Conservation Biology of the Golden Galaxias (Galaxias auratus) (Pisces: Galaxiidae) Scott Anthony Hardie AthesissubmittedforthedegreeofDoctorofPhilosophyattheSchoolof Zoology, UniversityofTasmania,Hobart,Tasmania,Australia 2007 Declaration of Originality Thisthesisdoesnotcontainanymaterialwhichhasbeenacceptedforthe awardofanyother degreeordiplomainthe UniversityofTasmanianoranyotheruniversityorinstitution.The materialthisthesiscontainsis,tothebestofmyknowledge,originalexceptwheredue acknowledgementismade. MrScottA.Hardie June2007 Statement of Authority of Access Thisthesismaybereproduced,archived,and communicatedinanymaterialforminwholeor inpartbythe University ofTasmaniaoritsagents,andmaybemadeavailableforloanand copyinginaccordancewiththe CopyrightAct1968. MrScottA.Hardie June2007 i Statement of Co-authorship Thefollowingpeopleandinstitutionscontributedtothepublication(orsubmissionfor publication)ofsomeoftheworkundertaken aspartofthisthesis: Preface Candidate*†(96%),LeonA.Barmuta(2%),RobertW.G.White*(2%) Chapter2. Candidate*†(82%),JeanE.Jackson†(6%),Leon A.Barmuta*(10%),Robert W.G.White*(2%) Chapter3. Candidate*(82%),Leon A.Barmuta*(14%),RobertW.G.White*(4%) Chapter4. Candidate*†(85%),LeonA.Barmuta*(13%),RobertW.G.White*(2%) Chapter6. Candidate*†(85%),LeonA.Barmuta*(13%),RobertW.G.White*(2%) Chapter7. Candidate*†(80%),StephenB.Pyecroft‡(10%),Leon A.Barmuta*(8%), RobertW.G.White*(2%) *SchoolofZoologyandTasmanianAquacultureandFisheriesInstitute,Universityof Tasmania,PrivateBag5,Hobart,Tasmania7001,Australia †InlandFisheriesService,POBox288, Moonah, Tasmania7009,Australia ‡AnimalHealthLaboratory,DepartmentofPrimaryIndustriesand Water,POBox46,Kings Meadows,Tasmania7249,Australia L.A.B.supervisedtheadministrationofthesestudies,helpeddevelopthekey concepts,and assistedwithdataanalysesforeachpaper.R.W.G.W.helpedrefinethe contentofthese papers.J.E.J.andS.B.P.contributedtothedevelopmentofthecontentof Chapters2and7, respectively,andS.B.P.alsoprovidedlaboratory assistanceforChapter7. ii Wetheundersignedagreewiththeabovestated“proportionofworkundertaken”foreachof theabovepublished (orsubmitted)peer-reviewed manuscriptscontributingtothisthesis: Signed: ……………………………… ……………………………… Dr LeonA.Barmuta DrSusanM.Jones Supervisor Head of School SchoolofZoology &TAFI SchoolofZoology UniversityofTasmania UniversityofTasmania Date: June2007 iii Summary Summary 1.Thegolden galaxias(GalaxiasauratusJohnston1883)isathreatened,nondiadromous galaxiidthatisendemictolakesCrescentandSorellincentralTasmania,Australia.Similarto thelacustrinehabitatsof otherthreatened galaxiidsinthisregion,theCrescent-Sorellsystem hasalteredhydrology andcontainsalienfishes.Theobjectiveofthisstudywastoexamine crucialaspectsofthebiologyandlifehistoryof G.auratus(includingage,growth,population structure,reproductivebiologyand recruitmentdynamics)intheseimpoundedhighlandlakes thatarelikelytobeinfluencedbyhydrology andlakemanagement.Aninvestigationof populationmonitoringmethodsforthisspecieswas alsoconducted.This workaimedto assessthevulnerabilityof G.auratuspopulations,andgaininsightintothe ecological attributesofotherthreatenedgalaxiids,threatstothisfamilyandothersimilarsmall-sized lenticspecies. 