SPERM WHALES . 2

,

INDIVIDUAL PHO'I:OGRAPmd . '", . IDENTIFICATION : A KEY TO THE ~--"' c~

. . SOCIAL ORGANIZATION ,OF '

'~-

SPERM WHALES . 2

~/

. .

BY

©

TOMAR~'EAR!\'BOM.B.Sc..

)

AThesis Submittedtot~eSchoolof.G rad uate Studiesin Part ial FulfilmentofRequirementsfortheDeg~eeo~

Master'ofScience

Depar tments of, Biology

.

and Psychology

,

M~morial Un~versit)CorNewfound la nd March,1987

St.-Jo hn's Newfoundland Cana da

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"p~rm'ission'has been granted -Ec the'National Library -o f Ccin.ada to'mic!='ofi lm this thesis and to·l e nd or -s e l l co p ies of thefilm,

The author (copyright owner)

has reserved othec

pub licat.ion ri g h t s. and ne Lt.h er' .'t h e enee Le' nor extensive extracts from it may'be printed or otherwise reproduced without his/he r writ tenpermission,

i.'

autori8Ati~n

a ete

_acco~de,e

a.

-re Bibliotheque natio nale du: Ca n a d a.,-4 e 1{licrofi lmar

~:t~~n:~:S~e;.t~x~emSll~~;:~g~

fUm_ .

-L'a utel),r (titu'laire du droit 4'auteu rj se re s e r v.e le s au t res droits de pUblication, .ni la t-he~e·,.ni "de'longs extraits -e e:celle -c i ne doh·ent.etre imprim~-8 ou autrementre p r o d ui t s sans son autorisationecrite.

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Spermwhales wen l.f1ckl"d \'isually anda«l~\tiC'lU,·inthe wqters westoft~~

Galapagosbf'l~'f!'f'nFebtullryand AprilHISS.Amt'tfiOQ:""f'Or photograpbitoall".

I

idt'Dtifr ing"individualspe rm whal esis~e5('ribtd.:Mea..~uret'lprtbe pbC;;tograph. quality werecomp aredwith'the certainty withwhich individualswer~idf'oiifi<!d.~·

Atotalof2i ofemalesor

immalures~

^7I,argeed ulr m:lles

a~d ~ c~h·.es

^,,:ert'

reecgebedwitb'certaint,y•.ed indh'idua llyidentified. A'si~ple"mo<It>I-lIuggPllled t}atupto9% 01theremal~s/immatur~^{couldnot be}idc~tified^{using this}

m ;ttiod . ._.. .

ofphotographicidt'Dtlfir ation ,.despite.big!'! qualit)'ph'olographs.

)i'

w~sh'~~'n ^.--c,-<,

~

^.thni these individualshave a lower number or uniquemath'onthe irIlukesthnn

~e ~HO

ia.en'tified

f~marC!s/immatures,.

^The

assu~ption

^of;andom

samplin~

^·...ben

·fl ingphg.tograpbltoC individualsperm whalesisdiscussed. TIll'time and

·geograp hical'_spm~whalespositions·or·t heprl!fl'rr!~ati£.bre-sightings of knownupwelling

.

area. individuals suggt1lt

.

^. Ihat the The 'id enliried remales:/im.mat ures'Are clusteredi~ to·.23discrete~iJps.• Thirteen

a !

t\~e groups contai ned mor e than six associa ted rlJembers.

·Observe ricns or calves and'the bighfrequency ordorsal finswith-acallus suggestedthat the groupsofsperm whales orrtheGalapagos-fell into thecate gory of "mixed groups", Whalesrecorded~escortinga eelr weremost probably (emales.DiCCerent(~males/immatures,wereobservedtoescortthes~ecalf,and ide ntifiedfemales/imm~tu reswere .observed withseveral differentcalv\s-. :

Luge maleswereobserved eitheras stngles,pairs or a setoft1~ree, In the observa t ions:oCidentifiedindividuals'there was no indieationth,:"tpartic~lar^pairs oflargemales, orlarge maleso(a similarsize, were preferredcompanions. No .,fresh'wounds oragon'is·tiebehaviourbetween large males was obse rved.Thelack' •

'::P:~~:~:i: ~: :;:i::=b'~b~a;:p:::i~~'o:bl:~,~b:'l:: ,:o~:~~;. ~::.~ . ,

suggesLl; that all largemalesdo not_migrateto the breedlt.g gro unds.and dO'DotJ · parti cipat ein.hreedin·g'every year.:

Id~~~ilied

^largemales wer e

obser~·ed, ~ilb

^.

dirterent mixedgroupsand,fur t her,differentlar~emetes-wereessoeleted wilb

.~"

part icular mixedgroups. There wasno indication that some mixedgroups associated more with largemales, th.·;nothers. Large malesseemedtoIollowa strateg}'ofsearching formixed groups,instead of

hold~g

^{harems. ..,}

Duringa~attac k by'killer.whal~00spermw~alesahigh degree ofcoordi6.a~ioo

•ofthesperm.whal~'behaviourwas noted. Twenty=p ne.pereent of the.sp erm whale nukes.hadtoothmark scars of.which a.majo!i~ywere'probablyderived from sbarkatta~s. A differencei~tb'e o'umberor unique marks'on the nukes between.dirrere~tgeographical.areas sJggeststhat,t he"metbpd ofindividu al photographiq identificatioD relying,?D uniquelymar ked nukes may be less s~cr~essfu l i~.otb erareaS.'

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· IthankMel Brooks,\'assili Papast.anou.Linda\....~i1gartand HalWhit('headfor th('ir

p~s

intJresearebalr and

D r,

GllnterReek,Dr.M-a.rio

Ilurta~o

and

•the

othe~

^slart,memben al. tttJslado: Citntifiu

Ch~'rle: Darw~n.

^{Also,I yo'ould}

liketo.than.k_ Captains CaloDa"i la.andMarioP.jnto ofISOCAR.and Miguel

Cirue~t~~of_'ibe G~lap'ag~

^{r\aiiol?:L1 PoarkServicesfor}

assi~tanc~

^1itbthe

~tudy

ⁱⁿ

.the Galapagos...Iespeejallyt.hankmy superviseeDr..Ha!.A\'ltitcheadforhi~

·h(>l pful'ideas end,.hisfaithin'my

'aLilit~,

^{'&$&.graduate'etudeat.1\}

appreci~lc

^the

ccinstiu:cth'ediscuSsion~~'itb:^1.Gordon(Deptarlment~f^{ZooIOQ' ,}tlnlvers'ityof Cambridge,U.K. )and Drs.J.Lieu andD.Renouf(DepartmentofrS)'~h{JI~g)'; MemorralUniversityorr\e...Ioundlandl .FI.em'i~gM~ng('1's-(Deparl nrenrorEll.rth Sciences, M.U.!\ .1apprl'c~al~d.

._

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.

also,andwishJ,Lawson' s.tot~ ank.help with Iiguresmy.exam iners,andDrs,eomp uung wereW.Monte.,'('crbi and

^.

greatly

^.

S.K~WD.a horld,\\}tdl~ll1FNenbe.rlands,Da"i dDa)' and DicierPlage Id~dly)~anedusvital equipment..Theiollowi~gcompaoiesd<?nat~,equipI!1entcr.

'<providedminimall)'priced equipmentu~ed tortbis,study;'CanonLtd,,Exp~rt _Fot~.Fjlllr t"en Ltd-n...

i

~ell):HansenLtd-.Tbe fieldrt'Se~rchwas'Iueded bI M.Clark. F.C,P.Whitehead.D..Plage,theO.EngkvistFOlJndatiOn, theqrten Island Foundat ion,the Connect icutCet4ceanSociety. andtheCenterforStudies

·or Wbalesand.ooipbins.Anal)'siswassupport~d^{by tbe O.EngkvistFoundation}

..eedMemorial

·U~i\"ersity.

^I

ap'pre~iate

^thegenerous

stud~nt

^{loans'I receivedtrom}

the Swedish.Government and t.~e'sc~:lar~hiP fromtbe--~can

·Foundation which made:_it possible (or me to ~mple~e.~stUdiesIn Newfcundlend.

..

TheSwedish

.

Ministfy of^'--' Agriculturemade^" tunds availabletorme

.to att end and presentpartsatmy study at the10S6scientificmeeting or tbe

Internationa lWbalingCommi5Si~n. I rinallI tbank Drs.F,A,AJdrichand J.Strawb~idge'^{(Scbool of.Graduat e.Studiesand}Departm~Dtof Psychology, MemoriaIU~h·.e~s~tyo,fNt'\doundla nd)fortheiri~\'aluab~esupportin the formof aburs~ry'andot b.er-tinancialassist ance duringmy studiesat MemorialUniversity ofNewfoundland.

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_{THE TAlL ./}

Th~^rompactround

boaii

of"itsrool' exprm d"inlotwobroad,firm, flat palmsorflukes,graduall yshoafil'l,g~way10leuthan an inchin thickness.At the.crotch orju nclion,'lhcscflukesslightly operlap then sidewaysre~edefrom eachotherlike.:wings;leavi nga widevacancy be/ween. Innp living thin g-are thelines of.beauty more.ex qui s it ely define d thaninIhecrescent i choarders0/the8efl1J. ~·e8.

