Conservation and restoration of the Allis shad in the ... · PDF fileConservation and...

Landesamt für Natur, Umwelt und VerbraucherschutzNordrhein-Westfalen

Conservation and restoration of the Allis shad in the Gironde and Rhine watershedsLANUV-Fachbericht 70

www.lanuv.nrw.deLIFE09 NAT/DE/000008

Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds

LANUV-Fachbericht 70

Landesamt für Natur, Umwelt und Verbraucherschutz Nordrhein-Westfalen

Recklinghausen 2016

IMPRESS

Coordinating North Rhine-Westphalia State Agency for Nature, Environment and Consumer Protection (LANUV)beneficiary Leibnizstraße10,45659Recklinghausen Telefon+492361305-0,Telefax+492361305-3215,E-Mail:[email protected] Project management North Rhine-Westphalia State Agency for Nature, Environment and Consumer Protection (LANUV) Department26FishEcology,HeinsbergerStraße53,57399Kirchhundem-Albaum,Contact:DanielFey

OfficeAllisshadproject RhenishFisheriesFederationfrom1880,Wahnbachtalstraße13a,53721Siegburg,Contact:Dr.AndreasScharbert Aquazoo-LöbbeckeMuseumDüsseldorf,KaiserswertherStraße380,40200Düsseldorf Co-Financiers •EuropeanUnion(FundinginstrumentLife+) •Agencedel’eauAdour-Garonne •BezirksregierungDüsseldorf •Conseilrégionald’Aquitaine •ÉlectricitédeFrance •HessianMinistryoftheEnvironment,ClimateProtection,AgricultureandConsumerProtection •HITenvironmentalfoundation •RhineFishingCooperativeNorthRhine-Westphalia •SportvisserijNederland •Federationofhessianfishermen

ExternalFunding HermannHoffmannGroup

Coverphoto AssociationMIGADO

Figures AndreasScharbert(7bottomleft,9bottom,14Centre,topright,17topright,bottomleft,18bottom,19top, bottom,22bottom),AssociationMIGADO(4detail,5bottomleft),BundesanstaltfürGewässerkunde (18centreleft),Bordes(6bottomleft,topright,8topleft),BürofürFischereibiologieundÖkologie (20topright),EgbertKorte(15bottomright,18centreright),Epidor(5topright,7top,centreleft,right, 8bottomleft,right,12top,22top),HannsHönigs(21bottomleft),Irstea(4map),JensBreer(20bottomleft, bottomright),LANUV(13Map),M.M.Foto-TeamDeutz(21topright,topleft),MarionWille(23bottom left),MatthiasHundt(16,17topleft),PeterBeeck(11top,12centre,bottom),PhilippeJatteau(23top), RolandPaschmann(21bottomright),Sméag(9Map,Centre,10Map,bottom),StefanStaas(14topleft, 27bottom,15top,18top,23bottomright),ThomasHöferer(20bottomleft),WalterFricke(15bottomleft, 17bottomright)

Layout LANUV

ISSN 1864-3930(Print),2197-7690(Internet),LANUV-Fachberichte

Informationsdienste Informationen und Daten aus NRW zu Natur, Umwelt und Verbraucherschutz unter •www.lanuv.nrw.de

AktuelleLuftqualitätswertezusätzlichim •WDR-VideotextTafeln177bis179

Bereitschaftsdienst NachrichtenbereitschaftszentraledesLANUV(24-Std.-Dienst):Telefon0201714488 Nachdruck–auchauszugsweise–istnurunterQuellenangabenundÜberlassungvonBelegexemplaren nachvorherigerZustimmungdesHerausgebersgestattet.

DieVerwendungfürWerbezweckeistgrundsätzlichuntersagt

Content

Introduction 4

ThecollapseofallisshadpopulationsintheGironderegion 5

Howcanthedeclineoftheallisshadpopulationbeexplained againstthebackgroundofbiologyandthewayoflifeoftheallisshad? 5

Limitedfunctionalityoffishways 6

Conditionofjuvenilefishpopulationsintherivers 8

Dangers in the lower reaches of rivers 10

Continuation and review of the success of the resettlement activities in the Rhine system 11