2.Analysisof a5year,monthly recordofpopulationandspawning attributesofboth populations,alongwithdetailedenvironmentaldata,includingwaterlevels andwater temperatures,showedwaterlevelsandthe accesstheyprovidetospawning habitatstrongly limitthereproductionandrecruitmentof G.auratusin LakeCrescent.Detailedlifehistory attributesofthisspecies supporttheseconclusionsandfurtherillustratethevulnerabilityof thisspeciestohydrologicalmanipulations. 3.Gonaddevelopmentbeganinmidsummerand spawning wasspreadoverlateautumn– earlyspring,peakingin winter.Demersaladhesive eggs(~1.5mmdiameter)werefoundon cobblesubstrates(c.20250mmdiameter)inlittoralareas(c.0.2-0.6mdeep).Patternsin larvalemergenceandabundancewere associated withthetimingofinundationofspawning habitats.In LakeCrescent,seasonalabundancesof larvaewerestrongly relatedtothe iv Summary magnitudeof waterlevel risesduringspawningand eggincubation(i.e.May-September). Despitetheoccurrenceoflarvaeinpelagichabitatsinbothlakesduringwinter,theydidnot growuntilspring;thus,couplingofwaterlevelandwatertemperatureregimesisimportant forrecruitment.Galaxiasauratusreachedupto240mminlengthand~10 yearsof age; however,most grewto<130mmandthe0+,1+and2+ yearclassesdominatedtheage structureofbothpopulations.Thereweremore>2+ fishin LakeCrescent wherepredatory introducedsalmonidswerelessabundantthaninLakeSorell.Growthoftheselargerfishwas slowerduetolimitedaccesstocomplexlittoralhabitatsin LakeCrescent. 4.In atranslocatedpopulation,fykenetting atnightwasthemosteffectivesamplingmethod owingtoincreased activityatnightandcover-seekingbehaviourbythisspecies.Inthelakes, monthly catchesof G.auratusincreasedsubstantiallyduringspawning,suggestingthat knowledgeofthe reproductivebiologyoftargetspeciescanaidpopulationmonitoring programsforother galaxiids. 5.Waterlevelfluctuationsplaya keyroleinthelifecycleof G.auratuswhichrelieson accesstocomplexlittoralhabitatsforspawning,feeding andrefuge.Seasonalhydrological cycles(i.e.risesduringlateautumn–winter)and aminimumwaterlevelof802.20mAHD in LakeCrescentduring autumn(abovewhichlittoralareasof cobblesubstrateareinundated) arecriticalto G.auratuspopulations.Becausemanylacustrine galaxiidsuselittoralhabitats duringseverallifestages,alterationstowaterlevelsandseasonalhydrologicalregimesmay impactontheirpopulationsbyrestricting accesstothesehabitatsatcriticaltimes.Toassist themanagementofother threatened galaxiidspecies,furtherstudiesshouldidentifyhabitats thatlimitpopulationsbasedonspeciesbiologyandexamineecologicaltraitsthatprovide resiliencetomajorperturbations. v Acknowledgements Acknowledgements Firstly,Iwouldliketoacknowledgethesupport giventomebymysupervisors,Leon Barmuta andRobertWhiteoftheSchoolof ZoologyandTasmanianAquacultureand Fisheries Institute(TAFI),UniversityofTasmania (UTas).Leonadministeredthisstudyand helpeddefineitsdirection.Hisbroadunderstandingof conservationbiologyand contemporarymanagementstrategiesforthreatenedtaxawereof greatvaluetotheproject. Leonhasawealthofknowledgeregardingthe analysisofecologicaldata andhisguidance (andunrelentingpatience)inthisareawasmuchappreciated.Rob’sthoughtsonthebiology ofthisspeciesandknowledgeofthe family Galaxiidaeimprovedthefinalcontentofthe thesis. Giventhevaried