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.
The extinction of large prehistoric animals is noted to suggest that ______.
选项
A、large animals were vulnerable to 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
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/jncO777K
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
"Whatdoesthemiddlemandobutaddtothepriceofgoodsintheshops?"Suchremarksareaimedattheintermediateoperationsb
ThenewPersonalDigitalAssistancecontainedalarge______ofinformationaboutanindividuallife.
Thefieldofmedicinehasalwaysattracteditsshareofquacksandcharlatans—disreputablewomenandmenwithlittleornomed
TheaffluentmiddleclasscreatedbytheAsianboomnowtakeupoverfromexportsasthemainengineofgrowth.
TheBritishHistorynotonlygivescitiestheirshape;italsomoldstheirself-image.Since1941,whenLondonemergedfrome
Currently,GISiswidelyusedtomonitorvehiclelocation,makingpossibleeffectivestrategiesthatcankeepthepassengersinf
下面你将听到外商有关中国零售业发展情况的一段讲话。China’seconomy,oncereliantonstatespendinginheavyindustry,hasincreasinglylookedtothe
美国人交朋友主要有四种方式:工作中、学校里、通过共同的爱好或者一个共同的兴趣,比如说志愿者工作,或者通过一个互相的朋友网。这句话主要讲的是四个方面,第一句话总的不难听懂,后面四个方面也不难听懂,这句话的翻译难点在于要作好比较。四个方面可以简单地记成work
A、TonybrokeanarmandalegforthesakeofBarbara.B、ThenecklaceTonyboughtwasveryexpensive.C、Tonywasnotgenerousen
随机试题
大道之行也天下为公选贤与能讲信脩睦故人不独亲其亲不独子其子使老有所终壮有所用幼有所长矜寡孤独废疾者皆有所养男有分,女有归。货恶其弃于地也,不必藏于己。力恶其不出于身也,不必为己。是故谋闭而不兴,盗窃乱贼而不作。故外户而不闭,是谓大同。《礼记·礼运·大同》
A.阵发性剑突下钻顶样疼痛伴呕吐B.突发性上腹剧痛伴腹膜刺激征C.外伤后剧烈腹痛伴休克D.上腹部绞痛伴畏寒、发热E.腹痛呕吐便闭,肠鸣音亢进或消失肝脾破裂()
护理质量控制和监测评价的指标有
在小儿年龄分期中,幼儿期是指
关于免疫对机体的叙述正确的是()
不能制止同事违规行为的要及时报告()。
为了改变传统课程过分强调学科本位的现象,新课程注重联系学生经验和生活实际,提倡和追求不同学科间的彼此关系,这体现的新课程的结构特征是()。
设y=f(x)是由方程确定的函数,且满足f(1)=1.求曲线y=f(x)在点(1,1)处的曲率;
Large,multinationalcorporationsmaybethecompanieswhoseupsanddownsseizeheadlines.Buttoafargreaterextentthanmos
Itwasaboldideatobuildapowerstationinthedeepvalley,butit______aswellaswehadhoped.
最新回复
(
0
)