Ark sites for White-clAWed crAyfish – guidAnce for the AggregAtes industry

through establishing Ark sites for White-clawed crayfish the aggregates industry can make a significant contribution to conserving one of the uk’s most threatened invertebrates.

cover illustration credit: ian Jackson, the Art Agency. cover picture credit: releasing Wccs © BreA. illustration credit above: ian Jackson, the Art Agency

Contents1 Introduction2 The White-clawed crayfish 2 Biology&ecology2 Distribution3 Conserving the White-clawed crayfish Threats ArkSites RegionalConservationStrategiesfor White-clawedcrayfish

4 Aggregates sites – their potential as crayfish Ark sites5 Selecting Ark sites6 Establishing Ark sites:

habitat creation and enhancement8 Integrating Ark sites10 Monitoring10 White-clawed crayfish and the law10 Conclusions11 Further information

IntroduCtIonThe aggregates extraction industry can, and does, play an important role in nature conservation. Many of the UK’s best wildlife sites are on former extraction sites, and as active sites come to the end of their working lives, they present great opportunities for creating habitats of high value for bees, beetles, dragonflies, spiders and other invertebrates. A whole range of other wildlife including birds, plants, amphibians and reptiles can also benefit. There are many circumstances where there can be a biodiversity gain by the activities of the aggregates industry, positives rather than negatives, and perhaps none more so than for invertebrates.

Post-extraction, habitat creation and site restoration projects have the potential to make a considerable contribution to the conservation of rare and threatened species and maintaining sustainable populations of invertebrates in our countryside –

many of which provide essential ecosystem services such as pollination. There are plentiful opportunities for delivering UK Biodiversity Action Plan (BAP) targets for the conservation of habitats and species. One species urgently in need of help and which can benefit directly from site restoration schemes is the White-clawed crayfish.

The White-clawed crayfish is the only native crayfish in the UK, and is one of our largest freshwater invertebrates. However, it has declined across most of the UK due to a number of threats – all a result of human actions. Unless measures are taken to help the species immediately it will continue to decrease in range and faces extinction in England and Wales during the next few decades.

One approach to conserving the White-clawed crayfish is to establish isolated new refuge sites - known as “Ark sites” - where new populations can be established, safe from threats. There is an urgent need to establish Ark sites to safeguard the long-

term survival of White-clawed crayfish across its UK range.

Flooded quarries, pits and other former aggregates and minerals workings can be potential Ark sites of the future. Setting up Ark sites can be straightforward and inexpensive, and they can easily be incorporated into site restoration schemes. Through establishing Ark sites the aggregates industry can make a considerable contribution to providing a sustainable future for the White-clawed crayfish in the UK. left: White-clawed crayfish (Austropotamobius pallipes).

theWhIte-ClaWedCrayfIsh

Picture credit: White-clawed crayfish © John Mason

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WhIte-ClaWedCrayfIshBiologyandecologyTheWhite-clawedcrayfish(Austropotamobius pallipes)istheonlynativespeciesoffreshwatercrayfishintheUK.Adultscanreachupto15cminbodylength,makingtheWhite-clawedcrayfishoneoftheUK’slargestfreshwaterinvertebrates.

Historically,White-clawedcrayfishoccurredmainlyinstreamsandrivers,buttheyhavealsobeensuccessfulinaverywiderangeofhabitats,fromheadwaterstreamstolowlandrivers,canals,amenitylakesandoldmineralworkings,whereverthewaterqualityisgood.

White-clawedcrayfishspendalloftheirlivesinfreshwaterbutcansurviveoutofwaterforafewhours.Theycancrossshortdistancesonlandtoaccessnewsites;forexampleanindividualcanwalkalongastreambanktoavoidashortsectionoffast-flowingwaterinordertogettomorefavourableglidesandpools.

White-clawedcrayfisharelargelynocturnal,whichhelpsthemavoidpredationbybirdsandfish.However,theyarestillvulnerableatnighttoottersandintroducedmink.Thecrushedremainsofcrayfishcanbefoundinotterspraintandthisissometimesthefirstindicationthatcrayfisharepresentinpreviouslyun-surveyedwaters.Thecrayfishhidefrompredatorsinrefugesonthebedorinthebanksandusetheirprominentclawsindefenceifattacked.Juvenilecrayfishareparticularlyvulnerabletolargepredatoryfishsuchascarpandeels;theyarealsoeatenbyarangeofpredatoryinvertebrates,includingothercrayfish.

White-clawedcrayfishhaveavaried,omnivorousdiet,includingleaflitter,submergedaquaticplants,otherinvertebrates(especiallyslow-movingonessuchasaquaticsnails,worms,someinsectlarvaeandeggs),deadfishandoccasionallyfisheggsorfry.Theactualdietdependsontheageofthecrayfishandtheavailabilityofdifferentfoods.

