INFORMATION TO USERS

INFORMATION TO USERS

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EFFECTS OF PREY DENSITY AND TEMPERATURE ON SURvtvAL.GROWDl, AND BEllAVIOUR OF NEWLY HATCHED STRIPED WOLFFISH(Anarlrichas

htptIs).

BY

Dena L.WlSCI1WI,B.S<:.

A TIlESIS SUBMITTED TO THE SCHOOL OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF REQUIREMENTS FOR TIlE DEGREE OF MASTER OF

SCIENCE

AQUACULTURE

MEMORIAL UNIVERSITY OF NEWFOUNDLAND MAY 1997

ST. JOHN'S NEWFOUNDLAND

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reproduitssans

SOD autorisatioo.

0-612-23188-7

Canada

Dedicated to the lifeandspirit afThaneF.F.Wiseman December20.19n·MayI8. /996

ABSTRACT

Two ofttlemain tactol'1contributing to thepowthandSUNival of ... fisharetOOdandtempenture.Adequatefood must beprovidedwhen thelarvaeswitchfi'omendogenoustoexoacnousfeeding.Temperature can ... _..mvoI, ... _ F..."' ...

werecarriedout

on

newlyhatchedstripedwolflish(Anarldchas bqnu).In.

pn::IiminarystudylarvlewerefedtbreedensitiesofAnemia, 10011, 30011, and 900II. Survivalwunotsipificandy differentamong treatments (mean L9.S±S.1r/o)butgrowthrates wereaffectedbypreydensity.Anon-feeding studyshowedthat larvaecan survive ontheiryolkreserves for2to4weeks withthefirstmortality occurringatLSdays post-batch. Larvaeraisedona combination ofAnemia and dryfeedshowedimprovedsurvival over the initial prey densitystudy.Thelevel ofAnemia intlUCDced

growth.

survival andweaningtime.FmalperoertauvM.lforlarvae fed900Anemiallplus dry diet was 94.3% IS compandto52.6% forlarvaefedLOOAnemia/lplus a dry diet.Growthwasalsosignificantlyfaster forlarvaefed at900/1.Larvae offered a largerdensityofAnemia initiallyconsumedmoreAnemia and weanedthemselvesontodryfeedtwo weeks earlier dwllarvae fed the smaller density ofAnemia. Larvae

were

alsoraisedat3 different temperature regimes.,high(B.o-L3.S°C),low(4.o-7.B°C), and ambient (l.O-Il.S°C).

High tempenturehadthe greatesteffecton survival in thefirst6weeks.

SuMvIIIleveledoIfaf\erthistime.. FtnIi aJrYivaIfoe"hip,low.mdambient wasSO.5%, 16.0%,ud 6.1% rapectivdy.0venIl1ar4epownathigher- tanpsatura:

were

~-.thoIe: ..thek)wcrtempenture...Specific powth .... _ - , , - - _ .. " " ' _ .

TheresuJuofthiselqICriment . . . . thatwolffishIriae IhouId be fed acombination ofAm",iaand drypeUeu immediatelyfrom hatch.

AmlrfiashoukI be continueduntillbout6weeksor alengthof30 nun. At this timethelarvaeshouklbeobservedconsuminSprimarily dryfood.

T~shouldbemaintainedat4-I·Cforthefirst 6weeks.Evidence sugcststhatthe temperatureshouldnotexceed IOCafter6 weelcshowever furtherinvestigationisneeded.

ACKNOWLEDGEMENTS

Thefirst penon tothankismysupervisor, OI".loe BlOwn.forencouraging me to apply to thisproaramand for his support andpidance. Thanksto my Committee members Drs.SteveGoddardandChris Parrish for their commenuandsuggestions.Thanksalsoto my intemalexaminer 01".Anne Storyandem:malexaminerDr.Richard Peterson.

ThankstoaUtheothenlitthelib who lent a hand. To Danny Boyce and Donna SomertonfortakingcareofmyfishdurinSmytrips to Wesleyvilleandassuring methatall gradJtudentseventuallycnckup. ToSandyFrucr, VeeGotccitus, and V. Puvanendran for gettingme started wnh SAS andputting upwith"Got •second ..bowdo you ..7"To KeIyMoretforherspecialwayofConfusing mewhenIthinkI have somethingfiguredout.

Thanks to theguysin theworkshopsandthegirls intheoffice forputtingup with annoying students.And to thenewkidsonthebloclc,Karen Whalenand MarthaHiscock. . good luck!

A largepartof my work would not havehappened withoutthe help and suppon of theWesleyvilleHatchery(and the greatfoodlittheYdIow Teapot). Thanksto10hn Watkins andBany WK:bandaspecial thanks toTraceyGrantc:rfOt-a superb jobofdailymainterlance ofthe temperaturestudy.

Financialsupponwuprovidedinpanbythe Canadian CerltrcforFisheries Innovation (CCFI)throughthe Wesleville Marine rtnfish Hatchery.

rJnally, butmostimportant,thank:youto Ralph whoselove and support make all my endeavorsthat much easier.

iii

TABLEOfCONTENTS

ABstRACT ACKNOWLEDGEMENTS TABLE OF CONTENTS LISTOFTABLES LIST OF FIGURES

CHAPTER 1.0 Generallntroduction

2.1 lntn>du<tion 22 Malerials4Methods 2.3

"""""

2.3.1 SuMvaI 2.3.2 Growth 2.' Discussion

CHAPTER 3.0 Weaning

3.1 Introduction

iv

p...

iii

viii

10 10 12

"

"

18 18

22 22

3.2 MaceriaIs.t.Methods 2J

3.3

...

²⁷

J3.1 s..MvoI 27

3.32 Growth 30

3.3.3

... ""'"

^J8

3.4 Discussion

"

CHAPTER 4.0

T_

^.3

4.1 Introduction .3

4.2 ....oriaIslt ... 64

4.3

...

^.7

4.3.1

T_

^.7

4.3.2 s..MvoI .7

4.3.3 Growth .7

4.4 Discussion 79

CHAPTER S.O Coocluoiooo 82

LITERATURE CITED 8.

USTOfTABLES

Table 1:

Tabte2:

Table 3:

Table 4:

TableS:

Table 6:

Table1:

0pcrMi0naI dc$criptionofModalAction hUems (MAPs)ofstriped

woIftishlarvae. 26

Results of ANOVA andprob.triliticsfiomIeutsquares means analysis,forefFectsof age(Inweeks)andpreydensity onpercent survivalofstripedwoJffishlatvae. ·inc6catesasignificantdifference

(P<0.0028,Bonferronicorrection). 29

M ...~' - "

<mm> ...

d<ywes!tt(ms)

("'> of

^otriped

woIffishIarvacfedtwodifftn:nt prey densities,100ATte",ia/l and 900

Arte",ialt,plus adrydiet 3 I

Results of ANOVA andprobabilitiesfromleastsquares means analysis forefFects ofage(mweeks)andpreydensity onstandard length (nun) anddryweight (mg) ofstripedwolffishlarvaefed differentdensitiesofAnemia (10Mand9001I.). • indicatesa significantdifference(p <0.00(3), Bonfcnoni correction). 33 Specificgrowthmes (VJday) ofstriped wolffishlarvaefedtwo differentpreydensities, 100 Artemioll and 900 Artemia/l plus a dry diet,c*ulatedfromstandardlengthanddry weight. 35 Results of ANOVA andprobabilitiesfromleast squares means analysis,fordfectofage(utweeks)and preydensityon frequency of Modal ActionPatterns(MAPs) amongstriped wolffishlarvae fed different densities ofAnemia (10Mand 9001I.). • indicates a si&nificantdifference(P <0.0031,Bonferronicorrection). 40 Results of ANOVA andprobabiIities.from least squares means analysis, for effects ofageCutweeks)andpreydensityon frequency of Bite (MAP)among stripedwoIffishlarvae (swimmingonly) fed differentdensitiesofAnemia(1001I and 9001I). Each food item and (Artemiaanddry diet)analysed separately.•incltcates asignificant difference(P<0.0031,Bonferroni correction). 46 Tab", 8 Results of ANOVAandprobabilitiesfrom least squares means

analysis,forefFectsofage(inweeks)and food item (Anemia or dry

diet)onfrequaIl:yofBite(MAP)amongwoIfIishlarvaefeddifferent densitiesofArtemia(100Iland900II).Each location(swimming or resting) andtreatmerIt(loo ArterJriaI!and 900 ArklfIiaIl)analysed

..-uetY. *

~asipificaDtdifrereoce(P<oJI031,Bonferronj

c:oaection). 49

Tabfe 9: ResultsofANOVAandpmbabilities&omleastsquares means analysis,fordfectsof-se(m weeks) andpr..,.detasityODpercent. of striped wolf6sblarvaefeddi1Fermt densitiesofArtnria (100/1and 9OO1I)tlw:areswimmirlg. *iodK:atcsasianificantdifference(p

<o.cm

I,Bonferronicorrection). 53 Table IOa,b: Resultsof ANOYA and probabilitiesfromleastsquares means

analysis, for effectsofage (mweeks)andtempedtUreonpercent survivIlof-wolffish larvaeheldat 3 temperattueBDgCS. •indicates a significant(P<0.0014,Bonferronicom:ction). 70 Table 11: Mean standardleqth. (mm)anddl)'weight(mg) (±se)of striped

woIf6shlarvae held at3temperature ranges. 72

Table 12: Resultsof ANOYA and probabilities from least squares means analysis,foreffectsof age (m weeks) and temperature on standard length (nun)and dry weigbt(mg) ofstriped wolffish larvae held at 3 temperatureranges. • indicates asignificantdifference(P<0.0042,

&m~rnoo~~.

