STATE OF SEXUAL MATURITY OF ATLANTICSALMON

STATEOF SEXUALMATURITYOF ATLANTICSALMON(SafmosalarL.) CAUGHT AT SEA.IN COMMERCIALFISHERIESOFF NEWFOUNDLAND,

BY

CONRAD CALVERT MULLINS

A thesissubmittedto the School of Graduate Studiesinpartialfulfilmentof the

requirements forthe degreeof Master of Science

Department ofBiology Memorial University of Newfoundland

April8.1995

St. John's,Newfoundland

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ABSTRACT

The stateof maturity ofmaleandfe male Atlantic salmon harvestedatsea during1990 and199 1 atthreesitesin Newfoundlandwas Investigated.Salmonlanded atSI.Barbe Bay. CcncreundTwillingate were sampledthroughout the commercial fishingseason (June- August). Themethodsused to determinethestate of maturityin maleandfemale salmon werehistologicalexaminationofgonadaldevelopmentand radioimmunoassay of plasma steroid hormonelevels.The gonad stage dcvelepmcut.

gonadosornaric index(GSI),bepatosomaticindex(HSI),coudttionfactorteFl, testosterone(T), l l-ketotestosterone (II-KT), vitcllogenin(Yg)and17fJ-estrndiol (E2) levels measured in commerciallycaught salmon werecompared with those01' cage-rearedandwild salmonof knownbackgroundto verifythematurity classifications.Stagesof gonaddevelopment.the levelsof T, E2,II-KT.Vg,and aSI.HSIand CF measuredinmale andfemale salmonof knownstareofmaturity wereusedtodevelop discriminantfunctions for predictingthe state of maturityill commerciallycaughtsalmon,Salmon sampled in St.Barbe Bayin the Gulf(If SI.

Lawrencewere100%spawners-of-the-year .whereas,samplesfromConchc and Twillingateon thenortheast coast of Newfoundlandconsistedofsalmonthat would nothave returned totheir native riversto spawn,Differencesinbiological characteristicsof salmon fromthe commercialfisherylocations tendtosupport the maritimeoriginofthenon-maturing componentofcommerc ial landings in

Newfoundland.Maleandfemale Atlanticsalmonthat are not spawners-of-the-year canberecognized by discriminantanalysistechniquesonthe basis ofthe stageof gonad development,plasmahormonelevels,andasl.

iii

ACKN OWLEDGEMENTS

Iammostgratefulto my wife Rosemar y, ourtwo childrenConradJr.and Allison,and myparen ts for theirinvaluable encou ragement.support.and understandi ngduringthe pastfour years.lowe a specia l[hankstoR.Claytorfor providing thequestion ,much neededadviceonthe discriminantanalysis,andfor his friendshipand encouragem ent. Iamthankful for the financialsupport providedbyIlly employer, the Departmentof Fisheries andOceans.Canada, andbyDr. J.Green.

Depart ment ofBiology.MemorialUniversity of Newfoundland through anNSERC grant.I am privileged tothankthemembersofmy grad uatecommittee,Dr.J.Green.

Dr.V.J. Steele,and Dr. L.Crim,for theirsupportandguidanceduring thecourse of this research , and especiallyfor their patience andmany helpfulsuggcsuonsdur ing the preparation oftheman uscript.Thetechnicalandfield suppor t pro videdbythe follow ing peoplewas greatlyappreciated:S.Walsh forprov idingadv iceon histological techniquesand lab facilities;C. Shortfor guidingmethroughthe rediotmm uncassays forsteroid hormone s;Dr.D.Idler and Dr.Y.P.So fordoing theplasmavitellcgeninassays;C.Collier, A.Sutterlin,R.Strickland. and C.Mullins Jr.fortheirassista nce in samplingat Bale cl'Espoir;P.Fitzpatrick,C.Hood,P.

Caines.D.Caines.andP.Downtcn forsampling inthecommercial fisheri es ;D.

Reddinforproviding samplesfrom theLabrador Sea:andR.Ficken for photograph y.

iv

TABLEOF CONTENTS ABSTRACf

ACKNOWLEDGEMENTS TABLEOFCONTENTS LISTOF TABLES LISTOF FIGURES LISTOF APPENDICES l.INTRODUCTION 2.MATERIALS ANDMETHODS

2.1StudyAreas 2.2Histology

2.2 .1Oogenesis 2.2.2 Spermatogenesis 2.3Radioimmunoassay 2.4Biolog icalCharacteristics 2.SDiscriminantAnalysis J.RESULTS

3.1ReferenceSites 3.1.1Females 3. 1.2Males 3.2 CommercialFishery

3.2.1Biological Characteristics 3.2.2Females

3.2.3Males 3.3DiscriminantAnalysis 4.DiSCUSSION 5.REFERENCES 6.APPENDIC ES

viii xii

5 10 11 18 22 2J 24 26 26 27 J6 45 47 47 SJ 56 6J 70 74

Table1.

Table2.

Table 3.

Table 4

Table5.

Table6.

Table7.

LIST OFTA BLES

Summaryof sampling locations, dates,numberandsex of Atlantic salmonsampled in1990and199 1.

Relationship between levelsofT.E2,

vg.

GSI,1-151. and CF andovarystage in cage-rearedSaintJohn Riverfemale 30 Atlanticsalmon,,**, "" significantrclaucn shlpatthe .OS leveland 'ns'=non-significantrelationship.

Relationshipbetween levels ofT,11-KT . GSI.I-lSI and 40 CFand testisstagein cage-reared SaintJohn River Atlanticsalmon.'**'''''significance relationshipatlhe.05 leveland'ns'encu-signifk aru relationship.

Numberof yearsspentin freshwaterby wildvirginsea- 4H age-IAtlanticsalmonsampled in 1990and1991.

Stepwise selectionofparametersfor discriminant analysts 57 ofthe stateof maturity in maleand femaleAtlanticsalmon sampledfrom the SaintJohn River cage-rearedstock(May andOctober1990), Labrador Sea (October 1991),Humber River (July-August 1991),and Western ArmBrook (August-October1990).Parametervaluesarc given in Appendices10-13.

Results of discriminantanalysisof the stateofmaturity in 5H maleand female Atlanticsalmonsampledfrom theSaint John Rivercage-rearedstock(May andOctober1990), LabradorSea (October1991) .Humber River(July-August 1991),and Western ArmBrook(August-Octobcr1990).

Parameter valuesusedin the analysisare givenin Appendices 10-13.

Calculation ofCohen'skappa for results ofdlscrlmiuaut 59 analysisofthe stateof maturity inmale andfemale AtlanticsalmonsampledfromtheSaint JohnRiver cage- reared stock(May andOctober1990).LabratlorSea (October 1991),Humber River {July-August 199 1), and WesternArmBrvok (August-Oc tober 1990).Test ! and

Table 8.

Tesarefer10 subsets of observations on malesand females.Testlused thefirs!50%of theobservations 10 predictthestate of maturityinthe second50s,.and vice versafor Tesa.

Resultsof discriminantanalysisof thestateof maturityof 62 maleand femaleAtlanticsalmon sampled fromthe Saint JohnRiver cage-rearedstock(May andJuly1991). and commerciallandingsat51.Barbe Bayand Conche in 1990 and 1991.Numbersin parenthesesare percentages.

vii

LIST OFFIGURES FigureI. Sampling locatio ns in Newfoundland.

Figure2. Ovary stage 3 (l6X) ofhatchery-reared female salmon 15 smolt sampledonMay 12. 1990(Samp leNo,5J IF29) showingoocyresatstages2-4.

Figure3. Ovary stage 4 (l6X)ofcage-reared female salmon 15 sampledon October15,1990(SampleNo.SJ2F28) showi ngoocyresatstages3-5 .

Figure4. Ovarystage5 (16X) ofcage-reared female salmon 15 sampledonMay4.1991(SampleNo.SJ3F50) showing oocytes at stages5&6.

Figure 5. Ovarystage6 (16X)ofcage-rearedfemalesalmon 15 sampled011May4,1991(Sample No. SJ3F42) showing oocyresat stage6.

Figure6. Ovary stage 7 (16X)ofcage-rearedfemalesalmon II>

sampledon November9.1991(Sample No,SJ5F9) showing oocyteat stage7.

Figure 7. Ovary stage8 (16X)ofcage-rearedfemalesalmo n II>

sampledon November9.1991(SampleNo.SJ5F4 6) showin g oocyte at stage8.

Figure 8. Ovarystage9 (l6X) of wildfemalesalmonsampledat II>

Concbeon August 4,1991 (SampleNo. C91F54)showing oocyte atstage 9.