Breedingandstockingofallisshad 11

Monitoringofjuvenilefishafterrestocking 15

Pilotfacilitiesforexsitustock 16

SearchingforthefirstreturneesintheRhine 17

ResoundingsuccessofthereintroductionactivitiesintheRhine 19

Transfer of knowledge and public perception 21

Conclusionandoutlook 23

ConservationandrestorationoftheAllisshadintheGirondeandRhinewatersheds4

TheallisshadisoneofEurope‘smostvulnerablespecies.Atthebeginningofthetwentiethcentury,itcouldbefoundinlargeshoalsinalmostallofthemajorriversystemswhichflowintotheAtlantic,theNorthSeaandpartlythoseflowingintotheMediterraneanSea.ThedistributionareastretchedfromNorthAfricatosouthernScandinavia.Duetooftenrigorousoverfishing,coupledwith increasing environmental degradation through water pollution, development and the progressive construction of weirs and dams, which block access to their spawning grounds, this species has died out in large parts of Europe within thespanofonlyafewdecades.VitalremainingstocksofthisspecieshavesurvivedinsomewesternFrench,Portu-gueseriversandoneMoroccanriversystem.Theallisshadinthesewatersarestillcommerciallyimportanttodayandfeedmanyfishingenterprises.Until2007,thiswasalsotrueforthehithertolargestremainingstockofallisshadintheFrenchGironde-Garonne-Dordognesystem,alsoknownasthedonorpopulationselectedforthefirststockingprojectofallisshadtodate,theLIFEproject„Re-introductionofshadtotheRhineSystem“(LIFE06NAT/D/000005).WhileanaverageofabouthalfamillionallisshadstillmigratedtospawnintheGaronneandDordogneinthe1990s,thestockcollapseddramaticallyearlyinthenewmillennium.Sincethenthepopulationhasbeenreducedtolessthanonepercentofthatnumber.Theidentificationofthereasonsforthisdevelopment,inadditiontothecontinuationanddocumentation of the success of stocking activities in the Rhine, is the aim of the Life+ project „Conservation andRestorationoftheAllisshadintheRhineandGirondeWatersheds“.TheprojecthastwodistinctandyetinseparablepilotmeasuresinordertoprotectthestocksofAlosaAlosa:theaimofpreservingthereintroductionofthespeciesinitsformer area of distribution and the investigation of the reasons for the decline of the largest remaining population with theaimofmaintainingandimprovingthestocksituationofallisshadinEurope.ThemeasuresarejointlycoordinatedbytheLANUVandtheRhenishFisheriesFederationfrom1880andimplementedincooperationwithpartnersintheFrenchAquitaine,theNetherlandsandintheGermanfederalstatesNorthRhine-WestphaliaandHesse.

Introduction

France

Adour

Gironde-Garonne-Dordogne

Loire

Oued Sebou

Mondego

Lima

F

P

MA

Map of the original (green) and current (brown) population rangeinEurope.Main rivers having accomodated populations of allis shadarelisted.

ConservationandrestorationoftheAllisshadintheGirondeandRhinewatersheds 5

As late as the turn of the millennium, around half a million adultallisshadmigratedtotheGaronneandtheDordo-gneinordertospawn.Atthattimethedeliciousallisshadstill constituted the most economically important target speciesofthenumerousfishingcompaniesintheGironderegion,whichusedabouthalfofthestock.Theyear2003seems to have been a turning point for the allis shad stock – indeed still a few hundred thousand adult allis shad migra-ted to the rivers at that time, but unlike previous years, a far lowernumberofmigratingjuvenilefishcouldbefoundintheGirondeestuaryforthefirsttimein2003.In order to be able to understand this development, it is necessarytotakealookatthecomplexlifecycleofthespeciesunderthemicroscope.

Theallisshadisananadromousmigratoryfish,whichbelongs to the same family as the herring and herring-type fish(Clupeidae),andspendmostoftheirlivesinthesea.Mature allis shad migrate to spawn in the middle reaches ofrivers(barbelregion).Whenthewatertemperaturerisesabove 11°C, the allis shad gather together in the estuaries andmigrateuptherivers.Thefishspawninthespring,whenthewatertemperaturerisesabove15°C,fromApriltoJulyandespeciallyinthemonthofMay(thisisthereasonfortheGermannameof‚Mayfish‘!).Spawningareasaremoderatelyflowinggrittyriversections,suchasthosefoundontheinnerbendbanks,overflowngravelbanksoratthemouthsoftributaries.Thepeculiarspawningtakesplaceatnightdirectlyonthewatersurface.Theallisshadbeattheirtailfinsincircularswimmingmovementsonthesurfaceofthewater.Thevociferoussplashingcanbeheardfromalongdistance.Thefertilisedeggssinktothebottomandaredepositedingapsinthegravelsubstrate.Ittakesaboutfourtofivedaysfortheeggstohatch.Afterwards,theyoungfishremainintheriversforafewweeksormonthsand migrate to the brackish areas of the estuaries in late summer/autumn.Theymigrateintotheseafromtheseareas no later than winter, where they grow to maturity in three to seven years and complete the life cycle with a rene-wedmigrationtotherivers.Thedeclineintheyoung-of-the-yearfishpopulation(fishthatarehatchedinthesameyear)observedintheGirondeestuaryinautumn2003,whichwasfinallyreflectedfromthree years later on in a similarly dramatic decline of the stockofsexuallymatureallisshadfromthisgenerationreturningfromthesea.ThedeclineinstocksintheGironde-Garonne-Dordognesystemcanmostprobablybeexplainedbyaninsufficientspawningsuccesssincethattimeortheincreasedmortalityofjuvenilefishpriortotheirarrivalintheestuaries.

The collapse of allis shad populations in the Gironde region

How can the decline of the allis shad po-pulation be explained against the back-ground of biology and the way of life of the allis shad?