'ThemoreJconsider thil! mighty tail,the~orl!doJdeploremy i~ a6i/jtyto ex preuit. At times tturearege8tu~esin i',which,though :,thty'would.wellgrace Ihe handofaman,remain whollyinexplicable.

In anezt en s ive- herd,80rem arkable, oecosio no tly,ar'ethes emy61ic gestures, thatIhave heard'hu nters whohave (fcC/ared them akinto Fre~:Mason~sign.a-nd sy";bols;thal thewhare,indeed, by these mefhoasintelligently conversed~jththe'world,

HERNAN IdELVILLE , 'M oby-Dick

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TABLEOF CONTENTS

''ABSTRACT'

THE TAIL'

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AC K N O WLED G EM ENT;;',

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i", TABLE OF CONT ENT S \'

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,vi

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LIST OF TABLES LIST OF FIGURES '1.INTRODUCTIO N

1.1.USE OFN\lN.Il\'T Rl:S IVE METHODS 1.2..ADOPTEDTERMINOLOGY 1.3,THE SPERM'WIi,>.LE

1.3.1.Generallire-bistor{

1.,'3.2.Sebcellng·bebnio~r

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1.3.3.Distribution_an~ediDg 1.3.4.Migration

xli.

10

14 10

13,

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,20

,16

.i 2,1.STUDYAREA

1.3.5.Caregiving

1.3. 6:

{ural·~redation

^.--

'1.4, .WHALING OFF TIlE GALAPAGOSA.''DADJACENT WATERS

2.METHODS AND M"TERIALS, . . .

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, 2.2,

sarr,

CREW ANDWAT CHES

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2.3.TRACKING SPERM WHALES

2.4.PHOTOGRAPHSFOR Il\'DIVIDUALIDEf',,'TIFI CATION'

20 '.(

21

MATCIDNG, 2

.s.

A)"ALYSIS

or

T~PHOTOGRAPHS

2.5.1.Measut~'or^nUke.ph6f~~aphs^.'J;

2.5.2. Shape~r^{thenuke notch}

·2.5.3. Dorsalfins~Ddcall uses 2.'.CATALOGUING,

IDENTIFICATIQ~._

2.6.1. Unique marks and certainty vaiue of Ilukes

26 ,

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. ^{, -~ ::}

IND~AL'

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2.6.2:Matc::hingofnukes and dorsalfinsand devt>Jopm ent.of a 28 c3,talogu e

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2.7.GROUPS 2.8.RELIABILITYTEST 2.9.IDENTIFIABILITY

2.10. SPEED OF THE WHALES 3.RES~,L'.CS ,; .

3.1.EVALUA'I'ION OrTHE ME,HOD

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37

39 39

~.

'0 3.1.1. The importance'of dirferent measurementsIoridentif ying 40

whatis.fromnuk~

(-,

3.1.2.Marksusefulfor individual idEmtificatioB

3.2. ir-.~rvIDJ~:~EN:rIFI~A;I~N ^{-- .}

3.2.1. Identified-nukes 3.2.2.Id!!ntifiabili~yofnukes

"

3.2.3.'I~eDtifi~dorsalfins

vii

46 46

,.

'8

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

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3.3 .RE-IDE;1\7IFICK~~IO~5: 3.3.1.Flukes 3.3.2.Dorsalfins

3.3.3.Matchingnukes and dorsalfins 3.•.CHANGESOF MARKS

~~S.

^PRESENCLOFCAlLU SES

• r-'.~

~. .3.6.G/t0'<PS

3.6.1;Numb: rorgroupsand individu als 3.f:.\.2. Differencesi~ m~rksand notchesbetween gro ups

;;.6.3.Calces,escqr~,andfollowers 3.7.

I~TERACTIONS

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3.7.1.

Belwee~ ~{~ups 5~

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.~7.2.Betwe~.I'l.grou psand,males'. 55

3.8.PREDATION 50

3:8.1.Akiller whalea.ua ck 61

3.9.MOVEMEf\'TS ANDSP EED 62

••D1SCUSSrON 6.

4.1~.EVALUATI0!'J ^{OF' THE} METHOD USING 1l\1)fVII)ti AL 65

PHQTO GRAPIUCIDENTIFI CATION

'.2.MOVEMENTS.DMNG.SITE-FIDELITY ANDSP~ED

4.2.1.Movement s ~

4.2.2.Diving

J

11.

4.2.3:Site-fideli"

4.2.4 .Speed

./

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? ^v~

"~:~i".~.

68 68.

, 68

~g 70

4.3.1.Fem ales andimmaturemales

-4.3.3.Males .4.3.2.Galves andescorts

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4,3.SOCIALOkGA1\~ZATION

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73

~5' 7.

78 7.

81 82' 84

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4.5,CONCLUSIONS

•.•.SUMMARY LITERATURECIT ED APPENDIXI

.4.3.4.PrOp<lrti~D.')! luge

males

tomaturefemales 4.3 .5.Associ~ti':lDS~et.weellI~emalesandmixed'gro ups

~4 .4.CARE-GMNG.ANnPREJ)ATlON

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C".

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List of Tables

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.T a b le2-1:' DeS~riQl i~n (,f phctcgeapb

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\ quality measurements

(XI.X'). ..

+ .. '

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'Table ,z..~: pescriptio~

^of.tbe'

u:iqu';"~Ii.~ks

^onnukesahi dorsal fins use~d

--..

for individualj~enliri("atioliorsperm whales. .. : 31

. D · .

':Cable2-3: Thetwo-analysersmeans~a reliabilitytest~rthe'

.: ' . , ) . f

phol o;qualit yffie~l!re.sandcertai.nt ~·values. .38 Table'3-1: Certa~nty \'al~es ao'd the differen t measu rements for '&

id~ntifiability, ~hcir mean, median" znnimum and 41

cer taintyvalues.

maximum values..,...

Number of nuke'photographs and their W\"tiryingi .:», 47

,~

.

Table a-i2:

Table3-3: Number of whales withcertainident ification and-number

~ ofdays~beseindividualswer;identi~edusing pbetograpbs

_

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^{" .}

. ^.

rable3-4:

of nukes.

Der ived groupingsofwhales,'number or animalsidentified a:d estimate lwithin each group,the numberof dayson which

gr~U'RiDg

^was

identiri~d ,

^the'timespa n' between,its

, .

.

.... ' -

f~rst."aDdIhStldenu t teeuo n,a~dassoc,i.ationswith,other

... ~~ '_.__ ,

:,..

_.:.

.. : ..

.\

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^,

groups.

Table 3·6: Summary ofattri~ulesof groups.

/

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...

.2 .4

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Table3·6: Idcntiriedlargemaies and theirestimated lengthand

~ge

[From'\\"~itehead a~dAmborn.in press),daysiden tffied, span ofdaysideDti~ed,and associationswithotherlarge

males an? mixed groups. 56

Table3-7: Types.and.mean~umbet^ornatu~almerkson,the

n ur

^{of •}

indiyidu!,.1spe..m-whale. . 60

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List ofFigures

FigureI-I: Photograph of breaching" sperm whale, Ph ytlcl er 'macrocephalus.

Figure1-2: Diagram of m;grati~Ds ^tilspermwh~Jc.g~ol.ipln.gll ⁱⁿ

.

.

relati on 1,0 la tit ude andmont hof theyear ,sout hern

hemisp here(irom Best,1fliQr Figure,2- 1: Mapofthe~ala~'agos.Isfand:;.

thel~OOmdepth-contoue.

\

Adashe dline.lndicnt es .16

.1,

,.J? Flg!Jre.2-2:-,Movements oftberese~rchvesselwhiletrack ingsperm. ' \ whales offthe Galapagos. A dashed line indicates the

1000mdepthcontour.

F.lgure2:'3: Photogr;phs'o( nukesotsperm'\lo:balesoUtbeGa lapagos:

18

Al with op en and B) with efos~d^nuke

notch, , : .

Photographs' of'dOl'5alfinsofsperm whales-orrthe

Galap~gos:

^Al

r:;;I~/~matu re ~itb

^acallus;

~)'Iar~~

.22

/

-rnale'wit hout acallu~. . 24

~igure2-6; ~h:tograp~s~~owingdirrerentunique rperks on nukeso~_

spermwhaleso~rthe Galap agos. 20.

Figur e 2- 6: Photo graphs'of matching n~lces or an indlviduelly .identified sperm.wbale:,AI identified~n24February,B)

~n^23March,~DdQjen11April, IOS5,

xii ~

33

Flgul'~

't.

2-7: Photogr aph s ofmatchingdorsal~iDSofaD iDd~viduall}'

ider:r.alfi~dsperm"-bale; A)iden tifiedOD21Marth,&.lid B)on31 Mereb.J\)85.•.... ... ....

