首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
When prehistoric man arrived in new parts of the world, something strange happened to the large animals: they suddenly became ex
When prehistoric man arrived in new parts of the world, something strange happened to the large animals: they suddenly became ex
admin
2011-01-10
63
问题
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 mason 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.
By saying "these figures are conservative" (para. 3), Dr Worm means that ______.
选项
A、fishing technology has improved rapidly
B、then 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
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/tncO777K
本试题收录于:
NAETI中级口译笔试题库外语翻译证书(NAETI)分类
0
NAETI中级口译笔试
外语翻译证书(NAETI)
相关试题推荐
Thestudentunion’spresidentwasappalledbythecomplacencyofhisclassmates;notoneoftheseniorsseemedtocareaboutthe
Wheninsectsfeedondecayingplantmaterialinacompostpile,theyhelpturnitintousefulgardensoil.
Generalacceptanceof3-Dfilmsmayprovehardtocomeby,astheexperienceofthreedecadesagoindicated.
Thisprogramwilltakekidswhohaveamanifesthistoryofviolentacts.
Oneoftheeffectivewaystolessenenvironmentalpollutionisthereservationandprotectionofmoreswamps.
AlphaZeroseemstoexpressinsight.Itplayslikenocomputereverhas,intuitivelyandbeautifully,witharomantic,attacking
AlphaZeroseemstoexpressinsight.Itplayslikenocomputereverhas,intuitivelyandbeautifully,witharomantic,attacking
中国西藏自治区位于青藏高原的主体,地势高峻,地理特殊,野生动植物资源、水资源和矿产资源丰富,素有“世界屋脊”和“地球第三极”之称。这里不仅是南亚、东南亚地区的“江河源”和“生态源”,还是中国乃至东半球气候的“启动器”和“调节区”。//西藏自治区面
当前,国际金融危机已从局部发展到全球,从发达国家传导到新兴市场国家,从金融领域扩散到实体经济领域,给世界各国经济发展和人民生活带来严重影响。值此关键时刻,我们在这里共同探讨维护国际金融稳定、促进世界经济增长的举措,具有十分重要的意义。//我们正在
A、Ten.B、Atleasttwelve.C、Two.D、Notmentioned.A
随机试题
规范有序的编码在系统设计中的地位非常重要,编码的规范性要求,编码时不要()
Themanagerlosthis______justbecausehissecretarywastenminuteslate.
[*]
A.窥器暴露宫颈,消毒阴道、宫颈后,钳夹宫颈唇B.膀胱截石位,复查子宫位置,消毒外阴、阴道C.探测宫腔深度,扩张宫颈D.宫腔负压吸引顺时针或逆时针转动吸引管E.确定组织已吸净后,取出吸管负压吸引手术步骤顺序
下列案件中不属于中级人民法院一审管辖的是:
图示雨篷剖面计算图,P=1kN,P对A点产生的弯矩正确的是:
建设工程监理实施中,监理人员应遵守的基本原则为( )。
根据单项选择题第18题的资料,计算该公司9月份资产负债表中.“未分配利润”项目的金额为()元。
下列关于个人理财产品的基本要求,不正确的是()。
罗杰斯对经验的概念来源于现象学中的“现象场”,它是指()。
最新回复
(
0
)