Scheme of the allis shad life cycle

The fertilised eggs are deposited in gravel gaps

The spawning act of allis shad, the so-called bull, takes place duri-ng the night on the surface of the water in certain river stretches

Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds6

OnepossibleexplanationforreducedspawningsuccessmightbethelackofsuitabilityofthefishwaysonthedamsoftheGaronneandDordogne.Duetothefactthatonlya small proportion of the allis shad population is able to overcome the dam structures in order to reach the ma-jor spawning areas of the rivers, the shads are forced to reproduce in the inferior spawning areas which lie below the damsinthelowerreaches.Asthegravelandthebedloadare trapped in the barrage sections and are not transported furtherdownhill,significantlylessfavourablereproductionconditions for allis shad can be found in the lower reaches because their eggs cannot deposit in these essential gaps between pieces of gravel, where they can develop until the larvaehatch.Therewereindeedpossibledeficitsinthefish-

Limited functionality of fishways

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

0

100.000

200.000

300.000

400.000

500.000

600.000

700.000

800.000

198

7

199

0

199

3

199

6

199

9

200

2

200

5

200

8

2011

2014

num

ber

ad

ult

allis

sha

d

spawners downstream dams

fishways

fisheries yield

YOY in estuary

nu

mb

er YO

Y p

er 100

0m

3

FisheriesforthedeliciousallisshadwereeconomicallyimportantintheGirondebasinuntilapproximatelyonedecadeago.Since2008amoratoriumtosavethepopulationisinforce.

The number of allis shad caught byfishermen,thenumber counted inthefishwaysat the dams and on the spawning grounds down-stream of the dams in the rivers GaronneandDordogne and the number of the YOY allis shad sampled in monitoring studies in the Girondeestuary

ways when the stock was still vigourous, however, it could be observed that the number of allis shad negotiating the fishwaysdecreasedwiththesizeofthestock,sothatfewerandfewerfishwerespawningonthemoreeffectiveproduc-tivespawninggroundsinthemiddlereachesoftherivers.Studiesontheuseofexistingfishwaysbyallisshad,whichwerecaughtonthefishwaysandprovidedwithradio telemetric transmitters before being released again downstream,pointtosignificantdeficienciesintermsofdiscoverabilityandattractivenessofthethreefishwaysinvestigated.Onlyoneofthe222allisshadequippedwithtransmittersmanagedtonegotiateoneofthefishladders.Thefishwayconcerned,theslotpassattheweirinBergeracontheDordogne,waseasiertoevaluatethanthefishliftsin

Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds 7

TuilièresandGolfech,alsowithrespecttootherparameterssuch as the number of entry attempts and the residence timeoftheallisshadinthefishway.

Recovery of a tagged allis shad from the narcosis prior to release

A shoal of allis shad in search of the downstream entrance of the fishwayattheBergeracdamontheDordogne

Searching for tagged allis shad in the river course

Inserting a radio-transmitter into the shad‘s gorge

Overall,thesuitabilityoftheinvestigatedfishwaysrelevantfortheallisshadintheGironderegionseemverylimited.Similar problems also appear in the more modern and significantlylargerfishmigrationfacilitiesatriversusedby shad (here concerning the American allis shad) on the

US east coast, as were revealed by a joint evaluation of the functionalchecksbyAmerican,CanadianandFrenchfish-wayexpertsfromtheLife+projectteam.Theoptimisationoffishwaysfortheallisshadthereforehasakeyfunctionforthe (re)development of spawning areas and the conservation


Another possible hypothesis for the collapse of the allis shadpopulation,whichhasbeenexploredwithinthefra-meworkoftheLife+projectandcouldexplainthedeclineofjuvenilefishstocksintheGirondeestuaryinautumnsince2003,isthedeteriorationoflivingconditionsintheriversandincreasedmortalityofjuvenilefishduringthefirstweeksoflife.Thiscouldbecausedby,forexample,changes in the conditions of the physical habitat, such as thecompositionofthesoilsubstratesorfoodavailability.A complicating factor when investigating this issue is that it was not possible to sample the juvenile stages of allis shad in the past, or even to quantify their populations, whichisdueparticularlytotheirpelagicwayoflife.Scientistsrepeatedlysucceededinfindingevidenceof

juvenile allis shad with specially designed push and drift-nets.RiversectionsbelowspawninggroundsintheGa-ronneandtheDordognewereexaminedinastudy.Duetothe continuing decline in the number of mature allis shad returning from the sea at the start of the investigations, whichsanktoanall-time-lowintheyears2012to2015,the natural breeding volume was so low that in total only afewjuvenilefishweredetected,andaquantificationofstocksandcomparativeanalysisoftheinfluenceofcon-ditions for growing to maturity on population density was notpossible.Inthisrespect,thesmallnumberofdetectedjuvenileallisshadreflectsthedramaticpopulationtrendsandtheirlimitedself-renewaltoalargeextent.

oftheallisshad.Basedonthesefindings,thefunctioningoftheexistingfishmigrationfacilitiesshouldbeimprovedinthecomingyearsandadditionalfishwaysshouldbe

constructedonthedamstructuresinGaronneandDordo-gnewherepossible.

AlthoughthethreedamsontheriverDordogneinTuilières(upperleft),Mauzac(lowerleft)andBergerac(right)areequippedwithfishways,onlyaminorpartoftheallisshadpopulationisabletopassthedams.ThesameappliestothedamatGolfechontheGaronneriver.

Condition of juvenile fish populations in the rivers


MapoftheGiron-de-Garonne-Dor-dogne basin with the location of the current spawning sites (green) and the YOY sampling sites (purple)

Spawningsites Monitoring stations at dams

YOY Samplingsites

Boatequippedwithpushnetsforthesampling of YOY allis shad and the push net (see construction in detail)

Juvenilefishmonitoring via

push nets in a river section below an

allis shad spawning ground in the river

Garonne


Location of the mudplug(Bou-chonvaseux)inthetidalinfluenceddownstream part oftheriverGaron-ne around the city ofBordeaux

Percentageofdayspermonthandyearinwhichhypoxia(<5mgO2/l)occurredinthemudplugsectionoftheGaronne.ParticularlyinAu-gustandSeptember,whentheYOYshadsmustpassthroughtheBouchonvaseuxtoreachtheestuary,theyencountercriticalconditions.