Figure3-1: Mea.arocu~andexposure•.measured fromphotogr aphs of 35

.

.

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spermwhalenUk.es,plcued againstcer taintyvalees., ,42

Figure3-2: Mean percenta ge ofthe Degatin(,o~'ered bythenuke plottedagainst c:erlairrtr valu es.

-F IS':Jre3~31 M;an devia tion of'orientati oD andtiltof thenukesfrom

being'perpendicularto thecameraaxis.plotted against

certaint),values.

Figu re3-4 : MU D percent age ofnukesvisibleabove waters~rra('e agai nstcertai nt)' \'alue s.

Figure,3. 6: DaysODwhichmixed,tOUps(GI. 13)IDdlargema~s

wereideotifi~. ....Each.iden tificat io nof the males'is..

repr esentedbytbeI~t^{digit of}~heide.nt ifica.uoncode....

42

44

44

l~.g.503= -a-j :... 57

Figure3·6: Posil~n~ ~D,wbichmixedgroups~.~~preseDted

b y

uneneled. / - numbers, and large ~.ales,.represen~ed by c~re1ed I.

.

\

numbers,wereIirst identified00·eae b'day. Eachrirs~

.. • ~• 4 ' .

id en tirical.ion isrepresente d bythe l~t digit of the

.

id~ntification' ('ode(e.~. G3= -3-, ·G10~"10· ~or grOU;~;

506=-6"and'S03=-3~for.tbemales~ A dashedHue indicates .the1,000rn dept hc~n tour. IM~ifiedfrom' Whiteheatl.

~nd

Ara bom, in press).

kill

63

~

Ch a pte r 1 Jl.'

INT RO DUC TION)

'During the.Iasttwo

('eDturi~

^{more-than i.300,OOOsperm}

-whal~

^{ban "'('(' n.o' "\}

:('au~ht

^{bywbalersaroundtheworld.'Despite}

tbi~_large

^eeteb.our

"n~~·i:dg(' ^{o r' . .. . ].. . ..}

sperm wbaie Liology isst ili

.iD('om~let1!

-IS;st,Canhamao'd'Maci rod,

H~841.

:.

[}grrlpllonsofthesocialbe ba\lour'ofthe'sperm~'hal('"^are ~Jmost^I'Xrlu!l.l\c1}•

airt'cdotal(e:g',Caldwell,Cald welland Rice,10.661.' .Despltef(>('entimprovements in"our"know ledge ofsperm whalesocial crgan iratic n.it•.shouldbestressed't! lnt

~("a rl~'

^{all the}

obs~rntion

^{madeSffarhavebeen}

ba.~('d

on'c xtlminat ionof

,,:,·'hol~

s('~ools^orwliales(or membersfromtbeinl'atonemoment01Iiml'(no rmall}'afLN dlJalbl.andsurbs)"nopticobservationsprovideveryli~lleinformationoninter- andjntras ehocl relationship s (Best,

li il).

Sperm whale soeial'behafiour is of special

i Dle~est

^tbtbe

m~mbers

^{ct t heScientilieCommiuc:I'ofthei}nlt'r'na(ional Wh aling Com missionIIWC)bec~useof itsimplica ti on s for maOlge-'rnt'1l1 of.the' species (Gordon;10 SSl,Twoissuesareofs~iaJecneeeefor managt'mc;nt:the' ,

na~u.re.of

^the

i~leractioDs

^{bet WefD}

g~oups

^orfemale

s~erm

^{whalesaD'dIUle}ma les;".

and wbethe remed ium-sized-males.take par l"'jD breeding (IWC,Igsa).

This thesis presents informa tiQn'onthe~cial'organization andb~b~.f~\l'-^of

.sp ermwb.aleSusiDgthemet hod of indjvidua]pbolographir ide nt.ification.Spt'r~

whaleswe,re track edr'romasrp~1I^{vessel,in'thewaters,we stof the}ClI.lapag~

,Islands

in

earl)'lOSS, The study provided a uniqueopporumh y to,com p art' ,sysl em ali~ observat ions of live ."animals wilh anecdotal d~~cri ptions ll~d ccne lusicns basedo~ wbll.ling,d~l8.,Photogr apbs of f1ukuand dorsaltinsmadeit

'possible toidentifyindividu~1^{sperm_whales.}Tbese,indi\'idualidenti ricalio~s^were

use dtoinvestigateassociation s and interl cti oDS between indiVidual,and groupsof spermwh ales.

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1.1.USE

O~ NON,INTltUsivE'~ETHODS

Duringthe

p~t

^{20 year;increasing}

llllmb"~;s

^ofstu d iesofrree.'lh'ing·v,'haleshave usedthetec bolqueof

,iDd!~jdU&1

photographic iden t ification usingnatural

~atks .

and'~cars. ^This ~e.ebDj~ue^bas "·{de~ed.^ouriDo}\'le~ge ^{'or the}migra.tio ns, pop ulationbiology-ao'dsocia l'bchavi~ur ~r^{seve;,,]ce tacean}popuJation~includ ing

·killer wbaies(Bigg,,·l g8.2);humpback~haiesMegapter a nOl,la ea ngliae (Katona and Wbitehead;

'i9 S 1 ;

Whitebe ad •.igS2; Darling and Jurasz,rgS3);minkewhales

B~ipen.~p~era ::~U~O~o8trat~

^(Dorsey,

19~);

^right

wbal~s Eu~aiaen:

^"(J usl ra.lis

:(P8Y~~Brazier,Dorsey,Perkins,Rownk~and Titus,1083 ); andblue whal es

BalaenoptcramU8culu, (S,a rs;lOS4}.Until recentl y,theem phasisCorthis work

·hadbee~^{on'species,whichspend}a~^least,some'6r, th.eirti~e^{dose'toshore.} T~e

sp e rm whal e . which generally inha b its deepwater,hadatt ractedverylittl enon- 'in t'rusi\'llresearch . untilthewcrfd Wildlife FundTulipPro j ectbega n in 1982, Thi~^thesis de\'el~psand te st the.r~liahm~y^ofnuk e pbotogr aplls.asa mean..o!

ind h·jdualidenti.l'ication of spersn.~h~l.es".

1.2.ADOPTED TERMINOL O GY

Therollo:wing ter mshav e'~een"edopted inthis thes,is{exeeptwhere dir ect eerere see ismadetothefindings or other aut hon): ,\

"~·ggr.egatiOn",^{A set}ofsev e ral groups,'-

•Association".Me~befSf~irrereu'hlVoUPS ~ereidentifie dwith in 120 minor ODe another, Ofthe 120 min, 110 mincorresp on dtotwicethemodedive' cycle [ie.divepe\iodplus timespent' ,a t .s urCa<:e betweendives;Whiteh ea d, lQ86e )and tbe remaining 10 min areallowedfor the vesselto'comewit hin

rangerof'id~ tification.

# .

·

. .

-c er-.

^A

wh~e

^less'than6.1

~ i~

lengtband'one Jjear01age (Bestet11.1..,108 4 ),

"Cluster·. A termCor eithera'single whaleor a "set·orwhales swimmingina

• coord in ated manner,ee cb!~than-1~^{m from}itsnear e stneig h bour within

~hecluster. ' , . , /'

·E ncounter.,A 5 minobser va tion period,

I

i

i I

~.;-.~

-Escort-. Awhalesytimmi~glesstplll1.5m lrom ataU. ~.whalewas 0111,,· 1scoredasanescortiC~onfirme(t^Cromaphotograph.

-Femele'",A matu refemale..

-Female/immatu re-.Awhale

kJ:

^{whic·bitisnot}kuc....e whetheritisamature

femaleoraimmatur e ofei~ber~tX. . • .

-Follower -.Awhale identi fied within tb·esameeacounterand duste rasa~.U.

wit bamaximumdustersizeoC-.3iexcludiDgcalveS).

~ .' , " . '

-G roup-. A set dCwhaleswhichispresum~tobeclosedoverperiodsofweeks.

.\'I~mat~re-.^{Eitherafemaleor male}imma t ure.

-Large,male".Malemcre'tb an13.7m~ong.presumedmature(Best.10' 9)..

-Lo b-tail-. Flukesliftedabevethe surface,end brought dowDnatontothe serraee,oft en witb'greafpower(White head,1985),

•Mixedgroup-. Nur, eryendharem schools are groupsoffem~leswiththeir you ngend alargemale present.(harem )~rnotpresent 'nu raery). Jwill follow Best(IU791aDd reCer tc theseasmixedgroups.

-NoD-int r usive-. Not purposely killing, inj uringordisturbingwhales.

•Set·

~

^g"er

~ te,,~

10;• hales ob.med

~"h"

^{. -/}

-Slde-nu ke-. Thewbaleswims00 ItsSideand onlyapartoCthenUk/eISabove

thesurface / . •

1.3.THESP E RM WHALE

The spermwhale(:Phy,et ermacrocephalu"unnae!',1758) belongs the order

•

CetlU:eL Twotaxo Domicn&m~,P. catodonand.P.macrocephalu" wllicb both rere rtcth esperm whale, occur'in.tbe.litera~ure,onthespeeies~.I general,P.

macrocephalu,wasmostwidelyusedbefore theearly20theetury,andP, calodon~8S'favoured therea·Clerfor some 60yea~s^untilabo~t^{10 ea rsago when} ,P.macrocephalu, wasgene~~lyreins tate d(HusSonand Holtbuis ~974;Schevill,

IUS6).