White-clawedcrayfishmateinautumn,andthefemalesthenbroodtheireggsundertheirtailsthroughthewinterandspring,whencrayfisharerelativelyinactive.Activityincreaseswithwarmertemperatureinspring.Theeggshatch,theyoungdevelopwhilestillattachedandarelaterreleased.Thetimingofreleasedependsontemperature-itcanbeasearlyasJuneinsouthernEngland,oraslateasearlyAugustinnorthernEngland.White-clawedcrayfishareslow-growingandtypicallytakethreeyearstoreachsexualmaturity(at24mmcarapacelengthormore).Thosethatsurvivetomaturitymaylivefortenyearsormore.

distributionTheWhite-clawedcrayfishisfoundacrossEurope,fromIreland,throughEngland,WalesandFrancetoSpain,southernGermanyandAustria,ItalyandtheeasternAdriaticcountriesasfarsouthasMontenegro.ExceptforIreland,itisunderthreatanddecliningthroughoutitsrange.AcrossEnglandandWalesitismuchdiminishedalthoughstillwidelyspreadwhereunderlyinggeologyissuitable.ThemostabundantremainingpopulationsareinnorthernEngland,especiallyCumbria,andpartsoftheMidlands.White-clawedcrayfisharenotnativetoScotland,althoughtherearetwopopulationsthatwereintroducedtositesinthepast.

left: White-clawed crayfish.

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Above: White-clawed crayfish (left) and Signal crayfish (right).

arksitesforconservationActionisalreadybeingtakentoaddressthecausesofWhite-clawedcrayfishdecline,includingimprovinghabitatquality.Despitethispopulationsarestillbeinglostatanalarmingrate.Therearecurrentlynopracticablemethodsforeradicatingnon-nativecrayfishfromcatchments.

White-clawedcrayfishcannotsurvivewheretherearenon-nativecrayfish.Mostoftheirexistingrangehasalreadybeenlost,orwillbelostinfuture,astheinvasionofintroducednon-nativecrayfishcontinuesuncheckedthroughmostrivercatchments.SpecialAreasforConservation(SACs)havebeendesignatedforWhite-clawedcrayfish,butthesearenotenoughtoconservethespeciesontheirown.Furthermore,someexistingSACsitesforWhite-clawedcrayfisharethreatenedbynon-nativecrayfish.

OneapproachtoconservingtheWhite-clawedcrayfishistoestablishisolatednewrefugesites-knownas“Arksites”-wherenewpopulationscanbeestablished,safefromnon-nativecrayfishandcrayfishplague.ArksitesarenowrecognisedasanessentialpartoftheWhite-clawedcrayfishconservationstrategyforEnglandandWales.

AnArksiteforWhite-clawedcrayfishisanisolated,self-containedsitewithrunningwater,stillwater,orboth,whichcansupportahealthy,self-sustainingpopulationofWhite-clawedcrayfishwithlittleneedforongoingmanagement.

AlthoughthereareafewexistingArksites,thereisanurgentneedformanymoretobeestablishedto

ConservIngtheWhIte-ClaWedCrayfIsh

threatsTheWhite-clawedcrayfishhassufferedseveredeclinesinEnglandandWalesandacrossEuropeasaresultofhumanactions.Themaincurrentthreatstoournativecrayfishare:

Invasive non-native crayfishAnumberofnon-nativecrayfishhavebeenintroducedthroughbothdeliberateandaccidentalmeans,mainlythroughaquacultureactivities.TheseincludetheAmericanSignalcrayfish(Pacifastacus leniusculus)whichisthemostwidespreadnon-nativecrayfishintheUKandavectorforcrayfishplague(seebelow).Otherinvasivenon-nativecrayfishincludetheAmericanRedswampcrayfish(Procambarus clarkii),Spiny-cheekcrayfish(Orconectes limosus)andVirilecrayfish(Orconectes virilis),andtheEuropeanNoblecrayfish(Astacus astacus)andNarrow-clawed(orTurkish)crayfish(Astacus leptodactylus).

Allofthesespeciesstronglyout-competeWhite-clawedcrayfishforfoodandotherhabitatresources.Oncenon-nativecrayfishhavebeenintroducedtolakesorrivercatchmentscontainingWhite-clawedcrayfishtheirlossisinevitable.Atpresentthereisnoknownmethodfortheeffectivecontrolofnon-nativecrayfish.Thelargenumberofnon-nativeintroductions,bothdeliberateandaccidental,alsomakescontrolanear-impossibletask.

Crayfish plagueCrayfishplague(Aphanomyces astaci)isafungaldiseasefrequentlycarriedbytheSignalcrayfish.ThediseaseisalwayslethaltoWhite-clawedcrayfish;asingleinfectionisenoughtostartanepidemicthatcaneliminatealloftheWhite-clawedcrayfishinawatercourseorlakewithinafewweeks.Theinfectivesporescansurviveinwaterforuptoabouttwoweeksandcanbetransmittedveryeasilywithfishforstocking,onwetnetsorotherfishinggear.Sporescanbekilledquiteeasilyusingdisinfectantsorbycompletelydryingequipment.