FrayèresStations de contrôle

Sites d’échantillonnage

Bouchon vaseux

Anotherfactorofgreatimportancefortheinsufficientself-renewal of the stock is recruitment, which has emer-gedasaconsequenceonlyinrecentyears:Becauseoftheextremeheatwaveandtherecordlowwaterlevelsin2003,theso-calledBouchonVaseux(siltplug)formedfromsuspendedfinesedimentsinthetidal-influencedlowerreachesoftheriver.Duetotheretentionoftheoutflowinreservoirsanddams,therewerehardlyanyfloodsintheriverswhichcouldflushthismudcloudoutintotheopensea.Becauseoftheconstantsupplyoffinesedimentsfromfarmlandinthecatchmentarea,especiallycornfields,theBouchonVaseauxsurvivesandregenerates itself, and it represents an increasing problem forthecommunitiesintheareaofthetidal-influencedlowerriverreaches.Aparticularproblemhereistheaccumulationofoxygen-consuming particles, which means that there is a lack ofoxygenintheBouchonVaseuxareainsummerand

autumn,i.e.duringtheperiodsinwhichthejuvenileallisshad are undertaking their migration to the sea through thelowerriverreaches.Itseemsreasonabletosupposethat only a few of the juveniles migrating through the zone oftheBouchonVaseuxsurvivethejourneyunscathedandthereforetherecruitmentisalsodiminished.Whiletheinvestigation of this factor is not the subject of the Life+ project, it is, however, likely to be of great importance for theallisshadpopulationintheGironderegionandshouldbecome a stronger focus of future action, especially as a similar problem has also been occuring in other European riverestuaries.

Danger in the lower reaches of rivers

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014OctoberSeptemberAugustJulyJune

100

Perc

enta

ge o

f day

s w

ith

hypo

xia

80

60

40

20

0


With the LIFE project „The re-introduction of allis shad in the Rhine“, the foundations and infrastructure for Europe‘s firstprojectforthere-introductionofallisshadinitsformerdistribution area have been created with the help of the development of mass breeding, transportation and stocking techniques and the construction of an allis shad farm in Aquitaine.From2008to2010aboutfivemillionallisshadlarvae bred in France were released into the Rhine system forthefirsttime(seeLANUVTechnicalReport28).ThestockfishweretakenfromtheGironde-Garonne-Dordognepopulation.AllisshadwhicharereadytospawnarecaughtduringthespawningmigrationintheGaronneandDordo-gne, and brought to reproduce in the breeding facility near BruchintheAquitaine.Theaimtomakeadultfishreturn

Allis shad breeding is carried out at the breeding facility in BruchintheAquitaine.TheFrenchprojectpartnerassocia-tionMIGADO,whichalsoconceivedandbuiltthebreedingfacility for the preceding LIFE Allis shad project, is responsi-bleforcatchingtheparentfishintheGaronneandDordogneand the work involved in the breeding and transportion of theallisshadlarvae.Thebreedingtechniqueshavebeenoptimisedtotheextentthataround80parentfishneedtobetakenfromtheGa-ronne and Dordogne in order to breed two million allis shad larvaeforstockingintheRhine.Thisnumbercorrespondstoapproximatelyonepercentofthesizeofthespawningstock and has no impact on the natural population size intheGironderegion.Afterbeingcaught,theparentfish

from the stocking programme and founding a population the restocking measures are continued as part of the Life+ pro-jectfrom2011onwards.byOtherkeymeasuresintheRhinecatchment area were studies on the behaviour of young allisshadafterrestocking,thesearchforthefirstadultallisshadfromtherestockingofthefirstLifeproject,whichshouldreturnasof2013,aswellasexploringthepossibilityofraisingallisshadinbreedingstockstosexualmaturityinordertobeabletoincreasinglydrawon‚exsitu‘stocksinfuture restocking programmes and therefore become more independentoftheoffspringfromwildstock.

are administered a hormone which which speeds up the maturingandthefisharesoonabletospawnindependentlyaftertheirarrivalatthefishfarmandtransferintoaspaw-ningpool.Thefertilisedeggsareincubatedforafewdaysin breeding jars before the allis shad larvae hatch from the eggs.Soonafterhatching,thelarvaearetransferredintoasolutioncontainingwiththefluorescentsubstanceoxyte-tracycline, which is incorporated in bony structures such as otolithsandmakesitpossiblelaterontoidentifythefishwhichhavecomefromthebreedingfacility.ThelarvaearethentransportedtoGermanyattheageof5to20daystobereleasedinwatersintheRhinesystem.Atotalofaround6.2millionallisshadlarvaewereproducedandtransferredintotheRhinesystembetween2011and2015.Intheyears

Continuation and review of the success of the resettlement activities in the Rhine system

Breeding and stocking of allis shad

Fine suspended so-lids accumulate in the lower and tidal influencedGaronneand constitute the socalledBouchonvaseux,themudplug


Adult allis shad in the hatchery

Aftertrappinginthefishways,theparentfishareinjectedwithahormonetoinducespawningpriortothetransportintothehatchery