\, The spe rm whale'(Figure H), the.largest cdcuiceete,

l

^moresexually

"~:., ^,'';

' ,.

^...~.~

dimorp hicthana(;y other cetacean species (Best,Ig79).M.ili~reacha lengthof 18',m(Clarke,Aguayoand Paliza, Ig68) andfemales

12~'3

^{m (Clarke,1956).}

~ales

may wclgh upto 60 tons 'lid

f~males

^{upto15Io ns}

(Lod~yer,

^{19 S.i i.Sperm}

wh ales.throu ghouttheworld aresimilarin theirexternalcharacterist ics(Best and Ga.mbell, "ig68;Clarke etel., UI68). The skinis"more wrink ledthaI:! thatof any o(.h~whale species andthe colourvaries fromadi..r kbluish~eyto iron~ (Matthews, 10.38;Clarke,1956),Thisvaria.t ionmay depend on thegeographic loc at ionwherethe whales'were caughtby whalers , butmay also arisefr om differenc~in environmentalconditions withinan area"(Bestand Gambell,)g68):

1.3.1.GeneraI Ure-:.hlatot')'"o

. Inan unexploited'popula:ti onfem ale sperm whalesreachsexual maturity at

appraxi~atelY

^{0 yearsat ageanda}"lengthor8.5-9,5m (Ohsumi, 106S; Best, 197 4).Th e'gesta.tionperiodis14-16 monthscestimated from mating andc~lving per iods(Matthews,~938;Ohsumi, Hl6S;Bes t, 1968;Gambe ll,IQ72),and 18.0 months(.\I:hcnestima.tedfrom neonataland ad ultbra inw~ight (B~tetal.,_~084),

At birth the calves are approxim ately4.0mlong [Clerkeet al.1068;Best et al.

19S 4)-aod aiier a year the calveshave~wnto 6.1m (Be'stet at,1984).There is nodirrerenceinlengt hbetw~enl~e^{sexes at}thi~^{'age(phsum i,}1065 ; Bestetel., 198 4).

Thelacta.tion perio d is normll.lly24-25 mo nths"(Ohsu mi,Ig6~;Best,1074) and lactatingcalveswilleat solid food"before'~De^year'~Lage (B~t^{etaI.,108 4).'}

,T here ;; one

re~Oi'd

^ora m:J& h&vin gmilkinits

st.om~ch

^at

a~

^{age of}13 year1 "

(Best et a!.,1084). Females.old er than 20 yearshave a morep~~loDgedlactation per iod th,!-nyoun"gerreinales (Best et.al.,1084) . '

'the restin gperiodbetween lactati on andconceptio nisusuall y 8-10mo~thslo ng tl}est,10;4) althouth itmay bepr~longed^{up to 5'}years (G a mbell,H1721_The calvin ginte rvalisevery5--6years"''whichisoneof thelow e stbirthrates'(6 % ) cbeervedinm~ritaIS(Best,^{1079)0' OIrsumi}(I065)" c'().nclude d~h&t remal~^are tom monly'reproduct ively active fot 15-20 'years whichagrees wit h Best eta!.

(l U84) who stated thatfemales~ve^{birth to4calves intbeirl ifetime.}

I. ·

\

•

Pjgur-e1·1= Pbotogr ap b of breaching"sperm whal e, PhY8etermacrocephalu8

'<'. J ..

'"hIesrea~bpubttrtyat anag~or0-10 r~&l'S.aed •lengthof ,.1»u1.9,S~ (N ishiwaki, Ohsu mi,and; Mu d&,J~~;Ber:r:il1.19i1;Best,1074). Qnly2.5 % of .males10.7-11.6mlong&Ad 1&16 years ofage are mature, 14% ofthose12.2-13.1

. .

~ loD~'and1~29...Ie~!S_~g~are mature,while75%ofthemaleslargerthaD 13.7

m

aremature'(~l,Ig; OI.•

ADinne<:tio,!poiDt~D^themalep'o~bcurve occursatabOut}0-20y.e~r~^{ofage" ..} (Best,1070; GaskinaDd Cewtbcm,Ul13)whkbisaboutthetime whenmales are

~B.turi~g

(Ohsumi, i066;.

C ul do

anal

C~wthorn .

^{Iv,03;Bes't,1070). Arou nda}

lengthof.14mhe avy.l caf shaVE;beenobser vedODthebeadsofmalesIrdmfights withotb er males(}(,Ate;1084). Best(i~7g1 di~ides'tbemal~intothree s;;e classes;smallbachelorsJI 0.7-11.0ml,'medium-sized bachelors(1"2.0.~7m]and larg ebacbel~(lar ger than,13.7m). . . '\}.,

1.3.2,Schoolingbeh&vlour

The spermwhalemayhave amarecomplexschoolstrui:ture..hanabYother largewh~Je(Mitchell,'19;7). Ohsumi(1971) proposedaror~^{of'matr iarcbal} org anizat ion.•Theeighteentbandn1n~teenth ce~turyopen-be atwhalers.were aware.tha t~edirterentk~Ddsofspermwhale sehcels segregated~ysexa.ndage [e.g.Beale,1839).' Clarke(1056 )noted thatmaleswere'eithersolitary or in schoolswhilefem ales_. were

,

invariably gregarious. Males,within.• schooltendto- occupya restrieted,bera nge with adifferenceor1.8m or less inlenlth bet....een .tbesmalles t andlar,estwbales (Best,

1079~

^He·abofound

ages~ .()';9.8

^years

range)to he~orevaria blethan.Iengtb witbinthe sebcol,whichsuggeststbat malegroups ereactually more~mogenousby size than byage(Best,1979 ).

Frommodemw.bali~gdat aan~observetloeeatsea,spe rm whale schools beve beendividedinto_dirr~rentdiscreteschooltypesdependin gon size.andlex:_m~ed~

(baremandnurs ery), juvenile,small bach elor, medium-sizedand larg eadult bacheior schools·(Oaskin,1070; Ohsum i,H171;Bet,1070). Howeve r,th,s€'"

proposals erenot welldoc~mented^withwellst~died^{group ,}or known ind iv id uals,

Mixedgro up e .

Tbemixed grou p..ppe ar'tobe adiscrete acboelwhenligbte d(Best, 1070).

.

•Caldwell.et aJ:

~d

^tight

sch~liDg

^behaviour

~t

^{individualmixed}

gr~IJPS

to be quitechll.tac~eristie. ^{The meanDumber ofwhales}

t:

t.be.mixed- group has been given as 28 (Best,Ig7gl,27.1 (O bsumi,lQ71)or 21.7-22.0(Gambell,1972).

The proportion01 remales within the mixed groupis"estin:'atedto be 0.78(Bes t, 197 9 );the

rest

^are~Ie^immaturesan, c~ves^..The proportionofmaturererhale~;

tototalIemales'Inthe mixed groups

i\

about0.75.Within a mixed groupat any. time, females'werefoundin allstages of

reproducti~D:

_. pregnant, lact a t ing_.

add

_I

resting (Best.•1070). Thereareseveral aecoimtsof long-term'relat ionships', between i('{Jld es.

On

Iour dirrerentOCC8$.iODS,_h'l'0 females weremar kedby:' Jap a neseres earchersand lat er.f~liapturedtogether altertimesp'~ns,'of^{5, 8,"10} andlO,yea rs , respectively(Ohsumi, 1071 ). ~

Ju'venllegroup s

,Best (107g)

ca~ulated

^theproportion of juvenilefemales andmalesobservedin mixedgroupsa~~DclUdedthatala r gepercentage of the juvenilefemalesend"

.males intbe populationwere not presentinthem~e4groups,andtherefore it seemedlik~IYthat both sexes mayform juvenile.groups..Therenil.few eetcb data fromthese groups due torestr ict ions on clj.tching whales lessthan10.6m long. ~~

•Sm al ibeehelcrgrou pe

The s!J1all'bachelor.groups contain 100:50animals'(Best ,1( 70). Malesare ' normal~y1O.7~U.''Dmlong. ¥ates seemtoleavethe mixed groups to formsmall .becbelcrgr~ups,att. 1~.7m10ngand at an age'ot15years butthey may departas

eerty.ee4-5:y~rsatage (Best,1970).

Medlum-stzedbach elorgroops

The norm al Dum ber of whales in a medium-sizedbachelorgroup is3-15 individuals"(C ask,in.1070;Best,1010) . Tbem~dium-sizedmalesorjginate fro m smill'hache ior

~oups.

^Thelength

~r

^the

mal~

in these groups

~

^{.betwe en}

12.~13.7m(Best, 1010j.