Loss of habitat or habitat qualityHistorically,populationsofWhite-clawedcrayfishwerelostfrommanylowlandriversduetourbanpollution.Inthelate20thcenturytherewereextensivelossesduetoagriculturalpesticidessuchassheepdips.Progressiveimprovementsinwaterqualitymeanthatmanywatercoursesnowhaveadequatewaterquality,butincreasinglyitistherapidlyexpandingpopulationsofSignalcrayfishthatareabletotakeadvantageandmoveintothecleanerriversandstreams.

Otherthreatsinclude:erosionofover-grazedriverbanks;siltationfromsoilrun-off;modificationofwatercoursesfordrainageorflooddefence;andabstractionofsurfacewaterorgroundwater,suchthatformerlyperennialstreamsdryoutperiodically.

Picture credit: crayfish © Peter sibley

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safeguardthelong-termsurvivalofWhite-clawedcrayfishacrossEnglandandWales.SettingupArksitescanbestraightforwardandinexpensive,andcanprovideasustainablefuturefortheWhite-clawedcrayfishintheUK.

regionalconservationstrategiesforWhite-clawedcrayfishWhite-clawedcrayfishfacesimilarthreatsthroughouttheirdistributionacrossEnglandandWales,butthecurrentsituationdiffersbetweenthevariouscountiesandregions.InsomecountiestherearehardlyanyremainingpopulationsofWhite-clawedcrayfish,whilstinotherstherearestillrelativelyextensivepopulationsinrivers,eventhoughthefutureprospectsforthosepopulationsmaynotbegood.Localstrategieswillneedtovaryaccordingly.

LocalactiongroupsforconservationofWhite-clawedcrayfishhavealreadystartedinsomeareas(see“Furtherinformation”).Theiraimsare:• toidentifyexistingpopulationsofWhite-clawedcrayfishforprotectioninsitu,and/orasdonorpopulationsforpotentialArksites.• toestablishthedegreeofthreatto

currentpopulations.• toreducetheriskstoexistingpopulationswherefeasible(e.g.throughpubliceducation).• toidentifypotentialArksites.• toestablishArksitesandmonitortheirsuccess.

Inmostcases,theEnvironmentAgencyandNaturalEngland/CountrysideCouncilforWaleswillbeinvolved,oftenwithlocalcouncilsorNationalParksAuthoritiesandthelocalWildlifeTrustandotherstakeholdergroupsandindividualstoo.LocalactiongroupsareakeysourceofinformationinhelpingtoidentifypotentialArksitesandsupportinitiativesonindividualsites.

Uptodatelocalinformationisessential,e.g.frequencyofcrayfishplagueinthesurroundingarea,theproximityofnon-nativecrayfishandtheirrateofexpansion,thelocationofremainingWhite-clawedcrayfishpopulationsandhowthreatenedtheyare(i.e.whethertheycanbeusedasdonorstocktostartnewpopulations).

ThelocalorregionalsituationwilldictatetheapproachtoArksiteselectionandassessment.InsomeregionstheremaybeplentyofpotentialArksitesandthereforescopetoselectthebestones,orcreatealargenumberofthem(orideally,doboth).InotherregionstheopportunitiesaremuchmorelimitedandpotentialArksitesmayhavemoreassociatedrisks,e.g.existingangling.Theurgencyofneedwillalsoinfluencetheapproach,i.e.inregionswithfewremainingpopulationsofWhite-clawedcrayfishwhichareunderthreatofimminentextinctiontheremaybeacaseforadoptinga“nowornever”approachandacceptingsuitablebutsub-optimalArksitesifoptionsarelimited.Thismayprovidetimetoseekadditional,morefavourable,Arksitesinthelongerterm.

Ataregionallevelcomputermapping(GIS)canbeusedtoidentifysitessuitableforArksitecreation;thisscopingapproachhasbeentrialedbyBuglifeinSouthWestEngland(see“Furtherinformation”).

Above: Ark site in a former sand pit.

Picture credit: Pomeroy sand Pit, ni © Ballinderry river enhancement Association

aggregatessItes–theIrpotentIalasCrayfIsharksItesAggregatesandmineralsextractionsitescanmakeasignificantcontributiontothenumberofpotentialArksitesandthereforetotheconservationoftheWhite-clawedcrayfish.ThroughestablishingArksitesinformerextractionsitestheindustrycancontributetonationalandregionalBiodiversityActionPlan(BAP)targetsandcanaddconsiderablevaluetositeBAPsandrestorationplans.

BecauseWhite-clawedcrayfisharesothreatenedacrosstheirexistingrange,alargenumberofArksitesareneededacrossmanycountiestogiveWhite-clawedcrayfishthebestchanceofsurvival.

