Dams, fish and fisheries : opportunities , challenges and conflict resolution PDF
Preview Dams, fish and fisheries : opportunities , challenges and conflict resolution
ISSN0429-9345 pCaorvteisraphvoerttoi:calI-ssolhoatafriashdpaamssownhtehreeaRisvtehreKeumpipjeorkipairntFiisnalaDnedn.iTlhfeisfhipsahspsas(sPh(ortiog:htG-haMnadrmsiudlel)a.coFnsAiOstFsiosfhetrwioesseDcetpioanrst,mei.net..thReolmoew)e.r Copyrightedmaterial Dams, fish andfisheries FISHERFIAEOS TECHNICAL PAPER Opportunities,challenges andconflictresolution 419 editedby GerdMarmulla FisheryResourcesOfficer InlandWaterResourcesandAquacultureService FisheryResourcesDivision FAOFisheriesDepartment aFnodod otAOUNfhgrnaergitiaticneouidnlzstautrieon CoRpoymrei,gh2t0e01dmaterial TaCogcphroanrointedm-rchpsmerleaiwucrresaseeocsiddsmoiommlaonaemosnnnwre.ddonatarhdnPctekuadoibitCnolrniosniegoimcscndamp.osteaimirpTsamoevhrsnedricinsbfotdbyohnayrrotetahspiitseehohocrepContafoWsiCmoiltowsrmhoimeliplfmdsluaiibsutCbslstieoishiomsonisnhmrfeoestidondrosafmcsontiasriondttonihsaionothrtinsaeniri>gdntenmeaohpltDtewilhaibiyeCtemnroerhitsmannemttdgn-iihodoaestrecnhsdstspeiie.utvomrboiTneeltpri'nhyo.ecsterpTtrooihCefnpwesofutenmohbvnmreltirimieeaatsspwuthshotseirehi.otodovc.nrniohs'ene'asrcwnfelsdiiuvnonsidifiediwowentanasghssses, TiwotdefenhhrlfaIerioihtmrdtesiometroaUsyaetin,tivgiioentconairenttdpyooifrnNoooanitrdttsshuieeacfomrrtnpoepasndarltcotoioeoyonnrrfeoscdtteoohrfariennmbiiFdpotnolsutgyonhaddtetuhahtpaerehrnioeledensesxtgeA.pianglertrseais.tsctisuaooiltnrotuusnorcfoeoomffnaOactraneegnrryayinncaiioolnzpuigainntnttiirthooyhi,nnes ISBN92-5-104694-8 AawipisIblrunnnrhyliftffooteooohvut-rrrroileimmmmrddngaaaaiehitttpzdtlibiieesoooedtrtnnnohmrpewiDacepriissodrostvsepdodhioirydrsuouvoiuneucrenocttgscdnthsoe.f.aftoefFrnidto©RsAyrrhfeeOefatpsepu.ooarlcrdl.liooVuyoetopidcrhrayoauaelrgrtccweiitrkogCoditinhhetnhootiltaenwelelrhlenfco.eaToolpdnredmegPdermroeuremmtbdsdirhel,isceidssrAisiRspiahenCpeoilpalomnnrrpiingaocun-fcdararcaatutpoolniciommlodtosamninet,esohsMr0nefouci0oflsirco1tpafos0rimlpoua0mmyhtacerpRietdhiubroeigirirpmahtaipeetelaord.SlsmhewieiIoriintssnlvtasdilhttiayecohhorreuoiiness.trs ©FAO2001 Copyrightedmaterial Ill PREPARATIONOFTHISDOCUMENT ThisFAOFisheriesTechnicalPaperhasbeenpreparedtopublishinformationthatwascompiledasa wpIsroseruvkeiiso,nugsilniyptaispauteebrdmibftoytreWdtChetDoWWoinrCltDhdeiCraospmrmFociAesOss'sisoofncorneotvnriiebDwuatiimnogsnth(teoWvCtaDhre)io.TuhsTeihmmeaptaimccattseRraeinvadliebpwernseesfoientnsteEodnfvdhieraromensimnewnhwtiaalsle preparingaglobalreviewon"DamsandDevelopment",TheWorldCommissiononDamshad etnhetrruesptoerdtFdAelOivteorerdevtioewW,CanDdtcoonrteapionrtedupfoonu,rminadjiovridfuiaslherreyviiseswusesthiantrhelaadtiboenetnowproerpladreddamtso.aAdsdraegsrseetdh,e followingcomplexesofquestions: Havereservoirfisheriesbeensuccessfulinreplacingriverfisheries? Whichmigrationmitigationmeasuresexistandhoweffectivearethey? Whatistheinformationbaseandcapacityrequiredforeffectivemanagementoffisheriesthrougha damprojectcycle(appraisal,design,construction,operation)? Whataretheexistingcriteriaandguidelinesconcerningdamsandfisheries? WFuerthaecrkmnoorwel,etdhgeefiwnaintchialthsaunpkpsortthbeyuWseCfuDlicsohmemreewntitshdaunldyascukgngeoswtlieodngsedb.yDr.T.Petr,Australia. Distribution: FAORepresentatives FAORegionalFisheriesOfficers FAOFisheriesDepartment InlandFisheries Authors This on® Marmulla,G.