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1、水产养殖专业英语OceanToday一OpenRivers,AbundantFishManyspeciesoffish,includingthosethatareimportanttotheU.S.economy,migratefromtheoceantofreshwaterriversandstreamstospawn.Afterspendingyearsintheocean,fishinstinctuallyreturntothesameriverswheretheywereborn,makingtheoften-treacherousjourneyupstream.S
2、omefish,likesalmon,travelnearlyathousandmiles.Iftheymakeitpaststrongrivercurrentsandhungrypredators,thesedeterminedfishmaythenfindthemselvesblockedbyman-madebarriers,suchasdams.AsmanyastwomilliondamsandculvertsarelocatedinthestreamsandriversoftheUnitedStates. Unfortunately,manyofthemblocka
3、ccesstomorethan600,000milesofriverhabitat. Special“fishladders”arebuilttohelpfishpassoverthesedamssotheycancontinueswimmingupstreamtoreachtheirspawninggrounds.Someofthedamsthatblockfishpassageareimportantproducersofcleanelectricalpower.Butotherdamsinthewayoffishmigrationsareoldandoutofuse,
4、evendangerousiftheyareleftuncheckedandnotmaintained.Oftenthebestsolutionistotakethemdown.In2007,PortlandGeneralElectricremovedtheMarmotDaminOregon,whichopened100milesoffreshwaterhabitattothousandsofmigratingfish.Amongthemwereseveralsalmonspecies,whicharelistedas'threatened'undertheEndanger
5、edSpeciesAct.TheMerrimackVillageDaminNewHampshirewasanothersuccessfuldamremoval.Thesmalldam,originallybuiltinthe1730s,hadfallenintodisuseanddisrepair.Loiselle:“RemovaloftheMerrimackVillageDamisgoingtomakewayforriverherring,Americanshad,Americaneels,andAtlanticsalmonthathavebeenblockedfromm
6、igratinguptheSouheganRiverforalmosttwoandahalfcenturies.…[bigsmile]weanticipatethatwe’regoingtoseemanymorefish,otherwildlifeintheareaandinourriversystemthanwe’veeverseenbefore.”NARRATOR:Whenweremoveabarriertomigratingfish,wenotonlyincreasethehealthandquantityoflocalfishpopulations,wealsoin
7、creasetheoverallhealthoftheriverandeventheeconomichealthofthecommunity.NOAAhashelpedremoveover50damsin12years,enablingmigratoryfishtofinallyreachtheirhistorichabitat.二FishonaFarmEveryweekendsmallfarmersaroundthecountryheadtotheirlocalfarmer’smarketstoselltheir
