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Echosoundertheory

Biomass

ProvidedthatyouuseanEK15withasplitbeam

transducer,orhaveavalidbiomasslicenseonasingle

beamtransceiver,youwillhaveaccesstotheBiomass

informationpane.

Thisbiomassvalueisanindicatortohowmuchsh

youcurrentlyhaveinthecurrentechogram,orinthe

zoomedarea.Everysingleshwillemitanecho,and

thesumofalltheseregisteredechoesarepresentedas

anumber.Smallerorganismssuchasplanktonwillalsoemitechoes,buttheseareso

weakthattheywillhardlyinuenceonthetotalbiomass.

TheEK15recordsallthetargetsfromthesmallestplanktontothelargestwhale,and

providesthesendingsasanumber.Forallpracticalpurposesthisnumberwillprovide

youwithinformationabouttheshabundancetoallowyoutodecideifitpaysoff

tostartshing.Y oumustalsoconsiderifthisnumberisaresultoflargeamountsof

planktonorbait,orifthereisrealshbelowthekeel.Thenumberprovidedtodisplay

shabundanceisrelative,andaftersomeuseyourexperiencewillbeavaluablefactor

whenthedecisionismade.

Thebiomassvalueisalsousedbytheresearchestocalculatehowmuchshthereisin

theocean.Ifyouknowtheshspecieandthesizeofthesh,youcancalculatenumber

ofindividualshesforagivenvolumeofsea.Othermeanstoestablishthenalresult

aretrawlingandcatchdatafromthesherycommunity.

Note

IfyouhaveotherechosoundersorsonarsrunningasynchronouswiththeEK15,the

EK15willalsomeasurethetransmitpulsefromthesecondarysystem.Thisiscalled

interference.

YoucanremovetheinterferenceusingthePing-PingFilterfunctionontheActivemenu,

buttheEK15receiverwillstillpickupthetransmitpulseandimplementitinthe

calculations.

Afullsynchronizationofthevariousacousticinstrumentsisrequired.Ifyourownvessel

producesexcessivenoisethiswillalsobetakenintothebiomasscalculationsand

provideyouwithinaccurateinformation.

Relatedtopics

•Biomasslineonpage121

•Biomassinformationpaneonpage125

•Echogramdialogboxonpage206

Dynamicrangeanddisplaypresentation

TheEK15echosounderhasadynamicrangeof80dB.

351718/C

271

Simrad EK15 User Manual

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