灭绝了，现在海洋里也可能发生类似的事情，由此可知，提到史前动物的灭绝就是为了表明大型海洋动物如今可能也面临同样的威胁，故C项正确。

2.词句猜测题。根据画线句后的“One reason for this is that fishing technology has improved. Today's vessels (船)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.”可知，其中一个原因是捕鱼技术有所改进，今天的船只可以通过卫星和声纳找到猎物，而50年前还没有，这意味着在海洋中被捕获的生物比例更高，所以现在和过去的真实差异可能比捕获量变化所记录的更大，由此可知，沃姆博士说这些数据是保守的的意思是其实海洋生物量损失会更大，故C项正确。

3.细节理解题。根据最后一段中的“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 idea 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 （产量）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.”可知，迈尔斯博士和沃姆博士认为，他们的工作给出了一个正确的基准，未来的管理工作必须考虑到这个基准，他们相信这些数据支持了海洋生物学家当前的一个想法，即“改变基线”。这个想法是，人们未能察觉到海洋中发生的巨大变化，因为他们回顾过去的时间相对较短，这一点很重要，因为理论表明，当一个目标物种的生物量达到其原始水平的50%时，可以从渔业中获取的最大可持续产量，大多数渔业都远低于这个水平，这是一种不好的经商方式，由此可知，他们认为人们应该根据情况的变化调整捕鱼基线，故D项正确。

4.推理判断题。根据文章内容，特别是最后一段中的“That matters because theory suggests that the maximum sustainable yield （产量）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.”可知，这一点很重要，因为理论表明，当一个目标物种的生物量达到其原始水平的50%时，可以从渔业中获取的最大可持续产量，大多数渔业都远低于这个水平，这是一种不好的经商方式，由此可知，作者主要关心的是渔业的最大生物量水平，故A项正确。