AggregatesandmineralssitescanprovideidealnewArksitesforWhite-clawedcrayfish.Theiradvantagesinclude:

• Sitesareoftenisolatedfromexistingstreamsandriversthatmaybecolonisedbyinvading

aggregatessItes–theIrpotentIalasCrayfIsharksItes

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non-nativecrayfish,andhencesafefornativeWhite-clawedcrayfish.• Extractionoperationsoftenproducepermanentwater-filledsitesthataresuitableforWhite-clawedcrayfishwithnofurthermodification.Additionalhabitatcanbeprovided,usuallycheaplyandeasilyfromlocallyavailablematerialduringorafterrestoration.• Astheseareoftennewlycreatedwaterbodiestheyareoftenoflowernatureconservationvaluethanmoreestablishedsites,andthereforelessecologicallysensitivetocrayfishintroductionorhabitatcreation/modification.• ThewiderangeofmaterialsextractedintheUKmeansthatmanydifferenttypesofsitearepotentiallyavailable.

• Historic,currentandfutureneedsfor aggregatesandmineralsmeanthatsitessuitableforWhite-clawedcrayfishareavailablenowandafuturesuccessionofsitescanbeplanned.

ProvisionforconservationofWhite-clawedcrayfishcanbeincludedinsitemanagementplansatvariousstages:• planningofnewsitesandtheenvironmentalassessmentofproposedextractionsites.• duringsiteworkingandphasedrestoration.• atanyrevisionofrestorationplans.• asaneworadditionaluseforrestoredordisusedworkings,eitheraloneorinassociationwithotherproposals.

left: Gravel pits and other water-filled extraction sites can provide ideal new Ark sites for White-clawed crayfish.

seleCtIngarksItesWhenidentifyingandassessingsuitableWhite-clawedcrayfishArksites,ideallytheyshouldbeisolated,freefromnon-nativecrayfishspecies,andthethreat

ofcolonisationbynon-nativecrayfish,withsuitableWhite-clawedcrayfishhabitat,andsustainableinthelong-term.

arksiteselection-coarsefilterIftheanswertoanyofthequestionsbelowis“No”,thesiteshouldnotbeconsideredasapotentialArksiteforWhite-clawedcrayfish,anddonotproceedtofurtherassessment.

1.Doesthesitehavepermanentwater?

2.Isthesitefreeofnon-nativecrayfishspecies?

3.AreWhite-clawedcrayfishabsentfromthesite?

4.Isthesitephysicallyisolatedfromthethreatofcolonisationbynon-nativecrayfishspecies?

5.IswaterqualitylikelytobesuitableforWhite-clawedcrayfish?(i.e.equivalenttoGQA1chemistryA-C)?

1 general Quality Analysis – a standard method for measuring water quality. the chemistry gQA is based on levels of dissolved oxygen, ammonia, and biological oxygen demand. the Biological gQA is based on macro-invertebrate survey data. Picture credit: gravel pit © nick Mott

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Thecoarse filterisausefulstartingpointandshouldeliminateunsuitablesitesatanearlystage.Siteswhichpassthisinitialassessmentshouldthenbeassessedinfinerdetailtodeterminesuitability.

Moredetailedcriteriahavebeendevelopedsothatwaterbodies(runningwaterorstillwater)canbeassessedforquality,orlikelihoodofsuccessasArksites(tobepublishedin2009).Insummary,thesedealwith:• Degreeofenclosure(sitesaresafestiftheyhavenoconnectiontoawatercourse,ortoanotherwatercourseifthesiteisanisolatedstream).• Terrestrial(land)barriers(e.g.thedistancetoawatercourse,andriskoffloodingfromwatercourses).• Aquaticbarriers(forsiteswithaconnectiontoawatercoursetherehastobeamajorphysicalbarrierdownstreamthatcannotbeclimbedbynon-nativecrayfish).

• Habitatsuitability–waterqualityandquantity(biologicalqualityisgood,equivalenttoBiologyGQA1AorB;theriskofpollutingdischargesis

verylow;ifthewaterlevelvariesthereareplentyofrefugesforcrayfishatallwaterlevels).• Habitatsuitability:sitestructureandrefuges(ifthisisnotparticularlyfavourableinitially,itisusuallyeasytoimprovebycreatingnew

habitat–seenextsection).• Habitatsuitability:foodsources (onlyapplicablefornewwaterbodieswhichhavehadlittletimetodevelopecologically;

usuallyeasytoimprovebycreatingnewhabitat)• Usage:angling(bestwithnoangling,butcanhavepotentialifanglersarecareful).• Usage:otherusage(proximitytourban areasmayincreaseriskofillegal introductionofnon-nativecrayfishandsomewater-basedrecreationmayincreaserisk

ofcrayfishplague).

estaBlIshIngarksItes:haBItatCreatIonandenhanCement

estaBlIshIngarksItes:haBItatCreatIonandenhanCementThepresenceofsuitablehabitatforWhite-clawedcrayfishisanessentialrequirementofanypotentialArksite.However,itisonefactorthatcanbeeasilyresolvedthroughcreatingnewhabitat,oftenusingmaterialspresentonsite,orrecognisingandenhancingwhatalreadyexists.

