FARMED ATLANTIC SALMON

INFORMATION NOTES

MARCH 2017

MARCH 2017

FARMED ATLANTIC SALMON

INFORMATION NOTES

Information supporting the RSPCA Approved Farming Scheme Standards – Farmed Atlantic salmon

© RSPCA Australia 2017

RSPCA AustraliaPO Box 265Deakin West ACT 2600

02 6282 8300approvedfarming@rspca.org.auwww.rspca.org.au

3 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

INDEX

Atlantic salmon lifecycle .......................................................................................5

Amoebic gill disease ............................................................................................. 6Biofouling ................................................................................................... 6Biosecurity ................................................................................................... 6Broodfish .................................................................................................. 6Closed Circuit Television (CCTV) ................................................................................ 7Crowding ................................................................................................... 7Environment ................................................................................................... 7Environmentalenrichment ....................................................................................... 8Escapees .................................................................................................. 8Euthanasia .................................................................................................. 8Fasting ................................................................................................... 8Feed ................................................................................................... 9Feeding .................................................................................................. 9Five Freedoms .................................................................................................. 9Flow rate ..................................................................................................10Grading .................................................................................................10Handling ..................................................................................................10Health ..................................................................................................10Incubation/hatching ........................................................................................... 10Injury .................................................................................................11Lighting ..................................................................................................11Mortality ..................................................................................................11Oxygen ..................................................................................................11Predators ............................................................................................... 12Sentience ................................................................................................. 12Shocking ..................................................................................................12Smoltification .................................................................................................12Stocking density ..................................................................................................12Stockpersonship .................................................................................................13Stress ..................................................................................................13Substrate ..................................................................................................13Temperature ............................................................................................... 13Triploid salmon ................................................................................................. 14Vaccination ..................................................................................................14Water quality ..................................................................................................14

4 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

Thispageisintentionallyleftblankforprinting.

5 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

INFORMATION NOTES FARMED ATLANTIC SALMON

TheRSPCAApprovedFarmingSchemeispartoftheRSPCA’sefforttoimprovethelivesofAustralia’sfarm animals. The RSPCA’s animal welfare standards for farmed Atlantic salmon provide therequirementsforrearing,handling,transportandslaughterthatmustbemetundertheScheme.TheRSPCAencouragesproducerstoexceedtheseStandardsastheopportunityarisesandcommittoapathwayofcontinuousimprovementinthewelfareoftheirsalmon.ThesenotesprovideinformationaboutarangeofaspectsrelatingtotheStandardsandtotheproductionoffarmedAtlanticsalmongenerally.

Atlantic salmon lifecycle

Atlantic salmon (Salmo salar)areamemberoftheSalmonidae familyandnativetotheAtlanticOcean.TheyarenotnativetoAustraliadespitetheAtlanticsalmongrowninTasmaniaoftenbeingreferredtoasTasmaniansalmon.Insalmonfarming,thelifecycleofthefishstartswithlayingdownofeggsinthehatcheryduringtheearlywintermonths.Eggsareharvestedfromlocalbroodstock.Eggsandmiltare‘stripped’onceayearbyhandfrombroodstockthathavebeenanaesthetised.

Eggsarefertilisedandthenincubated.Dependingonwatertemperature,eggshatchbetween40and80days.Theincubationperiodismeasuredin‘degreedays’(preferredtemperaturemultipliedbythenumberofdaysincubated)andisaround450degreedays.Thismeansthatif,forexample,thewatertemperatureduringincubationis8ºC,theincubationperiodisaround56days.Insalmonfarming, water temperature can thus be used to manage hatching time to suit the productionrequirements.Thehatchlings—or‘alevins’—absorbnutrientsfromayolksacattachedtotheirbodies.Itisnotuntilamonthormoreafterhatchingthatthefish—nowcalled‘fry’—arereadytoeataformulateddiet.Atthisstage,fryaretransferredtosmalltankswheretheygrowinto‘parr’.Astheygrow,theyaretransferredtolargertankswheretheyremainfor8to12months.Allthistime,theyarerearedinfreshwater.

Atabout80–150grliveweightorwhensalmonhavelosttheircharacteristicstripyparrmarks,thefish—nowcalled‘smolts’—arereadytobetransferredtothesea.‘Smoltification’istriggeredbyincreasingdaylength,sohatcheriesuselightandlightintensitytomimicthedaylengthchangessalmonwouldexperienceinthewildaswinterturnstospring.Atthispointtheyaretransportedintanksfromtheland-basedhatcherytothemarinepens.

Salmoncontinuetogrowintheirnewsaltwaterenvironmentwheretheyremainuntiltheyarereadyforharvestapproximately14-18monthsfromthetimetheyenteredthesea(atwhichtime,theaverageweightofeachfishisaround5kg).Atlanticsalmonhaveanaturallifespanof4to6yearsbutsomecanliveupto10years.Insalmonaquaculturesystems,fishspend10to16monthsinfreshwater(onland)plus14to18monthsinthemarinepensbeforetheyarereadyforharvest.