Figure 9. Ovary stage 10(I6X) of wildfemalesalmon sampledat 16 St.BarbeBay onJuly 14.1990(SampleNo. 511901"249) showingoocyteat stage 10.

Figure10. Ovary stageII(16X)ofwildfemalesalmonsamp ledat 17 ConcheonJuly15,1991(Sample No. C91F27) showing oocyteatstageII.

viii

FigureII. Ovary stageII(l6X) of wildfemalesalmonsampledat 17 St. Barbe Bay on July2, 1990 (SampleNo.SB9OF215) showingoocyte at stage II .

Figure 12. Testis stage I (I00X) ofcage-rearedmalesalmonsampled 20 onMay 4, 1991 (Sample No. SJ3M30)showing primary spermatogonia(Isg).

Figure13. Testis stage2 (lOOX) ofcage-rearedmalesalmon sampled 20 on May4,1991 (Sample No. SJ3M33)showingprimary (lsg) and secondary spermatogonia(2sg).

Figure14. Testis stage 3 (lOOX) ofcage-rearedmalesalmonsampled 20 on July 15, 1991(SampleNo. C91MII)showing secondary spermatogonia(2sg)and spermatocytes (sc).

FigureIS. Testis stage 4(IOOX) ofcage-reared male salmonsampled 20 onJuly17,1991(Sample No. C9 I M3B)showing secondary spermatogonia(2sg),spennatocytes(sc).and spenna tids(st).

Figure 16. Test isstage 5 (IOOX)ofcage-rearedmale salmon sampled 2\

on July30, 1991 (SampleNo. SJ4M49)showing secondaryspermatogonia(2sg) and large cysts of spermatids(st),and spermatozoa(sz).

Figure17 . Testis stage 5 (I00X)ofwild male salmo nsampledfrom 2\

the estuaryof theHumberRiveronAugust26.1991 (SampleNo.H91M14)showinglargecysts ofspermatids (at) and spermatozoa (sz).

FigurelB. SaintJohn River:stagesof oocyte developmentin cage- 28 rearedfemale Atlantic salmonon fivesamplingdates in 1990and1991.The values of nrepresentthe number of oocytes counted,

Figure 19. SaintJohn River:modaloocytedevelopment stagesin 29 cage-reared female Atlanticsalmon on five samplingdates in1990and1991.TIlevaluesof nrepresentthenumber of fish sampled.

ix

Figure 20. SaintJohn River:mean levelsorT.E2.

vg .

GSI.IISI, lI1d 31 CF incage-rearedfemale Atlantic salmonllt each modal oocytestageonfive samplingdatesin1990 and 199 1.

Vertical lines are standarderrors andthenumbersabo ve linesrepresentthe numberof !ishsam pled.

Figure21. Stagesofoocyte development in wildfemaleAtlantic 34 salmon fro mthe LabradorSea. Humbe rRiverand Western Arm Brook. TIlevalues ofnrep resent the number of oocytes counted.

Figure22. Modal oocytestages in wild femaleAtlanticsalmon fro m 35 the Labrador Sea.Humber River and WesternArm Brook . The values of n represent thenumberoffish sampled.

Figure 23. Meanlevels ofT, E2,Vg,GSI.I-IS[.andCF in wild 37 femaleAtlanticsalmonateachmodaloocytestage from the LabradorSea.Humber RiverandWestern Arm Brook.

Vert ical lines arcstandarderrorslindnumbers abovelines representthenumber of fish sampled.

Figure24. Saint Joh nRiver: stages of spermatoge nesisincage-reared 3.

male Atlantic salmonallfive sampling dates in1990and 1991.The values ofn represe ntthenumber offish sampled.

Figure25. SaintJohn River:meanlevels ofT,IIKT,GSI.I-lSI, and 41 CF incage-rearedmaleAtlalllicsalmonHIeachstage of spertnarogeneslsonfivesamplingdales in1990 and 1991.

Vertica l linesarestandarderrorsandnumbers abovelines represe ntthenumberof fishsampled.

Figure 26. Stagesof sperma togenesis inwild maleAtlantic salmon 43 fromtheHumberRiver. Thevalue ofnrepresents the number of fish sampled.

Figure 27. MeanlevelsofT.IIKT, GSI,HSIandCFin wildmalo 44 Atlant icsalmonateach stageofspermatogenesisfromthe Humber River.Vertica llinesarcstandarderrorsand numbersabovelines represe ntthenumbcr offish sampled.

Figurc 28. Dates of commercialsalmonfishery landingsbyselected 46 fishermenat St.BarbeBay andCandle,New foundlandin 1990and 1991.

Figure29. Oocyte stages in wildfemaleAtlanticsalmonfrom 49 commercial land ings atSt.Bar beBay,Concheand Twlllingate.The valuesof nrepresentthenumber of oocytescounted.

Figure30. Modal oocyte stages inwild female Atlanticsalmonfrom 5\

commercialland ings atSt.BarbeBay, Concheand Twillingatc.The values ofnreprese nt thenumber offish sampled.

Figure31. Meanlevelsof T.E2.Vg andGSI in wildfemaleAtlantic 52 salmonat eachmodal oocytestage from commerc ial landings at St.BarbeBay andConche. Vertical linesare standard errors and numbers above lines representthe number of fishsampled.

Figure 32. Stagesof spermatogenesistn wild male Atla nticsalmon 54 from commerciallandings at St. BarbeBay.Conche, and Twillingate.Thevalues ofn representthenumber offish sampled.

Figure 33. Meanleve lsofT. ll KTandaSIinwildmaleAtlantic 55 salmonat eachstage ofspermatogenesisfromcommercial land ingsat St.BarbeBayand Conche.Verti callinesare standarderrors andnumbersabove lines representthe number of fishsampled.

Figure 34. Canonicalvariatescoresformale and female Atlantic 6\

salmonusedinthe discrim inantanalysisof state of maturity.Arrowsindicatethe mean values.

xi

LIST OF APPENDICES

Appe ndix 1. Protocolsused for dehydratingand double embedd ing of 75 gonad tissuefrom maleand femaleAtlanticsalmall.

Append ix2. Protocols used forstaining ofgonad tissuefrommale:lIlll

"

femaleAtlanticsalmon.

Appe ndix 3. Protocols usedfor extraction ofsteroid hormo nesfro m 77 plas ma ofmaleand femaleAtlantic salmon.

Appendi x4. Protocolsused for preparationofthe standard curvesfor 7H RIAs cf stero id hormonesin plas maof maleandfem ale Atlan ticsalmon.

Appe ndix5. Protoco ls used for RIAsof ll-ketotestostcronein plasma 79 of maleandfemaleAtlanticsalmo n.

Appe ndix6. Protocols used for RIAsoftestosteroneand estradiolin 82 plasmaofmale and female Atlantic salmon.

Appendix 7. SASprogramusedfor discriminantanalysis and 85 classificationof thestateofmaturity in male andfe male Atlanticsal mon.

Appe ndix 8. CalculationofCohen's kappastatistic,statistical 88 sig nificance , and 95% confidenceintervalforobser ved and predicted state of maturityinmaleandfemaleAllalllic salmon.

Appendi x9. Parame ter values measuredinbloodand ovarysam ples ')"

fromfemaleAtlantic salmonsamp ledfromtheSaintJohn Rive rcage-rearedstock.The values of'Stain'refer10the colour ofstainedovary sections - 'A' =Acidophilic (pink);

'B'= Basophilic (blue);and'AB' =jmcrmcd iatc(mau ve), 'C P'refers to ConditionPacror.

xii

Appendix10.

Appendix II.

Appendix12.

Appendix13.

Appendix[4.

Parametervaluesmeasuredin bloodand ovary samples 91 from wildfemaleAtlanticsalmonat three reference sites.

The valuesof'Slain're fertothe colourof stainedovary secticns ,'A' =Acidop hilic(pink);'B'=Basophilic(blue);

and'AB'=inlermediate (mauve). 'CF' referstoCondition Factor,

Parametervalues measuredinblood andtestis samples 93 from male Atlanticsalmon from the Saint JohnRiver cage-rearedstock.'CF'refers to Condition Factor.

Parameter values measu redin blood andtestis samples 94 from wild male Atlanticsalmonatthree referencesites.

'CF' refers to ConditionFactor.

Parameter values measuredinblood and ovarysamples 95 fromwildfemale Atlantic salmonatthree commercial fisherylocations in 1990 and 1991.The valuesof 'Slain' refertothe colour of stainedovary sections~ 'A' = Acidophilic(p ink); 'B'=Basophilic(blue);and 'AB'= intermediate (mauve).'CF'refers to Condition Factor.