N

Table 13: Specificgrowthrates(*'/....day)of stripedwoIffishlarvae heldat 3 temperature rangescalculatedfromstandardlength and dry weight. 78

vii

LIST OF FIGUItES

Pog, Fiaure I: Weekly percentauvMI(±te)ofstripedwoUJisb feddi1feratt

denIibr:sofAI1taia. 16

Fiaure2: Weeldypercentsurvivlll(±te)ofnoe-fedltripedwolftish. 17 Figure]: Me...-rdleneIh(dI!l

+tel

ofscripcdwoH6shfed threediffmnt

densitiesofArlorla. 19

Figure 4: Wcddypen:entsurvival(*)ofstripedwoUIishlarvaefed diffeunl

densities ofArk",Japlus drydiet.. 28

Figure S: Melnsc..dardIerwth(nm+se}ofstripedwotffishlarvaefeddifferent densitiesofAr'InMJpkIs Iky diet.. •indicalesP<0.0063,Bonferroni CClI'T«:tion.(rr-IOClU':qIt1f"2O •...-0). 32 Figure6: Mandry

lW:isht

(nil+te)ofstripedwoIffishlarvaefeddifferent

densitiesofArlnJliapkl:sdlydiet. •indicatesP <0.0063,Bonferroni

corm:rion(piOperweekexceptn-2Oat~). 34

Figure7: Specific growth rate (Yw'day)caleu1aced fromstandardlength of striped wolffisb larvaefeddifferent densities ofArte",iaplus dry

diet.. 36

Figure8: Specificgrowth . .(%Iday)calcuWcd fromdry

wtisht

of striped wolffishiarvaefcddiffcrucdensitiesof Arte.uaplusdrydiet. 37 Figure 9: Manweeldy~(%Ie}ofa)<>ried,b} FIXate, c}Lunge.andd}

Bitein •2rinuteobserYUionperiod.forstriped wolffish

auv.e

fed differentdensitiesofAntutIiaPusdty diet. •indicatesP <0.0031.

Bonfmoni~(n-24perweek). 39

Figure 10: Meanweeklyfrequency(:t:se)of Forqein •2 minute observation periodforstripedwolf6shfeddifferent densities ofArle",iaplus dry c:tid.. • indicatesP<0.0031.BonferroniCOI'TeClion(n-24 per week).

41

viii

Figurell: Mcan _ _ ( - l of_MAP(Oriont. F...Lunge, Biee)in.a 2 ...obIavIbonperiodforIIripcd. wotftbblarvaeina) Tratmedt I, 100~pUsckydidaod.b)TrabDf:Itt2, 900

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

^{( _}

...

^{}. .2}

Figure12: ... _'"""""'(_}oIllilall.}_oodb}""' ...

a 2minAe~period

tor

ItripedwoIfIbh ...reddi:f'ferent _ o f _ .... ""' ....(0-24 ...}. 43 Figure13: ... _'"""""'(_}oIllilall·l_oodb}""' ...

• 2 ... pcriod""otriped....uliolllltvaefed_

denIitiesofATnfiaplusdry diet.Obtcrvations on

swimmins

larvae only.•indicatesP <0.0031,BonfctTOdicorrection (n-12perweek).

.,

Figure 14: ManwcckIyhqucncy(zse)ofBites at a)ATkM;aandb)drydietin a 2

n.ue

obIervacion periodforstripedwoIftishlarvaefeddiffmmt densitiesof...4J1mliapiusdrydid. ClbIc:rvabonsonrestinglarvaeonly

(n-12perweek). .7

Figure IS: MeanWiClCkIy~(.zse)ofBitesat ArtnIia anddrypelietsina 2minuteobsc:rvationperiod forstripedwoU6shlarvaefed at a'eYeI ofa) 100ArMIUaf1.plusdrydiet and b) 9OOA,..".ia/1.plusdry diet.

Observatiooson swirrming larvaeonly.•indicates P <0.0031,

80nfemlnicomction(1P'12perweek).

..

Figure16: MeanWiClCkIy~(.zse)oCBitesatArtuliaand drypelietsina 2 miruteobservationperiodfor'striped wolffishlarvaeredat •Ievd of a) 100A,....,plus drydidandb) 900ATk_iaIl piusdrydiet..

~onresrqilrv8eonly.•i:nlicaesP <0.0031,Bonferroni

c:orrection(n-12perweek).

'0

Figure17: Pen::ent ofstripedwoIffisb larvae

swimmina

(weeidymean:t:se)in adtfccdqJtratrnent •indicatesP <0.0031,BonferTOnicorrection

(

...

^".,

^...

^{). 52}

Figure 18: Percent ofresting (bottom)stripedwolffish larvaelyingsideways at the endofeachobservationalperiod ineachfeedingtreatment (n-4

perweek). 5.

"'

F1I'JR19: Maa weeIdyperiodfiorllripod _ _&eqaaeacy(2:ae)

"'-_ood_._

ofFonaeill •2 miIaItc observation p <0.0031,BoaCenoaicomc:tioa(..-24pcr-wedl:).

,.

FI8W'f'20: Me. weeIdyUIIlIpII'IIlft('"C)ilr ...bdd • 3ternperaIUreranges t:1Y'«12weeks.Noce:IIIIIpenIlRc:oatrol wasJoltinhightmIcs&om

Weck6ClftW1n1s.

..

Fipre21: Woddy...-ouMvoI (...)ofllripod _ " ' -bold .. 3

diffennttempenture

ranaes

OWl'12 weeks. 69

Figure 22: Mean standard1eD&th(mm+Ie)ofstripedwolffiJhWv.eheldat 3 different~rangesover 12weeU.(.,.30 except 00=40 at

- ) .

⁷¹

Figure 23: Mand<y,..;,ht(",,_)ofllripod_"'-hold.t3diff_, temperatureranges over 12 weeks. (n-30except n-4Oat age""O). 7' Figure24: Spocific _ "'.(Wday)Waolated&om ...wd _ of

IIlipedwoIfIdhlarvaehdd at 3differenttemperatureranges over 12

...

^7.

Figure25: Spocific _ "'.(Wday)""""'001 &om d<y ...,. of","pod woIffish ' - ' -heldat 3diffi:n:nl:tcmpenrure

ranees

over 12weeks.

77

GENERAL lNTRODUCTION CHAPTER. 1.0

lUSTORY

IntcratintheItripedwoU5sh~lips,LimM:us1751)u anewspecies 1iJr~'"n:re-din~yan. MOIl:~theresan:honthiswoIffishhu been c.riedoutinNorwayandthefannerSovia Union. With the dccinleinthe Newfoundland fishery,~hasbeenidentffiedu aprtlCIliJina economicaItemative.andwoIffish is oneofthespecies presendybeing iJM:IcipIedintftsprovince..Research into wolflisb culture inNewfoundlandbeganin1993 • theWesleyvilleMarineFmfishHatcheryin Wesleyville, Bonavista Bay. The hI1cberywue:stIIbIishedtowoc1con cu/tl.an! techniques for lump6sh (CycIoptuIIShuttpta) butresateh

soon.

expandedtoincludeworkon

omez.

nwinespecies _ _ ....< > < e o n p o u t ~ _ ) .

Striped woIffishare anattractivecandidateforfiuming in Newfoundland for several

reasons.

"TheyIrenativeto our

waren"

^thereforelikely to have a lower optimum growing temperature than manyothercultured species. They also toJerate a widerangein water

~andoxysenconlent(TJltdh,1990).areeuytoswt.feed(Ringeetal.,1987}, are easily waned to artificialfood(MobnessIttal, 1989; Ttlseth, 1990). produce large, weII-deveIopedlarvae.haveshown

JOOd

growthrates(Moksness.1994),tolentehigh

stockins

densities (Tullock et al.,I996) and produce a tasty white flesh.

Wolflisharemembers of the familyAnartUchadidae.Thesefish inhabit moderately deepwaterin the NorthAtlanticand NorthPacificOceans.. The three species that live off Canada'sAtlanticcoastarethestriped.sponcd(AnorlIidtas minor).andnonhem

(AIIlIrlIidIas'~woIffish.Ther'e is alsosomeevidenceofinterspecificforms

_ " - ...

A . _ ~195<). ... """"

W8ler"

^theItripedwolffish.Thespotted wolfthh isoflimitedccoaomicimpoItanceand isusually

<:aJBhI:

IS •by<atch..The DOrtbcmwoUIiIhisround in Arctic seas on both sides ofthe NorthAdanIic.Its8eIhisusuallya;dliedtextureand thereforenot:eaten. Striped woIfIish, abokDownI IconmonwoIIfish,AdanIK:

woIfIish.