Habitatcreationdoesnothavetocovertheentirewaterbody:ifresourcesormaterialsarerestricted,smallbaysorsectionsofsuitablehabitatmaybesufficienttosupportpopulationsofcrayfish.

recognisingandcreatingsuitablehabitatInmanyaquatichabitats,thenumberofcrayfishthatasitecansupportdependsontheavailabilityofshelter(refuges).Crayfishareversatileintheirdiet,sofoodsupplyisnotusuallythelimitingfactor.Crayfishcanuseawiderangeofnaturalandartificialrefuges,fromnaturalrockcrevicestotwig-filledsupermarkettrolleysordrinkscans!

Fromtheperspectiveofacrayfishcriteriaforasuitablerefugemaybe:• Bigenoughspacetogetthewholebodyinside,includingclaws,but• Notsoroomythatapredatorcanreachinsidetoo.• Stableenoughtoresisthighflow,ifthereisany,and• Withroughinsidesurfacesforbracing againstincreasedflow,orattemptedeviction byothercrayfish.• Notliabletosuddenlossofwater.• Easytokeepcleanofexcesssilt-sohorizontal

refugesarepreferredandslightmovementofwatermaybeuseful.• Closetogoodforagingarea.• Readilyaccessible,i.e.notsoflatorembeddedthatitlacksroomforcrayfishbeneath.

Thetableonpage7showsexamplesofhabitatcreationforWhite-clawedcrayfish.

Thefollowingfeaturesofpotentialvalueascrayfishhabitatmaybefoundonaggregatesandmineralssites,inadvertentlycreatedbytheextractionprocess,ornaturallyestablishingfollowingcessationofoperations:• Steeptoverticalrockfaceswithabundantfissures.• Pilesofbouldersandotherbrokenrock.• Cobblesfromsandandgraveldeposits.• Steepbankswithahighclaycontent.• Banksidetreeswithrootsexposedinthewater.• Brokenconcreteandbrickrubblefromformerbuildings.• Oldlogsandaccumulationsoftwigs• Standsofemergentvegetationwithasteepdrop-offbeyond.

right: A mixture of large and small cobbles and boulders will create numerous refuges for crayfish.

Picture credit: cobbles sketch by Vicky kindemba

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formofrefuge

technique Comments

Stone on the bed

Placelargecobblesorboulders(›20cmacross)onthebed.Stacktoleavegapsforcrayfish.

Bestindeeperareasnotregularlyexposedbychangingwaterlevel.Localstoneisbest.Materialshouldnotbeofuniformsize,agoodrangefromapproximately20-80cmwillcreateavarietyofrefuges.

Stone along banks

Placelargecobblesorboulders(›20cmacross)inthemargins.

Canstabiliseerodingslopeswithunmortaredstone.Useunfacedstonesotherwisegapsbetweenwillnotbelargeenough.

Notusefulifbanksaremainlyexposed,orshallowwateradjacent.Commentsonsizeofmaterialasabove.

Naturalbanksarepreferable,especiallyverticalbankswithprojectingstonesandtreerootsbelowwaterlevel.Gabionbasketsfilledwithsmallstone,‹15cm,don’thavegapslargeenoughforcrayfish,exceptafewjuveniles.

Wood or vegetation along banks

Planttreesalongsomebanksectionsforshade. Treesonvertical,slightlyundercutbanksarebest,withlargerootsandapoolbelow.Donotplanttoomanytreesasthiswillresultinthelossofaquaticvegetation.

Ifthereisaneedtostabilisebanks,canusestakeswithbranchesinterwoven(basket-weavespiling).

Canusefaggotsforfacingbanks–twiggycoppicestems,hedgecuttings,otherwoodybrashings,etc.tiedinabundle,thenpeggedorstakedingroupsacrosstheexposedbank.

Iffresh-cutwillowstakesareusedtheywillgrow.Willowwallsneedmaintenance–coppicingand/orcutandweave.

Faggotsneedtobereplacedovertime.Iffaggotsarebuiltuptosurfaceleveltheycanprovidenestingsitesforwaterfowltoo.Theycanproviderefugefrompredationbyfishforarangeofaquaticinvertebrates.

Aswithstone,oneshouldconsiderwhetherreinforcementisnecessary?Ifso,thisisabetteroptionforcrayfishthansolidwallsorpiling.

Artificial refuges

Wherethebanksareverticalandsomeformofhardreinforcementisrequiredonbuiltstructuresrefugescanbeconstructedusingbricksorblockswithholesin.Facethebankwithafewlayersofengineeringbrickssetonside,withholesfacingoutward.