6 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

Amoebic gill disease

Amoebic gill disease (AGD) is a parasitic condition common in Atlantic salmon farmed in Tasmania. Theparasiticamoebaeattachthemselvestothegillsandtheconditionaffectsthefish’sabilitytobreathe.Itaffectsfishgrowthandrequiresfrequentandrepeatedbathinginfreshwaterfortwotofourhourstokilltheamoebaebyosmoticshock,flushadditionalmucousandremoveopportunisticbacteria from the fish gills. Bathing subjects fish to multiple handling events and thus stress(particularlyoversummerwhenwatersarewarmer).Becausereinfectioniscommon,multiplefreshwatertreatmentsmaybenecessaryinamarineproductioncycleof15months.AGDmonitoring,particularlyattimesofincreasingwatertemperature,isrequiredtomanagethedisease.Vaccinedevelopmenthasnotbeensuccessfultodate.BreedingforAGDresistance isthemostpromisingsolutionandhasthepotentialtoreducethenumberofbaths.ImprovedresponsetodiseasecanbeexpectedwithongoingselectionforAGDresistance.However,somefishmayalsobebetterabletocopewithhandling(crowding,pumping,bathing)thanothers,makinghandlingresilience(toavoidincreasedmortalities)anotherimportantselectiontrait.

Biofouling

Over time, tanks, pen nets and other associated infrastructure surfaces accumulate algae andmicroorganismstotheextentthattheyreducethewaterflowacrossthenetortankwhich,inturn,canreduceoxygensupplytothefish.Thisaccumulationofmarineorganismsonwettedsurfacesiscalledbiofouling.Ifoxygensupplytothefishisreduced,thiscancausestresslevels(andsusceptibilitytodisease)torise.Antifoulants,whichweretraditionallyusedtocounteractbiofouling,particularlyon pen nets, are not used anymore inTasmania’s salmon industry.Antifoulant products form athinlayeronthepennetsurfaceandgraduallyrelease‘biocides’thatpreventtheaccumulationoforganisms.Regularcleaningofbiofoulingisimportanttoensurethatthepopulationofstinging,noxiousandotherpotentiallyharmful foulingorganismsdoesn’t reacha size thatfishwelfare islikely to be compromised.

Biosecurity

Biosecurity is thepreventionofdisease incurrenceand transmissionaswell as themanagementof endemic diseases. Appropriate and effective biosecurity measures include examination and certification of ova and fish prior to stocking; hygiene and sanitation/disinfection proceduresbetweendifferentworkingareasanddifferentsites,movementsofvisitors,vehicles,equipmentandstaff.Inaddition,inthemarinestage,biosecurityrisksrelatedtofishmovementcanbeminimisedby, for example, separating year class stocks, appropriate fallowing and site selection.

Broodfish

FarmingofAtlanticsalmonbeginsonlandatthebreedingfarmwhere‘broodstock’(sexuallymaturefish)areheldinlargefreshwaterpondsortanks.Broodfisharethesourceoftheeggsand‘milt’(sperm)fromwhich,afterfertilisation,thesalmonwillhatchandgrow.InTasmania,salmonfarmersusemainlyfemalefishinthegrow-outphasebecausetherelativelywarmseawatertemperaturescanresultinrapidsexualdevelopmentinmalefishwhich,inturn,resultsingreaterdiseasesusceptibilityandpoormeatquality.Acommonpracticeinaquaculture,therefore,issexreversalofsomefemalebroodstockresultingin‘neo-males’.Thisoccursatthehatcheryatfirstfeedingwhenfishareverysmall.Treatedfishareidentifiedbyclippingtheadiposefinwhichsitsjustinfrontofthetail.Thisallowsforeasyexternal identificationofneo-males.Removaloftheadiposefin ispainfulasthefinisinnervated(itwaspreviouslythoughtnottobe).Thefinalsoappearstoactasa‘precaudalflowsensor’anditsremovalcanbedetrimentaltothefish’sabilitytoswimefficientlyinturbulentwater.Analternativetofinclippingistagging,however,tagscanattractpredators,interferewithlocomotionandmayalsomake thefishmore susceptible to infection.RSPCAwill bemonitoringthe research looking into alternatives tofin clipping.Until then, the standards require that the

7 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

procedureisonlycarriedoutonanaesthetisedfish.Bycrossingneo-maleswithfemales,onlyfemaleoffspringareproduced.Onceayear,usuallyinautumn,individualbroodstockareanaesthetisedbysubmergingthefishinawaterbathcontainingananaesthetic.Broodstockshouldbeanaesthetisedbeforeundergoinganytreatment.Whileanaesthetised,eggsandmiltareremovedfromfemaleandneo-malefish,respectively(aprocessreferredtoas‘stripping’).Whilesomefemalefishareallowedtorecoverfromtheanaestheticandarereleasedbackintotheponds,themethodofmiltremovalfromneo-malefishrequiresallneo-malestobeeuthanasedpriortostripping.Producersshoulduseallavailabledataoffishperformance,survivalanddeformityratestoonlyselectbroodfishthatgivethehighestpossibilityofgoodwelfareoutcomesfortheirprogeny.