(IIQtMwot8ish,catfish (Scottand Scon, 1988) oceancatfish,andsraYwolffish,is themost common oftilethree species olf Newfoundland(Albikovskaya,1982).

ECONOMIC IMPORTANCE

Thedtaty natureofllripedwoIf&sh makesitdifficulttocatchinIargcrumbenand theyaretypicallytabnIS •by-atehin~groundfishfisheries (AIbikovsbya, 1982).

Totalreportedlandings for 199]~only 20,464 metric tonnes with more than half capturedin IcdaDdicwUen(FAO, 1995).

Wolffish have.tastywhite8cIhwhich can also besmoked,pickledordried. The liver, bi'e,and roe canabobeutilized and theskincanbetannedinfo.fine1eathcr(Butt, 1993).AJItifreczeproteinspresentintheblood can be e:xtnaedandutilizedinthe medical andfoodindustries(F1et<:her,pen.conun.).

HABITAT

StripedwoItfistt ranp &omtheaortbwatCOUl o{Frucc,to the

Berin&

andWhite

seas.

MlUIldGrealiInd andIc:dIad.

aDd'"

^{the eatCOUlof}North Americaasfarsouth as CApeCod(Benukov, 19S9). Toaarvive the . .zerowintertemperaturesofthe Nonb A1IMticwaIffishprocb::ehiPIndso£llIIIifreaeproteins.These

proem

aBow survivalIII ten1pCI'1lU[t$lIIlowu-I.1·C(IGrle:etaL,1989).OfI'eucern Newfoundland they have been reportedIII depthsof101-350 mandtemperatures of-0.4 to 4.0·C (Albikovskaya, 1982).

TrawtstudiesinthenonbAtlantic foundstriped woU'fishmostabundantatdepths lessthan 100metres. They

were

ClUJhtinwaterswithtemperaturesfrom·1.3-1O.2·C withthe greatestCIItChes between1-4·C(Beeseand Kandler, 1969). They are slowswimmers, movinginsidecosideundulltionsJibllleel(Bigdowand~, 1953) and prefer rocky bonoms (PavlovlidNoWcov,1993).In Newfoundlandwatersthey inhabit deeper offshore watersbutmo..-einIilore to depths0{5-15minthes:prifts priorto mating(Kewet.I..

1985).InIcelandicwaterswoIffish mip'ationisoppositeto thatfoundofrNewfoundland withmovementinto~spawninggroundsin uwm(J6nsIon,1912).Thisdiffen:nce inmigrationmaybe due toIoc:abonofsuitablegroundforspawning since wolffish tend to spawninrockycrevaces orburrows.AlthoughtypicaUy •soliwyspecies, then:illevidence that wolflishmaycongregateinsuitablespawniJla;areas. FOf" example, Powles (1961) reported a

hish

occumnce ofA. /1I[1flSeggscaughtinfishnetllin an area south ofLahave Bankoffsouthc:m NovaScotia,

suaestinII

thatthearea suPPPOf1ed.spawning aggregation of wolffish.Little ill known about the habiw ofjuvenilewoIffish.Both adults and larvae

haYebeen ClbItirwd

e

shIIIow - - . .boweYer.extenIive..-c:hesfornewlysettledjuveniles

were

UJlSUCCIeSIfiJl.ItislikelythatjuveaiIesiobIbitdccpcroffiborewaterandonlymove inshorewbmsexually maIUR(KcctlII.. 1986).

MORPHOLOGY

MdtwoIfIishhave ancIorI8*.laterallycompreaedbody with alargerounded head.

Theyareequipped withavariety oflarge, welktevelopcd teethdesignedfor feeding on bonom invenebrues. Teeth areshedandrepfaoedyearly during spawning (Templeman, 1916).

Wolffish have along,singte donalfinertendiftg tothebaseofthe caudalfin.The analfinishalf thelengthofthedonal.ThepectoraI:s areIatJe,pdvicsareabsent, andthe caudalfinissmaD.. WoIffisbhaveathick: tough skin, withathicklayer of rwcusand few scales (Banukov.1959).Itscolormayvrtryfromslaly toduDolivegreento purplishbrown..

Thesides aretrmsversc:d with10orIDORdad:strips(Scott and

Scott.

1918).J6cwon (1982)reporudanawnpsizerLll.6anatoneyelrupto 9I.Sanat 20yeanofagewith malesgrowirIsfascerthanfemales.Themaxim.un lengthwasconsidered10be120

an.

FEEDING

The dietofadult stripedwoIfIishconsists mainly ofbonom invertebrates. Analysis ofstomlK:h contentsofwolffish takenfronttheNorthwest: Atlantic showedthat8S% of the diet by volumeconsistedof bottom invertebrates includingwhelks,brittlestars,scallops.

cnbs,anclseaurchins..FJShc:omprisedthe~15%oCthediawidlredfishbc:iflgthc mIinc:ompor.-:(1.2%; Templeman, 1915). FeedinB is reduced

cbWts

spawninsandmales mayDOtfeedataD

whileauardial ...

(KatsdaI..1915).AnalysisofstomachlUJJness indicatedthatstripedwoIftish&eel.-weintensely&omsummerto aItUmn thanIUlUInnto wintcr"(AlbikoYsIcaya. 191]). FoodilcmswetypiQlyCNlhedllldelleft. Food istaken from the bonom

usns cmnes,

brokenand crushed withtheconicalteethand molars andthefine food

s-u

are scraped fiom theftaamen1susing the pharynaeal teeth (Barsukov, 1959). The calcareous exteriors ofthefoodaredmostcompkteIy dissofvedby the highconcentration ofHCIinthe stomach. The dipstive system is protectedfromthe sharpsheUfragments by a wdIdevdopedepithdiaIintegwnem andhigh c:oncentnl:ion offtICUSsecreling cells (Verigina,1974).

REPRODUCTION

Adult stripedwoIfIishmove into Newfoundland walersinearly spring. Thefishpair offOYer"the amuncrand

spawrq

tabsplaceusually inSeptember.()c:tob.«(Keats et&I., 1985,1916).IntheWhiteSea~occursfi'omliy-Sepl:ember.Aduttsinthisareaare sexuallymarure at 5·7 years at a lenathofJS an (pavtov and Novikov, 199]).

EvidencesuaeststhaI.,unlikemostfish species, the eggsof wolffishare fertilized intemally(Iohannessen,eI&I.,1993; Pavtov, 1994). ReprodUCIive studies by Iohannessen et .I.(1993)baveshownthat lhe1atc:swesmall (O.II%ofbodywapI)producing. maximum of 1.5mIof mih at strippina;. SpermswimlCIivelyin undilutedseminalfluid and can

lheRforebeiMeminued intothecMductwithout

beios

activatedby water.M.Icsabo dndop • papiUaOfttheUf'OIPtMalpore wtIidllibfyfiIIICtionsas • copulatoryorgan..

SIudies

olsc-wniaB

behaviourift thelabcnlory(1oMnDeAen., d &1_. 1993) showed

m.

coumbipbdIaYiour

bead ....

4-5IIJOIthspril:w

to.-wnina-

Femaleswereobserved toIIXM:'"resdesIIY'aroundthechMr:nmUe,Ieaninaand~apinstbim..MaJeswere

~excepttOra repeated"side«ndq( behaviourwbic:blasted from 10 minutes to over anhouI-.MalestndfemIIeswereobservedperfonninsacopulatory-like behaviour in which there wu close contactbdween theirsexualopenings. Thisoa:urred8~I 5houn prior 10 spawning,withthepain sometimes hokfing this positionfor1-2 minutes.

~tofifty hours pi«

to spawnins

the femaleswereobservedtoperformaseries ofbebavioun. The Canalewentthroughabout12·24 hoursof"~wilhlittle

~thenJ...6hoursof'1lbour'"'withdensebending, twistingand shiveringwithshoo periodsof rest.Copulationoc:am:dafter thisperiodoflabourfoUowedby&-15 hours of

"'TestirIB".

Theaet\IaIspawningIa:stedabout3-7miN.us.EJpweredepositedinastringof nu:us. The&:malethen wrappeditsbodyaround theeggs andbeganturNngthem..Wnhin 6-10 hours theeggswere6nnIyattached10each other. FemaJeswereneverobserved10 protect!he eas (Jobanne:ssen, et&I.•1993).MUeshavebeenobserved protectingmasses ofeasinbunowsand rodecrevicesinwaters off!he coast of Newfoundland (Keats et aI., 1985; Walkins,pen.comm.). The male oca captive breedingpairinNorway also provided careby MDIing meeggs and turning them more orlesscontinuously with its tail. The male enclost.dlheegll\lSSin a IayerofslcinIftICU.Sthatlikely hdped to protectagainst. parasites

and pathogenJ (RinpandLorcntsen,1987). Paternal care is the most common form of parental care

amana:

fish(SmithandWooten, 1995). For example male lumpfish (Cyc/opkt"llSIwmptu)providecarebymoldingthenewlyfenilizedeggs into thecreviceof hisnest.&nninsandpuffing ontheeggsforaeration.andguardingtheeggsbyremoving invertebratepredatorsandchasing fishfromthe nestarea (Goulet et

at.,

1986).Howev~.

among fishwithintcmaIfertilzation, maternalcareisII'IOfeconunon (Smithand Wooten, 1995). Forexamplefemaleoceanpout(~$americamls).a specieswith similar reproductiveand morphologicalfeatures towolffish, providecareto theireggmassforup to3 InOIdIs. Thefemalepout,likethemalewolflish,wrapsiudfaroundtheeggsandfans them,andlikely providesan antiparasitic

asent

intheskinmucus tokeep theeggs freeof leeches(YaoandCrim, 1995).

