首页
登录
职称英语
(1)More and more of the world’s supply of seafood is coming from farms. (2
(1)More and more of the world’s supply of seafood is coming from farms. (2
游客
2024-09-08
21
管理
问题
(1)More and more of the world’s supply of seafood is coming from farms.
(2)Although 80% of the world’s seafood comes from marine harvests, there is a major shift under way toward aquaculture now.
(3)Nearly 40% of salmon marketed today are raised in captivity, compared with 6% a decade ago. Forty percent of all clams, oysters, and mussels are produced in farm environments, along with 65% of freshwater fish. Between 1990 and 1996, fish-farming production rose from 12.4 million to 23 million tons worldwide, writes Anne Piatt McGinn in an article for World Watch magazine.
(4)"The fact that world seafood supplies continue to increase at all is due almost entirely to the phenomenal growth in aquaculture," says McGinn, a research associate at the World Watch Institute. Commercial aquaculture is driven by rising human population at a time when over harvested wild fish stocks are in decline and conventional farm production has leveled off.
(5)Biotechnology is contributing to high-yield aquaculture through transgenics—the transfer of genes from one species to another. Researchers introduce desirable genetic traits into fish, creating hardier stocks. For example, some species of fish have a protein that allows them to live in Arctic waters. By transplanting this "anti-freeze" gene into other species, researchers have created more fish that can survive in extremely cold water, according to Ag-West Biotech, Inc., in Saskatchewan, Canada.
(6)Biotechnologists are attempting to improve a wide range of genetic traits in fish used for aquaculture, developing fish that are larger and faster-growing, more efficient in converting feed into muscle, more tolerant of low oxygen levels in water, and better able to resist disease.
(7)Researchers also are seeking plant-based sources of food as a more efficient alternative to fishmeal. The use of plant protein on fish farms could take some of the pressure off wild fish stocks and address the problem of phosphorous pollution because plants do not contain high phosphorus levels. Wheat, canola, and canola oil are being used as alternative feed for aquaculture, according to Ag-West Biotech, Inc.
(8)While aquaculture produces a reliable source of protein, the industry is rife with environmental problems, asserts McGinn. Perhaps the biggest concern is water pollution: Fish waste and uneaten food accumulates at farm sites and can float directly downstream into water supplies. Farm-related nutrient wastes as well as nitrogen and phosphorus also promote the spread of algal "blooms" that deplete oxygen and kill marine life.
(9)Aquaculture is also an inefficient user of resources, McGinn charges. Fish farms need protein feed, and about 17% of ocean fish, an over harvested wild resource, becomes food for captive-bred fish. "An estimated five kilograms of oceanic fish reduced into fishmeal are required to raise one kilogram of farmed ocean fish or shrimp, representing a large net protein loss," says McGinn.
(10)Fish farming does not have to be an inefficient or polluting industry. McGinn predicts that many consumers will choose sustainably produced fish in the future, just as they prefer dolphin-free tuna today. [br] All the following statements are the reasons why commercial aquaculture is pushed forward EXCEPT_____.
选项
A、the human population is increasing fast
B、the wild fish stocks are decreasing due to over fishing
C、the cost of developing aquaculture is comparatively low
D、there is no improvement in conventional farm production
答案
C
解析
细节题。第4段末句提到了三个刺激水产养殖业快速发展的原因,只有C项不是原因之一。注意题干中的EXCEPT。
转载请注明原文地址:https://tihaiku.com/zcyy/3749041.html
相关试题推荐
Alongwiththeletterwashispromise______hewouldvisitmethiscomingChris
Thetuitionfeesare______tostudentscomingfromlow-incomefamilies.A、approa
PASSAGETWO[br]Whatgoeswithasciencebecomingmoreadvanced?Theagreementa
(1)Easternmedicinesarebecomingmorepopularinthewest,butfewpeoplere
Thetuitionfeesare_____tostudentscomingfromlow-incomefamilies.A、approacha
[originaltext]M:HeySusan,whatareyoucomingasthisyear?W:Cominga
[originaltext]M:HeySusan,whatareyoucomingasthisyear?W:Cominga
[originaltext]M:HeySusan,whatareyoucomingasthisyear?W:Cominga
[originaltext]M:HeySusan,whatareyoucomingasthisyear?W:Cominga
Thecountrywasonthevergeofbecomingprosperousandsuccessful.Theunderlin
随机试题
VocationalSchoolsTheuniversitiesarenotabletomeetallthe【T1】____
Thethiefranawayatthe______oftwopolicemen.A、sceneryB、seeingC、screenD、
冰岛雷克雅未克(64°09’N,21°58’w)驶向甲、乙港口的海上运输线曾是“
以下经脉名称错误的是A.手厥阴心包经 B.手少阴心经 C.足少阳三焦经 D
洁净室空气环境使用A.0.2%苯扎溴铵 B.干热灭菌 C.热压灭菌 D.微
可用于抗铜绿假单胞菌的药物是 A.链霉素 B.庆大霉素 C.卡那霉素B
下列关于本公文发文机关署名和成文日期的编排,表述正确的是:() A.成文日
企业财务报表是根据按照会计准则确认和计量的()交易和事项编制的。A.计划发生的
堤心石坡面验收后,应按设计要求抛填块石垫层,其作用是()。A.倒滤层 B.找
慢性粒细胞白血病的临床特点是() A.寒战、高热、出血并迅速衰竭 B.头痛、
最新回复
(
0
)