Demonstratingthebenefitsoflarge-Scaleriverrestoration

TheMurrayRiverResnaggingExperiment

Demonstratingthebenefitsoflarge-scaleriverrestoration

Background

Widespreadremovalofstructuralwoodyhabitat(snags)intheMurrayRiverisrecognisedasamajordriverofdeclines inriverhealthandnativefishpopulations.Toalleviatethishistoricaldegradation,theMurray-DarlingBasinAuthority’s(MDBA)‘TheLivingMurray’(TLM)programundertookalarge-scalehabitatrestorationprojectofresnaggingtorestore4,450woodyhabitats(>1tonneeach)throughout194kmoftheMurrayRiverbetweenLakeHumeandLakeMulwala.Todate,thisprojectisthelargestrestoration(andsubsequentmonitoring)projectofitskindwithinAustralia.

ResnaggingworksbeingconductedintheMurrayRiver(PhotoCredit:MartinCasey)

Monitoring aresponse

Complementingthisrestorationwasaseven-yearresearchandmonitoringprogram(2007-2013)whichwasdesignedtoquantifytheecologicalbenefitsoftherestorationefforts.Weinvestigatedthepopulationresponsesoffouriconiclarge-bodiednativespeciesincludingMurraycodMaccullochellapeelii,troutcodMaccullochellamacquariensis,goldenperchMacquariaambiguaambigua,andsilverperchBidyanusbidyanus.Ourmonitoringstrategywasdesignedtoestimateannualchangesinpopulationsizeofeachofthese fournativespecieswithintheresnaggedreachaswellastworeference

reaches(LakeMulwalaandtheOvensRiverbelowWangarattaand;belowLakeMulwalatothetownshipofTocumwal),wherenorestorationwasundertaken.Thecoredataforthemonitoringprogramcomprisedanextensivemark-recaptureprogramimplementedbyannualboatelectrofishingsurveysof335-424sitesannuallyfrom2007to2013.Thisdatawascomplementedwithmeasuresofspecies-specificageandlengthstructure;biomass,asderivedusingregionspecificlength-weightrelationships;movementdataderivedfromapproximately1400radio-taggedfish;andfisherydependentdatacollectedthroughananglerlogbookprogram.Annualchangesinpopulationsizeforeachofthespeciesinourtargetriverreacheswerethenassessedusing aBayesian capture-recapturemodeltojointlyanalysethedifferenttypesofdatacollected.Themodelallowedformigration,individualvariationincapturerates,movementbetweenstudyreaches,deaths,andsurvival,andaccountedforchangesinelectrofishingcaptureefficiencyfortargetspecies.

BoatelectrofishingbeingundertakenintheMurrayRiver(PhotoCredit:JarodLyon)

Anadditionalcomponentoftheprojectwasthedevelopmentofaresearchanglerprogram whichcommencedinJuly2007.Theresearchanglerprogramenabledlocalanglerstobecomeinvolvedinalarge-scaleriverrestorationprojectandbecomeavaluablepartofthemonitoringbycollectinginformationessentialtothestudydesign.

TheMurrayRiverResnaggingExperiment

MurraycodwithanexternalT-Bartag(PhotoCredit:JarodLyon)

Has itworked?

Researchanglersinvolvedintheproject(PhotoCredit:JustinO’Mahony)

2012

Thisstudyincreasedcommunityawarenessandactivelyengagedmultiplestakeholdersinbuilding knowledgearoundtheimportanceofhealthyhabitatfornativefishandriverhealth.

Thisstudyhasprovidedrobustscientificevidence oflarge-scaleriverrestorationeffortsenhancing nativefishpopulations,whichfacilitatesecological andrecreationalfishingbenefitswithintheMurray River.

Estimatedpopulationsize(totalnumberoffish200mminlengthinsamplingsites)ofMurraycodbetween2006and2013withintheresnaggedreach.Greyshadingrepresents95%credibleintervals.

ThisprojectwasfundedbytheMurrayDarlingBasinAuthority’sLivingMurrayProgram(TLM).

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PublishedbytheVictorianGovernmentDepartmentofEnvironmentandPrimaryIndustriesMelbourne,[July2014]

©TheStateofVictoriaDepartmentofEnvironmentandPrimaryIndustriesMelbourne[2014]

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PrintmanagedbyFinsburyGreen(Jul2014)ISBN978-1-74146-018-6(Print)

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