EGGS AND LARVAE

The young ofmanymarinefishspecies aresmallandundevelopedwithfemales producing1arge numbersofpelagicegasmeasuringabout 1nun in diameter. At hatch the young are usually 3-5 mm long andliveoff'the)'{llk sac for aperioduntiltheeyes andjaw developandexogenousfeedingbegins(B1axter, 1981).

WoIfIishdiffergrady from most marine6511.Approximately 2100~g(relative fecundity,Pavlov, 1994) areproduccd,each measuring about 6.0 nunin diameter.Theeggs undergo a long incubationperiodof 7-9 months,and hatch in the spring. Eggs held at

ambienccernpemures (ulowu-!.SoC)"the Ocean SCiences CentreinNewfoundland hatched&om the end ofFebruuyintoApril.

LarvK hau:h. 20nan or moreMhveryIildeyolk.. TheyhaveIargc,wdI-pigmcnt.cd eyes,darIdypigrnenIcdskinwith.silverygutregion.and wdl-developed fins.Athalchthey possessthouc

so

teeth(Banukov,1959). Pavlovand Mobness (1994) compared wolffish ontogenywiththItofsaImonids.TheyfOundthattheperiodfrom euactivation to hatching is twiceulonginwoIffish uinAdanticsalmon(SQIIfIO SQ/ar). Athatch,wolffish are more developedwithonlyaremnant:ofyalesacremaining.Following Balon(I98S) theyproposed thatwoUIishhavedirt.ctontogeny.devdopmsdiR:ctly into ajuw:ni.lcwithouta larval period.

Fish ontogenyand namingoflifc stages canbequilc complicatedand beyondthescope of this study.Thefishused in thesestudies

were

newly hatchedand for simplicity willbe rcferredlo aslarvae.

Feeding begins withinthelintfewdayspost-hatch(personalobservation).

Infonnalion onlarvalfeedinginthewild issparse. However gul analysis of samples from ichthyoplankton surveys off northern NorwaynMaledChal stomach contents consisted mainlyofcrust:accMs (1-3 mm)andfish larvae (6-10 mm) (Falk.PetersenetaI., 1990). Gut analysis of1larvaeandftybyPavlovandNovikov (1993) showedthailarvaefeedon crustaceans,fish

esss.

andfishlarvae. Larvae arcpredominantlypcl.agic bul also spend a considerableamountoftime resting onthebottom.

The studies reponedinthis thesishad threeobjectives:

I) Todeterminetbcpreydensitywhichproduced thebestgrowthandsurvivalinlarval

"""""'.

2) To

detamine,.-na

behaviouralobeervation.asu.cegytoweanlarvae from live food 10adrydiet.

3) TodeterminetheternperllhUewhich producedthebestgrowthandsurvivalofluvaJ wolJfuh.

CHAPTER 2.0

2.1 lNTRODUCTlON

MostmarineIu'VIIIfishbat<:h withayolksacwhichprovides thelarvawithnutrients during theperiodfromhalchtoexogenousfeeding. After this, manylarvaego through a periodofmixedfeedingwhenyolk reserves are reduced and they switch from endogenous to exogenousfeeding.Thistransitionis&eneraIlyconsidered a"aiticaJperiod," with an incmueinmortality~on the availability of food (Blaxter, 1981; Kamler, 1992; and May, 1974). During this period there is apoint-of-no-retum(PNR) which is described as when 50',4ofthestaM:dlarvaearelivebutnotstrongenough to feed (Blaxter and Hempel.

1963).

Whenculturingfish, optimumconditions mustbeprovided tomaximize survival throughthisearlycriticalperiod.Informationon feeding protocols for newly hatched striped wolf6shis limited.Most available informacionis basedonI.ViJd-caught or juvenile wolffish anddoesnotconsiderfeeding at hatchor feedingbehaviour.[nstudieswherelive foodwas provided,the amountoffoodwasnotexamined (Molcsness 1990; Moksness eta1.,1989; and

~"~.1"7).

Whenfeedinglivefood to larvalfisbit is imponant to determine the optimum prey density. Increasing prey levels can resuhinincreased rates of survival, growth, and food consumption up to acertainlevel (WernerandBlaxter, 1981). Iflevels are too low, larvae may notobtainadequate~on.lflevelswetoohigh,feedingbehaviour may be negatively

10

aftU:ted..For

exampe

sbonhomscuipin().fyoxgctpltahu~)larvaewereround to have bcttw..-..ival. whmfedlow lewis ofAI"IItMia. Itittbou&flttha1 thelarvaebecome discnlt;::tedwhmpreyIlMiItre 100hiPand

feedins ,..

decce:ue(Brown,pen.comm.).

lligh,..,. ... _ ... _ ... f", _ _<C",- lw:rnIps)I.arwereeGiD&II: •pt"CydensityofJOOM~theirgutmorequickfythan thoseredII:lowerpreydensities.TheA,*",ia werenocwell disated and passedthrough the gutvinuaUyincaet(Werner and Bluter. 1981). Also since live rood production is expensive andlabourintensive.optimum levels should bedeterminedto prevent overfeeding and keep operating costs down.

Rinpet

at.

(1917)roundtbI1newlyhatched woUIi.shfednatw2Izooplankton (AartiaJongireMisorAMtricia1onzo)..Mvedpuc120dayswhilethose red • codroediet survived10sodayspost...ch.In.studyby Moksness et

at.

(1989)sutVivaI wubenet among larvaefedANlMJiaanddrypeUeuu compared to those red onlypellets..Howevc- the groupsSIUdiedwereheld under differenl:IiJhtand tcrnpenture conditionsandredat differml~ThegroupgivenArtnriareoeMdthisfrom 24 to 71dayspost-hatch andpreydensitywunotreported. SincewoIffishbqin exoaenous reedingwithinthe lim rewdl:yspoIl-ha1chitrnlkesIinJeJenSeIO givetheJarvae drypdIeufirstthen1M preyifthe aimis toweanthem onto dry reed.Inanother studyby Mobness (1990), WIld caught wolffishwerefedmoist and dry pellets uwellu An'mia naupLii and natural zooplankton.

TotalmortaIit:yranged &-om49.6to69.3%.The1arvaewereestimatedtobe about 33 days oldatthe timeortheex:perimentandthemorepossiblypasttheperiodor mixed reeding.

II

In apreviousstudy bythe authoI"(Wisernan,1993).preylevels fornewlyhatched woIffishwere mairUincd •8M and24M.Survival at bothdensities

was

low.Studies at the WesleyvilleHatcheryprovidedArk".It3001l and totalmortalityoccurred byWeek 5 (Blanchard,1994).Mylintexperimentwudesiped todeterminethebestpreydensityfor Iarvalwolflish.

Determiningthe age when theyolk:iscompletelyabsorbedwouldhelpidentify the timeframewhenlarvaemust switchfromendogenousto exogenous feeding. Amajor mortality attfU

tne

wouldindicatethat theswitchto exogenous feeding was not successful and thefishdiedofstarvation. Pavlov (1986)reportedthat focWhiteSeawoIf1ish,held at 7.8·C.the switch to exogenous feeding continuesfor10-15days,ending with complete absorption ofthe yolk:.RingeetaI.(1987)reportedthatwolffish held at 1-3^QCabsorbed theiryolkin10-14 days. I conducted a second study to determine how long larval wolffish cansurviveontheiryolkreserves andifyolk absorptionrateinwolflish from Newfoundland walen issimilartothatfoundinwolffishfrom other areas.

2.2 MATERIALSk METHODS

Approximately30 stripedwoIfIishegg masseswerecollected from Bauline.

ConceptionBayin October1993byWesIeyviIe FmfishHatcherySCUBA divers.Theywere distriluted10OcanSciences

Centre

inLogyBay. theMarine InstituteinSI.John's.and the hatcheryinWesIeyviJle. One of theLogyBay masses was discarded due to fungal contamination. A second mass

was

incubltedinambientseawltcr throughout the winter in

12

apIaIic bakec with tcreenedsidespIKedon aW'dbendLThe bukecwassiphonedwhen necessarytoremovedad ClIPlid sedirneIa.The firstmIjorhalchwasOIl February 27.

1994 ..aIaI'lpentUreof-1.0·C.

Fortheprey density Ill.tdy, onehundredDe'WIyIwchedwoIfIisbMnpUcedineach ofsiltJO.itre ....-.pria.AprinledpieceofPVCpipewitha capped end wasattached tothebonom ofthe tank..Waterenteredthis pipe

throuah

fle:xibIetubingattached fOthe other end of thepipe.Thesidesofeachtankwerecoveredinblackplasticto prevent disturbances. Thetankswereplaced in wetbencttesandprovidedwith ambient seawatCf".