Similarly,standardconcreteblocks(breeze-block)canbeused,placeonside.Packspacewithsectionsofplasticpipe20-50mmdiameter.Glueinplace,orbedintomortarattheback.Setatrightanglestoflow.

Ifabundantfissuresarepresentwithintherockface,thesemayprovidesufficientrefugeswithouttheneedforenhancement.

Takeeithercoarsehessiansackingorplasticnetting(e.g.strawberrynet).Filllooselywithstrawina‘pillow’or‘sausage’.Pegbagtobedinsubmergedmargins.

Goodforjuvenilecrayfish.Canuseinalakeorgravelpit.Usingnetswithbarleystrawclosetowaterinletshelpsreducegrowthofalgae,ifnetsareinplacebeforestartofseason(February).Needsatopupofstraweveryyearortwo.Canmakejuvenileseasiertodetectinsurveys,ifsamplethebags.

Water-filledgravelpitsoftenhaveaveryshallowgradientandarelativelyuniformbedofsandandgravel,sometimeswithfewstoneslargeenoughtohidecrayfish.Iflargerstonesarenotavailable,goodhabitatcanbecreatedquicklywithfaggotbundlessecuredoranchoredtothebed.

Faggotbundlesshouldbeusedingroupssotheybulkuptomakelongerandwiderstructures.Iffaggotsarebuiltuptosurfaceleveltheycanprovidenestingsitesforwaterfowltoo.

Faggotsneedtobereplacedovertime.

habitatcreationandenhancementforcrayfish(adaptedfromGuidance on habitat for White-clawed crayfish–see“Furtherinformation”)

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habitat creation and enhancement

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Above: Engineering bricks can be used to create artificial refuges for White-clawed crayfish.

Picture credits: crayfish in brick © stephanie Peay; submerged stone revetting © stephanie Peay

Above: When submerged, stone revetting provides stable refuges for crayfish.

IntegratIngarksItesThroughcarefulplanningwildlifecanbeprovidedforalongsideotherafter-usesandsiterestorationobjectivessuchaspublicamenity,recreation,agricultureandconservinggeodiversity.

CombiningWhite-clawedcrayfishconservationwithotherrestorationendusesMostafter-usesofmineralsitescanbecompatiblewithconservationofWhite-clawedcrayfish,althoughsomearemorefavourablethanothers(seetable).Arksitescanbeintegratedwithinrestorationschemesthathaveamenityasapriorityafter-use,andarecompatiblewithmostwatersports.

Inmostcases,theland-useofterrestrialareasisnotimportanttoWhite-clawedcrayfish,providedthatanyuseofadjacentlanddoesnot:changethequalityandquantityoftheaquatichabitatsusedbythecrayfish;orincreasetheriskofdiseaseorcolonisationbynon-nativecrayfish.

natureconservationCompatibilitywithothernatureconservationobjectivesishigh,exceptpossiblyinafewcasesonexistingsitesofveryhighvaluefornatureconservation.

IntroducingWhite-clawedcrayfishislikelytoleadtoslightchangesinthedetailedecologyofexistingwaterbodies;however,thebenefitsforconservationmeanthisislikelytobeacceptableinmanyrecentlyestablishedwaterbodiesandinsomelong-establishedonestoo.

TheintroductionofWhite-clawedcrayfishwillhavesomeeffectsontheexistinginvertebratefauna

throughchangesinpredationandcompetitionamongspecies,withsomespeciespotentiallydecreasingandothersincreasinginabundance.Someslow-movingspecies,suchassomecaddisflylarvaeandaquaticsnails,maybeparticularlysensitivetopredationbycrayfish.Ifasiteisalreadyofhighimportancefortheconservationofaquaticinvertebrates,andincludesrareandthreatenedspecies,theimpactofintroducingWhite-clawedcrayfishwouldhavetobeassessedcarefully.Insuchcircumstancesitmaybebettertoconsiderothersitesifavailable.Ifnoexistinginformationisavailable(ornorecentsurveydata)thenasurveyshouldbeundertakentoassesstheecologicalimpactofintroducingcrayfish.

anglingAnglingisaverycommonafter-useofwater-filledextractionsitesbutithasrisksforWhite-clawedcrayfish.Nevertheless,anglingispossiblewithinArksitesforWhite-clawedcrayfish,butcareisrequiredfromallparticipantsiftheArksiteistobesuccessfulinthelongterm.

Indescendingorderofpreference:• noangling-best.• coarseanglingbyaresponsibleclub– reasonablechanceofsuccess.• coarseanglinggeneralpublicuse- possible.• put-and-take-fishery,e.g.rainbowtrout–unlikelytobecompatible.

TheriskstoWhite-clawedcrayfishfromanglingare:• transmissionofcrayfishplagueonwetnets andequipment.• transmissionofcrayfishplaguewithwaterandstockedfish.

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• accidentalintroductionofnon-nativecrayfishwithstockedfish.• accidentalordeliberateintroductionofnon-nativecrayfishasanglingbaitorfoodforfish(alsoillegal).• introductionofpredatoryfish(e.g.catfish).• unsympatheticfisheriesmanagement(e.g.regularuseofherbicides,over-stockingwith

fish,orexcessiveuseofground-baitcontributingtoeutrophication).

Allofthesecanbeavoidedormitigated.Ingeneral,actionstakentoprotectWhite-clawedcrayfisharealsointhebestinterestsofangling.

CompatibilityofWhite-clawedcrayfisharksiteswithotherendusesofaggregatesandmineralssites

restorationenduse Compatible Comments

Nature conservation yes,very White-clawedcrayfishcanco-existwithamphibians,fish,wildfowlandarangeofaquaticinvertebrates.

Amenity and education yes White-clawedcrayfishmakegoodsubjectsforenvironmentaleducation(althoughpublicaccessmayincreasetheriskofaquariumorponddiscards,includingnon-nativecrayfish).

Watersports yes Banksmayneedtobeprotectedfromexcessiveerosionassociatedwithsomeactivities.Wetsuitsandotherequipmentneedtobecleananddrytoavoidriskofcrayfishplaguecontamination.

Angling yes,possiblewithcare Highriskofcrayfishplagueunlessmeasuresaretakentopreventtransmissiononcontaminatedgearorfish.Possibleriskofintroductionofnon-nativecrayfishwithstockedfish.

Agriculture yes,usually Waterbodiesneedprotectionfromfertiliser,pesticidesandotheragriculturalrunoff;forexamplethroughtheuseofbufferzones.

Industrial/ commercial/ housing development

yes,usually Waterbodiesneedgoodprotectionfrompollutingdischarges(plannedoraccidental).CareisneededindrainagedesignandabufferofvegetationaroundtheArksite.Waterlevelsshouldnotfluctuateexcessively-permanentwaterisnecessaryasissuitablehabitatatallwaterlevels.AnydrainageoutoftheArksitemusthaveasecurebarrieragainstnon-nativecrayfish.

Above: Angling brings the risk of introducing crayfish plague unless all anglers are careful with cleaning and drying their equipment.

Picture credit: Anglers © stephanie Peay

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monItorIngMonitoringthesuccessofsitemanagementtechniquesandhabitatcreationschemesisvital.Monitoringofhabitatcreationandsubsequentmanagementwillflagupfeaturesormanagementthatneedtobeimproved.Witheachnewschemeourknowledgeofthesubjectdevelopsfurther.Everyhabitatcreationschemeshouldbeviewedasanopportunitytolearnandsharebestpractice.

ThesuccessofanArksiteisdeterminedbythepresenceofahealthypopulationofwhite-clawedcrayfishatanabundanceconsistentwiththeamountofsuitablehabitat.Ittakestimeforapopulationtodevelopanditmaybedifficulttodetectinsurveysforthefirstfewyears.Crayfisharelikelytobeevidentinaboutfiveyears,althoughitmaytakemuchlongertoreach“capacity”.

monItorIng WhIte-ClaWedCrayfIshandthelaW ConClusIons

Above: This Ark site is within a former extraction site that is now a country park.

Picture credits: holme © stephanie Peay

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WhIte-ClaWedCrayfIshandthelaWWhite-clawed crayfish are protected under UK wildlife and fisheries legislation, which means that a number of licences are required to catch White-clawed crayfish and/or move them to new sites. Professional advice must be sought when planning Ark sites.

TheWhite-clawedcrayfishisprotectedfrom“takingandsale”undertheWildlifeandCountrysideAct1981(asamended).ItislistedundertheEUHabitatsandSpeciesDirectiveandisaUKBiodiversityActionPlanPrioritySpecies.

AprotectedspecieslicenceisrequiredforanysurveysforWhite-clawedcrayfish.LicencesareissuedbyNaturalEnglandandtheCountrysideCouncilforWales.SurveyorsareexpectedtohavehadsuitabletrainingontheconservationofWhite-clawedcrayfishandsufficientpracticalexperienceofcrayfishsurveys.Acrayfishsurveylicenceisnotrequiredforgeneralmacro-invertebratesurveys,orsurveyswhereitisreasonabletoexpectWhite-clawedcrayfishtobeabsent.

ConsentsforcrayfishtrappingarerequiredundertheSalmonandFreshwaterFisheriesAct1975;theseareissuedbytheEnvironmentAgency.Aconsentisrequiredforanyuseofcrayfishtraps,evenifcrayfisharethoughttobeabsentfromasite.

AnyproposaltostockapotentialArksitewithWhite-clawedcrayfishrequiresaprotectedspeciesconservationlicencefromNaturalEnglandortheCountrysideCouncilforWalesasappropriate,inadditiontothesurveylicenceheldbythecrayfishsurveyor.FisheriesconsentsmustalsobeobtainedfromtheEnvironmentAgencyundertheSalmonandFreshwaterFisheriesAct,tointroduceanycrayfishtothereceptorsiteandaseparateconsenttoremovestockfromthedonorsitetoo.

ThelandownerwillneedtogivepermissionpriortosettingupapotentialArksiteforWhite-clawedcrayfish.Itisadvisabletosecuretheco-operationofanyotherstakeholderstooincludingsitemanagersandanglers.

ConClusIons• White-clawedcrayfishneedhelpnow–newArkrefugesitesareessentialtopreventfurtherextinctionsofpopulationsduetothespreadofnon-nativecrayfishanddisease.• Formeraggregatesandmineralsworkings,andthoseinoperationorplanned,canprovideexcellentArksites.• Mostaggregatesandmineralssitesaresuitable,ifwaterconditionsaresuitableandtherearegoodbarriersagainstcolonisationbynon-nativecrayfish.

• ArksitesforWhite-clawedcrayfishcanbeimplementedeasilyandatlowcost.• HavingWhite-clawedcrayfishonrestoredmineralsitesiscompatiblewithmostafter-uses,iftakenintoaccountindesignandmanagement.• ProvisionforWhite-clawedcrayfishonaggregatesandmineralssitescancontributetolocalBiodiversityActionPlans,toregionalcrayfishconservationstrategies,andtotheconservationofWhite-clawedcrayfishnationally.

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Conservingthesmallthingsthatruntheworld

Buglife - The Invertebrate Conservation TrustFirstFloor,90BridgeStreetPeterborough,PE11DY.Telephone:01733201210Registeredcharityno.1092293Companyno.4132695www.buglife.org.uk

Picture credit back cover: White-clawed crayfish © John MasonPrinted on 100% recycled stock using vegetable oil-based inks.

furtherInformatIonrestoring aggregates and minerals sites:Davies, A.M. (2006) Nature After Minerals: how mineral site restoration can benefit people and wildlife. RSPB, Sandy.

White, G.J. and Gilbert, J.C. (ed.s) (2003) Habitat creation handbook for the minerals industry. RSPB, Sandy.

Whitehouse, A.T. (2008) Managing Aggregates Sites for Invertebrates: a best practice guide. Buglife - The Invertebrate Conservation Trust, Peterborough.

White-clawed crayfish:Holdich, D. (2003). Ecology of the White-clawed Crayfish. Conserving Natura 2000 Rivers Ecology Series No. 1. English Nature, Peterborough. p. 17.

Holdich, D., Sibley, P., Peay, S. (2004) The White-clawed Crayfish – a decade on. British Wildlife, 15, pp. 153–164.

Kemp, E., Birkinshaw, N., Peay, S., Hiley, P.D. (2003) Re-introducing the White-clawed Crayfish Austropotamobius pallipes. Conserving Natura 2000 Rivers Conservation Techniques Series No. 1. English Nature, Peterborough.

Kindemba, V. & Whitehouse, A.T. (2009) Using GIS to prioritise and identify regional Ark sites for White-clawed crayfish: South West aggregate and mineral extraction sites. Buglife - The Invertebrate Conservation Trust, Peterborough.

Nightingale, J. et al (2009) South West White-clawed Crayfish Conservation Strategy 2008 – 2012. Bristol Zoo, Bristol.

Peay, S. (2003). Monitoring the White-clawed Crayfish Austropotamobius pallipes Conserving Nature 2000 Rivers Monitoring Series No. 1. English Nature, Peterborough. p. 58.

Peay, S. (2003) Guidance on Habitat for White-clawed Crayfish. R&D Technical Report W1-067/TR. Environment Agency, Bristol.

Websites:Buglife-TheInvertebrateConservationTrustwww.buglife.org.uk

NaturalEnglandwww.naturalengland.org.uk

EnvironmentAgencywww.environment-agency.gov.uk

WildlifeTrustswww.wildlifetrusts.org

ThIS rEPorT ShoULd BE rEFErENCEd AS:Whitehouse,A.T.,Peay,S.&Kindemba,V.(2009)ArksitesforWhite-clawedcrayfish–guidancefortheaggregatesindustry.Buglife-TheInvertebrateConservationTrust,Peterborough.

ISBN:978-1-904878-95-7

AcknoWledgeMentsThank you to: Jamie Roberts and our other colleagues at Buglife, Peter Sibley at the Environment Agency, all those who have contributed photographs to this report.The Ark site selection coarse filter has been developed as part of the Southwest England White-clawed Crayfish Conservation Strategy between the authors and Jen Nightingale (Bristol Zoo), Peter Sibley, Martin Frayling (Environment Agency), Lydia Robbins (Avon Wildlife Trust) and Paul Bradley.