conservation and restoration of the allis shad in the ... · pdf fileconservation and...
TRANSCRIPT
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
Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds8
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
ConservationandrestorationoftheAllisshadintheGirondeandRhinewatersheds 9
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
ConservationandrestorationoftheAllisshadintheGirondeandRhinewatersheds10
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
Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds 11
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
Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds12
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.
Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds 13
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
Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds14
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
ConservationandrestorationoftheAllisshadintheGirondeandRhinewatersheds 15
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.
Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds16
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
Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds 17
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
ConservationandrestorationoftheAllisshadintheGirondeandRhinewatersheds18
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
Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds 19
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
ConservationandrestorationoftheAllisshadintheGirondeandRhinewatersheds20
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
ConservationandrestorationoftheAllisshadintheGirondeandRhinewatersheds 21
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.
ConservationandrestorationoftheAllisshadintheGirondeandRhinewatersheds22
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
Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds 23
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
Conservation and restoration of the Allis shad in the Gironde and Rhine watersheds24
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