FreshlyhatchedallisshadlarvaeinthehatcheryinBruch

TheallisshadhatcheryinBruchintheAquitaine

inwhichdamp,coolweatherandfloodconditionsprevailedintheGironderegion,thebreedingsuccesswassignificantlylowerthaninfriendlyhydro-climaticconditions.Inaddition,as due to the stock situation only a limited number of parent fishcouldbetaken,thestockshortagewasunderamillioninthreeoftheseyears.As the stock was dependent on the conditions in the Rhine basin(waterlevelandflow,presenceofcompetitorsand

potentialpredatorsetc.),certainwaterswereselectedinorder to guarantee the optimal chances of survival for the youngallisshadlarvae.Basedontheexperienceofthefirststocking year, after transportation to the river the allis shad were kept in circular tanks and fed until the evening in order to facilitate adaptation to the new habitat and guarantee highersurvivalrates.


Map of stocking locations in the Life+ project duration in the Rhine basin

Lippe: 2012, 2014

Rheidter Laach: 2013, 2015

Sieg: 2011

Rhein: 2011, 2013, 2014, 2015

Erfelder Altrhein: 2011, 2014, 2015

Baggersee Lerchenloch: 2011, 2012, 2013, 2014


Delivery of allis shad larvae at a stocking location After delivery in the morning the allis shad larvae are kept in round tanks and fed to recover from the transport before they are relea-sed in the dark

Allisshadlarvaereadytobereleased.Thegutsoftheyettranspa-rentlarvaeappearredduetojusthavingbeenfed.

Feeding of the allis shad larvae in the tanks

Number of allis shad larvae released in the Rhine basin in the Life (green bars) and Life+ (blue bars) project

480.0001.745.000

2.642.0002.225.000

980.000679.800

2.030.000280.000

0 0,5 1 1.5 2 2.5 3 Mill.

20082009201020112012201320142015


Monitoring of juvenile fi sh after restocking

Fishing for shad larvae with drift-nets in the river Sieg Searchingforjuvenileallisshadwithfloatinggill-netsinthe river Lippe

SearchingforjuvenileallisshadbymeansofelectricfishingintheOxbowErfelden

SamplingtheOxbowErfeldenwithapush-net

The studies on the behaviour and habitat use of the young allis shad following stocking are aimed at evaluating the stocking strategy and assessing the survival rates and opti-misationofthestockingprogramme.Similarly to the search, which was carried out at the same time,andpreviousstudiesofthejuvenilefishintheriverhabitatsintheGironderegion,itcouldbeseenhowdifficultit is to track the juvenile stages of allis shad by monitoring therestockedwaters.Despiteintensivestudies,whichwerecarried out immediately after restocking and in the vicinity ofthestockinglocationsusingfine-mesheddrift,pushandseine nets, they did not provide any new insights on the behavior of allis shad larvae, which apparently spread in smallshoalsandcreated‚nichepartioning‘afterrestockingornaturalhatching.Itisdifficulttofindevidenceofthem,especially given their small number in comparison to the im-

mensehabitatarea.Thisappearstoapplytoanevengreaterextenttothejuvenilestages,whichweresearchedforintheweeksfollowingrestockingusingpush,driftandfixednetsinaccordancewiththeexpectedsizeofthefish,aswellaselectro-fishingfromtheareaoftherestockinglocationsuptoseveralkilometresaroundthem.Despitetheconsiderableamount of work and time spent, there was no success in recapturingtheallisshad.Nevertheless,evidencefindsofju-venile allis shad in the by-catches of an anchored stow-net in the mid and lower Rhine and in the cooling water intakes of power plants along the Rhine showed that the juveniles were abletofindgoodgrowingconditionsintheRhinesystemandmigratetotheseainautumn.


Pilot facilities for ex situ stock

In order to guarantee stocking measures for Alosa alosa in futureregardlessoftheexplorationofthewildstock,thepilotfacilitieshavebeenputintooperationforexsitustocks.In these pilot facilities, the aim is to grow allis shad larvae fromthebreedingfacilityinBruchtojuvenilesandfinallytoadult,sexuallymaturefish,inordertousetheseasfuturebreedingstockfortheproductionofstockingfish.Thesuccessofthismethodisnotcertainduetothecomplexlifecycleofthespeciesandtheirstayatseaoverseveralyears.Partofthestudy,whichisimplementedattwositesinAßlar(Germany)andinLaRochelle(France),istoinvestigatetheimportance of food composition, salinity and water tempe-ratureaswellastheinfluenceofthecircadianrhythmonthegrowthanddevelopmentofsexualmaturity.The growth of the allis shad in the pilot facilities has been encouraging.ThefishinAßlarreachedatotallengthof20cmintheirfirstyearandthetwo-yearoldallisshadhadalreadygrownto33cm.AttheLaRochellesite,thedeve-lopmentofsexualmaturityunderfarmconditionsisbeingfollowed by accompanying histological and physiological studies.Itappearsthatthesexualorgansoftheallisshadinthefarmhavebeendevelopingnormally.Thefirstmales

weresexuallymatureattheageoffour,withalengthof32cm.Despitethissatisfyingresult,therestillremainsalotofworktobedoneforthedevelopmentofefficientbreedinginexsitustocks.Sofar,itisunclearwhetherthefishlivingunder farm conditions have high fecundity (number of eggs per individual) and how large the stocks would need to be in order to produce the required number of allis shad larvae for stocking.Furthermore,itneedstobeclarifiedwhetherthecomplexmechanism of the development of maturity can be simula-tedunderfarmconditions.Problemsarestillposedregar-dingthefunctionofthebiofiltersinrecirculatingsystemswith changing salinity values, and the nutrient supply to thedemandingallisshadunderfarmconditions.AstudyconductedbyscientistsattheUniversityofGiessenonthenutrition optimization of juvenile allis shad showed that the phenomenonofjawdeformityandextremenervousnessofthefishrepeatedlyobservedinthepastcanbepreventedbyan appropriate diet with probiotic bacteria and certain es-sential fatty acids, resulting in a generally better constitution ofthejuvenileallisshad.