Parametervaluesmeasuredinblood and testissamples 97 from wild maleAtlantic salmonatthree commercial fishery locationsin 1990and 1991.'CF'refers to ConditionFactor.

xiii

I.INTRODUCTION

Atlanticsalmon<Sa1nm..IalarL.)may spendone (sea-age- I),two{sca-agc· :n ormore years at sea before returningto theirnatal streamsto spawn.Ontheir retu rn spawningmigration,bothsea-age-landsea-age-zsalmon havetraditionally contributedto commercialsalmonfisheries harvestsineastern Canadianwaters. jthas been widelyspeculated.however.thatnot all of the commerciallycaught.sea-age-l salmonare returning spawners-of-the-year but are instead.non-maturingFishwhich would have remainedat sea for an additionalyear beforereturningto spawnas sea- age-zsalmon.Itisimportant to know ifthisisthe casebecausesea-age- Isalmonthat are not spawners-of-the-yearwouldgenerallyattaina Jergersizeand have ahigher fecundity if they couldbepermittedto completethemarinephase of the ir life histo ry andrcturn tospawnat sea-age-2.

Also.from the pointofviewofresource management.therecogn ition or salmonthatare not spawners-of-the-yearincommercial landings wouldexplainsome oftheannual variationinthe numberof large ,sea-age-2 salmon returning\0spaw nin easternCanadianrivers.Oneof theproblemsinforecastingthe relativeabundance of sea-age-zsalmon(fromcommercial catches ofthe sea-age-l cohortintheprevious year)has beeninnot knowingtheproportionth.'\t arecaught incommercial fisheries

beforethey reachsexualmaturity(Chadwick.1985).Ifcommercialharvests"couldbe restrict ed10 spawners-of-the-year,then the potentialvalue of theAtlanticsalmon resourcewould be increased.

The resultsofseveralmarinelagging andrecapturestudiesconducted by the Depart mentof FisheriesandOceans.Canada inthe pasttwo decades.have beenused 10support theview thatcoastalcommercialsalmon fisheries in Newfoundland in particular.exploitnon-maturing salmon.Ithasbeen speculated (Turner.1975a;

Turner .1975b; Pepper.1982;Pepper.1983;andPippy,1982) that maritimeorigin (laggedassmottsjadultsalmon(sca-age-I ,-2,-3)caught off Newfoundlandinlate May to late July would havemissed,had theynotbeen caught, the peakmigration period(July) for salmonascendingmaritimeriverstospawn.Ithas been suggested Ihatthesefish are notspawners-of-the-yearbutinstead would haveremained atsea toranotheryear before ascending theirnatalrivers to spawn.Reddinand Lear (1990) pointed outthatseveralsea-age- I salmon.taggedoff northeastern Newfoundland, wererecaptured the yearafter tagging,suggesting thattheydidnot spawn in the year taggedbut rema inedat sea andwould return to spawn thefollowingyear. However.

no buormation on theslate ofmaturityof therecaptured fishwas presented.Itis also possible,givena swimmingspeed of about 32 kmper day (Pippy,1982),thatsalmon

,Footnote: The Newfoundlandcommercialsalmon fisheryhas been closed since 1992, bUI the fisheryremains openin Labradorand offwestGreenland.

present offnor theastern Newfoundlandinlate Julycouldswimthe approximately 1,600 km distance in timetoreturnas part ofthefall-runtomaritimerivers.

However,thispossibilityisusually givenonlysecondaryconsiderationinthe literature.

In aprevious studybased on physiological indicators of relativematurity, Idler et. al(1981)concluded that86-91% of the femalesalmon capturedinthe commercia l fishery offnortheas tern Newfoundlandwerespawne rs-of-the-year.Female salmon withaplasma vitcllogenin(Vg)level higher than396ug/ml were co nsidered tobe maturingfish.However ,this valuewasdetermined fromsilt and19 femalesofknown maturityin two separateyears,and maynot completely represent thevariabilityin levels of Vginmaturing Atlanticsalmonat sea.Furthermore,the Vg methodology of the time(Idleretal.1979).was1I0t completely quantitative for plasma Vg (D. Idler, OSC.MemorialUniversity of Newfoundland,personalcommunication).

The present study was basedupon an improvedquantitative method for measuringplasma vitellcgeninlevels. So et at.(1985)succeededin isolating vitellogeninfrom landlockedAtlanticsalmon plasmaand developed a homologous radioimmunoassay to quantifycirculatingvitellogenin.Thisnewtechnique was adopted in this studytomeasure plasmavitellogen inincommerciallycaught female salmonand to evaluate the seasonal profile of vltellogenlnin Atlanticsalmonof known background. Severalsteroid hormoneshave alsobeenassociatedwithsexual maturationinmale andfemale Atlanticsalmonthatmaybeuseful toevaluatethe state

ofmaturity ofindiv idualfish,The steroidhormone.tt-ketorestosrerore (I I-KT),was firsttdentified in theplasma of sockeyesalmon(OncorhynchuS nerkal byId ler et at.

(1960)andwasquantifiedastbemajorandrogen inthe plasmaof maleAtlantic salmonduring sexual maturation(Idleretel.1970).Testosterone(T)was alsofound illthe plasmaof sexuallymaturingmale Atlantic salmo n (Idlereral.1970).

Extremely high levels oftestosterone insockeyesalmon during their upstream migrationdecreasedsignificantly afterspawning (T ruscottetal,1986).The steroid.

estradiol(E2),wasmeasuredin progressivelyhigherconce ntrations in theplas maof femalebrown trout~during seasonalmaturation(Crim and Idler ,1978).

Theobjec tives ofIhisstudyare:I.10developphysiologicalandhistological criteriato discriminatebetween spawners-of-the-yearandnon-spawners;2.10use these criteria10idemifyspawners-of-the-yearand non-maturingsalmon incommerc ial salmon fIsherylandings.

2.MATERIA LSAND METHODS

2.1StudyAreas

Bloodand gonadsampleswere collected from 297commerciallycaughtvirgin sea-age-lmale and femaleAtlanticsalmonof unknownslateofsexual maturity.Their stateof maturity asdetermin ed on thebasis ofre ferenceprofiles of gonad developmentand steroidhormone levelsestablished for433 maturingand11011- maturing salmonsampledatfour reference sites.Thesalmonsampled from the reference sitesincludedvirginreared and wildfish (TableI).

Commercial land ingswere sampledat St.BarbeBay. Conchcand Twlltlngarc . Newfoundland (Fig.I).St. BarbeBay, in theGulf of St. Lawre nce,waschosen because of alowincidence ofrecapturesinthearea of salmon taggedas smolls in maritimeriver systems (Turner,I97Sb;Pippy,1982;Peppar,1983) whichsugges ts thatcommercia lcatches inSt.BarbeBayarepredominant ly of local or igin.Lo ng- termstudiesin theSI. BarbeBay areaindicate that spaw ning adultsalmoninloca l riversareabout 99% sea-age - Ifish.Therefore, commercia llycaughtsea-age-l salmon in thisarea arelikelytobe spawners-o f-the-year.Conchoand Twillingare, located onthe northeas t coast ofNewfoundland,were chosenbecauseof therelatively high incidence ofrecapturesof sea-age- lsalmon, duringJulyand August which were taggedas smoltsinrivers ofeasternNew Brunswick(Saunders,1969;Turner, I975b).

• Commen:ial ... Hatchery

~Sea-cages Ann Brook· River

Figure I. Samplinglocations in Newfoundland.

TableI.SlImmaryornmpling Joc:alions,dates,numberandsexcompostuona! Allanllc salmonsampled in1990 and1991.

Total

TOlal nllmbcror Number Number perce nt

Sampling Sample virginrlSbal Virgin Virpn Virgin

Locanon Dale S. . Sea-ageIV! Males Females Females

Commercia lFishe rySites:

SI.BarbeBav Jlln.26-JIII.14,1990 37 32 9 2J 713

St.Barbe

Bay

Juo.28-Jul. 25,1991 12

•

^{I 3 75n}

Concbc Jun.I3 - Aug.J,I 990 161 91

"

^{34 37A}

Co nche JilL 9-A lIg.4 , 1991 52 .9 32 17 34.7

Twil.lingate Jun.24-JuI.4,I99t 35 35 13 22 6~9

Sub-IOlal :m 211 112 99

RerC~CDccS itC5:

SaintJo hn River Reared Stock

Hatchery May 12,I990 52 0 2J 29 5,.

