2006年Text 3

　　When prehistoric man arrived in new parts of the world, something strong 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 over-fished 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 de 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) inanes 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 to 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 noise.

　　Dr. Myers and Dr. worm argue that their work gives a correct baseline, which future management efforts must take into account. They believe the date 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 form 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 de business.

33. By saying these figures are conservative (line in ,paragragf-3), Dr worm means that
[A] fishing technology has improved rapidly
[B] then catch-sizes are actually smaller then recorded
[C] the marine bio mass has suffered a greater loss
[D] the date collected so far are pit pf date.

[答案] C

[解题思路]

　　本题要求判断Worm博士说的"这些数据尚未保守"这句话的具体含义，其对应的信息是文章的第三段。该段第一句话后面的内容是对这句话内容的补充说明，指出现代渔业技术的改进、鲨鱼的减少等因素都大大提高了捕鱼率，正如该段所说的，"the real difference between present and past is likely to be worse than the one recorded by changes in catch sizes"（现在和过去的真正差距可能会比之前通过捕获区记录变化得到的数据更大）。也就是说，这些数据保守的原因在于实际的捕鱼量可能比现有数据更大，即海洋动物总量损失的实际情况比现有数据显示的结果更加严重，因此C选项为正确答案。A选项是解释这句话的原因之一，但不是其含义。B选项的表述与文章意思相反。D选项认为这些数据已经过时，但数据保守并不意味着它已过时，文章中也没有提到这一点，因此该选项错误。

[题目译文]

Worm博士说"这些数字是保守的"（第三段第一行）这句话的意思是          。
[A] 捕鱼技术得到了快速提高
[B] 捕鱼量实际上没有记录的那么大
[C] 海洋生物量受到了更大的损失
[D] 迄今为止搜集到的资料已经过时