Juvenileallisshadinatankinthepilotfacilityatthe Aquarium La Rochelle


Searching for the first returnees in the Rhine

AfterithadbeenfoundthatthejuvenilefishintheRhinehadgrownandcontinuedtothenextstageoftheirlifecycleby migrating to the sea, the burning question remained astowhetherthesefishwouldreturnfromtheseatotheRhineafterreachingsexualmaturityandwhetheritwouldbepossibletodetectthefishinthelargeriverarea.Ontheassumptionthataboutonein250stockedallisshadlarvaesurvived the subsequent stages of the life cycle and will returntotheRhineasanadultallisshad,andthatabout40percentofthefishbecomesexuallymatureintheirfourthandfifthyearoflife,therewashopethatasoftheyear2013(the initial stocking of allis shad in the Rhine took place in 2008),thefirstreturneescouldberecordedintheRhine,infishwaysintheUpperRhineorinthelargertributaries,andthattheirnumberwouldcontinuetoincreasebetween2014and2016.Infact,anallisshadwasobservedinafishwayintheMo-selleinJuly2013–whichwasthefirstallisshadtobeseenintheMosellefor60years.IntheRhineitself,thesearchforreturneeswasmoredifficultduetomaintenanceworkatthefishwayinIffezheim,whichmeantthatthefacilitywas out of operation during the migration season, and due

toalong-lastingflood.However,sensationalevidencewasfoundbychance:whilemonitoringtheamountoffishatanextractionpointofcoolingwaterfromtheUpperRhine,three juvenile allis shad were discovered in September ofthesameyearforthefirsttime.Whenexaminingtheotoliths,notracesoftheoxytetracyclineusedformarkingofthefishwerefound,meaningthattheanimalsdidnotori-ginate from the stocking of the LIFE+ project, but were the descendants of allis shad reproducing naturally in the Rhine -thefirstrecordofanaturalreproductionofallisshadsincetheextinctionofthestockaroundahundredyearsago.Thecapture of a demonstrably spawned female allis shad by aprofessionalfishermaninthesamesectionoftheUpperRhinenearKarlsruheinautumnunderlinesthefactthatallisshaddoactuallyspawnintheRhine.In2014,whenalargernumberofallisshadweretobeexpectedduetotheintensificationofstockingfiveyearsearlier,thesearchforshadwastobeintensified.

Young-of-the-yearjuvenileallisshadfromanexsitustock

Three year old allis shad in the Aquarium la Rochelle

TwoyearoldallisshadfromtheAßlarexsitustock

RecirculationsystemintheAßlarpilotfacility


Anchored stow-net near Rees at the Lower Rhine

ThefirstallisshadseenintheriverMoselfor60years.ItwasdiscoveredbyaVAKIfishcounterwhileclimbingthefishwayinKoblenzinJuly2013.

Frenchfishermenfishingforadultallisshadswithfloatinggill-netsin the Lower Rhine

Young-of-the-year juvenile allis shad caught with an anchored stow-net in the Lower Rhine

Estimated number of adult allis returning from the stocking measures based on the numbers of released larvae andanassumedsurvivalrateof0.4percent

0

1.000

2.000

3.000

4.000

5.000

6.000

7.000

8.000

9.000

10.000

20

11

20

12

20

13

20

14

20

15

20

16

20

17

20

18

20

19

20

20

20

21

Pro

jcte

d r

etu

rnee

s

2015

2014

2013

2012

2011

2010

2009

2008

Year of stocking


Like the juveniles, due to their pelagic lifestyle, adult allis shadarealsodifficulttotrack,whichmeansthatthemo-nitoring of adult allis shad in a big river like the Rhine pre-sentsasignificantchallenge.TheotherwisepositivefactthattheRhineisfree-flowingforthefirst700kilometresand, unlike the other major rivers in Europe, no interfering damstructuresexistwhichrestrictfishmigration,inthiscasemakesthesearchforallisshaddifficultbecauseofthelargeriverarea.Forthesearchforreturneesprofessio-nalfishermenfromtheGaronnewerehired,whohadlivedfromfishingallisshaduntiltheimpositionofthefishingprohibition and therefore knew the migration habits of the speciesandhadmasteredthefishingtechniqueofdriftnetfishing.Theythereforesucceededinfindingevidenceof three adult allis shad in the Lower Rhine at Rees during themonitoringinvestigation–thefirstadultallisshadinNorthRhineWestphaliawhichcouldbeidentifiedas

returnees from the stocking of the LIFE project by means ofthemarkingoftheotolith.Thiswasonlytobethebeginning of the sensational return of allis shad in the Rhineduring2014.318allisshadalonewererecordedinthefishwaysatthebarragesofIffezheimandGambsheim,wherebyboththetiminginwhichthefishwereregisteredat the two successive locations and the differing length distributionssuggestthatthemajorityofthefishobser-vedinGambsheimhadmigratedovertheshippinglocksof the Iffezheim barrage and had not been registered in thefishway.More allis shad were found in the bycatches of profes-sionalfishermenintheUpperRhineorwereregisteredinfishwaysinthelargertributariessuchasMoselleandNeckar,ortookthebaitofsurprisedanglersfishingintheNidda,LippeandSieg.NumerouscarcassesfoundintheRheinindicatedthatthefishhadspawnednaturallyinthe