Large bache; lorgroups

L";ge bacb elorgroup s contain1-5members(Best.1070).These'meleeereIDQre than 13.7m'longend are'presumedto he

bree"d~D~tnales

^who

j~in tb~

^mixed

/:

/

:.'::~,

schools during the breeding season_(Be~let al.,Ig84), althoughRlce(inCaldwell etal.,1Q66)suggeste d.th a tsmall bacbelors whichare rou n dyear'a round iD the

~ same

area as-.:m1:ited gTOUpScould- alsobreed.

Howe,'~r,

^Best_(197g) Doted th a tthe lowsp.ermato~ensityⁱⁿthe semen Iluidofsmallbache lorsindic a testhat it is unlik ely small bach elors'areeetivebreeders .

1.3,3.Distributionand feeding '.

The sper mwhalehasthe mostwidespr ea d-di stribution ofall tbe cetaceans' (Tormcscv; 1077J. Itisfo undfro~'the^tropics't~^thepol ar regi onsinall'~he oceansaOud

is~o:st

^{abund an tin}productiv ewetere ,such

~where 'curre~t~;

^meet.-

(Benner,1840),.. Accordin g to -Townse"nd (lg35) the.dist ribution ofthe'sperm whale isde termin ed bytw o major factors':-foodand reprod uctiveneeds. Spe rm .wha les feed mainlyoameso- an·dbathypel~giccephalopods(Best,IQ70\ bu t also•

onfish (M a tthews,'1038). AJiell ob jectssuc has stones,cocoeuts-arrdglass-b uoys, ha v e alsobeen·f~u.odinstomachs[Nem o to and Nasu, }QBaI, Clarke (1080)' showedthal'the sizeo!asperm whale '!Vascorrelated withsize ofit sceph al~pod prey , Stomachs fromlarge malescontainedlarge rcepha lo podst)l~nthosefrom sm a ller females'(Cl arke, }OSO). Tbis maybea.ttribu ~dtodifferentdiving abilities,efficiellcy.of cat ch ingcep halopods ,spatial distritluti on of the whales,'ora combinatio n01these factors(Best,1070). Earlywhalerswere~eli a~are^o(tb;

,divi ng abili tr or spe rm whales(ee.Beale,1830;B~nnet;18 40).Harpoonedlarge mal es some t imes hauled out},500 m lineica presume d'reru e aldlve;while

femal~ an~ sma~ler ? ies

^hauled

~ut

^{les slice}

(Be~~, 1~0).

^Heezee()g51)

rh~~OllSten accoun tsoCspermwha les founden t a ngledi~deep~eaca~le~ ,the deepest ob se rvatio n being

1,I16m :

Mixed endsmall bachelorgroupshavegenetally'beenfoun~betw e en50"'.Nand 40·8,especlsfly intheJropie elan dsubtro pical wat ers(Figure1-2)."lbe reere- several

re~o~d!

of fernal; spe rm whales

~hich-were

^markedand the n recaptured

i~

, tbesamear~awit hin thetime-span'ofOD~^orseve ralyears (Best.l07gJ~ ^Tbis ,indicates.t h a.ttheymay use.thesamemigrationroutes in

aucce8Siv~·tu.r8·

^(Best,.

._._. .lQ7 gj, Benin (IQ7'IJepecu lated thatfemalesmay~sethe samewlnterillggroun~~

I.' , '

','

10 butduri pgthe~ummera wider ~re~ma)0>e visited. Gordon (lIJOO) pr-esented datafro~Sri,L ankawhiebsho wedtha.t,~~esaJ!le indiv idually identi.fied mixed groupwesre-id enunedwithinalfewkrnfromthe loeat ioninwhich it hadbeen observed ayear earlie r . Smallbachelo rand juvenile groups bsvea.similar

distribuli~n ~. m~ed

^groups.

T~e m~di~-::n-sited

^bachelorSare

~bserved

^inwaters.

"fromtbetropics toletitu desof4~50· . Thelargebachelors are fo undin tropical 'a nd pola rregions:

,move~ellts

into';he colderwaters arepr obably mostly.seasonal.

1.3.4.Migr&tlo~

, '

Wh1iiu g 4at$ sh~.... a'\geneJ:al migr~tionof ~ixed groups towards' bigber' latitudes

dU~ing

summer. [Tcwas end,

}Q.35 t

Sma ller

bac~r.

and juveniiegroup's erebelie ved,to bav~similar migrations to the mixed gr.oups. M~ium-sjted bacbelor.senter tbepola r region in smallnU~b ersduri ngthe summer. Ofthe la rge bec belore,7-5-00% arefoun d in thepolar regions'during thesumme~and ,10-25% arefou n d in lower latit udeS(Ohs umi,Ig 66;Best,1074). Several large milesare know nto'han It1igrat~d'fro~lb~ ^{aortbernto sou}thern Atlantic lIvashin,19S1)•.Theremay alsobe'migra tion'inanwest~east dir ection.Amale was ma r kedart Newfou~d)and and Mcaptur e d eight yearsla ter off Spain {Mitchell, '1075).:Ther e

ar~

^{differentmi gration}

pattern~'

^{h.t be}northern and soetjernhemispheres,duetothe seasonal differen ce ofsix months. ...

,1._S.&.Care glvlD!--

Firstve e rcalveshave'poordivin g ahili ty(Bestel aI., IgS4).Thecalf, at the s~tt~ce,eeenatotollow theadults'«t dep t h(Bestet al., HI84jGo r don, 198 6 ) ead

c~)ves

^are'enen

rejoiDed'.~y adults sUrfaci~g'

^c101eto-the(lGordoD, 1086).

Cordon{1986).found thatcalves,associa ted'c)etse ly withseveral ditrerent adults withina grou~and,that,acmeadults associa tedwit~·more.than onee etl, Calves

J8SS9c1at';,dwit~adllltfem alesaswelleaimmaturemales[Gordon,IDS6).

CiIdwe U ead Caldwe ll'a.,(19 66),revie w of,in formation on the,eplmeletle

". behaviour orspe r m whales show thatdescription sby ninet eenthcenturywhalers

."._an·d more

r~cent ob~erv&tio'ns

of--bIO(gis u are rem;k.-biy simil a r. Th'ereare 'i

'::-;i

.~

.. .

.-

...

, .

< .

Figure1- 2: Diagramofmigrations,ofspermwbelegroupings in relationtolatitude,andmonth.ortheyu.~~

. soutbern~emispb el'lethom Besl,19791, .

,

^.

.L

.---

.-~

'" ':'-;i ' .,',

.. ... ..

•

12

-r-

M9NTH LAtiTUDE

---,---'-- 0 ·' - : . - - - -

MONTH

'V VII

V,

X/HI XII-II

"' _; , ..

-r:

"

,,

~ I

,

I

,

,

^'

• ME9·&

I LARGE

.4MALES

,

I

,

,I

, ,

.

I

/'

MED.MAlES MIXEDGROl.iPs .-&SIi!AlL MALES

<.

,~-:"''''''' _._--- - ---'- -,

"

, !\

: ,

, :

+ , , ,

"

:\

VII

VIU

'x

x,

XIHI XII-II

/'

LARGE MALES ^"

13

Dum_crousaccountsof females st.aDdingby otherInju red femal es and calves.No observations exist

or

eith er mat ur e or immatur e males.helping othersperm 'whales. j{isbiwaki (lg62)observed.20-30..spermwhales surroundingII.large harpoonedwhale~ypoinl1og/beir b; ads towardsthelarge whale and'tk~a..~hin g.

theirflukes 60 tbeoutski~ Best etal.(lQS4) -deecn be killerwhales(OrCiJlU8 orca)attacking

s~ales

when severalcalves, werepresent. Thecalves

w~re

s~rro~.~ded^bylarger spermwhaleswho appeared to protecttb~^{caU Irc m}.~·e kille rwhales.

.c An.·:ex~m~le'o~

^"tbetight

~bond betwe~n ~pecific members~f. mix~d

^groupsoccu[5

when theystra nd"onshore(Robso nand van Bree, Ig71;StephnSOD ,Hlia;Mate,_

19S5).'Robson'andvan.Bree(lQ;i )_.

d~sci'ibed

sper m ....'hales·_I

stran~iing

^in'small..

subgroupsonealter_t~eotberin New Zealand..

'.

}'.3.6.N&tu r a.1pred~tton

Bulle n(1~99)'describes an attickcit two killer whetee and a swordfish(Xiphi.U8_ gladius)on'a larg~malesper mwhale . A reviewby Perk.i.nsan.dWhitehead (IQ83)crecccuete of-swordfishand}bresbersbarks a.ttllckingwhalessuggested tbatthe story; may oftennotbeliter ally true,even thoughsw~rd(jshswords have

. ' .

~

.

beenfoun~in whales:[Jonsgerd , HJ63). None oft,besewliiles.,wereseno usly injure d b)'theswords, This may beduetoth efact that ....:bal~which have been: lethally injuredare notfound.'