Sea-Ca ges Oct.IS,1990 51 0 21 30 58$

Sca-cages May4 ,1991 .9 0 20 29 592

Sea-cages Jul30.1991 SO 0 2J 27 S4n

Sca- Cages Nov. 9,1991 53 0 27 26 49.1

Sub-Iolal 2SS 0

"'

^{141 55.37}

Wild Stocks

HumberRi\'C~ JuI.18-Aug.26.1991 16 16 5 11 68$

West ernAnn Brook Aug.9.&:0Ct.18 .1990 12 12 3 9 7Sn

LabradorSn Oct.6-0Ct.J.t1991 ISO 145 34 111 76.6

Sub- lol.l 178 173 42 131

The landingsofseveralfishermen were sampled during the commercialfishing season at SI.Barbe Bay andConchein 1990and 1991 , andduringthe 1991 season at Twillingate. The season opened on June 5 and closed on October15in1990 and 1991 at allthreelocations.However,noland ings were made before mid-June and few were made afterthe end ofJuly at either SI. BarbeBay or Conche.The majorityof landings fromthese twoloc ations werein month of July,whereas,thosefrom Twillingatewere inlateJu ne and early July.

Commercialsalmo nlandingsareusually culled intosmall«2.7kg) and large (2,.2.7kg). Smallsalmon were generallyless than 63.0em fork length and large salmon were greate rthanorequal to 63.0 em fork length. A minimum of 6 male and6 female smallsalmon were sampledper week, during thefisheryin1990, and aminimum of II malesand II females were sampledper week, in 1991.Large salmonwerefewer innumber,therefore,these weresampledopportunistically, throughout the fishingseason.

Reference samplesofreared salmonwere collectedatBaied' Espoir, Newfoundland(Fig.I)in 1990 and1991 from hatchery-rearedsmoltsand cage-reared post-srnolts whichoriginatedfromthe SaintJohnRiver,New Brunswickstock.About 50male andfemalesalmo nweresampledonfive occasions (TableI).The first sampleswcrecollectedon May 12, 1990 whenthe cohort(18 monthold smelts) was transferredfrom thehatcher y in51. Alban's, Baied' Espoirinto sea-cages located at Roil Bay,approx imatelytokm south.Subsequentsamples werecollectedfromthe

sea-cagesonl.October15. 1990.prior10winter freeze-up; 2.May4.1991.

immediatelyafter springbreak-up;3. July30.1991, correspond ing10theperiod of samplingin the commercial fishery; and4.November 9.1991.duringthe harvestof maturing adults.The6.0m depth sea-cage enclosureswerelocatedill ailarea with a bottomdepth of 40rn.The summerwater temperature inRot iBay ranged from 13.0 to15.0 C andthesalinitywas20 partsperthousandat a depth of2-10m.The caged fish were captured by sweeping the enclosurewitha smallmeshseine. FishlikelyIII beholdingnear the bottom of thecage were enticed towardsthesurface priorto sampling by agitatingthecagewithalong stick. This ensured a randomsample, especially duringthelattersampling periods.when sexuallymatur efishteud cdtu occupythebonom of the cage asthey stoppedfeeding.

Refer ence samplesofwildsalrnonof aknown state of sexual maturity were sampledfromthree reference sites:I. theLabrador Sea oft'thesouthwestenlistof Greenland,2. WesternArmBrookwhich flows intoSt.BarbeBay, and3.the HumberRiver(Fig.1).TheLabrador Seasamples wereobtainedill October.199 1 froma researchcruise.Wes ternArm Brouk samples were collec tedin August and October,1990 from a countingfencelocatedatthemouth ofthe river;andthe HumberRiversampleswere collectedin July andAugustin1991from a uapncr.

located inthe estuary of the river.TheWestern ArmBrook and HumberRiver salmonwerecaughtduringthei rupstreammigration,therefore,were considered10be maturing spawners-of-the-year. On-the-other-hand,theLabradorSea salmon,caught

10

in Octoberof1991,well away from theirNorth Americanspawning grounds, were not going⁽⁰spawnin theyear of capture.

2.2 IIb10logy

One cubic centimetre of tissuewas removed fromthe middleofthe left gonad ofallthe fish sampled. The tissue was fixed inBouin'sfixative for 24hours and rinsed in 30% and50%ethanolforIhour each, priorto storage in 70% ethanol. All gonad samplescollectedin a givenday wereplacedinindividual containersandfixed as a batch. The volumeof thefixativewas atleast twicethetotal tissue volume.

Ovarianand testis tissue(1.0 em x 0.5 em x 0.5 em) from the original sample was dehydratedin successive rinses of 85%.95%and100% ethanoland thencleared intwo changesof toluene(Appendix1),The fluidswere agitated with magnetic stirrerstoreduce thedehydrat ion and clearinglimes. Clearedtissueblockswere infiltratedwithparaffin wax at approximately60 C and embedded in paraffin for sectioning.

Paraffin-embedded ovariantissue,especially fromadult fish was veryfriable and requiredan additional infiltration stepfor stabilityduringsectioning.Thedouble infiltrationtechniquedescribed byHurnason(1979) was used whichadds celloidin dissolved in methylbenzoate before the paraffin infiltration(Appendix1).

"

Al least five good sectionswereselectedfrom those cut fromeach tissue block,Ovarian tissuewas cut atathickness of 10- 12 tim.Testiculartissuewas sectionedat 8 urn.Sectionsweremou ntedonglassslideswithalbumin.stained with Harr is'haematoxylinandeosin (Hum ason,1979) (Appendix 2) .

Histological specimenswere examinedundera Leitz(DIA LUX-20)compound microscope equippedwith amoveable stage.Eachslide containedserialsectionsInuu thesamegonad. Thesection10 be examinedwas chosenatrandomusing therandom numberfunct ion of an HPlie calculator.

2.2.1Oogen esis

Fem ale salmonwereclassifiedintoovary development stagesontheh'l.~isof the mostadvancedmodaloocytedeve lopmentstage present.The most advanced modaloocyte stage was considered to be representativeof thclevel of ovar ian development in individualfishandwasdetermi ned from thcfreq uencydistributionof oogoniaandoccytescor respo nd ing to12 stagesofoogenesis.Thesestages were basedon crite riadescr ibed forAtlantic salmo nbyMurzaand Khristoforov (1993), Chadwicket a1. (1986),Sutter linand Maclean (1984)andIdler etill.(198 1)andfor adultchum(Oncorhynchusketal andsockeyesalmon byIshida cral.(96 1).For example.an individual fishwithoocytemodes at stages3 and 6wouldbeclussiflcd into stage6,if the number ofoocytesat stage6 wasgreaterthanal stage 3.

12

Thefrequency distributionof oocyreswas determinedby countingall the ce lls in a ra ndo mlychose nhistologicalsec tio n of ovary.Oocyteswere classifiedand counted in aseries of transects.Oogon iaandnucleatedoocytcs atstages 2·6 were

countedatamagnificationof 250X andoocytes at stages 7-11 were co unted at25X.

Becauseoilglobulesoftencoveredthe nucleiin stages7-[I.thesecountsincluded

non-nucleatedoocyres.

Femalesalmonfrom WesternArmBrookin1990thatwere sampled onthe ir upstream migrationwerenot sacrificed. but were assigned to ovary stagelion the basisofthefrequency distributionofoocytes recordedinone dead spec imen.

Thehistologicalpro tocolsusedforovarieswith stage1-11oocytes (Appendices 1-2) werenOIsuitableforthosewithstage 12 oocytes.Therefore,stage

12oocytcswere norcounted.

The crucrta (or the12stagesofoocytedevclopm..«usedto classifythe ovaries of Atlantlcsalmonarcdescribedbelow :

SlngeI.Ougu";,, • "ng"'l;aarernund IIInval in~ha pewitha smallcenlral1yl" "aledl1ucl~u, ;u<ually ingroups

or"ncsts"nr S-4ucclls.5·(,nminsize.

SI1l!:l'2.Prin1ilr Y '~lCyle-lh" nueleusuccupi"srnostofth""""yteandccmains cne large nucleolu•.IfJ-20 " m in site(Fil.\.2).

Sla!:l'.,. E<lrlyperi lludenlus -llucleniiarcsmall,""1l1crnu.alldlocatedamunt! thep~riphefYoftilenucleus.

Inlcl ~""ly.l"ini ng duUtl. nrlllilnchnlld r ill rBalh i:'lliht,die'")a re COnC"nl raled arnu nd or adjltCelll tolll~ nucl ells . 2U· IlMInminSil.e {Fig. 2).