Closed Circuit Television (CCTV)

ThesalmonstandardsrequirethatCCTVbeusedtomonitorfishbehaviour inthoseareasoftheslaughteringfacilitywheretherisktoanimalwelfareisgreatest.CCTVshouldnotreplacetheneedtoemploypeoplewiththerightattitudetowardsanimals,comprehensivestafftrainingandgoodstockpersonship.CCTV,however,isanexcellentmeansbywhichfacilitymanagementandauditorscanmonitor compliancewith standards and regulations relating to animalwelfare.CCTVallowsproblemareastobeidentifiedandpromptlyaddressed.ItisimportantthataprotocolisinplacetodeterminetheuseofCCTV.Suchprotocolsshouldincludeinformationaboutthepositioningofthecameratoallowaclearviewoffishstunningandslaughteringprocesses;abouttheperiodforwhichthefootageshouldberetained;aboutthereviewofthefootageandwhoshouldberesponsible;andhowthefootageshouldbekeptsafeandsecure.ThesalmonstandardsalsorequirethatCCTVbeusedtomonitorfishbehaviourduringwellboattransport.

Crowding

Crowdingistheprocessofreducingtheareaavailabletothefishsothattheycanbemoreeasilyremovedfromthetankorpen.Crowdingmaybeusedtomovefishtowardsapumporliftthatmaycarryfishontoawellboatorintoanotherpenforthepurposeofcarryingouthusbandryprocedures.Crowdingisalsorequiredwhenmovingfishontoawellboatorintoaslaughteringplantatharvest.Crowdingisstressfulandoneofthekeypotentialcausesofpoorwelfareduringfishhandlingasitincreases thedensityoffishwithinaparticularvolumeofwater therebydecreasingtheamountofoxygenavailabletothem.Crowdingshouldbecarriedoutataspeedthatdoesnotfrightenorunnecessarilydistressfish.Iffishareattemptingtoescape,burrowingintothepennetorswimmingfast,thenfisharestressedandthecrowdneedstobeslowed.Fishthatpanicwilluseupoxygenquickerandwillinjurethemselvesonthepennet.Fishthatarebeingcrowdedshouldbecarefullymonitored.Additionaloxygenshouldalwaysbeavailableandbeprovidedtofishassoonasoxygensaturationlevelfallsbelow80%.Thecrowdshouldbeslowedandfishgivenmoreroomifanysignsofstressareobserved:fastswimming,burrowing,tryingtoescape,thedorsalfinandpartsofthebackofthefishareexposed,fishscalesareseensuspendedinthewatercolumn,orthesnoutisdamaged.Agoodcrowdiswhenfisharecalm,swimmingleisurely,notburrowingortryingtoescape,andgentlyturningwhentheyreachanobstruction.

Environment

The farming enterprise should be operated with respect for the natural environment and staffshouldrecognisetheirdutytocareforthewiderenvironment.Thesitingofmarinepensshouldbe carefully consideredwith regard to fishwelfare, staff safety andminimising adverse effectsupontheenvironment.Allreasonablestepsshouldbetakentominimisetheecologicalimpactofthefarmingsystem(e.g.byavoidingfeedwastagethroughoverfeedingoffish).Thesestandardsareprimarilyaimedatthewelfareoffarmedfish.However,thepotentialforaquaculturetohavewiderenvironmentaleffectsshouldalsobeconsidered.CompliancewithregulatoryrequirementsinrelationtoenvironmentalimpactmanagementandmonitoringisaprerequisiteoftheApproved

8 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

FarmingSchemeasisongoingcompliancewitharecognisedcertificationschemethatpromotesbestenvironmentalpractice.RSPCAwillassessthesuitabilityofsuchschemesonacase-by-casebasisandconsiderwhether,amongotherthings,thefollowingelementsaresuitablycovered:managementandmonitoringofecologicalimpact,benthic(thesedimentsurfaceandtheorganismslivingincloserelationshipwithit)andwaterquality,pennetbiofouling,fallowingpractices,escapeeprevention,predator control, extraneous species management, and waste and wastewater management and monitoring.Inadditiontofullycomplyingwithallrelevantlegislation,thefarmershoulddemonstrablyand proactively review their environmental protection policies as developments in research andtechnologyallow.Itistheresponsibilityoffarmmanagementtoensurethatallstaffrecognisetheirdutytocareforthenaturalenvironmentandmonitorandlimitpossibleimpactsonit.