(ed.) Dams,fishandfisheries.Opportunities,challengesandconflictresolution. FAOFisheriesTechnicalPaper.No.419.Rome,FAO.2001.166p. ABSTRACT TidheentiffoiuerdpbaypetrhsepWroerslednteCdomimnisthsiisopnubolnicaDtaimonsa(dWdrCeDss)maanjdorKAfiOshefrosr'tihsesupeusrpinosreeloaftioWnCDto'sdagmlsobaals reviewon"DamsandDevelopment”.Characteristicsofriverandreservoirfisheriesinvariousregions oftheworldarereviewed.Asreservoirsprovidesignificantcontributionstoglobalfreshwater fisheries,productionfiguresforreservoirsinAfrica.Asia.LatinAmericaandtheCaribbean,aswellas fortheCommonwealthofIndependentStates,arementioned.Alsofishproductionfiguresforlarge riversareprovided,emphasizingtheimportanceoffloodplainsforfishproduction.Theextentto whichfisheriescanbedeveloped,sustainedorprotectedalongriverineecosystemsmodifiedbydams reflectsbasintopography,geologicalfeatures,watershedhydrology,andclimate,aswellas engineeringfeaturesofthedamitself,andoperationalprogrammesforretentionandreleaseofwater fromthereservoir,throughthedamandintothetailwaters.Compensationforlossinyieldfromriver fisheriescanbedifficulttoachievethroughdevelopmentofreservoirfisheries.Evenifcompensation isachievedfromafisheryperspective,specificneedsoffishspeciesthatarenotincludedinthe fishery,butarethreatenedorendangered,mustbeconsideredtoavoidnegativeimpactstothesefishes. Theimportanceoffreelongitudinalpassageofriverfaunaisstressed.Theconstructionofdamscan blockordelayupstreamfishmigrationandthuscontributetothedeclineandeventheextinctionof speciesthatdependonlongitudinalmovementsalongthestreamcontinuumduringcertainphasesof theirlifecycle.Mortalityresultingfromdownstreampassagethroughhydraulicturbinesorover spillwayscanbesignificant.Habitatlossoralteration,dischargemodifications,changesinwater qualityandtemperature,increasedpredationpressure,aswellasdelaysinmigrationcausedbydams, ainrefidsihspcaussssecdo.nsVtarruicotuisont,ecahrneicstarlesssosleudt.ioAnsnaorne-esxuhgaguessttievdearnedviceriwtiocfalthpeoicnutrsr,etnhtatsthaatuvseotfotbheecuosnesiodfefriesdh NfaocriltihtiAesmearticdaa,msEutrhorpoeu.ghLoauttinthAemewroirclad.iAsfrpirceas.enAtuesdt,ralwiiat.hNtehewmZaeianlatnadr.geJtasppaenciaensdcAosnisai.deTrheedmfarionm challengestomaintainingandenhancingreservoirfisheries,aswellasassociatedsocialandeconomic benefits,arefishhabitatandenvironmentaldegradation,inadequatefishassemblages,inefficient harvestingsystems,stakeholderconflicts,andinsufficientinstitutionalandpoliticalrecognition. dFeisvheelroypmaednmtisniasftfreacttoirnsgffiisnhderiitesdiafnfidcualqtuattoicdeefnevnidronthmeentinstearreestsoftoefntmheaidresewcittohr;mdienciismiuomnsorovneor considerationofthesesectors,mainlyforlackofreliableeconomicvaluationandlackofpoliticalclout bytheusers.Giventhislackofpoliticalpower,theinterestsandneedsoffishersandfisheries managersareoftennotproperlyrepresentedwithinexistingpoliticalframeworks,andthusneglected orignored.Fisheryadministratorsandstakeholdersshouldseekeveryopportunitytocommunicate theirneedsanddemonstratethevalueoffisheriesandtheaquaticnaturalresources.Themulti-sectoral natureofwaterresourcesdevelopmentinthecontextofsocio-economicdevelopmentmustbe recognized.Managementpolicymustbecountry-specificandtakelocalconditionsintoaccountas blindapplicationofimportedprinciplesmayleadtopolicyfailures.Fisheriesmanagementcapacity aidnedntiinffiocartmiaotni,ondbaamsedreesqiuginr,emdeantmsaprreojreecvtieawpperdaifsoarl,thedsaimxpchoanssetsruocftitohne,ddaammproojpeecrtatciyocnle,ani.de.ddaamm decommissioning.Effectiveenvironmentalassessmentandmanagementcoupledwithimprovements