Slllge". Mid-pc r illud eolu." "B" lhiani "'>dies" art:(rlll.\t1Iel1lcd,Ilo JOtll.\~f Cut1cetl!raredneilrrhenucleus,bUI migmt inJ!.luWitrdthe peripherynftbccell.Imenshy of cytoplasnrlcsrainingradcs. [(Kl·2OU"minsize(Fig.

J).

13

Stage~ . L31el'erinucleolus- 'B~lhiHllil'udi"s';trt'cUm"'lllrmed11\;lrinj:;lllhcpcri l'hcfy"l' th" ""cylc,;II!d u.~uHllyfadefromview liS theydi~per"."into thecylul'l;~'IIl:marhthe clllI"ttheprc-virellogeuicpIli!'"..r development.2S0-400pminsiit<l(Fig.4).

S(age6 .Y"l k ~icl e· cte"r y"I" ve .icles ;'I'Pcmi llthc c yt"l'l;lslll . inil i;,11 y armlll,Jtll" l"'fipl1Cf)'I,"d thcn towards thenucleus.TIlenuclcushasa~1\lMJlhuul1illeIIllhel>egi nninj!.Urllll: ShlJ!;Ch4.ll",",C'NlIesiudeutc d in thetatter paTlortheSlage.Thc"8II1hiani hodics"aredisl'erscd. 111cti.Ilicu];lfcpilh clium m g r"' \\I1nsal" ycf thic kel1s:l1lda lhinl<lycruf zoMTadi alllisvisihh,t Fig.~) .

Slagc7.0i lglobule- uil globulcsappear tir Sl neM lhe IlwlC\lS;lI'.1thcl!thruughllutthe cytll].la "u,"t)Cll o1J1ileral ing lhenucleus.0"91es increasedr;llnalk allyin sizeIrom theprevjnussl;l~e.TIle1.ll1~1I;uliatais dearlyvisiblefindradial striationsare....,~~Igniz;,hle(MI(.fI).

Slage8.PrimliTYyulk·yUl\,glnhuksareenn~'t'nl ral edinthe 'Merrilrl "rllt<;cylnplasm.(.Jluhule.•stain vi..lcl lu 1l1ack (Fig.7).

SlageII.Secondllr)')'"Ik•)'olkgl"hule< lire )'ellmv ill,uluur .lar~er,mdI" nr..,m,mcru. ".,mil .. n·" I'y;'~rc,ucr parl"flhec)'loplllsll1lll<1l\lhepreviuu<,'la~e.y"I"Vt:sicles;,repusl",<.Jlnw;!Tllthepc ripherym uJnillll"" ule.

<.JiSllppear(Fig.Il).

Stage10. Tel'lillryyolk·yolkglnhulcsliresmallaruundthenu~leus muJhlrg"rHIlhejlcriph"ry.Y..l.vc~i,les formIIvery lhinlayer:.t lheperiph.rynf th" "n"'ylC{Fig.9).

StageII.Migrmo ry nucleus·nucleusmignuesl" wmds nnerule: ynlk g.lnhule,.nrc <lnaller ahc"d"rIhe lIligrali ng nucleus:ll1 any yulk l,lh,bules hee"llIe ru.'IC<.J lu r"rml:lrgcr yulk mas.< CFig. IIl·II).

Sillge12Ripc~U11<td•O"C)'Ic<callheespclled easilywithgellll" pTcS.<;Urt: In Ih"ahdum"".

14

LegendstoFigures2-11.Sta gesof ovary developmentobservedin femaleAtlantic salmon.

~

Figure2.Ovary stage 3 (16X)ofhatcher y-reared femalesalmon smelt sampled on May12,1990 (SampleNo. SJlF29)showingocc yrcs at stages2-4.

Fig ure3.Ovarystage4 (I6X)of cage-reared female salmonsampledonOctober15, 1990(Sample No. SJ2F28) showing ooc ytesatstages3-5.

Figure4.Ovarystage5 (16X)of cage-reared female sal mon sampled onMay4, 1991(Sample No. SJ3F50) showingoocyresatstages5&6.

Figu re 5.Ovarystage 6(16X)ofcage-rearedfemalesalmonsampled onMay4, 1991(Samp leNo. S13F42)showingoocyresat stage 6.

~

Figure 6.Ovarystage 7 (16X)of cage-rearedfemale salmonsampled on November 9, 199\(Sam pleNo. SJ5F9)showing oocyte at stage 7.

Fi~lIre7.Ovary stage 8 (\6X)ofcage- rearedfemalesalmonsampledonNovember 9.1991(SampleNo. SJ5F46 ) showing oocyte at stage 8.

Figure8.Ovary stage9 (I6X) ofwildfemale salmon sampledat Concheon Aug ust 4,1991 (SampleNo . C91F54) showingoocyteatstage 9.

I"igure9.Ovarystage 10 (16X)of wildfemale salmonsampledat St.Bar beBay on July14 ,1990 (Sample No,SB90F249)showingoocyte at stageto,

fJ.a!cl.ll

Joigure10.Ovary stageII(16X)of wildfemale salmon sampledat Concheon July 15.1991(Sample No.C91F27) show ingoocyteatstage II,

FigureII.Ovarystage II (I6X) ofwildfemale salmonsampledatSt.BarbeBayon July 2.1990 (Sample No.SB90F2 IS)showing oocyteat stage11.

15

16

17

18 2.2.2 Spennatogencsis

Testes atstages1-5 were examined at1000xmagnification. In contrast to female cocytes , thegerm cellsof salmo ntestesaretoo smalland100numerousto count. Therefore ,malesalmonwere classified intotestis developmentstagesonthe basisof the most advancedgermcellstage.

Testistissuewasnot obtai nedfromupstrea mmigrating malesalmonsampled fromwester nArmBrookin1990.butitwasevidentfromthe mil texpelledduring

the bloodsamplingprocedure thatthese fish wereatstage 5.

The most advancedgermcellstage presentwasdeterminedusingcriteria describedbyHiroiandYamamoto (1968), andMurzaandKhristofo rov(1993).

Thesecriteriaaresummarized below:

SlageI.Primary 1\crmCtlll·!<f'crmalng"niaarelhelargestcellsint lretescis.Nude us7-1 3.um cytorl~"l1l 1U-2() ,nn{Fig.11).

Stnge1.Spemliltugunia-some spemnuogoniaare smallerthanin therrevious~t~geandslain darker. Nucleus

~-7 ,nn c ylllpllISI1l 7-1 4"m { Fig.13).

Stage.'. Spenna lucyte -gemlcells aregruuped indistinctcysts; the cytoplasminindividualcell.'is almost indistinguishahlenom~dj;ICUt1lcells.Nucleu.~3-4"m(Fi!:. 14).

Slngr4.Spent lillid•cyst.,aremuch largerIh~nin thepreviou.~stage; germcells areroundin !\hapeandmuch rnorcnumercus.Nucleu52 -2.S.um (Fig.IS).

Stage~.Speml:llozo~-largecysts with spemlatidspredominate.111ehead of mature spermis round or ellipticalin shape.Nucleusl-I.S"m(Fig. 16-17).

SlagI.'6.RiJ'C1\001:ul - cyl'lsrupture releasingspermatozoaMlichareexpeneuell.~ilyby gentle pre...suretothe ahlllll11Cn. Testesm this.'~lgewerenot examinedhist~'lugieally.

19

Legendsfor Fign res12-17•Stagesof testicu lar developmentobservedinmule Atlantic salmon.

Plale-IV

Figure 12.Testisstage l (I00X)of cage-reared male salmonsampled on May4.

1991(Sample No. SJ3M30) showingprimaryspermatogonic(lsg).

Figure13. Testis stage 2(lOOX) ofcage-rearedmale salmon sampled onMay 4, 1991 (SampleNo.813M33)showing primary(lsg) andsecondaryspermatogonia (25g),

Figure14. Testisstage 3 (lOOX) ofcage-rearedmale salmonsampled011July 15, 1991 (Sample No . C91MIl)showingsecondaryspermatogonia(2sg) and sperrnatocytes(sc).

FigureIS.Testis stage 4 (I00X)of cage-rearedmalesalmonsampled onJuly17, 199 1 (Sam ple No. C91M38 )showingsecond aryspermatog onia(25g), spcrumtocyrcs (sc),andspermatids (st).

~

Figure 16.Testis stage5 (I00X) ofcage-reared male salmonsampled on July30.