Environmental enrichment

The impact of providing environmental enrichment on the behaviour of farmed fish throughouttheirlifecycleshouldalwaysbeconsidered.Enrichmentmaypromoteforagingabilityandreducefininjuriesaswellasbehaviouralflexibilityallowingfishtocopebetterwithdisturbancesandotherstressorsintheirenvironment.ThereispotentialtoimprovethewelfareoffarmedAtlanticsalmonin the freshwater (rearing) stage, for example, by better aligning these systemswith the fish’sbehaviouralneeds.Areastoconsidermay includeaspectsof tankdesign, tankcolour, substrate,overheadcoverorhideaways.Thesecouldofferopportunitiesforfishtoisolatethemselvesorescapefromaggressiveencounters.However,alackofknowledgeon,forexample,howfishmayperceivesuch‘enrichments’andwhattheeffectsofprovidingenrichmentinthefreshwaterphasemayhaveonbehaviourinthemarinephase,meansthatfurtherresearchinthisareaisrequired.

Escapees

Farmedfishwhichescapemayhaveanadverseecologicalimpactandarealsolikelytoexperiencewelfareproblems.InAustralia,farmedAtlanticsalmonarenotconsideredathreattowildsalmonwhenitcomestointerbreeding(becausetherearenosalmonspecieswithwhichitcouldbreed),competitionforfeedandhabitat,ortransmissionofsealice(currentlynotanissueinAustralia).Escapedsalmonhavebeenfoundnottofeedonnativefaunasoeffectivelystarvetodeath.Thisinitselfmeansitisessentialthatallreasonablemeasuresaretakentopreventfarmedfishescaping.

Euthanasia

Fishwhichareunlikelytorecoverfromaconditionorarelikelytobeexperiencingpainordistressmustbehumanelykilledwithoutdelay.Itisunacceptabletoleavefishtosufferwhenitispossibletocatchandremovethem.Forexample,ifaseriouslyinjuredfishisnoticedduringcrowding,itshouldberemovedimmediately,ratherthanbeingsubjectedtofurtherproceduressuchaspumping.Similarly,moribundfishthatcanbeeasilynettedshouldberemovedandeuthanased.

Fasting

Salmonmaybeheldofffeed(fasted)forvaryinglengthsoftimepriortotransport,priortoslaughteror handling events. Fasting lowers the fish’s metabolic activity thereby reducing their oxygenconsumptionandammoniaandcarbondioxidebuildupinthewater.Salmonbodytemperatureisdictatedbytheexternalenvironment(referredtoas‘poikilothermic’)butbecauseinaquaculturesystemstheyarefedhigh-energydiets(comparedtowildstock),theirmetabolismishigherthanitmightbeinthewildandthisfastermetabolismincreasestheiroxygenconsumption.Byevacuatingthefish’s gut and reducingoxygendemandandwasteproductionprior tohandling,fishwelfareis improvedduringtheprocess.Althoughsalmonmaynot feedfor longperiods in thewild,e.g.somefishdon’tfeedduringwinter,holdingafarmedfishofffeedwhenithaspreviouslybeenfedregularlytosatiationmayhaveanadverseeffectonwelfare,particularlyifaggressionincreases.

9 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

It is unacceptable to deprive salmon of food for perceived meat quality reasons. In farmed Atlantic salmon,theminimumtimerequiredtoemptythegut,regardlessofwatertemperature,isthreedays.Thelongertheperiodofffeed,thelowertheavailableenergyreservesthatallowfishtocopewiththestressorsofhandlingandmanagementproceduresthatrequirefasting.

Feed

Salmonarecarnivorousandtheirformulatedfeedcontainsfishmealasasourceofproteinandfishoilasamainsourceoflipidsandessentialfattyacids.Fishmealandfishoilisobtainedfromwild-caughtspeciesofsmalloceanfish(e.g.anchovies,sardines)andfromprocessingwaste(trimmings)fromfishcaughtforhumanconsumption.Effortstoreducerelianceonwild-caughtspecieshaveseenasignificantreductioninfishoil/mealasafeedingredient.In2015,theequivalentof1.7kgofwild-caughtfishwasusedforevery1kgofAtlanticsalmonproducedandthefutureaimistoproducemorekgofsalmonthankgofotherfishusedinitsproduction.Incomparison,itisestimatedthatsalmoninthewildwilleataround10kgofforagefishforevery1kgofbodyweight.Responsibleaquaculturecompaniessourcetheirfeedfromsupplierswhosourcemarineingredientsfromresponsiblefisheries,i.e.notfromIllegal,UnreportedandUnregulated(IUU)fisheriesorfromspecieslistedasCriticallyEndangeredorEndangeredontheInternationalUnionforConservationofNature(IUCN)RedList.Salmonfeedforproductionfishdoesnotcontainaddedhormones.

Feeding

Afish’swillingnesstoeatcanbeusedtodeterminefeedinglevelsandshouldbecloselymonitoredaslossofappetitemaybeanearlyindicatorofstress,e.g.disease,highstockingdensity,poorhandlingorenvironmentalfactorsthatcouldresultinpoorwelfare.

