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
39
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.
Dr Myers and other researchers hold that ______.
选项
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 be restored to its original level
D、people should adjust the fishing baseline to changing situation
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/3ncO777K
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
Allthestudentsofthisuniversityhavefree______totheInternetviaabroadbandconnection.
AsanEnglishmajorstudentatoneofthemostfamousuniversitiesinChina,IstronglybelievethatbusinessEnglishismorepr
Thefieldofmedicinehasalwaysattracteditsshareofquacksandcharlatans—disreputablewomenandmenwithlittleornomed
Ourcompanyhasbeenmadeoneofthelargestmanufacturersinthefieldofchemicalindustry.
Humanbeingsaresuperiortoanimalsthattheycanuselanguageasatoolofcommunication.
Richardhasan______manner,althoughhecomesfromamiddle-classfamilybackgroundandhasreceivedhiseducationatCambridge.
Therearemanywaystodisseminateinformation.Oneofthemosteffectivemeansofgettingamessageacrossinvolvesaneasytri
加强区域能源合作共创亚太美好未来资源节约与综合利用司副司长 刘显法2002年7月25日各位来宾、女士们、先生们:上午好!今天,我们在这里
A、Three.B、Four.C、Morethanfour.D、Notmentioned.A
随机试题
食品杂物污染的主要途径有哪些?
Φmm的孔与Φmm的轴相配合是()
A.化脓性链球菌B.轮状病毒C.风疹病毒D.冠状病毒E.单纯疱疹病毒感染可致性病的是
产褥感染是指
既能补血,又能止血的药是
A、破瘀散结B、理气行滞C、先攻后补D、攻补兼施E、先补后攻体质较强的瘕瘕患者,其治法是
甲欠乙400万,甲将自己的房屋无偿为戊向己借款的合同提供担保,该担保符合形式要件。甲又将该房屋以极低价格转让给了丙,该买卖也符合形式要件。后因甲无力清偿乙的债权,戊无力清偿其债权人已的债权,己欲行使对甲之房屋的抵押权。
refertothefollowingadvertisement.ThefinancialPlanningOfficeisofferingaFamilyBudgetGuide(No.1063X)tohelpmembersc
设区域D={(x,y)|x2+y2≤4,x≥0,y≥0},f(x)为D上的正值连续函数,a,b为常数,则=()
A、Togiveanexampleofnaturalshapes.B、Todescribeearlysculpture.C、Toillustratetheiruseastools.D、Todemonstratethei
最新回复
(
0
)