1991(SampleNo.SJ4M49)showingsecondaryspermatogonia (2sg) andlargecysts ofspermatids(st),andspermatozoa (sz).

Figure17.Testis stage 5(tOOX) of wild malesalmonsampled (rom theestuary of theHumberRiveronAugust 26,1991(SampleNo. H91M14) showing large cysts of spermatlds(st)andspermatozoa (sz).

20

~I

22 2.3Rad ioimm unoassa y

Approximately I.S ml ofblood was extracted (romlhecaudal veinusinga heparinizedsyringe.Thebloodwaskt1'ton ice.in the syringe.for 1-3hours before being transferred 101.5ml Eppendorf rubes.Tubeswerecentrifugedat 10.000rpm for two10four minutes thentheplasmalayer was removed usingaclean Pasteur pipetandtransferred to a cleanI.Smltube.Plasma sampleswere frozenandstored at-20 .0 Cuntilprocessed.

Allsalmonweredead at the timeofblood sampling.Salmonfromsea-cages weresacrificed quicklywithseveralquickblows tothehead immediately before sampling. They wereusuallydeadafter thefirstblow.Incommerciallandings,the pen -mortemperiodbefore samplingvariedconsiderably.Salmonthat werealive whenremoved from the commercialgtllreuwerekilledsoonafterbeing taken imo theboat.andbythelime they were landedatthewharf themajority had been dead for abour onehoor accordingto fishermen.Someof(he blood samplescollectedfrom commercial landings wereclottedwhencentrifugedand theextractedplasmawas contaminatedwithrupturedredblood cells.Thiswasfoundto be the case whenpost- mortem periods inexceeded twohoursbasedontrialsconductedonblood samples collectedfromsea-cages.Hence. shorterpost-mortemperiods arerecommended.

Contaminatedsamples werediscarded andnOI usedinIhe analysis.

23

Bloodplasmalevels oftestosterone(T). estradiol·17B (E2).11- kerotestosrcrone{ll-KT)andvitellogeniu(Vg) were measuredinduplicateby rad ioimmunoassay (RIA)as describedby Methven et al. (1992).The proce dures used forRIAs ofII-KT.T.andE2 are outlinedinAppend ices3-6.

2.4BiologicalCharacteristics

Salmon were sexedandmeasuredfor forklength (FLT),to thenearest 0,I em;wholeweight(WWT) to thenearest200gm:gonad weight(GOWnandliver weight(LWT)to the nearestO.Ol grn.Scalesamplesfor age determi nationwere collectedfrom wildsalmon, Scales wereremoved from anareaabove the lateralline andjust posteriorto thedorsal fin.TIleriver-age.sea-ageandevidenceofprevious spa wning inwildsalmonweredeterminedbymeans ofscalereading accord ing to establishedcriteria(Anon.,1984).

Onlyvirgin male and female salmon thathad a sea-ageofnne year were used in analyses of thestateof maturity.

Ilonadosomaric index (OSI;:OOWTIWWT x100):hepatosom aucindex (HSI;:LWfIWWTx 1(0); and condition factor(CF ;: FLT³IWWTIIOU) were calculatedfor eachfishsampled.

24 2.5 Discrimin antAnalysis

Discriminantanalysis is a multivariatestatisticaltechniqueusedto identify the relationshipsamongdistinctgroupsof observationson the basis ofmeasured parameters. Thistechniquewas usedto identifythestate of maturityin maleand female Atlantic salmon on thebasisof levels of T,II-KT.E2,vg,aSI,HSI,CF and gonaddevelopmentstage.Maturing spawners-of-me-yearweresampledfromthe Humber Riverin July-August1991 and WesternArmBrook in August-October1990.

Non-maturing salmon weresampled from theSaint JohnRivercage-rearedstock in May and October1990 and fromthe LabradorSeainOctober1991.Those parametersaccountingfora significantproportionofthevar iation betweenmaturing andnon-maturing groupswereselectedfor useinthe analysis.Theselectionwas donein a stepwisemanner usingtheSAS'STEPDlSC' procedurefor personal computers (SAS Institute Inc.1985).The discriminantanalysisand resulting discriminantfunctionswerecomputedfor maleandfemale salmonusingthe SAS 'DISCRIM'procedure forpersonalcomputers (Appendix7).

Accordingto Tituset al.(1984),a problemoften encounteredin the appllcaticn ofdiscriminant analysis,is unequal group sample sizes.Theycontend that unequalsamplesizes may leadto very high percentcorrect classification,but the improvementover random correctclassificationmayhe slight.FOi suchsituations they recommend that a chance-correctedprocedurebeused ininterpreting the percentageof agreementbetweenthe actual and predictedgroupmemberships.They

25

describe a statistic, kappa,developedbyCohen(l960)which was found tobe useful in interpretingtheclassification results ofdiscriminant analyseswithequalor unequal samplesizes.Kappaexpresses the average proportio nof individua lsthatwere correctlyclassified,after removingthe effect of correctclassifications due 10ChUllCC.

Because the samplesizes for the maturi ngand non-maturing salmongroups used ill the discriminantanalysiswere unequal.the kappastatisticwasused10 evaluate lhe effectivenessofthe discriminantfunction.The equationsused in calculationof the kappa statistic areshownin Appendix8.

Thediscriminantfunctions derived for male and female salmonwere used 10 classifythesalmon sampledfromtheSaintJohn River cage-rearedstock (May.July and November 1991) andthe commercialfishery into maturingandlion-maturing groups. The assumptionof a multivariate no rmal distributionwithineachmaturity groupwas assumed tohave beenmet.

Theaccuracyof thediscriminantfunctionsinpredicting state of maturitywas tested by randomlyselecting 50%ofthe observationsonsalmon of knownmaturity to derive adiscriminant functionfromwhichtopredict thogroupmembcrship

or

the rcmaining50%of theobservationsandviceversa. Thepercentage(11'agreement between theactualandpredicted state ofmaturity was evaluated using Cohen'skappa.

2.

3.RES ULTS

3.1ReferenceSites

Salmonat eachsite were prcdominamlyfemale,but thepercentage of females in the SaintJo hn River cage-rearedstockwasthe lowest ofthe four reference sites (Table I).

Preliminary RIA resultsindicated that II-KTlevelsinvirginfemalesand Vg andE2levelsin virgin males were eitherverylow ornOIdetectable.Theaverage11·

KTlevel infe maleswas less than 0.50ng/mland theE2levelin maleswas less than 0.50ng/m1.Subsequently,onlyRIAsfor levelsof Vg and E2infemalesand II·KT inmales werecarriedout.

TheRIAand histologicalparameter'valuesmeasuredin maleand female salmonfromthe fourreference sitesare given inAppendices 9-12.

27 3.1.1 Females

111cSaintJohn River hatchery-rearedsmeltsinMay1990had oocyrcs at stages2-5,but mOTC than 50% were at stage 4 (Fig.18a). Insubsequentsamples from sea-cages (October1990 and May199 \)the percentage of oocyrcs at stage4 decreased.and the percentageat stages 5-6increased (Fig.ISb-c),IIIJuly1991 (Fig.

18d), thedistribu tionhad changedlittle fromthat intheMay199 1 samples.However.

byNovember199 1 (Fig.IBe)stage7 and 8 oocytcs were present, as wellas.~Oll1C stage12oocytes in sexually mature fish.

The ovariesin96.2% of thehatchery-rearedsmelts sampledinMay 1990, werectasslfted into stage 4 (Fig.19a).In October1990.the majority were stillat stage4 (86.7%)(Fig. 19b), but hadadvancedto stage5 (58.6%) in May 1991 (Pig.

19c), and were at stage 6 (37%)inJuly 1991 (Fig.19(1).Stage 6 recordedinJuly 199 1 was the mostadvanced(Fig. 19d).InNovember199 1. themajorityofi1111l111lure fishwereat stage 6 but7.4%(2127)had mature ovaries (stage12) (Fig.1ge). These fish werespawners-of-t he-year.

Plasmalevels of E2 andVg,GSI,HSIand CF were significantly correlated with ovary stages in Saint John Riverfemalesalmonsampled011live occasionsin 1990 and 1991 (Table 2).The highestR'values werefor Vgand(iSIsuggesti ngthese parameterswerethe best indicatorsor ovary development.Levelsof Vg andUSI werehighestatstage 12 measuredin November1991(Fig. 20e-d),butTand E2 levels werehighestat stages 7 and 8 whichweretile nextlowest stagesrecorded

28

10 11

. .... I

No"""'bcr9. 19111 11-1318 (NollO:'!&f':12 or:q1101 DOlco..,1Od)

8 STAGEOF OOGENESIS

~ _, rII _{LO _}

W .b_ ============;

~;':: CUIIC)

-c so -

~;g ffi~ •

"" -

~ f·

IO f

7g ~=~~~~~~~~========~

OJ0) SO 40 30 20 10

,

Figure 18.SaintJohnRiver:stagesof oocyte development in cage-reared femaleAtlanticsalmonon fivesamplingdates in1990and 1991.The values ofDrepresent the numberofoocyteecounted.