Five Freedoms

TheFiveFreedomswerefirstmentioned in 1965 in aUK report on theWelfareofAnimals keptunderIntensiveLivestockHusbandrySystemswhichstatedthat“farmanimalsshouldhavefreedom“to stand up, lie down, turn around, groom themselves and stretch their limbs”. Following theestablishmentoftheUKFarmAnimalWelfareCouncilshortlyafter,theconceptwasfurtherrefinedintotheFiveFreedomsweknowtoday:freedomfromhungerandthirst;freedomfromdiscomfort;freedomfrompain,injuryordisease;freedomtoexpressnormalbehaviour;andfreedomfromfearanddistress.TheRSPCAconsidersthatthewelfareofananimalincludesitsphysicalandmentalstate.Goodanimalwelfareimpliesbothfitnessandasenseofwellbeing.CriteriaforassessingthewelfareoffarmedAtlanticsalmonagainsttheFiveFreedomsinclude:• Freedomfromhungerandthirst—byaccesstoadiettomaintainfullhealthandvigour

• Freedomfromdiscomfort—byprovidinganappropriateaquaticenvironmentandwell-designed enclosures

• Freedomfrompain,injuryordisease—byprevention,rapiddiagnosisandtreatment

• Freedom to express normal behaviour — by providing sufficient space, proper facilities and companyoftheanimal’sownkind

• Freedomfromfearanddistress—byensuringconditionsandtreatmentwhichavoidsuffering.

Anoverallwelfareassessmentcanbemadebylookingatthefish’sphysicalenvironment,itsbiologicalfunctioning andby observingfishbehaviour in response to challenges in their environment.Thelatter,inparticular,requiresanunderstandingofnormalfishbehaviourandbeingabletoidentifybehaviourindicativeofpoorwelfare.

10 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

Flow rate

Flowrateisabasictooloffreshwaterhusbandry.Itisausefulmeasure,becauseitsetsawaterqualitystandard,whichisindependentofstockingdensity.Itshouldbemeasuredassoonasfisharefeedingintanksandcontinuewhilstthefishareinthetanks.Theaimoftheflowrateprincipleistosetoptimallevelsforwaterflowinfreshwatertanksystemsandthereforepreventsub-optimalrearingconditions,whichcould impingeuponthewelfareofthefish.Optimalflowrates inbothfreshwaterandmarinephases,willensurethatharmfullevelsofcarbondioxide,ammonia,faecesand excess feed etc. do not accumulate.

Grading

Toreduce/removetheneedforgrading(sortingbysize)orhandlingfish,considerationshouldbegiventostockingtanksandpenstoplannedfinalbiomassfromtheirinitialstockingattransfertosea.Optimisinghusbandrypracticesandfarmingenvironmentscansignificantlyreducethecreationof size hierarchieswithin populations, and therefore also reduce the requirement to grade. Forexample, evidence shows that feed distribution and ration size are extremely important, as isknowinghowmanyfishandofwhatsizearepresentinthepopulation.

Itispreferabletogradeallpopulationsintonewpensinordertopromoteoptimalwelfareforthedurationofthegrade.Pre-grademortalityremovalshouldbeundertakenwhereverpossible.Passivegradingisrecommendedwherepossibleandpracticaltodoso.Lightingstrategiescanalsoreduceoreliminatetheneedtogradematuringpopulations.

Agradingplanshouldinclude:thereasonfortheneedtograde,apre-graderiskassessment,thenumberoffishtobegradedperday,thelocationoffishpopulationsbothpre-andpost-grade,thepre-grade fastingperiod, thehealth statusof thefish, theequipment tobeused, including thetypeofgrader,expectedtimetableforcompletionofthegrade,therequirednumberofstaffanddutiestobeperformed,thephysicalcharacteristicsofthesitesuchaswatertemperature,tidesandweatherconditions,thetrainingrecordsofthegradingteam,therequirementforapostgradinghealthcheck,postgradingmortalityrecords,anyrelevantcontingencyplans,andtheagreementandsignaturesofthesitemanagerandthepersoninchargeofthegradingequipment.

Handling

Removingfishfromthewater,crowding,pumping,bathing,andtransportarestressfuleventsforfishthatmayresultinreducedappetite,reducedgrowth,diseaseoutbreakandmortalitiesinthedaysfollowingtheprocedure.Fishmustbehandledinaconsiderateandskilledmanner.Caringandresponsibleplanningandmanagement shouldbeemployedto safeguardwelfareduringessentialprocedures.

Health

Fishmustbeprotectedfrompain, injuryanddisease, throughgoodmanagementandhusbandrypractice, and by rapid detection and treatment of disease. All producers must develop a veterinary healthplaninconsultationwithadesignatedveterinarian.Diseaseisamajorcauseofpoorwelfareandmortalityinfarmedsalmon.Thereforeitisessentialtotakeallreasonablestepstominimisethelikelihoodofdiseaseoutbreaksinthefarmedstock.

Incubation/hatching

Eggsandmiltfromselectedbroodstockaremixedtogethertoproducefertilisedeggs.Thefertilisedeggsarethenplacedinpurpose-builtincubatorsatspecialisedhatcherieswheretheirenvironment

11 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

aimstomimiceggincubationinthewild,forexample,byprovidingcleanwaterflowwithplentyofoxygenfortheeggstogrowand,lateron,substrateinwhichhatchlingscannestle.Asthesmallpea-sizedeggsdevelop,theeyesofthesalmoncanbeseenasablackdotontheorangeegg.Thehatchlings (called ‘alevins’) absorb nutrients from a yolk sac attached to their bodies and theyremaininthehatchingenvironmentuntiltheyareabletofeedindependently.

Injury

Damagetofinscouldbeasignofaggressionorchronicinfectionandmayberelatedtohighstockingdensity,underfeeding,poorwaterquality,poorbodyconditionandhighstresslevels.Skinconditionscanbecausedbymechanicaldamageorbacterial/viral/fungal infections.Damagetofinsorskinislikelytocausepainanddiscomfortparticularlywheretissuelossanddepth/sizeofthewoundissevere.Skindamagemayalsocauseosmoregulatoryproblemsresultinginthefishbeingunabletomaintainfluidbalanceandelectrolyteconcentration.Observationsofrecurringsimilarphysicaldamageinasignificantproportionofthefishpopulationshouldbeinvestigated,as it is likelytosuggestacommoncause.Examplesarepoortankorpendesignand/ormethodsofhandlingorahusbandryprocedure.

Lighting

Inadequate light in the freshwater phase can lead to spinal deformities, suppressed growth andreducedsmoltquality.ExposuretohighlevelsofUVlightmayresultincataractssoprotectingfishbyusingshadeclothoveroutdoortanks inthefreshwaterphaseorbyprovidingsufficientdepthinmarinepens is important. Sudden changes in lighting levelsmay causedistress andprovidinggradualdawn/duskperiodsinindoorhatcheriesaspartofthelightingprogramwillhelppreventthis.Farmedsalmonswimdeeperduringthedaywhilerisingatdusktoswimnearertothesurfaceatareducedswimmingspeed.Useofsubmersibleartificiallightingatnightseessalmonmaintainingtheirdaytimerhythmofcircularschooling,verticaldistributionthroughthewatercolumnaswellasdaytimeswimmingspeed.Providingsubmersiblelightinginmarinepenswillavoidsalmonschoolingathighdensitiesnearthesurfaceatnightandpotentiallybecomingfrustratedinanefforttoobtainlight.Manipulatingphotoperiodshouldnotresultinfishcompetingforresourcessuchasaccesstopreferredtemperature,lightorsalinityzoneswithinthewatercolumn.

Mortality

Highmortalitylevelscanbeanindicatorofpoorwelfare.Duringthemarinestage,mortalitymaybearesultofdisease,injury,problemswiththequalityofsmolts,handling,andotherproduction-orenvironment-relatedfactors.Inaddition,lossesfrompredator(e.g.sealsandcormorants)attacksalsooccur.Duringthefreshwaterstage,diseaseandremovalofsmallorpoorperformingfishmakeupalargepartofthemortalityrate.

Oxygen

Fishextractoxygenfromthewaterthroughtheirgillsinexchangeforcarbondioxide.Inaquaculture,oxygensaturationisameasureoftheamountofoxygendissolved(orcarried)inwaterandisusedas a parameter inwater qualitymonitoring.The ability of oxygen to dissolve inwater (and beavailableforuptakebyfish)isgreatestincooler,lesssalinewater.Fishwilltendtoavoidareasinthewatercolumnwithlowoxygensaturation.Ifoxygensaturationdropsbelow50%,salmonarenolongerabletoregulatetheirmetabolismtocopewithhypoxia.Generally,ambientoxygensaturationlevelsabove80%areassociatedwithpositiveperformance,reducedillnessandincreasedsurvivalofAtlanticsalmoninthemarinephase.Inthefreshwaterphase,reducedgrowth,reducedefficiencyofyolkconversion,prematurehatching,reducedsizeathatching,increasedmortalityandchangesin salmonmorphologycanresult if the incubationenvironment isoxygendeficientand less than

12 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

optimal.Optimaloxygensaturationisnotalwaysachievedinthemarinefarmingenvironment,e.g.intimesofextremeweathereventsorhighalgalmassinthewater.Mitigationstrategiessuchasinjectionofoxygenintothewatermustthenbeemployed.Therearemanyfactorsthatplayaroleintheamountofoxygenavailabletofishincludingwaterflowthroughpens,biofouling,husbandryprocedures,stockingdensity,andfeedmanagement.Theseshouldallbeconsideredwhendealingwithlowoxygensaturationlevelsinthewatercolumn.