Fishway with monitoring station at the Gambsheimdam,thesecondobstacleformigratingfishintheRhine

Resounding success of the reintroduction activities in the Rhine

NumberofadultallisshadobservationsintheRhinebetween2000and2015

0

50

100

150

200

250

300

350

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

20

12

20

13

20

14

20

15

nu

mb

er o

f d

etec

ted

ad

ult

s

River Main

River Neckar

River Mosel

Rhein - carcasses

Rhine - fisheries

Rhine - fish way at Gambsheim dam Rhine - fish way at Iffezheim dam


current.Overallanincrediblenumberof341adultallisshadwereregisteredintheRhinesystemin2014.Notwi-thstanding a somewhat lower number of allis shad, which probablywerenotabletofindentryintothefishwaysduetoalong-lastingfloodontheUpperRhine,thewaveofre-turningallisshad(atotalof231)continuedintheRhinein2015.Numerouscarcassesofadultallisshadwhichdieddue to spawning activity, are a clear indication that there areseveralactivespawninggroundsinthefree-flowingstretchoftheRhine.Thediscoveryofnumerousjuvenile

fishwhichwerenotallprovenasoriginatingfromthestocking, but from the natural reproduction of the Rhine returnees, demonstrates that the natural build-up of the stockrecurringhadbegun.Whensearchingforspawningareas of allis shad in the Rhine – due to their characteri-sticflappingoftailfinsonthewatersurface,thespawningactivities of allis shad are audible from a long distance – spawning shad in a characteristic habitat in the Middle RhinecouldbeheardnearKoblenzandthusanactivespawninggroundwasidentified.

Curious discovery from an angler on the bank at the middle Rhine nearCoblenz:bigpikeperchsuffocatedafterpreyinganallisshadof48centimetres

Potential spawning habitat in a side channel of the middle Rhine

AllisshadpassingthroughthefishwayattheIffezheimdamonthe Upper Rhine

Perfect conditions for shads to spawn and for the monitoring ofspawningactivities–amildnightinearlyJuneatthemiddleRhine near Coblenz

An important objective of the LIFE+ project is to distri-butetheproject‘scontents,findingsandachievementsat different levels and to make this information available to both those involved in science, planning and manage-mentaswellasthegeneralpublic.

The project has the aim, in addition to the technical is-sues, to connect with the once great cultural and culinary importance of allis shad along the Rhine and, along with associationssuchas‚PollerMaigeloog‘dedicatedtopre-servingtraditionalcustoms,toreviveallisshadfestivals.

Transfer of knowledge and public perception


Together with a group of pupils the Minister of Environment of North Rhine Westphalia, the state-secretary in the hessian Ministry of Environment and the mayoress of Cologne released allis shad larvae at the allis shad festival in Cologne-Poll

In the allis shad school class programme children discover practical knowledge about the allis shad and other communities in the river, particularlytheseofmigratoryfish

Parallel to these events, a classroom programme is being conducted in which children learn about the allis shad as anexampleofthehabitsofmigratoryfish,thewildlifeofthe Rhine and the function of the current as a habitat and migration path, and to release a new generation of allis shadintotheRhinetogetherwithpoliticiansandofficials.These events, which are carried out annually at different locations along the Rhine in North Rhine-Westphalia, as well as the opening of the pilot facilities for keeping parentallisshad,generatedgreatmediainterest.Sometelevision reports of the LIFE+ allis shad project can be found on the allis shad YouTube channel along with video documentationoftheproject.InexhibitionsorganisedbytheprojectattheAquariumLa Rochelle in France and the Aquazoo Löbbecke Mu-seum in Düsseldorf, hundreds of thousands of visitors can enjoy a unique opportunity to see live allis shad and

to learn about the type of conservation and stocking measurestakingplaceundertheLIFE+project.BeingtheonlyprojectinEuropewhichisdedicatedspecificallytotheconservationofthespeciesAlosaalosa, the Life+ project is closely linked to national and international institutions and communicates its goals and achievementsinconferencesandsymposia.AtaninternationalsymposiuminBergerac,allisshadexpertsfromFrance,Germany,Portugal,theUnitedKingdomandNorthAmericadiscussedpossiblewaysin which the critical situation of the allis shad stock in theGironderegionandfurtherallisshadriverscouldbe overcome in the remaining distribution area of the species, and what lessons can be drawn from the positive re-introductionofallisshadintheRhine.


Photoabove:InternationalallisshadsymposiuminBergerac.Photobelow:Debriefingwithinternationalshadexpertsattheallisshad symposium about the ways out of the crisis of the allis shad populationinEuropeandparticularlytheGirondebasin.