TempenturewasmaintainedatapproximatelyUOC byadjustingwaterBows.Each tank t.d an airstone.

Liam was

prov;dedbyowme.d Ouoresunttubesas well as daylight from _ _( _ ~ " " l l O L u x o t_ _).

Thewotftish

were

fedttfte differ'entconcentrIItionlofenriched (ORASoperSdco.

{nvc)ATte1IIia~(Instar

m.

10Mitre, 3oc.t1titu,and 90Mitre twice a day(10:00 a.m.and4:00p.m.).Thereweretwoaquariapertreatment.Ark",facysts (Sweetwater

Exp<ao) ...~ o n d_ _. Onthe_doy _ _Wio.

At10ffia~enriched with DHA Super Sdeo (Artemia Systems,Sorgdoosetat.,1986)to increaseHUFAlevels.Ark",iawerewashedwilh filtered se&waler to remove enrichment residuesandcoUccted in

a

beaker.CouruoftheArte",iaculcurc weretakenon three0.1ml

sarnr*:s

andaveragedtocIetenNnehowmuchvolume toadd to the tanks.TheAnemiawere cooledin thewetbench for about 10 minutes prior to Iddingtothetanks.Fwe hundred ml

13

or cooled aIpe (lsoclry.sisgo/boIttI)WllS abo added toachtankprior tothe morning

,_

IvainitiII.-DpIeoCtwed)'woISsh, IsstMnonedaypost-blld\. waskilled withMS- 222andirNnedWeIy rinsedindistilledfreshwater.Standard Lensth(tiporthe mouth to the endoCthe notocbonf)wasmeuured10 thenearacO.Smm

LlIins.

dissectingmicroscope.

&champ&e wuthenpI-=cdonpmwiahedaIumiIU'IICoilanddriedat9O·CCor41houn bein~Fivefishpel"tankwatlsampledfOr

standanllcnslb

atweeks 2 and S. Day oneorthe~wasMIrdlland it adirued untilApril7(Day31). Mortalitieswere removed daily andIXlUftted.IlauIuwerecombinedinonewedc. intcJvab.

Inthenon-feedins;SIUdy,sewntynewlyhalched woIffishwere stockedin eachortwo white plutictanIa.To help contend with Ntrogen supersaturationintheW1Iler, degassers wseplaced ineKh tar*. They consisted simply oran Er1eruneycrflaskplaced on • brick in thetankandequippedwith an aitstone with high airiIow.Theinflow linewasplaced in the depsaeraIIowqJ:theWIleI"to becomewdlaenledbeCore itenteredthe tank. Water exited

throush.

tmaIIscreen at oneendorthetank..NofoodOf"alpewasaddedto thetanksfor theentirestudyperiod. Temperaturewumaintained at U·C. Mortalitieswereremoved and counted daily.Results werecombinedin one weekintervals.

ResultswereanalyzedusinS SAS/STAT (SASlnstitute.,1988). A acnerallinear modelwuused 10determineifpRY densityor IF influenced the survivalOf"growthoflhe larvae and10 test fortankeff«u.If.significant .-treatment intenctionwasfound,the resulu werethen analyzed using.Ic:astsquares meanstestwith • Sonferroni corrected p.

14

value todleck:forsipli6cance.adt.. A8onfcrToni~P-valueisfoundby

<IividinI

theoripnu

'-vaIue

(0.05)bythe productoftheaamberofasestimesthe number of1r'tlUmerll(SobIand~1995).WbentesmsrrUtiPecomparisons areducedP-value aJlows a more robust test of sipificance. Priortostatisticalanalysis.survival datawas ranked transformedsinceotha" UIftIfonnations(u.

los

transformation,square root

'-"c)<tid""'..,..,._.

This _

the data with theirranksabowin&the usualparametrictell:tobeappliedto therub (Conowra In-., 1981).GrowthdIta

was 101

transfi:Innedto meet the assumptionsofthe

2.3 RESULTS

2.3.1 SURVIVAL

For !hepreydensitystudy, suMvalwasdetenninedforeachtank by subtracting the runber"ofmortalitiesfromthe total (anitialtotalminussampled fish).Anavenge was1bc:n caJculatedforachtre:l1JllCftt.

Altheend of1be1tUdy(W-6)percentuvMiwas20.6 (:l:O.55)for100ATtortilJll.

16.9 (±5.2.S) furlOOATk"'iaII, a21.1 (:t11.55) for900ArtntUaII(Fig.I). Therewuno signi:6cantciffinnoeinsurvivalbetwecnrreatments(ANOVA, F^al.7l, df-2,18,~.2088).

The mean survWa1for1heexperiment was19.5 (:t$.7S)O/t.

Inthenon-fcedinIstudyrnortalitiesbepn at 15dayspost-hatch (Week 3) and all fish

were

deadby 12 dayspost-hatch(Week 5) (Fig.2).

"

6 ___ 100

Artemiall

____ 300

Artemiall

- 900

Artemiall

4 AGE (weeks post-hatch) 100

80

~ ₆₀

;>

;>

0:: :>

'" _'<f- 40

20

0

0 2

Figure I:Weeldy percent survival(::t:se)ofstripedwolffishfed different densities ofArte1fl;a.

16

100

~ 80

> :> ₆₀

..: ::>

'"

E-Z to>

40

ail

_to>

0.

20

0

0 2 3 4

AGE (days post-hatch)

Figure 2: Weeklypercentsurvival(±Ie)ofnon·fedstripedwoIffish.

17

2..3.2 GROWTH

No~~Mftiuldbetweerlreplicaletaak:s(P:>O.OS).Allwchthc Iarwe'Mlft20.72:0.09un(a-20)long.There

was.

sipificDdifI'amccirtstandard~ betweentr'eatJnM:I (10011) and 3 (900/1) at Week 2 and WeekS,andbetwocntreatment2 (30M)and3 (9OOIl) at Week 5 (P<O.OOIl, Bonferroni c:omction). By WeekSthelarvae measured 22.0:i0.27 mm (n-IO) fortratmcnt I, 22.1%0.13 nun (n-IO) for treatment 2 and 24.4*0.36 mm (n-IO) for treatment)(Fig.)

2.4 DISCUSSION

SurvivIIIindieslUdy_lowlXlq*Idto otherstudies..However,the periodofhigh mortalitybetweenweeks3 andS(21.35 days)wassimilartothatofmanywoIffishstudies.

Moksness ctaI.(1990) found that larvaefeddrypellets&&oneand drypeIIctswithArte",ia showedhigh monaiitybetween20and 40 days. Blanchard (1994) compared.varietyof diets consistingofArlnrIia,drydicts, andcombinMionsoflive andinertfoods. AUgroups diedat the same ratewith.peak inmortalitiesbetweenday 27 and 36.

Preydensitydidaff'ect

arowth "* ^as

^eIriy

^as

^twowcdcsposl-batch. Prey densityhas been found to afIect growth and survival ofmany 0Iher' species. Houde (1978) investigaled optinun preylevels inlarvalbay anthovy (AndJoa ",itehiflij,linedsole(AchiFils linea'us), andseabream(AI'Chosorps rhotttbokJaJis).Over.16dayperiodtheywerefedwild plankton atlevelsofSO, 100, 1000,andSOOMforbayanchovy, SO, 100,and1000/1 forlined

18

o ^{2 5}

AGE (weeks post-halch)

o

30

c::::::::J

IOOArtemiall

25

_ 300Artemiall

E

^_ 900Artemiall

.E-

X

20

e

f0-

z _w

15

...I

~ ¹⁰

~ tii

Figure 3: Mean standard length (mm +te) ofsttipedwoIffish fed three different densitiesofArlemia.

19

soieaod10. 25. SO. tOO.andSOO'I~sa.brewn. Survivalandpowthinaeuedwith

inaeuins

prey~

iJr.

tinespecies. SuMvIIrceofsa.bR:am inaeuedfrom 3.9% • •preylevelollMto12.7%ItSM IDd upto72."% • • preylevdofSOO'l. Mean standardJeqgtbincreased from ...JS ... 1M to 7.76. SOOIl.Thepreylevels.wbich 10%survival10metamorphosiswupredicted

were

10711forbay anchovy.13Mforlined sole.and341l

ror ..

bram...

ThequesbonariJes as towhyIUI'\'i\'aImeis

sam.-

underthethreepreyden5ities but growthisfasterforluvaefedat900Am",kIIt?ADthreegroupshad thesame success in switchingfromanendogenousfoodsource to an exoaenous one.Growthwas better for larvaefed.900Ark",ioIlthan thosefed!OOAmnrial1asearlyutwoweekspost.hatch.

In._byDw>y ....Bapmao(I...~... w-(e-""'""")"""abruplly

~fromrotifen 10silldifferentutific:iaIdiets. The controlwas weanedontoArIUJIiQ.

Thosewemed ontoA'*"tSagrewthefasteabutsurvival

was

lowIt"2%. Those fish fed an arti6ciaIplanktondietweretheonlygrouptoshowlsiPficantJyhighersurvival (63%).

they~. . growthwasnpidlOrtbosefed~because ofappropriate predator.

prey behavioural chancteristics ofthenlupliiMilJdishareparticulate visualfeedcn on plankton, so food shouldbepermanentlyavailableinthewater column.