Predators

FarmedAtlantic salmonmay be vulnerable to attack by sea birds and fur seals. Protecting thewelfareofthefishisasimportantascontrolmethodsthatconsiderthewelfareofthepredator.Salmonfarmsmaybesubjecttohundredsofsealinteractionseachyearwithsealscapableofbitingfishthroughthepennets,jumpingintopens,rippingholesinthenettingandsometimesthreateningstaff.Cormorantsandcommonseagullsarethemainaerialpredatorsthatareattractedtosalmoninthemarinepens.Althoughthemarinepensarecompletelycoveredbybirdnetting,somebirdsfindtheirwayinthroughholesormaybecomeensnaredinthenetting.Onceinside,birdsthatareabletoperchwithintheenclosurewillgenerallysurvivebutthosethatcannot,maydie.Exclusionmeasures,bothaboveandbelowthewater,shouldbetheprimarymethodofdeterringpredators.

Sentience

Scientificevidenceshowsthatfishhaveanervoussystemthatrespondstonoxiousstimuli,inotherwords,fishcanexhibitanunconsciousresponsetopain.Iffishareconsciouslyawareofthispain,thentheyhavethecapacitytosuffer.Thereissufficientandgrowingevidencetosuggestthatfishcanexperiencepain,fearanddistressandshouldbegiventhebenefitofthedoubtwhenitcomestotheircapacitytosuffer.Attheveryleast,thepotentialforfishtoexperiencepainordistressshouldbetakenintoaccount.Fishmustbetreatedhumanelyandpracticesthathavethepotentialtocausepain,injuryorsufferingavoided.Itisessentialthatpersonsresponsibleformanagingfarmedfishaimtoensurethatfishwelfareisanintegralpartofeveryaspectofproductioneveryday.

Shocking

Shockingistheprocessthatallowsunviableeggstobesortedfromtheviableonesandisusuallydonewheneggsreachtheeyedstageandaremorerobust.Theprocessinvolvespouringorsiphoningeggsintoabucketofwater,andthenreturningtheeggstotheincubator.Infertileorpooreggswillturnwhiteafterthisprocessasaresultofthedelicateyolkmembranerupturing.Theunviableeggscanthenbecarefullyremovedandtheviableeggslaiddownforhatching.

Smoltification

Salmonundergoaseriesofphysiologicalchangesastheyadaptfromlivinginfreshwatertobeingabletoliveinseawater.Thisprocessiscalledsmoltificationandthesalmonatthisstageintheirlifecyclearereferredtoas‘smolts’.Atthisstage,theyaretransferredfromthefreshwaterhatcherytothemarinepens.Thetransferofsmoltstothemarinepensisapeakstressperiodinthelifecycleofsalmon.Inordertoavoidhighmortalities,fishshouldnotbetransferredtoseawateruntiltheyareconfirmedtobefullysmoltified.

Stocking density

Whilestockingdensityonitsownisnotanadequatepredictoroffishwelfare,athigherstockingdensities,fisharemore likelytobecome injured(eitherthroughcontactwitheachotherorthepen),andaremoresusceptibletoinfectionsanddisease.Stockingdensityalsoaffectstheamountofspacethatfishhaveavailabletoexpresstheirbehaviouralneeds.Inmarinepens,fishtendtoschool

13 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

(swiminthesamedirectioninacoordinatedmanner)duringthedaybutatnight,theyrisetothesurface,swimslowerandgraduallymoveawayfromeachother.Stockingdensityaffectsthewayfishareabletorespondtochangesinwatertemperatureandavailableoxygenatdifferentdepthswithinthewatercolumn.Fishshouldbeabletoavoidhigherwatertemperaturesandareasoflowoxygenwithout resulting in overcrowding in parts of thewater column they doprefer. Stockingdensity calculation should take into account the actual depth and different levels of thewatercolumnthatthefishuseratherthanthetotalvolumeofwatertheymayhaveavailable–particularlyinsummer,fishwillseekoutcoolerwatertemperatures.Therelationshipbetweenstockingdensityandwelfareneedstobeconsideredinconjunctionwithwaterquality(includingoxygensaturationandflowrate).Inotherwords,welfareneedstoreflectthebehaviouralneedforspaceaswellasthebiologicalneedforasuitablelivingenvironment.

Stockpersonship

Theattitudesandcompetenceofstaffareavitalfactordeterminingwhetherhighstandardsoffishwelfarecanbeachieved.Itistheresponsibilityofmanagementtoensurethereisawelfareethosamongstaff.Itisessentialthatstockpersonsaresuitablytrainedandexperienced,andareabletorecogniseindicatorsofpoorwelfareatanearlystage.Theymusthaveagoodworkingknowledgeofthehusbandrysystemusedandtheanimalsundertheircare.Highstandardsofhusbandrymustbemaintainedatalltimeswiththewelfareofstockbeingconsideredasapriority.Thestockpersonisresponsibleforoptimisingtheenvironmentthatfarmedfishrelyonforsurvivalandmustmaintainthehighestenvironmentalqualityatalltimes.Itiswidelyacknowledgedthatgoodstockpersonshipand reduced stress are key factors in meat quality.