componentsofthisthesisandsubstantialamountoftimespentinthefield,I wasfortunatetohavereceivedassistance frommanypeople.Iamespecially indebtedtothe Tasmanian Inland FisheriesService(IFS),where I initiallybeganstudyingthegolden galaxias.Kindly,IFSallowedmetousemuchof thatinformationforthisthesisandprovided furtherlogisticalsupport onmanyoccasions.J.Diggleprovided guidanceinearlystagesof theproject.Fieldwork,whichwasconductedinthevariable andsometimesarduous conditionsoftheTasmanianCentralPlateau,could nothavebeenundertakenwithout assistancefrom IFSstaff includingB.Mawbey,A.Uytendaal,K.BrehenyandH.Mulcahy, T.Byard,R.Walker,A.MacDonald,D.Jarvis,C.Wisniewski,M.Schottmeier,P.Donkers, A.Taylor,R.CordwellandS.Frijlink.Further assistancewas alsoprovidedby B.Mawbey, K.Brehenyand H.Mulcahy (processingoflarvalsamples),A.Uytendaal(watertemperature modelling),D.Hardie(preparationoflocationmapsandaquaticmacrophyteidentification), A.Taylor(otolithpreparationandsectioning)and S.Solman(generalfield assistance). Additionally,S.TraceyandG.Ewing (TAFI)providedguidanceintheinterpretationof vi Acknowledgements otolithincrementalstructureandS.Tracey alsoperformedthesecondaryotolithreadings. S.Wotherspoon(UTas) helpedwithgrowthmodelling,M.HigginsandT.Wilson (DepartmentofPrimary IndustriesandWater(DPIW))withmicrobiologicalandmolecular geneticwork,andC.Marshall(DPIW)withhistopathologicaltests. Thefollowingpeoplearethankedforfruitfuldiscussionsandcommentsregardingdifferent elementsofthethesis:J.Jackson(IFS),S.Pyecroft(DPIW),T.Raadik(ArthurRylah Institute,Melbourne),R.McDowall(National InstituteofWaterandAtmosphericResearch, Christchurch,New Zealand),B.Mawbey(IFS),R.Stuart-Smith(UTas)andJ.Patil(CSIRO, Hobart).I wouldliketothankmytwo examinersfortheirconstructive commentsand suggestionswhichhelpedstrengthenthecontent of thethesisandwillalsoassistmein preparingfurther associatedpublications.Iamvery gratefultotheMcShanefamily fortheir hospitality andaccessto theirpropertyat allhoursoftheday.Financialsupportwasprovided bytheNaturalHeritage Trust,EnvironmentAustralia(nowDepartmentoftheEnvironment andWaterResources),TasmanianStateGovernmentvia IFS,andTAFIthrougha postgraduatescholarship.TheTasmanianMuseumand ArtGallery,Hobartalsoprovided logisticalsupport. I amvery gratefulto BrettMawbeyandAdamUytendaalformemorabletimesspentonlakes CrescentandSorellandforwhattheytaughtme.I thankmyparents,GrahamandMargaret, for givingmethefreedomtopursueanddevelop my interestinthe aquaticworldduringmy childhood.Finally,Iam especiallythankfultomy wife,Danielle,forherconstantloveand supportthroughoutthisstudy. vii Dedication Dedication Ihopetheknowledge gainedfromthisvolumeof workhelpsraise awarenessofthe uniquenessandimperilledstatusofsmall-sizedinconspicuousfreshwater fishes.Ibelievethe naiveandcarelessviews expressedinthefollowingquote* regardingEuropeanfishesstill holdtruetodayinseveralsectors;tothedetriment ofmanyspecies whichareoflittleorno commercialor recreationalvalue. ‘ThereisalsoalittlefishcalledaStickleback:afishwithoutscales,buthathhisbodyfenced withseveralprickles.Iknownotwherehedwellsinwinter,norwhatheis goodforin summer,butonlytomakesportforboysandwomenanglers,andtofeedotherfishthatbe