ArterrUmaybeIIJIritionaIIy~fur some species resultinginstarVation when the larvae switchfrom endogenous to exogenous feeding. Inl studybyKlumpp and WestemhIgen (1986).pIaice(Plevronec:Iesp/alessa)andblenny(B/enniwptlWJ)larvae were successfiilly raised onAne",iafrom6rslfeeding tometamorphosis.Inthesame SlUdy

20

howe\«,herring(Chq¥altannps)larvae grew, butshoweda suddenhighmortalityat38 days afterfirst feeding. It

was

sugesud thatadietofAm",io may caase species specific

Pf'Obierr- ..t

have

Iona-teml

toxicityor rutritionaldeficiencyfor

herrins.

This may alsobe thecase forwolfIishin Ibisstudyas adietcomposedsolely ofAne",iamaynotcontain all the nutrientsfoundintheyolk.Thereforewhen theyolkisexhaustedthe larvaedie.

Newly hitched wolffishIarvIc cansurviveon theiryolkreserves for 2-4 weeks. The first mortalityinthenoo-feedingstudyoccurredatIS days post-hatch. This would indicate thatforlarvae heldat4-6"C,thec;ritigJperiodforsuccessfuUy switching&omyolk utilizationtoingesting anddigestingel:ogcnous foodmustoccur prior to15 dayspost-hatch.

A major mortality startingatIS days or shonly after would indicatethat larvaewere unsuccessfulinswitchingfromendogenous to exogenousnutrition. StrandetaI. (I99S) reponedthat themain cause of mortality of wolffish larvae fed fonm,dated dry feeds was failuretoinitiatefeeding.Survival curves

were

similarinallexperimental groups with the greatestmortality between30 to 40days.Mortality ofthe fed groups corresponded closely to theshorttimespanin wtUchtheunfedgroupdiedofswvation.

Inconclusion wolffisbshow lowsurvivalwhenfirst fed a diet ofonlyAnemia.High monalityin weeks3to5 indicates an unsuccessful switch to exogenous feeding. This is supportedbythecomplete mortalityofstarvcdlarvaein2to4weeks. This maybethe result ofthe larvaenotreceiving enoughfoodorthat thediet was inadequate.

21

CHAPTER 3.0 WEANING

3.1 lNTRODUcnON

Typic:aUymarinelarvaeM'efirstred on1ivefoodandlaterwanedonto prepared peIctcdfeed. SmallmarineIarv.e maybefirstfed onsmall naturalzooplankton or rotifers (Brachiomu plicalilis)and

anduaDY

wanedtoIarprzooplanlctonorArklffiaandthen pelletedfeed.The

Iarae

sizeandIIdvanceddevelopmentofwolffish11hatch allowfirst feedinaonArvlffia.However,input experiments wotffishlarvaefedonlyATt~lffiashow verypoorau'Yival. Even whenpreyIevds were

900II.

asintheJWdiminary experiment cIesaDed eartier,survMIremained~w. Theuse of livefoodinc::ukuringfishis expensive andIabow"intensive soweanin&to preparedfeedsas early aspossib4eisdesinble.

WeaninR

Llrvlllfish0I'Il0dry foodcanbe difficult.Thepellet must be the proper size, lextuleand odour. Itmusthave"!henecessary nutrientswiththe proper levels ofproleins.

lipids.mincnls, and vitamins, aswdlas the rightcomplimentofessentialamino acids and essential&tty.::ids. These nutrientsIIIllIlthenbeeuiIydipsted bythe rudimentarysysl:em oftheyounglarval6sh.

ThisIeCOfldslUdywill~tbedliectofpre)'densityonbehaviour.growth,and swvivalwhenArtrlfflaaregivenin c:ombinationwith • dry diet rightfromhatch. Detailed behaviow-al observationsareseIdornusedas.toolinaquaculturestudies. Observations of feedina: behaviourcan help explain growth and survival results. Behaviour studies arc particularly useful when thelarvaearcfed two food types. Important information such as

22

roodpreference.feedingsuccess..feedingrates,.and waning times canbegathered fix"use indevdopins

fecdina

proto<:o!s.

3.2 MATEIUALS.t. MEmoDS

One hundred newly hatchedIatvae

were

placedinindividual30 lim glass aquaria.

Flows

were

adjusted10maintaintempend:Urebetween4-7·C. Thesideandbackwalls of eachaquarium

were

wrappedinblac:k.plastic toprovideadark.backgroundandto separate eachtank..Thefi'ontwallwaskftopen 10 allowforeasy observation.Alliankswere located in a wetbenchwhic:ftwascompktelysurroundedbyablack:curtain. Lightwas providedby overheadfIuoracenttubesasweDasRIballighr:fromnearbywindows(natura! photoperiod;

60-80Luxatmidday). FrveIundredmlofcooledalpe (/. galbana)wasaddedto eachtank daaly. Tankliweresipboneddailyto remove feces and excess food.

Mortalities were removed daity andcounted. Percent survival was determined by subtractingthen.uri:ler"ofdC'Adfishfromthetotalanddiyjding by thetotal (the oomber taken fordryweightsandoomberntissing11the end of thestudywu subtractedfromtheinitial total of100andused

as

thetotalfor mortalities).

Twenty larvae

were

sampledatthe stan. of meexperiment(age 4 days) and used as initial samples foralltanks. Standard lengthwasmeasured anddryweightsobtained following drying at 9O"C for 48 hours on pre--weighed aluminum foil. Five larvae were sampled fromeachtank~two weeks thereafter.

23

Theexperiment consisted oftwofccdiJlg trcatmenb (duplicatetanks for each tratmerW:).Tratmert lllrwewere&d erwicbedAnmtia II a density of 1001IandTreatment 2 •900'1.These preydensitieswerethehighestandkJwest usedinthepreviouspreydensity experiment.Arlnriawereprepared andcountedinthesame manner as described earlier.

Anwine larval dry diet(LansyN4 500-800 ."m)wuadded to thetanks following the addition ofArtemJa.Ateach

feedins

about 0.3grams(0.6 gramslday) of dlY dietwas carefullydropped onto theSUJfaceofthewater so thatitfloated. Thiswasobserved to be inexcessofwhit the Wv.ewouldconswnesincetherewouldbe excessfoodonthebottom ofthetank.Foc mostofthcexperimentaUIarvac werefed twicea day (10:00 a.m. and 4:00 p.m.).InWedc 8thclat\'acwereobserYedtobetaking most oCtilefood.50an extnt feeding ofdrydietwasaddedat12:00 noon.

Feedingobservations began2 Weeks post-hatch and wereperformedtwice a week until theendofthe experiment.

FoIlowin&

themorning addition offood(Anemia and dry pdlets) theobscrversatquiedyin fiontofthetank. Since larval. wolffish arcnotexclusively pdagicandmaysitor rest (ie.incotUctwiththe bottombut withsome forward movement tocapturefood)forperiodsorUme. observationswerecarriedout onfish inboth locations.

Sixfish(tine

S\Wnmins

fish andthreeresting)werearbitrarilychosen and observed fortwo minuteseach. Similarobservabontimeshavebeen usedinother luvaifishbehaviour studies (Brown,1986; Brown and Colgan, 1984).The timeClIchfishspent swimming or resting, in eachtwo minute observation,wasrecorded.

24

ThefeediDBbehaviour perfonnedby the larvaewasdescribedbysix.Modal Action PattemI(MAPs).s.rtow(1968)defiDed. MAPas • spWotempora.l patternofcoordinated movement,wbidtdusters Ibout somemode,makingthe behaviour recognizable. The feedingMAPsrecorded

were

Orient,F'1XIle. Lunge,Bite,

Miss.

and Reject (TableI).The occurrence ofeachbehaviour during thetwo minute observation periodwasrecorded. A distinctionbecweenbites atAneMiaandbitesatdry dietwasmade.Inaddition,theMAPs ofOrient, FIXate. I..unge. and Bite

were

combinedinto. CltegorytermedForage.

Fo8c:nUlstheobscrvations ineachtri;theIUfI1ber of6shswimmingand restingwas detemjned.

Uq

ahand-bddcounter the number resting or rMnberswimming(whichever

was

smallest)

was

counted.Ahhoughnotthe mostaccuratemethodthis permitteda fast

meIltSofcountingthe6sbbefure they moved. Thermnberof 6sh inthe other category was determinedby addingthe mortalities to the oomber countedand subtractingfrom the total.

Ofthe fish resting on the bottomthe number lying ontheirside u opposed to those in an uprightpo5itjonwasalso reconkd. This hasbeendescribed as a behaviourinthelarval stage ofwolflish(Moksncss,. et a1., 1989).

Theexperimentwassetupfor 10weeksbut endedafterninedueto technical problemsandlossofwatcrlJowin one ofthctanks.Survival data wucollcctedupto week 9howevergrowth andbehaviourdatawereonlyavailableupto week 8.

25

Table I: 0pcnIi0nIIdescripIionofModalAction Patterns (MAPs) ofstriped wolflish larvae.