29

"" 1 4,1 991

"",,12.1990

My 30, 1991 n-:Z1

-

11 12

H ber9,19\l1

0· "

~[J ================

I~ []b)

o -

~

100!

80 C)

; sce-

I

- ~ ^- ~.~=========

1 ----

~f' J - ^,

MODALOOCYTESTAGE

Figure19.Saint JohnRiver: modal oocyte stages in cage-rearedfemale Atlanticsalmon on five samplingdatesin 1990 and1991.The values of n represent the numberoffish sampled.

30

Table 2.Relationshipbetweenlevels ofT,E2.Vg,aSf,HSI,and CF and ovarystage incage-rearedSaintJohn River femaleAtlanticsalmon.'n' ""

significantrelationship at the ,05 level and'na'enon-slgniflcantrelationship.

Ovary R' P

stage versus:

T .03 .7539 ns

82 .22 .0001

..

Vg .69 .0001

..

aSI .98 .0001

..

HSI .15 .0076

. .

CF .29 .0001

..

31

,•• i~

3 4 S 6 7 612

, i

I U , 5 LJ • I II , I II 2 I

~D

3 4

A~SffiP

4 S 4 S 6

- -

3 " ^{_ _}S 6

'

3 "

2 •...

S 6 1 8 1 2

-" :

~U :lll^{. • .'. I ,ll , I II 1 I J I 4 " I}

v.i1- , ',

=0.: :,:\;:

~-

_,,' . ,

1 :1

"'I' . ... ' ' " .'. ".. ,' ,

U : >'i: " • II I

• '; C'. _ I t

: 2 3 " 4

~

^{4 S 6 3 " S 6 3 " S 6 7 • 11}

May/90 Oct.l90 May/91 ~ Nov./91

MODAL OOCYTE STAGEandSAMPLEDATE Figure20.Saint John River:meanlevelsofT, El, Vg,GSI,HSI and CF in cage- rearedfemaleAtlanticsalmonat eachmodaloocytestageon fivesamplingda~

in1990 and 1991. Venica1Jines are standarderrors and the numbersabovelines represent thenumber offishsampled.

32

<rig.20a-b).·However,plasma levelsof theseparametersmay have continuedto increase atstages9· 11beforedecreasing at stage 12.There was unte change in HSI withincreased ovarydevelopmentexceptfOTasharpincrease at stage12(Fig. 20e). In contrast10theother parameters , conditionfactor(C F) decreasedwithovary developmentanddropped sharplyat ovarystage 12 (Fig.200.

InMay1990.17.2%(5129)ofthe SaintJohn River femalesmolts had higher thanaverage(1.2ng/ml)levels ofT.In October1990.20.0%(6130)had much higherthanthe average (1.24/TIg/ml)levels of Vg (Appendix9a.b),but GSJinthese fish wasrelativelylow andtheirovarieswere atstages 4 or 5,indicatingthatthey were not spawners-of-the-year.

InMay1991. thelevels of T, E2. Vg and GSI werestillrelativelylow inall Sa int John Riverfemales sampled.but27.6%(8/29)had advancedto ovary stage 6 (Append ixge;Fig.20a-d).

In July1991.stage 6 was still the mostadvancedovary stagepresentin27%

(7126)ofthe Saint John Riverfemalessampled(Appendix 9d).However.14.8%

(4127)of the femaleshadhigher thanaveragelevelsof T(1.19ngtml).E2(0.21 ng/ml) and/orVg (1,48 mg/mn (Appendix9d). suggestingthatthesefish were potential spawncrs-of-the-yearand that these parame tersmaybe indicatorsof sexual maturity atthistime of year.The minimumlevels of T.E2 andVgrecorded in potentialspawnerswere 2.16ng/ml.0.61 ng/mland 1.81 mg/rnl.respectively (Appendix 9d).The irovarieswereat stages 4-6(Appendix9<1).

33

In November1991. 7.4%of the femalessampled werespawners-of-the-yearas evidencedby ovariesat stage12.111is was about one halfthepercentagethat was anticipatedbased on samplesin July199 1. Comparedto otherfemales in November, the maturefish had the highestlevelsof Vg.GSI andHSI,and either thelowest or among thelowest levelsof T.E2 and CF recorded (Appendix 9c). ThelevelsufT andE2 recordedinNovember,were higherin females at stage 7 and 8 than in spawners-of-the-year.butit is veryunlikelythat thesefishweresexuallymature because their CF wasrelatively high, indicatingthatthey had not stopped feeding, and theiraSI levels wereonly0.35-0.39%compared to19-25 %ill lish HIsragc12 (Appendixge).

The maturingwildfemalesalmon sampled fromtheHumber RiverinJuly- August 1991had a bi-modal(stages4 and 7) oocyte frequencydfsulbutlon (rig.2Ih).

Themode at stage 7 was probably representativeof spawnin the fallof 1991,while the mode atstage4was representative of oocytesthat would have continuedto develop. These fish were classified into ovary stage 7 or higher(Fig.22b-e).

The singlematuringfe male sampledfrom Western Arm Brook (August 19l)() had cocyres at stage II(Fig.2Ic).

Non-maturingwildfemale salmonsampledfrom the LabradorSea inOctober 1991,had oocyres at stages 3-7(Fig. 2Ia).Those with oocytes at stages 3-5had been at seaforlessthan oneyear (sea-age-O).whereas,fish that had stages3-7 had spcnt one yearat sea(sea-age-l). Themajorityoftile sea-age-efemaleswere c1assi!;edinto

34

IJ

10 11

t§

_~ b)HumberRiver

i ^~ ~~~~uauatl991

UIO

III

s

e,

:::I ^I3 O ~~~~~~~

^{c) Western}AllJllltl990^ArmBrook

so_ a..IO 40

"

"

'g - - . ^,

STAGEOF OOGENESIS Figure21. Stagesofoocytedevelopment in wildfemale Atlanticsalmon fromtheLabradorSea,HumberRiver and wesremAnnBrook.Thevaluesof n representthenumber of oocytescounted.

35

7 10

MODAL OOCYTESTAGE

Figure22.Modaloocyte stages in wild femaleAtlanticsalmon from the Labrador See,HumberRiverand WesternArmBrook. The valuesIIfn represent thenumber of fish sampled.

36

ovary stage5 andlhemajorityofthe sea-age-lnsh were stage 6 (Fig.221).

Theplasma levelsofT. E2,Vg,andaSIwefthigher in HumberRiver females at ovarystage1 thanin labradorSea females althesame stage (Fig. 23;

AppendixlOb).indicatingtha ttheHumber Riverfish were potentialspawners-or-the- year.In westernArmBrookfemalessampledin October1990theselevelswereeven higher (Fig.23;Appendix lOe).Thelowest valuesof T.E2.Vg,andaSIrecorded inHumberRiver and Western Arm Brook spawners-of-the-yearwere 1,40 ng/ml, 0.81 ng/ml,0.75mg/rnl, and 0.24 %.respectively (AppendixIOb-c).The valuesfor T,E2.andaSI weresimilarto thoserecordedin SaintJohnRiver femalesthai were

predictedto bespawners-of-the-year in July1991.However. thevalue forVg was aboutonehalftheminimumvalueinlheSaintJohn River females.

J.1.11\1ales

Saint John River (hatchery andcage-reared)male salmon withtheexceptionof precocioussmoltsin May1990.didnot mature beyond spermatogenicstage2 until May1991 (Fig.24a-c).Inthe next three months.male gonadsdevelopedrelatively quickly.In July1991.56.5 %(13/23)ofthemalessampledhadreachedstage 3 or more(Fig.24d).andbyNovember1991.61.5%(16126)weresexuallymatureat stage 6 (Fig.24e).111issuggeststhat themales81stage3orhigherintheJuly1991 sample werepotential spawners-or-the-year.Immature males(38.5%;10126)in November1991 wereat stage 2(Fig. 24e).

37

UbndorSea Humber Rivet

i:: 1 J ^{1 :1} ~IY

'-' Z J OS

f-oo.s

a ..

^{5 .}L,-,....,.,.."...