Stress

Themechanismthatallowsanimals(includingfish)tocopewithchallengesintheirenvironmentiscalledastressresponseanditallowstheanimaltoovercomeoravoidsuchchallenges(referredtoas‘stressors’).However,wheretheanimalisnotabletoescapethestressororwherestressorspersistbeyondtheshortterm,chronicstressresults.Chronicstresscompromisesanimalwelfareandcanusuallybeobservedthroughphysicalandbehaviouralchangesintheanimal(e.g.lossofappetiteandweight,compromisedimmuneandreproductivesystem,impairedmentalfunctionandcopingability).

Substrate

Inthewild,assalmoneggshatchandbecomealevins,theirnaturalsurroundingswouldbegravelwhichprovidesthemwithsolidsupport.Withoutthissubstrate,alevinsinahatcheryenvironmentmaycrowdintocornerstoseekthissupport.Providingsubstratewillpreventalevinsbunchingwhileat thesametimereducingactivity levelswhichmeansenergy (fromtheyolk sac) isdirectedatgrowth. In addition to improved utilisation of the yolk sac, the use of substrate has also beenassociatedwithimprovedfryweightandstablerespirationrateandheartbeatfrequency.Suitablesubstratesmayincludeplasticgrids,rubberspikesonmats,modifiedartificialturf,orgravel.

Temperature

Ideal water temperature for salmon at the marine stage is around 10–15ºC in terms of salmonpreferenceandpositivegrowthrate.However,watertemperaturemayincreaseinwarmermonths.Salmon are able to adapt to higherwater temperatures, at least in the short term, as long assufficientoxygenisprovided.Aswatertemperaturesrise,oxygenlevelsdecreaseand,particularlyathigherstockingdensities,fishmaybecomestressedastheystruggletoobtainsufficientoxygenfromthewater.Asaresult,theyaremoresusceptibletodisease,growthperformanceisreducedand mortality may increase.

14 INFORMATION NOTES — FARMED ATLANTIC SALMON MARCH 2017

Triploid salmon

Triploidsalmonareproducedbyapplyingthermalorpressureshockstotheeggandspermmixatfertilisation.As a result, rather than having two sets of chromosomes (one inherited fromeachparent)thefertilisedeggnowhasthree(onefromthefatherandtwofromthemother).Triploidsaresterileandusedinsalmonaquaculturefortheirlackofsexualmaturation.However,triploidsmaybemoresusceptibletodeformities.Triploidsaremoreeasilystressed(e.g.duringhandlingevents),aremoresensitivetowarmerseatemperaturesandlowoxygenconcentrationsandhavegenerallyhighermortalitiesthannormaldiploidsthroughouttheirlifecycle.Atslaughter,maturefishwithjawabnormalitiesmaybecomestuck in thestunningequipmentandmaynotbeadequately stunnedpriortobleedingout.Skeletalproblemsintriploidscanbeaddressedbymodifyingtheirdiet,e.g.providingextraphosphorous.Superiorbreedingtechniques,carefulhandling,closemonitoringandtimelyinterventionarerequiredifthewelfareoftriploidsalmonisnottobecompromised.

Vaccination

Anumberofinfectiousdiseasesareabletobepreventedthroughvaccinationandtheintroductionof vaccination procedures in hatcheries has seen antibiotic use reduced dramatically. However,somefishsufferadversereactionstointraperitonealvaccinesincludingadhesionsbetweeninternalorgansorbetweeninternalorgansandthewalloftheperitoneum.Ifeffectiveoralvaccinesaredevelopedtheseshouldbethepreferredmethodofvaccination.Adversereactionstovaccinesmayalsoincludereducedgrowthrate,poorcarcassquality,behaviouralrestrictions,spinaldeformities,eyeinfectionsandautoimmunereactions.Careshouldbetakenwhenreturningfishtotherecoverytankfollowingvaccination.Forexample,loweringthepipegoingintothereturntankcanmakeitamuchgentlerexperienceforthefish.Abdominaladhesionsshouldbemonitoredtoallowvaccinationprocedures to be improved where necessary. Where possible, vaccination should coincide withgradingoperationstominimisehandlingoffish.

Water quality

Waterqualityandwaterflow,servingthesupplyofoxygenandthedisposalofwastes,arecriticaltofishhealthandwelfare.Waterqualityisaffectedbystockingdensity,feedandotherwaste,oxygenandammonialevelsamongotherthings.Poorwaterqualitymayresultinstress,reducedgrowth,disease,finerosion,gilldamageandmortalityinfish.Waterthatissuper-saturatedwithoxygencanalsocompromisefishwelfare.Levelsofoxygen,carbondioxide,ammoniaandnitrogenshouldberegularlymonitoredinordertoavoidthis.Asourknowledgeofthewaterqualityneedsofthefishimproves,itmaybenecessarytochangeand/oraddtotheparametersneedingtobemonitored.Forexample,theinclusionofparametersassociatedwiththemineralcontentofthewatermaybeappropriateasmoreinformationbecomesavailableabouttheireffectonthewelfareofthefish.

RSPCA AustraliaPO Box 265Deakin West ACT 2600

02 6282 8300approvedfarming@rspca.org.auwww.rspca.org.au