MAP

ORIENT

FIXATE

LUNGE

BITE

MISS REJECT

DESCRIPTION

ResponseoflaNa tofOodiIan,wNdJ. involves. movement of thetNnktobringthehead oflaM.facingandinalignment withtheprey.

Pausebetweenorientation and food capture. The head of Iuvafacestheprey.Larvafocuses onfood item.Doesnot

oJ...,.,....,...

^ondlrite.

Aprey-captuteresponseinwhichthetrunkof larva assumed an s-shapc:dposition andprecedes a fast forward movement towardsfooditem armorethan1/4 bodylength.

Usuallyprecededbylungebutnot always. Involves opening and cioAnI ofmouthquicldy.No nOliceabl.e forward movement(\essthan114bodylength).

Larvais unsuccessfulincapturingfooditem.

Larva ejects or spiu out captured food item.

FORAGE"" ORIENT+FIXATE+LUNGE+BITE

26

The . .were~'Whenneeesury to meettileaMUIIIptionsoftbesraristicaI tats.IfdatawereIbllDOtDOC'1naIIy

diIIrhIled.

they

were

thenranktrIDIfi:wmed.Effects of~IeYdsand • onIUf\'ival, growthand behmourwereaallIyzedusinI;-general Iincar model. In.motlanalyses.signitkar:t.~inIerKtion

was

foundso_least squares

rrans

tellwith •Bonf'ertonicorrectedp·vaIuewasUIedto test significance ateach . . Ifnosignificantage-treatment interactionwas foundthen.Duncan'slestwas used to testforsignificanceateach

aae.

A linear regression

was

usedtodel:ennine ifthefrequency offoragingincreuedordecrcuedovertime.

3.3 RESULTS

3.3.2 SURVJVAt

Urv8c&Ill • tip densiI:yofAr*Miashowed •sigJ:m::nIyNgher survivalfrom Week 3 onwns(p<o.OO2I) (FiS-4, Tabie 2). Bythe endofthestudy94.3% (:t:O.9)oflaNxfed 9OOArau1t.d...MeLfordme fed100~anivaI

was

significanllylower(P<

0.0021,Bonferroni CClfTUtion)at52.6%(::1::2.6).Mortalitiesranainedlow throughoutthe experimenI:in theNIhdensityAI'ImIiaWlksbutincreuedcont.iooouslyafter Week 3for the low densityAnemiatanks.

94.3(±O.9)%

80

54.8(±2.6)%

20

. . - . 100 Arlemiall + dry diet . . . . 900 Arlemiall + dry diet

o ^{2 4 5 6 7}

AGE

(weeks post-hatch) 9

Figure 4: Weeldy percentsurvival(±$e)ofstripedwoIffish larvaefed different densitiesofA,te",iaplus dry diet.

28

I ₈ ^! f ~

!

[ 1

if ! _!

'5! ~ ! !

.lI ..

rig 1-

^~

i~ II!>

^~

~

i I ^L ~

it ^j _!

~ ; r

U _q ^!!!

~ !!!!!!!!!

~

..

~ t

~

;~~

H _N! ^~" _~

j h!

H

29

3.3.2GROwrn

Attheswtofebe study (4 dayspost-hal:ch)IarYae

woere

22.2:l:O.09nun (n"'20)in

_cr...,).

F... _ _ - _ ... (I'<O.OO6'.

Bonferronicorreaion)inthoseluwefed.Naberdensity ofA,*",ia (Fig.S, Table 4). By theIat~day.1aMcred900~meaand36.7-HJ.S6(lFI0) mmwher"eas lhose fed100

A,...,

^meaandonly 30.4:iO.72mm(n-10:P<0.0063,8onfaToniCXlfll!Ction), .di1feraK:eof6.3mm..

IaiciIldcy . . . theltartofchclbJdywu 11.3.t:O.llmg(1P'20: Table 3).L.arvae sampled&omthe900~ ~Md.1iaNficandyhiJberdryweight11-ek 6 and week 8(P<0.0063,Bonfcrronicorreccion.Table 4). By theIascsamplingday, larvaefed a high densityofAnr",ia(9OO'l)bada dryweightof76.lJj:S.10 rna (n-IO), whereas thosefed 100IIweighed 41.1±4.01 mg (n-IO: Fig.6), • difference005.8ma.

Specificgrowthrates (flb&e S)wereCIIcuIalcdfromstandard~gths(Fig.1)and dry weigbu(Fig.8)usingthefonnula:

SGR-(IoLYt-Iog.YaYO,·I.)-IOO wbere , - timeandY -

6'"

size

SGR

ransed

from2.68-tJday 10 4.2SWday (based ondryweight)among larvaefed 900Artemiat ForlarvaefedIOOAI1c'~SGRftuetulted throughootlhestudy with alow

'0

I ¹

^~

^{4' ~~~;~}

^~;;;;

!

'i

~ E

J it _~~i~;

« ~ I

"'!~"'l~O-;

I

^{:::~ ~ ~;5l}

~

!~ t

^:::;;~~~

H

'i'i ;; I: l

it ^{4' 2tigg;;}

H _~~ ^{1 81-}

- ]

HiH

-1 I

I) ^~a~~;

h _I

H ^~t

h i

31

40~---~

c:::::J tOO

Artemiall

+ dry diet • 35 - 900

Artemiall

+ dry diet

o 2 4

AGE (weeks post-halch) Figure 5: Meanstandardlength (mm :tse)ofstriped woIffishfed different densitiesofArk",ia plwdry diet. •indicates P <0.0063, Bonferronicorrection.(n-IOcxc;:epln-2Oat1p"'O).

32

II 8 .• ^{~ ~}

~ ~

Ii _[; r

). § ~

1~

f~ I ^"

²

n

^!~

^{~ :}

'"J

H L - - 8

~U

~l Ua

1.