=!!!nJ

~~ I"~d·"·'· 1 f.... ^{jj ~D l}

^{456 8 9 1011}

~ g:~

^JI..

~ ~:~

w0.3 2 J O.S

~§I ";~"' ''''·llDJ I2J4.s6189101l12 :: 0

! ~::

^{J ,.}

:~

^{l' :.:}

>0,04 5 I .

~:[J"''''''IIr:::::~:D _gO'

_tzae^11.. _{r ss renu}

_(~[]]

^{1 , 0 ,}

_{, . "} gl

^0.1

_{0 '} '''''''''TI ''' ''''''0111'

~

^U

~ ^{: ':[lJ}

123¹4

^"

s

^{" "}

tI 10 11I2

^r;

^1.00.9

^{U J J}

I

^{" ,.}

^I

^'

I

g

^~:;0

o

123 -45678SIlO112 MODAL OOCYTESTAGE

Figure23.MeanlevelsofT. E2, vs.aSI,H51andCFin wildfemaleAtlantic salmonateachmodaloocytestage fromtheLabradorSea.Humber River.and WesternArmBrook.Verti.ca1linesarestandarderrorsand numbersabove1m represent the numberof fuhsam~:c:d.

38

""'14,1 "1

,.W

OI:lDbwU, I9911 a..11

i lL I

~tIlII~~1

i~[dC) I

ffi _~~

e, ,

"L L : J I d )""" . "" -,

I

40 ...23

"

"

",

l Li'----_ 1J

^{I ,}_STAGEOF SPERMATOGENESIS Figure24.Saintlohn River:stagesofspermarogeneslsin cage-reared male Atlantic salmon onfive samplingdatesin1990and1991.Thevaluesofn representthenumber of fishsampled.

39

Plasmalevels of T,l1-KT.aSIand CFmeasured incage-rearedmalesalmon sampledbetwee n May1990andNovember1991(AppendixIla-c)were allcorrelated with test is stage(Table3).The highest R'vatueswere for T.11-KT andaSI indicating thattheseparameters werethebestind icators of testisdevelo pment.Levels ofTandII· KT wererelativelylow inmales atstages 3 and4.hUIincreasedsharply atstage5and peaked at stage 6 (Fig. 25a-b),alongwithaSt(Fig.25c).Allcage- reared males atstage5in Julyhad higherthanaverage T andII-KTlevels and CiSI . but only a fewofthose atstages3 and 4 hadhigherthanaveragele velsforthese parameters (Appendixlid).

Incontrastto females,plasma Tlevels incage-rearedmale salmon were correlatedwithgonadstagebut HSIwas1101(Tables 2-3; Fig.2S).

InNovember1991,61.5% (16/26)oftheSaint JohnRivermal es salmon sampledwerespawners-of-the-year.Thesefish allhad testes atstage6lindlevelsof T.II·KT.and GSI that were S·IO timeshigher thaninstage2males which wasthe nextloweststage recorded. Levelsof Trangedfrom6.3610IS.80 ng /ml.Il-KT levels rangedfromIS.49 to 63.56ng/ml,and GSIrangedfro m:\.0%10 7.5%in spawners-of-the-yearinNovember(Appe ndixlie).Thehighestlevels(1f T .II-KT.

andaSIin stage2maleswere 1.15ng/ml,2.05ngl ml.and 0.11%.respe ct ively.

40

Tallie3.Relationship between levels

or

T,II~KT.GSI.HSI and CFand testis stagein cage-rearedSaint JohnRiver Atlanticsalmon.'**'= sig nificance relationshipat the .05 level and'ns'wnon-signiftcamrelationship.

Testis stage R' p versus:

T .69 .0001

..

l1-KT .64 .0001

. .

GSI .72 .0001

..

HSI .10 .0657 ns

CF .13 .0047

..

41

.~

i.s

U. Il J l

U 1 " n., '.. 1" ,.'••: ID , 1 • to Ll

O·.s .~ c <', ~.,

o "', ".'..',....^,.~ .. ....,' '

1 2 4 1 2 I 2 3 1 3 4 s 2 S

May/90 Oct./90 May/91

- - W I

Nov.l9 1

STAGEOF SPERMATOGENESIS and SAMPLEDATE Figure25.Saint JohnRiver: meanlevels ofT, l l KT,GSI.HSI.andCF incage- reared maleAtlantic salmon at eachstageof epermetcgenes'son fivesampling datesin1990and1991.Vertica1lines are standard errorsandnumbersabove lines represent thenumber of fishsampled.

42

The percentageofSaint John Rivermalesthatweresexuallymaturein November 1991could have beenpredictedfromthe October 1990 sample (61.9%), based ontheratio betweenthenumbers withstage2andstage l testes (13121) present inthe sea-cages.However,nopredictioncouldhave beenmade based on plasm a hormone levelsoraSIas meanT.l1-KTandGSllevelswere similarfor stage I and 2males (Fig.25a-c; Appendixlib). In May1991,the predictionofspawners-or-the- year wouldhave beenthesame.Tile levels of T, l1-KTandGSIwere similarto those in October1990and 66.7%(14121)of male salmonwereat stage 2 (Appendix lie).

In July 1991,56.5%(13/23)of the malesalmonhaddevelopedto testisstage 3orhigher and thelevels of T,II-KTandaSIin these fish werehigher thanin those at stage 2 (Fig.25a-c;Appendixlid), suggesting thatthey were potential spawners-o f-the-year .II ispossiblethat some of the stage 2 malesill July 1991 were alsospawners-of-the-year,because thepercentage oftheJuly 1991 samplesthat were IIIstages3-5didnot fully accountfor the percentageof malespawners (stage6) recordedillthe November1991 samples (Fig.24d-e).

TheHumber River male spawners-of- the-yearsampled inJuly-August199 1 were at tes tis stages 3 and5 (Fig.26) andhadmeanlevels ofT,II-KTandaSI whichwere withinthe rangesrecorded for cage-rearedspa wners-of-the-year in November(Fig. 27).The largevariabilityinhorm onelevels observed inHumber Rivermales at thesame testis stageprecludesthe establishment of minimumsteroid

43

,

STAGEOF SPERMATOGENESIS HumberRiver

JulJ· Augut1991

n .'

w,.

~

..

ffi :

U lO

~ 20

1OL.._ -:- -;-_ _

Figure 26.Stages ofspermatogenesis in wild maleAtlanticsalmonfrom the Humber River.The value ofn represents thenumber of fish sampled.

44

!H if ^l ---'IJJ _,

STAGEOF SPERMATOGENESIS

Figure27.Mean levelsofT,l1KT,OSI,H51B.l~j(F in wildmaleAtlantic salmonat each stageof spermatogenesis from the HumberRiver.Verticallines are standard errorsandnumbers abovelinesrepresent the numberof fish sampled.

45

levelstoidentifyspawners-or-the-year in July.For example.The lowestII·KTlevel recordedin a maturingmale salmon(stage 5) from the HumberRiverwas 0.17ug/ml andthe highest was 60.72ng/ml(Appendix 12b).Someof the SaintJohnRivermale salmonat stage2,inNovember.alsohad II- KTlevelswithinthisrange.No gonads werecollected frommalesalmonsampledatWesternArmBrook and thosecollected fromthe LabradorSea samplewere unsuitablefor histology.

3.2 CommercialFisher)'

The presenceof ice onthe fishinggrounds at51. BarbeBay andConchoin 1991resulted in [owerlandings thanin1990.andlandingsoccurredlaterin the season than in1990 (Fig. 28).

TheRIA andhistological parametervalues measured in malelindfemale salmon from commerciallandings arcgiveninAppendices 13and14.

46 a

a) St.Barbe BayI1900

·

0

· ^I ,1111,1

·

a0 I I

I """,-

,

I

... ,....,

·

S791tI3lJl1192123ZSmSlI3j 7 SlI1 131.S17J9212325272 Sl312 468 11l1214IliIB b) Conche,1990

, .1,1. """,-

0

"II'TI'

0

lA"pSIl/mou

.57911131'171921232:127291 3.5 7911131'1711121232.52729312..6 81012141li18

0 c)Conche,1991

+-~

0

0

0

I

0

... ,....,

.57II 11I315171921232S2729I3.5 7911131517 192123252729312"6 81012141618

r _{... ' e}

Illloo

'" ~15D .

¹⁰s

..

70

"

ae

Io

I

;.

June July August

DATE

Figure 28.Datesof commercial salmon fishery landingsby selected fisbennen atSt.BarbeBayandConche.Newfoundlandin 1990and1991.