Exa~mftioD or.~iUer

^whaie

stomac~

^contentslias

'revealed remnantsofsperm wha les(Yukhov,vincgredoveand Medvedev,_lQ?51~

Amovie ",as appa rently,made byRusslee whalersshowing''6killer whaleattack ' on spermwhalefe~~les^{andcelves(Yukbcvetel.,1975), However,}there is no descript ionor the attack itself",B~tet al-l(1084)exa-mined.stran de dand net- entangled'spermwh~lecalves alon gthe SoutbAfr icancOjLSt and round-that .sev era lof

th~

^{calveshad severe}

IDjU~ies

^'due

~ ki1lc~

^whales.Sperm

~Dales i~ken

byRussianwhalers'had toothmarkscars (rom killerwbeles,andthese mllrks were most'.(requentlyroun d en.'pectoral and ell-ud al'fins {Sbevchenk o,'1(76).

Remain~:ot sper~

"':ha les inkillerwhale etomaebs were'more Qft en

' r?un~ i~

~ropicalandsubt ropical~aters(Yukhov etel.,Ig75) . Duringan'atiac~observed

•

,4-

offSouth AI.rica,killer whales wer eseenswimmingaround

a

sperm whale school (Bestet at,IgS4). Sharks havebeennot edtofollowschoolsofspermwhales

(Gambell,IQ68;Best etal.,lQS4). " ( .

1.4.WHALING OFF THE GALAPAGOS'AND ADJACENT'

WATERS' )

Captai n Coinedwho visited the Galap-agosIsland sin'17ga,mentionedthe.vast numberofsperm whalesand thepotentia).for~upporting^"future sperm.whale fisheries(Colnett ,17gS). Other ,,¥haling'literature.alsocitesthe Galapagosas a spe rm whale

g~Ound' ~ e.g,-

^Beale,

183.~;

^{Beace t,}

~8.40;

^{Melvilie,1851).'Astudyor"}

j

.oi'nefee~ thcentu.afY,l~gbooksf':9.ni.t~e.~pen.~oatwh alingw~torr-t il.e Cala,paglls Islands , bowed8steady,decline'inthe averageweigh tofth~halescaught end the Dumber01whales observed, which'was att ri but ed to'whaling'pressure .(Shu st er,'IQS31.No.repor ted whal ing has beencond u ctedduri ng the ias tcen tury' oC(theGalapag~s^{Islan ds.However, an}iDt~nse^fisheryforsper m whaleshas been going onCorsevera l de!ades art the west coast·oCSout b America (C la rke,Agu.&yo , 'an d,Paliza,IOSG). JtisDotknownirthe sperm whal es'ortGalapag osbelongto theuortbem,or·souther~hemispher e stockorwhether

!t

isasepara t estockl Rice, l~;5). Therelse vt decee·that tbe stock exploitedo'rrPeru hasdiminishedsince

H~·59.;I,

_,

~nd

_.'it has been_I ;hown thatthe-prcportioa_.

o r

males_.

or

breeding_I

statu~

ⁱⁿ

.t~ecatchhasdeclin ed fro m 36%InlO?G-61 teabout 11% in !07S-77 {Cla"r}.;e et al.,1080). 11.was alsoconcluded tha,tihe declinp in pregnancyrateo.!. whales killed orrPeru,betweenIOSO·(H and1075·17 ,was due toInsufficientlargl,! males (Clarke etal.,lOgO).

-:J.;

. .

^,

Chapter 2

METHODS AND MATERIALS

2.1.STUDY AREA

. ,

..Using',asmallsloop,a,total-,of jl6,hwerespentin\'i$u~foracousticcon.l.a~t wit haggrt !\:ationsof spermwh alesintoe waters west ofthe Gal apagos1!;land$.

(1:oo's;01" 00'W 1betw ee n

~?ruary

^{·23•;April}

20-nI8~. T~i~

^{isthciughtto-be.}

the height ofthe bre edingseasonfor Nort hPacificspermwhal es('Oh$umi,tll,OS;

Bemn,Ill; l ) and thetim~·orthe year that theweathersho uldbepredict ably calm

~u\:~naghel,

^lQ78).The

la~ter.

^{was a}

m~jor

conside ra t ionin tbe choice of thestu d)' area, andtime.orrtheGa~apa~os,large malesperm whalesaodg~oups of (ema.les,bad beenobserve d [Coln ett.1708; Clarke,1962; Schuste r,lQ83). The Galapa,goslsland swer~)a [50 consideredtobe ealvinggrou~d's.(Oclneu,17g~;

Melville,185"}. . ). . '. . '._

The Galapagos'are volea nlcisla nds tbat rise froma sealloor 2,000 • 3;500m deep And that are.situated ontheEquator965km west 9f mainland Ecuador (FigUre'2-1),"T hehighestvoleen crises1,677m above sea .Ievel..West ofth~

islands the shelfbreak is very steep, fallingfromthecoas t to1,500m dept hwithin Ikm from land. The study wasconducted1'-175km west andsouth~es~^of Isab elaIsland, c:r2';',S;91'05'W(Figure2⁰2).',West/ofJsabel'a,theEquat orial Undercurrent ,ajsuhsurfa ce

east~a.rd,nowin~

current . hitstheshelfbreak,Thusa cold water;,upwrtPngisusually present westof'Isabela Island 1Houv enaghel,1978).

'T he study was divided into fpur periods in 198';:21-28.February , 5-1,6 March,20' I,

March0"3 April, and 8-23April. Between:,periodst~boal was re-supplied at PuertoA~:oraon Sa:ntaernIsland {Figur e 2⁰1}.

\

;":'-'

.. ....

\

·','"

. .

Figure2-1: ,Map or the Galapagos Islands.

/'>.dashe~lineindicat esthe_lOOOm depthconto ur.

_ .-

^";

~_.

I

17

.! -

orfw

Figure2-2: Movements

or

theresearchvessel while tra cking spermw halesorrtheGalapagos.

A dashed line indicatesthe 1000 m

• . _depth contour.

, (

---~\...-.

. ,tw

.

,"",.

• •

20

2.2.sHIP, CREW AND WATCHES

Theuudy

was

c~rriedout trom~be10 m speciallyequippedsloop,theElendi l, 'orthe'Gledleteurclass. The"1matwas manned with a cre worrivewho paruleipated as scientists and sailors. Elendil.issuffioient lzsmallto be.

man oeuvrableandflexible enoughtotracksperm whales,yet larg e enoughto ,prov idea

rel~th'ely

stable platformfrom'whi ch to'wc rk,'Enginenoisemadethe sper mwhalesaware of the boat,but"itdidnotseem,todistresstbejn(Arnbom, Pepestevrcu,WeilgartandWhit;head,in press):

~

Mastst eps madeit possibletoc'limbuptothespreade rswhit;wer eused-asan obs~rvatfon^platformwith an eye height0.2mebovesealevel. •

Aeontinous record waskeptorthe ships'. movements(Figure2·2' . Positi ons weregjvenbyTracort~an'starSatellite Navigator,giving aIlx,accuratetoabout '0.2 nauticalmiles(0.370km) approximately every..2 h. Inaddition , compass bearings'on landma.rksandsunsights witha sextant.were usedforconfirmatio~. "

Whenfo·Uowing.sperm~halesduring daylight the crewtooke-bshirt's at four differentlocations~_o~esteering,onetak~iDgnotes,oneobserving and taking photograpbs~bile standin~on thespreadets(a sbort range VHFwalk~e-tal~iewas usedtoreportobservationsfrom the spread erstot~e~ote-takerondeck),'and one taking photographsfrom thebow, Thefirthcrew member eith errested , cooked or helpedone of tbeot he!s-,- J;)uring the night each crew membertooka .3-b watch,steeringand tracking the whales. Ntersun;et , allth~d coe d

that da)'were checked.

• 2.3. TRACKING SPERM WHALES

Sperm whales were normally foundin deeper waters (ortthe she d the first 15 h afterI~a~ingPuerto Ayorawere spent·.steaming towards de'ep water west of Isabell. Island.When the boatreac~ed.the.edge'of th\,s belf, an omni.directional\

hydrophone (BenthosAQ17) was lowered for 5

m

every h,and monitoredforthe distinctive'elicks of spermw'h~es(Backus and Schevill,1066). The hydrophone wD.sused in conjunctionwith aBar~u~Berry^StandardPreamplifier: U~bt!and visibility permitted, a -Iook.oout- was kept from thedeckand from the spreaders. .-

:.".

)

21

Wh~nsperm whaleswereheard-on thehydrophone,a~earing(ac$urateto IS degrees)wastaken witb a dhectionalhydrophone[builtby Dev-Tec Inc.],andthe subjectiv;_ac.pustic

iDteJ;lsi~y

^ofthespermwhale clicks wes-eoted [scale0-5:sile"'nt. toveryJcud]. The estimateddete acethe hydrophone canpick upsperm whale clicks is r.s km.The boatw~dir ect ed towardsthesper m~aleclicksataspeed ,of 7-10km/h,Every11).15 min anewbe-a.ringWIlStakenaccordingtowhere-the sperm whaleclickswere mostintense, Thisprocedure was eonrinued..untilthe sperm.wha les wereseen, oratnight ,until~oundintensit), wee s-s,ina-icating that .thewhales~ere _nearby.^(within~pproximately.^{,5,00 m].} Sperm whaleswere traCked,~~ousticaJlyaadvisually day and nightuntilthewhaleswer.~lostor-Iert.