indesignofcivilengineeringstructureshasmadesomerecentdamprojectsmorefishfriendlyand environmentallyacceptable.Theneedfordraftinglegalinstruments,whichwillfacilitatemodification ofdamstructurestoincorporatemitigationmeasuresandhelpalteringdamoperationrulestobemore beneficialtofishbiodiversityandfisheries,isemphasized. Copyrightedmaterial ) TABLEOFCONTENTS Page THEINFLUENCEOFDAMSONRIVERFISHERIES 1 (byDonaldC.JacksonandGerdMarmulla) ENVIRONMENTALISSUES.DAMSANDKISHMIGRATION 4£ IbyMichelLarmier> ARERSEEVRIVEOWIROSFAGMU)IDAASNSCOCEIAANTDEDCRRIITVEERRIIANEFOERNVMIARNOANGMIENNGTS TOBENEFITFISHANDFISHERIES 21 (byLeandroK.Miranda) MENAVNIARGOENMMEENNTTAOLFIFSISSUHEESR.ICEASPAAFCFIETCYTAENDDBIYNDFAORMMSATIONBASEFOR U2 (byGarryM.Bcrnacsck Copyrightedmaterial I THEINFLUENCEOFDAMSONRIVERFISHERIES by DonaldC.Jackson ProfessorofFisheriesManagement DepartmentofWildlifeandFisheries MississippiStateUniversity Box9690,MississippiState,USA and GerdMarmulla FisheryResourcesOfficer InlandWaterResourcesandAquacultureService FoodandAgricultureOrganizationoftheUnitedNations VialedelleTermediCaracalla,00100Rome,Italy EXECUTIVESUMMARY Theextenttowhichfisheriescanbedeveloped,sustainedorprotectedalongriverineecosystems modifiedbydamsreflectsbasintopography,geologicalfeatures,watershedhydrology,andclimate,as wellasengineeringfeaturesofthedamitself,andoperationalprogrammesforretentionandreleaseof waterfromthereservoir,throughthedamandintothetailwaters.Compensationforlossinyieldfrom riverfisheriescanbedifficulttoachievethroughdevelopmentofreservoirfisheries.Thelargerthe river,andthemoredownstreamthelocationofthedam,thelesspotentialthereisforareservoir fisherytocompensateintermsofyieldforlossessustainedbytheriverfishery.Compensation potentialsapparentlyarehigherinshallowerreservoirsintropicalregionsthantheyareindeeper reservoirsandinmorenorthernlatitudes.Evenifcompensationisachievedfromafisheryperspective, specificneedsoffishspeciesnotincludedinthefishery,andorthatmaybethreatenedorendangered, mustbeconsideredtoavoidnegativeimpactstothesefishes. Thereisconsiderablevariabilityinfisheryproductionamongandwithinregionswithrespectto reservoirandriverfisheries.Riverfisheryproductionisdependentonlengthofriver,catchmentarea and.forspecificsectionsofrivers,thepositionofthesegmentalongtherivercontinuum.Intropical andtemperaterivers,fishyieldsperunitsurfaceareaareconsiderablygreaterinriverswithflood pulsesandfloodplainsthaninnearbyimpoundmentswherefloodpulsesarereducedorabsent.Inthe tropics,forexample,large,slow-flowingriversaveraged30-100kg/hayearandthefloodplains averaged200-2000kg/ha/year.Fishyieldsinfloodplainriverecosystemsaredirectlyrelatedtothe heightanddurationoffloods.Ifalteredhydrologyresultingfromdamscurtailsoreliminatesnormal, historicaldownstreamflooding,overallfisheriesproductionthroughoutthesystemcanbenegatively impacted. InAfrica,largereservoirssubjecttomoderatetoheavyfishing(e.g.Kariba.Nasser/Nubia,Volta),have yieldsranging27-65kg'ha/year.Incontrast,however.LakeKainji.anotherlargeAfricanreservoirhas yieldsofonly3.5-4.7kg/ha'year.Formedium-sizedAfricanreservoirs,estimatedmeanyieldwas approximately80kg'ha/year.MeanyieldfromavarietyofSub-Saharansmallwaterbodieswas 329kg/ha/year.Substantialoveralllossestooverallfisheryproductioninriverbasinshavebeen rpeeproyretaerdwaesraerleossutltinofthdeaSmenceognasltrRuicvteironsyinstAefmriacsa.aFroersuletxaomfpdlae,macnonasntnruuacltinoentaslossoscioafte1d1w25it0htLaokfefidseh Guiers. Copyrightedmaterial MajorconcernthroughoutAsiaisthatmovementsofmigratoryfishesalongrivercourseswillbe blockedbydams.Additionally,dewateringofstreamchannelsimmediatelydownstreamfromdams canbeaseriousproblem.ReservoiryieldsinChinaarereportedtorangefrom127to152kg/ha/year, butthesehighvaluestendtobetheresultofintensivestockingprogrammes.InIndiareservoirfishery yieldsrangefrom11.4(largereservoirs)to49.5(smallreservoirs)kgha/year.Reservoirfishery yieldsinSoutheastAsia(e.g.Malaysia)andCentralAsiaandKazakhstanarereportedtobemuchless thaninotherpartsofAsia,withvaluestypicallyaround15kg'hayearorless.YieldsinSriLanka rangefrom40to650kg'hayear.buttheseyieldsareprimarilytheresultofstockingreservoirswith exoticspecies. InAustralia,damshavegenerallyresultedinnegativeimpactstonativeriverinefisheswhile encouragingexoticspecies.Thishasbeenattributed,inpart,todisruptionofseasonalfloodcycles,and todamsactingasbarrierstofishmovements.TheMurrayRivernowhasthelowestcommercialfish yieldperkm:offloodplainofanyoftheworld’smajorrivers,althoughhistoricalcatcheswere comparable.InreservoirsconstructedonQueenslandrivers,fishstocksaremaintainedthrough stockingofnativefishspecies. InLatinAmericaandtheCaribbean,reservoirfisheryyieldstendtobehigherfortheCaribbean(Cuba 125kg/ha/year;DominicanRepublic29-75kg/ha/year)thanisgenerallyrecordedforCentral andSouthAmericareservoirs.RecordsavailableforBrazil(2.1-11.5kg/ha/year)andPanama (4.8-63.2kgha/year),suggestthatreservoirscanhavequitevariableyields,dependingonflushing rates,elevation,andbasinmorphology.Higheryieldsthroughouttheregiontypicallyresultfront stockingofexoticspecies. Similarpatternsexistwithregardtofisheryyieldsfromreservoirsintemperatezones.Theaverage yieldfromNorthAmericanreservoirsisonly24kg'ha/year.InEurope,recordsindicatereservoir fisheryyieldsrangingfrom21to76kg'ha/year. Damscanenhancesomeriverinefisheries,particularlytailwaterfisheriesimmediatelybelowdams thatresultfromdischargeofseslon(primarilyplankton)fromtheupstreamreservoir.However, dischargeofsestonistypicallyattenuatedquicklydownstreamfromthedam,withcorresponding attenuationoftheassociatedfisheries.Ifdischargeisfromthehypolimnionofthereservoir,lowered temperaturesinthereceivingtailwatercancurtailoreliminatewarmwaterriverfisheriesandrequire stockingofexoticcoldwaterspecies,eg.salmonids(assumingthatthewaterissufficiently oxygenated).Productivetailwaterfisheriestargetingthesecoldwaterfishescanresultbutgenerally requiresupplementalhatcheryprogrammesandintroductionofcoldwaterinvertebratestoserveas forageitemsforthesefish.InNorthAmerica,yieldfromcoldwatertailwaterfisherieshavebeen recordedforupto339kg/ha'yearwithfishingeffortseventimeshigherthantherespectiveupstream rSeosmerevoiorf.Tthhiessehicgohldawmaotuenrttoafilewfaftoretrrfeifslheecrtisehsigchansteanxdtienngdsctooneskiodfersaabllmeondiidsstainncetshe(see.ge.nv>iro1n5m0entksm. downstreamfromdamsinArkansas.USA). Reservoirsresultingfromconstructionofdamscaninsomesituationsresultinproductivefisheries. Thisisparticularlytrueforlocationswhereriverfisheriescontributelittletooverallnationalfishery yields.Beneficialreservoirfisheriesalsoexistindrierregionswheredamsareconstructedfor agriculturalirrigation,andfisheriesaresecondaryconsiderations.Benefitsseemmorepronouncedfor smaller,shallowerreservoirsthathavereasonablyhighconcentrationsofdissolvedsolidsandthatare locatedintheupperreachesoftheirrespectiveriverecosystem.Stockingofexoticspecies(bothin arensdercvuolitrusraalnldyainccteapitlawbalteersto)tchaenseunrhraonucnediynigelhdsu,maasnlpoonpgulasattihoen.exIontitchifsisrheegsaradr,eceanuvtiiroonnmisenwtaarlrlayntseodunidn cultureswherefishingandfishconsumptionarenon-traditionalactivities.Buildingreservoirsinthe contextofsuchculturesmaynotachieveprojectedfisherybenefitseventhoughexploitablefishstocks mayexist. Copyrightedmaterial 3 Developmentofreservoirplanktonreflectsnutrientscapturedbythereservoir.Thisplanktongenerally relatesdirectlytofisheriesproductionoftherespectivereservoir.However,whenseveraldamsare constructedonupstreamtributariesofariverecosystem,thecumulativeeffectsofthesedamscanbe thatofblockingtheflowofnutrientsoriginatingfromthecatchmentbasinfromthelowerreachesof theecosystem,therebynegativelyaffectingfisheriesproductionindownstreamportionsofthe ecosystem(includingestuaryandmarineenvironments).Damsalsocanblocktheflowofnutrients fromoceanenvironmentsupstreamintoriverineenvironmentsbypreventinganadromousfishesthat dieafterspawning(e.g.Pacificsalmonids)fromdepositingthesenutrientsviacarcassdecayin upstreamreaches. Furthermore,andiftheriverinefisheryissustainedbystocksofmigratingfishesthatbecomeblocked byadam,theriverinefisherycanbeseverelyimpacted.Ifthemigratingfishesareanadromousor catadromousspecies,linkedtooceanfisheries,orthoseofinlandseasorlargelakes,thenegative impactstothesestocksandtheirassociatedfisheriescanbecatastrophic. Becausedamstendtobeconstructedtoenhancesocio-economicdevelopmentactivities,theytendto attractpeopleandindustry.Subsequently,riverecosystemscontainingdamsmustcontendwith secondaryenvironmentalpressuressuchasincreasesinpollutionaswellasincreasedexploitationand extractionoftheirresources(primarilywater,fish,andsubstrates),thatareindependentfromandin additiontothedirectinfluencesofdamsandreservoirsonthephysicalandbiologicaldimensionsof thesystem. Determiningtheimpactofdamsonriverecosystemsandtheirassociatedfisheriesdependsonspatial andtemporalscalesofinterest.Ifspatialscalesaresufficientlylarge(planetar)',continental,perhaps regionalandbiome),andtemporalscalesaresufficientlylong(decades,centuries,millennia),placing adamonariverdoeslittlemorethanincreaseatmosphericwatervapour(throughevaporationfromthe reservoir),reducelong-termstreamfiowsdownstream,desiccateterrestrialenvironments,salinate esxutrirnocutnidoinnagtavraeraiso,usanscdalsehsifotfbrieos-oelnuteirogne)t.icWeproccaensnsoetsas(ssiogmnethoeftwehrimcsh“gcoaond"leoard"tboadf"lortaolanayndoffatuhneasle phenomena.Theysimplyreflectanthropogenicactivityonthisplanet.However,ifwelookatsmaller spatialandshortertemporalscales,(whichweobviouslycannotneglectsincewehavetomake decisionsthathavebearingsonthepresentandfuturehumangenerationsandalsoonpresentand futurelivingaquaticresources)wehavetokeepinmindthatdamsandtheirreservoirs(whichcan undercertaincircumstanceshelptobetternourishpeopleandmaketheirlivelihoodsmoresustainable) can-ifwronglyplaced-alsoleadtosignificantdeclinesoffisheriesandtoextinctionofaquatic species. Givensufficienttime,geophysicalandclimaticforceswilloverrideanderodethephysicalinfluences oCafudtaimosn,iasnwdarervaonltuetidontaoryavefrotrcepsotwenitlilaalltneergahtoiwveliifempfaocrtmssfirnotmeradctamwsithwitthherreesspuelcttintgoefnivsihreorniemsenatnsd. associatedhumaninteractionswiththeseandotherriverresources.Suchcautionunderscoresthe realitythatpeoplearedependingonus.thescientists,theresourcemanagers,thedecision-makers,to beright. Copyrightedmaterial
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