ExcursiontoshadspawninggroundswithaGabarre,ahistoricalboat, on the Dodogne as part of the allis shad symposium

AquariumexhibitionattheAquazooLöbbeckeMuseuminDüsseldorf


The results of studies on the situation of the allis shad and itshabitatsintheFrenchGironderegiondemonstratethedramatic development of the allis shad stock and short-fallbottlenecksoftheirmigrationandreproduction.Anindependentrecoveryofthepopulationisnotexpecteddue to the alarmingly low levels of the stock of spawning fishontheonehandandalsothelimitedavailabilityofhighqualityspawninggroundsforallisshad.Thismeansthat concrete measures must be taken in order to secure the recovery and medium-term increase of the population and to improve the reproductive success of the popula-tion.Thisrequiresthataccesstohighqualityspawningareas must be procured for a larger part of the stock than previously, which presupposes on the one hand the optimisationofthefishwaysacrossdamstructuresortheconstructionofadditionalandmoreappropriatefishmigrationfacilities.In addition, measures aimed at improving spawning habitats in the lower reaches of rivers would be desirable, in particular regarding the presence of gritty river bed

substrate to ensure that developing allis shad eggs are deposited in the gravel gap system and therefore a higher percentage of these eggs will be able to hatch into lar-vae.Furthermore,measuresshouldurgentlybereviewedand then taken that would lead to an improvement in the oxygensaturationinthelowerreachesofriversandensurethesurvivalofjuvenileallisshadmigratingtotheGirondeestuary.As a consequence of the successful restocking in the RhinesystemitstandstoreasonthatascientificallyorientedstockingprogrammeintheriversGaronneandDordognecouldalsobestarted:bystockingtheriverswith marked allis shad larvae, monitoring investigations could take place to estimate the survival of juveniles in the riversandtoidentifydeficiencies.Withasimilarsuccessin stocking to the Rhine system, the spawning stock would alsoincreaseinthefutureasaconsequence.Incombina-tion with the improvement of the conditions for natural reproduction as described above, a recovery of the stock seemsconceivable,andinthebestcase,renewedfishing

Conclusion and outlook

AllisshadintheexhibitionattheAquazooLöbbeckeMuseum

ExhibitionattheimAquariumLaRochelle

PressconferenceinthecontextofareleaseeventattheriverLippe


Further information under www.alosa-alosa.eu and www.lifealose2015.com

The LIFE+ Project “Conservation and restoration of the Allis shad in the Gironde and

Rhine watersheds” (LIFE09 NAT/DE/000008) was supported by:

BezirksregierungDüsseldorf

Landesamt für Natur, Umwelt und Verbraucherschutz Nordrhein-Westfalen

Hessisches Ministerium für Umwelt, Klimaschutz, Landwirtschaft und Verbraucherschutz

activity could be possible under the umbrella of a manage-mentplan.The positive development in the Rhine system can be at-tributed to the success of the actions taken so far by LIFE andLIFE+.Thereturnofallisshadfromthestockingofprevious years and their natural reproduction in the Rhine impressively demonstrates that the ambitious goals of this unprecedented pilot project have been achieved and that thiscanactasamodelforfuturereintroductionprojects.For the Rhine this means that the assessable development until the end of the project shows that building a native allisshadpopulationbeganbyrecruitingjuvenilefishfromindependently spawning returnees and thus the basic requirement is provided for sustainable population deve-lopment.Thissensationalfindingagainstthebackdropof a threatened stock situation across Europe must not hidethefactthatonlythefirststepshavebeentakenwithregard to the development of an allis shad stock which can surviveintheRhineindependentlyintheRhine.Thereforethestockingmustbemaintainedoverthenextfewyears

to ensure that the base population is large enough to pro-videasustainablepopulationdevelopment.Thebreedingofstockfishinthefuture,ifpossible,shouldtakeplaceamong returnees which are already better adapted to the Rhineriversystem.Theywouldbecaughtinthefishwaysin the Upper Rhine region and taken to a breeding facility to be created there along the lines of an allis shad farm, wheretheycanbereproduced.Simultaneously,amonito-ring procedure must be established that makes it possible to follow and assess the further development of allis shad and its recruitment in the Rhine, and for which pilot stu-dieshaveshownthatkeepingallisshadinex-situstocksispossible.Theexperienceswillbeincorporatedintoopti-mised systems, which will make it possible to collect stock fishfromsuchparentfishinthefuture.These measures should ideally be implemented together with the proposed stocking and monitoring activities in the Gironderegionandtherebyhelptodevelopmanagementplans which will be transferable to other river systems and whichwillcontributetorecoveryacrossEurope.

What‘s Life+?Life+ is a promotion program of the European Union aiming on supporting Environmental and Nature conservation projects withinthecommunity.BymeansofLife+BiodiversityandNatureconservation projects like the “Alosa alosa” project are sup-ported, which serve the maintenance and the reestablishment of wild populations of the endangered allis shad as a part of the Natura2000network.

Landesamt für Natur, Umweltund Verbraucherschutz Nordrhein-WestfalenLeibnizstraße 1045659 RecklinghausenTelefon 02361 [email protected]

www.lanuv.nrw.de

Conservation and restoration of the Allis shad in the ... · PDF fileConservation and...

Documents

Transcript of Conservation and restoration of the Allis shad in the ... · PDF fileConservation and...