Reasonsfor.Iosing orleaving,thesp~rmwhales included fuelshortag e, engine failure anddolphin -jam-[the-dolphinsounds masked outthe.soundsofthe' spermwhales),

--2.4. PHOTOGRAPHS FOR INDIVIDUALIDENTIFICATION

Wheneverdistan ce(usuallylesstban'100 m]towbales andlight conditions p(lfJJlitted, black,andwhite photogra phswer~takenof the nukes(Figure 2-3).

Pictur es were taken eitherwhe~tbe^nukeswere~aised^{in the air}ber~re^preparing

tOI'.ap'ro'k:nged dive;orthewhaleslob-tai led orwhen wha lesside-nu ked. Tbe part of thewbalewhich

J. ·Ss photogra~ hed

wasnot ed together withthetrame numberonaIilmsheet. Photographsofthe nukeswere

~~ed

^bymanoeuvring theboatas discreetly es.pteeiblebehind the whales'anistaying

th~re

-uur il the.

'whales raisedtheir~kes. .,

T,hedorsalfins were,photographed whenthe whales wereperpendicular toand lessthan40m{romthebo.at(Figure 2-41:Thephotogra~h~f'~~ed

to

photogr aph thedorsal~iDofeach visiblewhale successively, when.everpcesible. ,

The nuke' anddorsal Iinphotographs usedror individual identiticationwere normally takenIrom'~bedeckatthe how using oneor more35mmca meras (CanonA-I,~l and'Ftb)and 300 mm telephoto lenses (Canon F-sl.op4).

Duribg thestu~154 rolls or blackend white film.ofvarious lengths (20, 36an~

72 framesper roll) were used. To achievegoodresclutlcu,phol.ographa-for.

"

"-c":<,,;

•

Figure2-3: Photogr aphsor nukesof spermwhales

o rr

theGalapagos:A)with open nuke notch;

and B)'with dosed nuke notch:

B

..t-- 'I

)"

_~.

Fl8~re^2--4;•Photogr aphs

o f

dorsalfins ofsperm whales orrtheGalapagos:A)remale/ imJtllat ure

'.wi.tb.a callus; B) largemalewithout a callus.

,'-.(.,;.;,",..'"

25

',.

" .

- 2. ^,

individual i4en,tifieationwe~etaken withashutterspee4 ofl°OO/s~wheeligbt permitted. . /

"Ea ehfilm wasi.D.dividuallymarked'witha numberwhichwas alsorecorded ona filmsbeet, Foreaeb'ph~tograpbthe rolfo:""ingdat.a v.;ere noted ontbe film she.tt:

rramenumber,time,par t.·ofwbale'pbotogi aphed\numbero!w~aleswith in..th~"

pbo~apbedgto~~,.photogra pher, aild~r~e~eb"rq~:^ASArating~d^brandat film(U!ord FP4 andlIPS,KodakP.IUS-'xPan,or,,t"r..X). Toseparate.serjesor photogr aphs,ODeor5e~ei'~^{-blan ks-}weretakenasreferen cepointsObtherilm.

A"'blank-was normallya pbotograph~ranidentifiable obj ecL 2.5.ANALY SIS OF THE PHOTOGRAPHS.

2.6 .1 .Measures

or

nuke:photographs

,Measures orthe pbo(ographqualityweretakentoinvest igat e how theyafreet indh'idual

identifieat~n

^{orsperm.&Ies.} The"eXpOs;dbleckand whiteIllms w.eredevelopedan~eont aetsheets wereprint~~an~markedwitbthe _r~

number. The begatives showing nukeswere analysed under ~disseet ing

•mleroscope(Wn.oM7,Heerbrugg)with amagDificat ion or6-~^times.F~r'e~e.h

·nuke negat ive, the rollowingmeQures-or pho togra ph quality were noted:

pereen~age

^ofnegatin covered'bynukes,Ioeus,exposure,

o~i;ntati'on

^and

~ilt

⁰¹

the.nuke,

a~d

pert entage or !lie nuh vb ible

.~above

the "'·ater

.su~raee,

^Full

descriptions orthem: asures

c an

be.JcuadiI!T~ble2-1-."Mean s orthephotocra ph Cj;ualitymeasures were·plot tedat4instthe eertaint y valueoran individual"

identilic~iion^(see~dion^2.6.1.ro'rcert ainty value). .. .

2.6.2.Shape or thenuke botch

Vein.ger (1980) statedtha t the ehepe.ofthe nuke'notch'can'beused to

·dis~nguishditrere~tpopulationsorspermwhales.:H'edivide d'th~shapeorthe .nuke aoteh intoth ree type3bu~he didDot explainthedirtere nttypes.I div!ded the nUke notch into twotypee-open and closed(Figure2.J). Tbiswas DotedIcr e&th.iden;ifi~whale with.·•.eertaib ty,value of.. or6(~eclioD2.&.1).

J a.;

i

l

\

.i-

."...

I

Table 2--1.

D..c~ipt.iOJ:l.of photo quality mlasures.(Xi"-X6).

Xl Focu;

X2

~!', D.ega~ive;

X3 lilt;

X< Ezpollure~

\-

X6 Ori.ntat1on;

X. .·l'ldble ;

the lIb:arpneBlI of the photograph.,Each photograph. wa.8giVeD. a focus grade bet.un .one andf i. .:1. Very blurry;2:"'Blurrybut·generaloutlll111s vieible;

3.Reasonable but emall nicks not dlfible;4.Reasonable"and'elUll nicks ddble;6.Ezcellent,lI1'erythlng in fO·¢U8.'a'n r y good picture. .

::

:;:~::lo~r::·Je~~:Il::::t~;:~ ,

^t:e

s:::~;~:::~a~~::em::::~~:: ·r;~;:~ve

.was . used w;th'dlfferentencloseda;rn-s!zee '<0.76. 1.66. 3·.13.'6.26.12.6 .26.0.

60.0 and'{OOI)draG to scale.whi ch gave the percentage of the negatiTe'the flute~ovtred. Flukes cov.eringlee8 than 11 were'u t i mat ed to·t he nlarest 0.11.

mor·. than.11 u.4.le.~stb:an 61,t o·0.21! IU1d more thu.6"I to the nearest"0,61 , the angle b.twe.n the uls of tb. flu·t;eand the water slirhce. I'hen'the flute .all perpendiettlarto the .ater surface. the1.ilt- .as 0 degrees. Ihen the flute wall'.~igl1lldw{th the •.~ter'llur f a ee~hetilt was·-gO,degrees. the relat-b. 4arkness or l1ghtne'ssof the photograph. Exposure was 41'1"14ed'11lt,o881'10. light conditione. with the 1'Iry light.

photograJJh at +.3. tbe normal' at 0 and the Tery dart at -3. CAb,soluteYalne aaed in regr,.doll). . the angleb.~w..n the lurface of the fluke ud a plus perpendicular tothe u h of the camera ltne, Ihen the VlIntral side of a • fluke w. . perptndicul:Uto the uie of the call1.ra leDII•.th e. dll1'iatioD.',&e0 degreee, Ihn the fluke^WilliaUgo.ed with the; uis of. th.c~lralenl.the dniation 'ae 90 Aegr.... . pe.reentageof &rea of fluke photographed Le, 1001 wheD the whole flute ill-risible.

'""

~

T

2.6.3.Dorsalnns and ealluses

•Kasu~'&and Ohsumi(1066) haveSb?WDthat 63%of thefemal es and 30% ofth e immaturemales haveacallus presentand no large males have scallus. The callus is aderor~ityof the epidermis andtbou ghtto beregulatedby hormones (Kasu)'aand Obsumi,1066). Negatives o! dorsal fins wereexamined visually'a.D~

iLwas notedwhethera calluswaseither present,Dot present,orititspresence was uncertain[Figure2·4).

2.6.CATALO GUING;MATClfiNG, AND INDrYmU,-\L. IDENTIFICATION

2.6.i.Unique maries and certaintyvalue of nukes

Individualnukes

.

varied from baving smoothtorougf}r edges. Inextreme

..

cases, large portion sweremissing, Marks usedIcr ,.individualident ificat ion ofnukes

~ .., 1 -

were smalland distinctnicks,waves, scallops, tooth markscars.missingportions, boles,the general shape of nukes and the nuke notch and,incuecase,growthof barnacles{Plgure2-5 and Table2-2). Eachphotographwas given'.ace~tainty value~Q)of 0-5 with0 representingnon-identifiable,and 5 indicatingabsolute certai~tyofident~rication. ~ identifiedwhalehas the potential to be r-97 identified on-.. later occasion, while a whalewbichwas not identiriablefrom the photograph he:' no potentialtobere-ideDtil'i~d. Thecertaint yvaluegradedthe certaintyof an individual'sidentification,and not the qualityo~the photograph.