^{c e o}

U

^~

~~~ ~~~

J! p _~~ i~~

^~;:;~

J1

^i~~

ill _! ^{t t}

P _~~ ^{h~ h~}

le Hj

p,.; ..

~§

'1~ J

~

~ -" ^.Ii _~

.. !~

l ^I

n~ ^i!

^~

a

33

9 0 , - - - , 80 c::=::J 100 Artemial1 + dry diet

. . . 900 Artemial1 + dry diet 'Oil 70

g

!c ⁶⁰

o <il 50

~

~ ⁴⁰

~ ³⁰

;;;: 20

10

o 4 6

AGE (weeks post-hatch)

Figure 6: Mean dry weight (ms::I::se)ofstripedwolffish larvae fed ditferentdensitiesofArtemiaplw dry diet. • indicates P<0.006], Bonferronicorrection (n-IO perweekexcept 0=20 at age=0).

]4

I ^{} !~5~}

~ ~

i )

4

it: ~t

II _n !

^{0 _ 0 0~~s::}

Jt P ⁱ

t! ¹

^~

^~!;;

l~ I

~I _li h

~~ ! ^gg2:

Ii U ^j

"~ ti

':'~~~

h i

^{0. . . . '0}

J5

2 ....- - - , c::::J 100

Artemia/l

+ dty diet

_ 900

Artemia/l

+ dty diet

2 4

lJJ

6 AGE (weeks post-hatch)

Figure 7· Specificgrowthrate ('YJday) calculated fromstandard lengthofstripedwoIffish fed different densitiesofArlemiaplus drydiet

36

6

4

~ :!1

~Cl

~~

2 a: "

'"

0 -1

c:=J 100Artemiafl + dry diet _ 900

Artemiafl

+ dry diet

n _-

4 6

AGE (weeks post-hatch)

Figure 8: Specificgrowthrate (Wday) calculated from dryweight ofstriped woIffisb larvae fed different densities ofAnem;o plus drydiet.

37

of..0.07 %lday(baedondty weight) caIaIIaledfromwedcs410 610 ahighof5.14YJday inweeks6to 8.

3.3.3 BEHAVIOUR

LarvM:red. 900 A,.",ia/l showed asipUic.antIytqherfrequency of eachMAP (~FIQIe.

Lunse.

Bite)at2 weeks~-hatch(P<OJI031,Bonferronicorrection).In weeksJ to9there~nos¥i&clntciftinnca(p>O.OOJI,Bon&rroni correction)(Fig.9a, b,Cod; Table 6).SimiJarresukswaeobtaincdfOrfortsiag<F.,.IO, Table 6). Foraging amanSthoseIaMlefed900A~idtdeaeued sip6c:andyoverthee:xperimenl(linear

~sIopt:o:..o325429, P-0.0001).LarvacfedIOOArklflia/lmaintained thelrlevd offoraginSbehaviour overtheexperimenI(slope--0.053911, p.e(J.3168).

AmongIarYaefedIOOArlemio1asigni6canIdifference(F-U3, dM,136, 1'-=(.1.0025) wasfoundbetween~ofMAPs averlbeexperWnent (Fig.Ila). Thelarvaeperfonned moreOrient andFDtatebehaviours thanLunge andBite behaviours(P<0.05.Duncan rrukipIe

nrve

tell).1MvIeinthe9OO.At1eIIrioII ueatmentshowed nosignificantdifference (Fa2.2I, df.-J,736, p=(I.0858)

amons

frcquencjesofMArs(FIB-lib).

lMwefed 9OOArlmlit¥'tt.la~""'hquencyofbitestowardAnemia in weeks 2 and 3(P<0.0031,Bonferronicorrection)thanthosefromthe 100Arlemiall treatment(FiS.I2a,Table 6). Therewas no significant differenceduringtherestof the experiment(p>0.0031,fIonfernnc:omICtion). Therewuno dift'ercnceinfrequency of bites

] I

. . . lOOArtemiall+dJydiet . . . . 900 Arkmia'l + dry diet

"

!Z

12

~IO

~

.

>-

;:

~2

b.

"

"

2 3 4 5 6 7 1 9

"

d.

2 3 4 5 6 1 8 9

wl2

'"

~IO

~

.

>- fiE •

L ~.

*

12

~ ^!ii,O

^w

^{~:~ ~.}

^~2

^{~I ~}

2 3 4 5 6 1 8 9 2 3 4 5 6 7 8 9

AGE (weekspost-hatd1) AGE(wtdcs post-hateh) Figure 9: Mean weeklyfrequency(~)of.)Orient, b) Fixate, c)Lunge.andd}Bile in .2 minute observatie:.tperiod forstripedwoIffishfed different densitiesofArlem;a plus drydiet. • indicaleS P <0,003 I,Bonferronicomctie:.t (0=24 perWIlde).

39

~

! ^s I ! ^E

^~~

S

i ^. _{~ !}

^~

_{! !}

^~

_!

^.;~3

~

1:-

^{.; .;}

f~

^~

! ! ^~ ! ! ^{§ 18}

[1

^{.; .; ~}

~~ .

~ ! " ^~ !

^~

~

if

^~

^{: :}

~

^~

^{s ~} ~ i ^:

:a'S ~ ,. _:

~J .. ^{::: ~}

^.;

^..

^.;

^{a § S}

^.;

^!

!I

^$

^{: ~ :}

^.;

P

^{j~ t;;}

:

^~

: ~ ! :

^~

~ ~

I! ^l~ _~

! _~ ~ ^{~ E} ~

il~ ³

^.;

] ~ (1 1 ~u

^doci

~!~ ~~~ !~~ ~n ^~u

^coo

^~ia

^ooci

.g-] !~~ !~~ ^U! !~~ !~~ ^{ilU !U}

=~l '"

^{..:..:~ _'..:r.:} ...:..:...:

tL 1"§ ~~ ^{55~ SS5 ~:s ~S~}

^{~:, ~~8}

,,:.

<!~

^04"';N .... ::!..,.; .;::;".;

U _~ !' _{~ ~ ~ ~ ~}

H~ ^{j h! h!}

^{.. < ..h~}

^{h! h! h! !!'~}

-Ii

^~

_~ ^! j I ^~~ fl

L:

^~

_" ^{i =5}

40

5 0 . . , - - - ,

UJ

40

~

- 30

15 >- u ~ ²⁰

~ '" 10

. - . 100

Artemiall

+ dry diet . - . 900

Artemiall

+ dry diet 2 3 4 5 6 7 8 9

AGE (weeks post.halch)

figure10:Meanweekly frequency (±se)ofForagein a 2 minute observationperiodfor striped woIffishfeddifferent densities of Ark",1aplusdtydiet. •indicates P <O.()OJ I,Bonfc:rroni correction (ft&14perweelc).

4\

14 - , - - - ,

~

¹⁰

.. ~ .

~ .

~

⁴

2 3 4 S 6 7 S" 9

14

- r - - - ,

12

<i)-0orient . . fuwe ... IUftge ... bite

S 6 7 g. 9

AGE(...I<h)

Figure II: Meanwuklyfrequency(m)eXeachMAP(Orient, Fixate,Lunge, Bite) in a 2miruteobseYationperiodrorstripedwoIffish larvae in a) Tratment I, 100 Nlellfiallplus<bydietandb) T'eatment2, 9OOAnoIiaJIplusdrydiet(n-24 pcl"week}.

42

12

+ - - - ,

. . IOOArte",ja/l +drydict . . 9OOArtemial1

+dry diet

2 J 4 S 6 7 • 9

2 3 4 S 6 7 8

AGE (weeks post-hateh)

Figure 12: Mean weeldyfi-equency(m)alBites at a) Artemiaandb) dry diet in a 2 minute observationperiodferstripedwoIffish larvaefeddifferent densitiesof Arle",iaplusdrydie!:(n-24per week).

4J

• drydietbetween.tratmenuovertheexperiment(P> 0.003 I. BonferroniCOCTection) (Fig.I2b. Table 6).

ConIiderias

onlymo.!arwe:wtK:hwereswir'mWtBduring thetreatment.therewere sigrUcandymorebitcsn.se.Ar*flfiainweekJ21lld 3(P< 0.003I.Bonferronicorrection) amorwilrvleliedAM.iaat9OOllthanamoaathoteredthclowerlC'o'd(Fig.IJa. Tat»e7).

TherewasnodifI'erax:edurirwtheraeofthestudy(P> 0.0031. 8onferroni Correction).

TherewasalsoDOsipi6cantetitfermcein frequencyofbilestoward drypellets between t:reatmeIU(F.. 13b) (p>0.003I,Bonferroci:comaion; Table 7).

Among

restins

fishtherewas110

sianificant:

diffemacebetwemtratmenlSin ffequencyol'bita.AnnIUa(F'I- 14a)(F-I.44. cV-I.174, P-O.2312) or drydiet(Fig. 14b) (F-I.82. d.fS1.174, P-=O.1786).

Amongswimming fish fed100ArtemiG'1(Fis-ISa)thcrewasno significant difference inbitesalArkMia ordrydiet forthe6nt7weeks(P>O.0031. Bonferroni correction; Table 8). Byweda 8 and 9, significantly more(P< O.ooJ I, Bonferrooi COfTection) bites where n.setoWanldrydid..Inthe . . .fOodtris(F..ISb)~larvae mademore attempts towWsAraliainWeeb2 and 3 (P<O.OO3I, Bonrerroric::orTeCtion;Tab&e 8) andmorebites towardsdrydietfromWeek 6(P<O.OO31.Bonferronjconoction) onward. Therewas1'10 significantdifference inbitesinWeeks 4 and S (Y>O.0031,Bonfc:rroni correction).

Among

restins

fish fedthe 'owdensity01'ArIe",ia, significantlymore bites were made towantsAntmiacbingthe 6rst6 weeb(Fig. 16.) (P<O.0031,Bonferroni correction;Table 8).[Itweeks7-9 therewasnosignificant.differenceinbites.lhe fooditems(P> 0.0031,

44

14 - ; . - - - . - - - , 12

~ ,.

!5 t; ~

⁶

~

⁴

. . lOOArtemiall +drydiet . . . 9OOArtemio/1

+drydict

b. 2 3 S 6 1 8 9

14~---, 12

~

¹⁰

.. !5 t; ~

⁶

~

⁴

2 3 4 5 6 7 8 9 AGE (weeks post-hatch)

Figure 13: Mean weekly frequency (±se)ofBites at a)Anemia and b) dry diet in a 2 minute obsavationperiodfor striped woIffish larvae fed different densities ofArlemia plusdrydiet.Observationson. swimming larvae only.• indicates P<O.OO31.

Bonferroni correction (n= 12 perweek).

45

~

^~

iJ

^~

~

..

I- =1 i ..

^~

fl f~ ! ~

1~

_~

~ !

il~ g~1

~

s

~jl

^~

!~ 1· ^{~ ~}

il~ ..

-( 8 ~ •

~ ~

l!; I ~" r

~ ~

I d _f· ^~M

lit

^{~. ~ 8-~}

^{~~~ Uii}

^odo

pi

^~-

^"

^{!:!:~...:~~ ~t!t:..:..:~}

lr _~~

^;:::2~

_~~~

~d

..;".;".;

~H ^{j ~ ~}

hi ^{h! h!}

';;1" ^~ i

~~1 ~ ~

^g~

46

11

~

¹⁰

..

~

o •

i

⁶

~

⁴

14~---, . . lOOArtemiall +dry diet . . 900Artemiall

+drydiet

14 b.

11

~

¹⁰

..

~

o •

i : ~

1 3 4 6 7 8 9

2 3 4 5 6 1 8 9 AGE(weeks post-bateh)

Figure 14: Meanweddy frequency (±se)ofBiles at.)Artemiaand b)drydiet in a2minute observationperiodfor striped wolffish larvaefed different densities of Artemiaplusdry diet.Observations on resting larvae only (n"'12perweek).

47

,,;:.---,

12

~

¹⁰

~

o •

>U

~ .

~

⁴

14

-r-.---,

12

~

¹⁰

o

~

•

>U

~ .

~

⁴

"Ar1DrIia . . drycliet

2 ) 4 6 7 B 9

AGE(""",, "",,-hatoh)

Figure 15: Mean weekly frequenqr(:l:::se)ofBitesItArlemiaand dry pellets in a 2 minute observationperiodforstripedwoIffish larvaefed at • level ofa) IOOATle",iall plusdrydiet andb)9OOATtUI'io'I. plusdrydiet.Obtervations on swimming larvae only. • indicates P <0,0031. Bonferroni comction (n-12 pel"wedc).

4.