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
49
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://jikaoti.com/ti/zbQYFFFM
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
The______discoveryofdinosaurs’completegenesshockedtheworldandwasreceivedwithdisbelief.
______isnecessaryforpeopletodevelopstrongbonesandteeth.
Theexaminerfailedsomecandidates,and15ofthembeingstudentswithoutworkexperience.
Thefieldofmedicinehasalwaysattracteditsshareofquacksandcharlatans—disreputablewomenandmenwithlittleornomed
Hotelsandrestaurantsarean______partofthecity,withoutwhichthetouristindustrycouldnotexist.
下面你将听到一段有关中美贸易关系的讲话。在冷战结束后的新形势下,两国要不要及如何发展双边关系,是中美两国面临的重大课题。“永久正常贸易关系”的通过表明,在美国,支持发展中美关系的力量占了上风,美国政府、国会、工商企业界和公众的主流都支持以建设性的
旅游是一项集观光、娱乐、健身为一体的愉快而美好的活动。旅游业随着时代进步而不断进步。从20世纪中期起,现代旅游业在全世界迅速发展。游客人数不断增长,旅游业规模持续扩大,旅游经济地位显著提升,旅游活动愈益成为各国人民交流文化、增进友谊、扩大交往的重
中国经济高速发展,需要大量的矿产品及相关的能源与原材料加工制品。每年消耗的矿石量达60多亿吨,位居世界前列。中国政府为实现经济的可持续发展,在矿产资源勘查、开发领域制定了一系列的法律、法规和政策,形成了既适合中国国情又基本与国际接轨的矿产资源勘查
A、ThemanisgoingtotakeatriptoBarcelona.B、Themanoftentakesflightsintheairport.C、Themanisnotusedtothenewa
A、TonybrokeanarmandalegforthesakeofBarbara.B、ThenecklaceTonyboughtwasveryexpensive.C、Tonywasnotgenerousen
随机试题
设随机变量X的概率密度函数为(Ⅰ)求常数A,a;(Ⅱ)求E(Y).
混合型政治文化
采用慢速维持荷载法对某直径为1.2m、桩长为20m的桥梁桩基进行竖向静载试验,已知桥位处地基土为坚硬黏质土,请回答以下问题。当出现下列()情形之一时,应终止加载。
纳税人如果不能按转让房地产项目计算分摊利息支出,那么其允许扣除的房地产开发费用应为取得土地使用权所支付的金额加开发成本之和的( )。
甲公司是一家国有独资公司,以下表述正确的是()。
下列属于统计分析报告的特点的有()。
被称为“中国工艺美术三长”的是()。
土地增值税,指对转让房地产,即转让国有土地使用权和地上建筑物及其附着物并取得收入的单位或个人征收的税。土地增值税按照1994年1月1日起施行的《土地增值税暂行条例》征收。下列情况应征收土地增值税的是( )。
Airpollutionkilledaboutsevenmillionpeoplelastyear,makingittheworld’ssinglebiggestenvironmentalhealthrisk,theW
ThefirstfarmanimalJackever【51】fromastockyardwasalamb【52】Hida.aamSanctuary,180acresofveganheavenintheFingerL
最新回复
(
0
)