Certainty values of4 and 5 indicatea photograph with certain individua l ide~til'icationJselleiiabilitytest;section2.8).

2.8·~2.Matchingofnuk es anddorea.1 nosanddev el opm en tofa catalogue

._..Each negative was rirstobserved under a dissectin.gmicroscopeand compared

with printsio anuk e catalogue.Itthenuke onthenegati;edid notmatchwith anyprint,oritther~wasany uncertaintyIa printwas- made of the negative.A nukeon a pegative which did~ot match withany,prin~.Wasgiven anew

.J

). .

. .

^~

.

^-~..

Figure2~6: Photographs showingdifferentuniq ue marksonflukesofspermwhalesoff

tbeCalapagos.

I

.~·I

30

Table 2-2.

DelcriptioD of unique marh 011 fluk. . and donalf i l i i.hicb are ueful for individual identification of .perm .balel.

3J

') "

Sma.ll nickll;

D1&tillct nicks;

..re only dietitlg1lhhed .hen the fluke .... e relatively clon .ben photographed. ' .r,..

,

."

are dllltillguhhed at relatively longdi.~ancu.

~ave.;

Scallops;.

r

..re,. hl.l i C;.·.d epre Bd on·1 ..long the tranibgedge .of the !.luke.

•er~on~1TIlcorclfd for flllk... Looke'ae though a .eemi-circle h... beeD carved out of t.he t.r ..iling edge.

Minillgportion.: arelarge partll of tbe fluke-tip. lll1edng.

Thllle ID&rte are diltinguiebabh at distance:

Holee; are~D17recorded.hell the fluke11 perpendicular to~beaxieof the clJIleia.

Tooth mark: IlC;l.TII; are otten IUD al eeveral parallel.bite iinee.

.Callue ee; a.re greyieh deformiti. . on the dorsaltill'. The callus variee:in colour,ebape And poeit.ioD ont.b~doreal fill.

Skin eheddillgc; are obuTTed "I .lighter are ... or linnOil tbe bacb

J ot't he ..hal . ..

,,~

" -:.

identifi cation'Dumber. Wlien a match (Figure2,6)wasfOlln~the identifieation number of the'matchmgcat~l~giIeprint was gj"l!ntothe nukeon the negative.

A print was madeif thenega ti ve wasofbetter photo graphic quailty than the . print already catalogued.•The bestprintQreachidentifie dindiv id ual wasused to estim ate thenum~erof unique marks0Ii.the nukes, The orderoftheprinls in the ca talogue was basedODthe smoot h nessof thetrailing edges,of thenukes,with the mostruggededges'atthe beginnin g,~ndnomarksatall on,nukes at the end of thecatalogue.

Ea ch

anal~se,d d~rsai

fin neg at ive

w~ give~. ~

classificationwhichrepresented eitherthe possibility orimpossibiJitY4ofident ifying individua1J? Thosenegatives' which were.eleseiried as"possible1.(1identif,.indi\'id~als·,wereprinted anda catalo guewas'made. Match ed dors,atfillS'(F igure 2-7 )were giventhe same ident.ification number..Thematchingwasrepeatedtwicetoensurethat all 'identifiable dorsalfinswereincluded in the catalogue. Catalo gued dorsalfins wereseparate dinto~hosewit hcertain and.Dotcertainindividualidentification.' This wasdon e to scr een out thosewhales whichwere possiblybutnot certainly.

.individ ually identified. Tbecatalogue,wasdivid ed intoleltand rightdorsalfins dependingonwhichsideof thed~r~al.rinwasphotograph ed. .

DorsalIin andnukesof the-sameidentifiedindividualw~rematc hedwhe n possible. Altboughit waSnot'alwayspossible to identiry'tbe indiv idual with cert aintyfrom thedorsalfln, it.wassome~in'lespossible~det e rminewhethera calluswas pr esentor not. Thesedorsal rins werematched,whenever possible, withnukesfrom idenrifledindividuals, and tbe presence ofacallus was recorde d (Section2,5.3).

2.7.GROU PS

To achieve an obj ective descriptio n of the soci al cvganizatio n o'r t he femal es/ imma t,ures0((the Galapago s,identificaUonsof particular iDdiv.j~uals' w,ereused.Aeoetficientof a..sso'ciation,R(x,y), wascalc uli ted bet':l'een each'pair' of ide ntifiedfemale/ immature wheles x andy:

R,b:.r) ~

f

5!(5+t,(1» , U/Hb :)+1/HCy»/2

i,V,

,~

Fig u re:"8: Photographsormalthin gnub s or a.nindiViduall}'identifiedspermwhale:

AJ ident ifttdbn24 Febr uary,0) on 23Mar~b,I.lldC)onIIApril,1085.

A

3-1

B

·" ...

Figure2-7:'Photograpbs of mat.ehing dorsalfins' ofaniodi\'iduallyide ntified sperm whale:

A)"ideotified0021March,end B)00 . 31Mareh ,1985

--~ -~~-_._-_._.- _~-

I

_'~'

"

A

36

- 37

whe r e the summat ionismadeover i,those occasio ns onwhichxIand'Jwere ide n t ified<2 40 min apart(240 min_waschos e n

ras

thecut~orr.asthereappeared tobeoccasiODJI,I,eha n ges inth eprim a.TYsetorwhales beingfollowed overIntervals ofth is dura t ioD');an dt(i)isthetimeinterval'inmin betwee.n-iejdeQtHicati~~~r.~

x and}'on occasioni(times recordedtc-aearest5min).N(x)and N(y}arethe total number of idenlHicaUon sof xan d;Y.Thus-if

2

'whales were eac hidenti fie d .. on3occasio n s,alway swithin Sminofone anot her,th~n:

tCi>

=0 (obeetved .Uh1nthelIameenc~unt.er)

1/M(x)~1/:~~),="1lr+l/3e2/3,t.hen R(3,3)=Ei...1 5/6+0 .( 2/ 3)/ 2 =1.0

The association matrix, IR(x,y)], ~'as^{us ed as inputina Gro u pAvera ge} Hier archicalCluste r'Analys is(Eve r itt,lQ74)..Groupsweremergedusing this clus t eringte chnique untila likelihood ratiotestshowed asign ificant(atP<O.O&) decr easeinthefitoftheda.ta(oft.hedayaon whic h individuals wej-eideDt ifi ed) (orther~ultan,t.grouptoa.model ofclosur ecomp a redwit hitstwoconstit uent grou ps.

2.8.RELIABILITY TEST

Areliability tes:t wascon d uctedto seeif theanaly~er(Ar n bom)WB.$coosistent inhis estim a te ofmatchingand_gr~dingthe negativ es(Tab le 2-31. Tworolls or Iilmwererandomly,selectedwith 10And.22 nuke photographsrespe cti vely. The matchingandgradi ng methodwas explained byawritte nstateme ntend was .presentedtoan

experieneed~ta.lo~r

^{(H .}IWhit e beadl,....Whitehead was Dol permittedto seethenegat ives before the test. 'thenuk~graded at,cerl:a inty valu es " or S(N= 22) werematchedide~tically ^{by Am bornand} Whiteh e ad, except for threeIlukee,whichWhitehead scored "wbil e'Arnbo mscored' 3.

Althougb·the twoanalystshad sign ificantly different meees for the measuresXl·

X6, all,but"one,~e'recorrelated..¹(Table 2-3). The on lymeas ure i~^which 'Ar nbom's and Whi'ehea'd' s estimates were not correla t edsign ificantly...wu

exp osure (r=O.24,P<O.20).

,.,",~

"~"-" 0 "

Tablez..a

...

^,

... .

^:

.

·n. wo--..17"1"· _ _a,.loh _ absolat., ...&1.o.eof the 41It.. r811.c: eb.C. •• ••

. th'-ual1••r.·

.'U',.

corrdatioD, blt..U tbeualy"uoecer..·u el the IipifiC&Ilct1".1 for-2-tailld t-tut of th••'UI. ut.li for the

.... I"'-.I._t,to. of t.k • • •t.hocloftui.Yldllalph o tog r a p h i c ld.at,lf :icat. l oll. Tb.

~~::::: .. ~~~~_::~-~~~+:~-~: ~:_:~::~-~~: _::::_~~-~~:~:~::~~~ ~

"._url 11__ Abeo1.lIot..'1'&1111 2- ,... 11e4i.-To••t

CW) (II) diU.ilIaD r P<

Fo ~. 3.69 3.26 0.34 ~O.O I52

Jconr ".23 3.91 0.32 0,936 0.001

.

: Esposun 0.63 -0.37 0.90 0.235 0,196

Orientation 23.06 13.69 9.41 0.8406'

Tllt 13044.\a.09 4,66 0.90a 0.001

:I't'ldble 78.00 82.8e 6.66 0.979 0.001

Qa.&litoy

i/ /

I

v.

i

-- ~

J;: