4:*,R.@A~# Ii , , (9 F CANAD a L, ' )

FISHERIES RESEARCH /4:*,R.@A~# ii , , (9 F CANAD A L, ' )

\ \:\

MANUSCRHBT REPORT SERIES (BIOLOGICAL)

No. '653

AUTHORSHIP

Establishment ARCTIC UNIT) 505 PINE AVE, 'd,) MONTREAL, QUE ,

2 1 A L \ I,, Datad APR~L1958 A,W, Mansfield The Bialogy of the Atlantic Walrus OdoQems Poçrnarilç ( Linnaex P rosrnarxs 1 i~ the Eastern Cana-dian Arei;icl

Aùa tract

Sections of molarif~rmteeth rsveai welh definaed hcremental layers tz~hichare almost certâlnly amual In formationJ Cornparison or" speciaens from nor-tbern Eudson Bay and the Bering Sea shows that the Atlantic walrus is slightly smalfer in body size and much shorter in %usk length than the Paclfic walrus, The specinens from Foxe Basin are slightly lasger In body size than those from Hudson Bay, which suggests that comparatively isola'ced breeding groups have been formed, Males mature when six years olci 2nd appeâr to be in rut $rom Movember ts May, the peak of SacedLng activity occurrlog In ApriJ and early May, Th2 youngest sermally mature fernales are five years old, though the majosity do not bueorne mature until seven yeârs, Breedlng maturity may be delayeif â âurther year in most fernales shce frnpregnation does not usually follow the first ovulation, The gestation period lasts just over a year, and the majo~ityof calves are born in April, May o- Jwe, Tne low amal birth rate of 0,3S caEves per adule fernale Is comterbalanced by great materna1 solici-kuds for the calf with a correspondangly TAULE OF COTiTENTS

Page

LIST OF TABLESeeaeo.ee,eeo**.ae.eoeee***aiieee*ae***eeeeo*~

LIST OF FIGU"nESesee~eoe*eoOooooocceoee~~*eee*eeeee.~eeeoaa~i

LIST OF APPENDICES~oea~eeea~*eeoa~oasoes~~e~et>oeee:<

ACKTJO\JLL;DGK~~TI\TTSooee e ee eo Je.0 a o 0.90 e e e o .e oaeaoe eao.ed

IWRODUCTLOI$aeeoeeoooa~oseo~ooeoeoYeveoe*aseo****~eeeo~e.1 General Rema~ks,.~.~~~~~~~~~.~~~~~~~~~~~~~~~~~~~1

Previous Blorlr ..,,...oo,oe.00.e~~8eOBuO(LOd~BOI)e~ 2 ~o~~~c~~~u~~~.~,,~,~~~~~~~~.~~~~~~~~~~~~~~~~~~~~3

KETBODS AND bLnTERIALSoaoo,seeo0eoeo*eooi~+osseee*so~eoe~e5 Field Localitieso9eOB0...B~~O~P~B.oOOP.~VOP000ee5 Northern Hudson Bay,, ..,...... ,.,...,,5 Northern Foxe Basin,o...e~o,..,e..~e~e~.BO~O038

n lravel~oJOOÎOe~~POo~~~g.U~~OoO~ODO~Oe~~e~ee~o~ee~~L~

C~~~t~~eeoaoee~*e~osseoeeee~eeee*eoeo.~~~oeoauoo~~

Marking POoDO~~~O~e~~OeO~OODO***UO~~D~~O~~~~~o~oO~~ Materials C~Lfe~t~d~~~~~~.~~..~~~~~~~~~~~~~~~~~~15 n~reatrncnt of MateriaPs....e..OOl.deaeOeOe~OOOoOe17 AGE DETERMI~~ii1TION~oO.ORb~esOO~~e~~~~~OO~e~~~~~eee~~~~~~a~153

M~~h~d~~~~~~~~..~~~.~~~~~~~~~~~~~~*~~~~.~a~e~~o~19 Body length me~s~~~~ents,..,,~...~~~~~~~~~~~~~3-9 Tusk and baculum measurements,,,.o,..~~OO.~IoO~~ ~~a~s~.~.~~.~~~.~~.~~~~~~~.~.~.~~.~~~~~..~~~~~23

Teeth e~O~JOIe~~OIee~~B~~O~ss~O~~~~~~e~~~~~~~oo~~

iTJ PAGE

Fasting ...... ~e~o~~~e~.O~.~~

TKT-, MAL3 REPRû"UUCTTVT-, CYCLEeeeeeemeee*eeeaaoeueeeeee4ee79 SexuaL llaturity 04aopo*9bee~s9e.ee-0.a*.e**e.weem*Q79 Crowth of the baculum and teçti~,,.~..~.~~~.~79 His tology of the testis and epididymis ...... 80 The Testicular Cycle in the Adclt Male ...... 84 Chronology of Events In the.Adult Male ...... 85 THE FEPLALE REPRODUCTIVE CYCLEeo, ....ee..e~e~.D0.ee.o00088 Sexual "laturity...... e...... -...... 088 Ovulation in nulliparous fernales., ...... -89

Ages at first ovulation.e~~~aa~~~~~s~eOe~~aD~8~ Birth Rate ...... 92

The Ovarian Cycle 0a~~~~~e~~eOIOo~e~D~O~eeoeELD~d~O~3 Development of the follicles and ovulation..,33

The corpus luteum ...... s.OO..O.e...... B.b~. *97 Implantation and Growth of the Embryo ...... 102

Birth and Care of the Young o~e..a...e..~.o.~.~e0107 Chronology of Events in the Adiilt Fezale...... 108 DISTKIBUTION AND rlli3UiJDANCE ..,...... O.eeO.~~~~...e~,~lL Relation to th9 Land .,,...... e....e.....Je.~eeeI112 Relation to Sea Ice ...... 800...,ees...*"gt.e8B115 Local Movements and Migrations,...... ~a.Oe..e.ilBS_l~

S~4?4ARYesoeeeeeaO.e..s.ee*oeeooee...e.eeaa~ee-eoo..eeeel22

BIBLIOGRAPHY e**ee6~.~..0..~.~-.e*.~.~~*oe.a.~*oee~26 LIST OF TABLES

TAB LE PAGE 1 Weights of Various Interna1 Structures of an AduEt Male Atlantic 46 II Comparative Sema1 Dirnorphisrn in the W~L~US~~~~...~~~.~~~~.~~...~~~~.~.~~.~~~~~~ III Observed Variations in the Dentiti~n,,..,~~~ IV Food Organisms taken from Stonach Contents89ee.b.0e.ee.eceee.eQ~.eBe..eee~~~8. V The Mou~~,~~~~o.~~~oB.o~o.*oQ=o~Bo.~oooooo.Q VI semal Waturity in the Female,,,eoe.see..s.s

VI3 Calculated Average GestatFon Period derived from Lengths of Eleven Foet~ses,.~, LIST OF FIGURES

FIGURE PACE M2p of Southû.mp-ton1s land sfios?ing pos itio~

of Ud.j& and Lirnit of Winter Fast Ice, a a ., Map of Foxe Basin showing Bathymetry and Limit of Winter Fast IC~.....,.~~~.~~~.~~

Stainless Steel Tag used in marking 3Jalrus,, Froquency Analysis of Body Length Measure- ments in In~hes,,,,,,~~~~.~~~~~~~~~~~~~~~~~

Cornpôrlson of Tusk Growth in a Foetal, %?O Year Old and Adul'c Male I.Jalrus,o.g.Buesoooo

Cornparison of Male and Female Tusk Lengths in th3 First Yiiree Years of Gro~qth,. ,. Photograph of the Tusk of a 21-Pear-Old Male to show Root Ridges and Medial Depressions. (a) Illustration of the Root Xidges on an

aLufJa1.e Tusk after exfoliation of the Cemen-t;um (b) The Dentine and Cemen-tu~nLayers on the Tusk Roo-L in Longitudinal Secti~n,.,...... ~.~.., Longi-tudinalSection of the Lowr Molar Too-th

of a 7-Year-ûld-Female ( x 3e5)01*ec*eeeo9* Part of a Transverse Section of the Lower Canine Tooth of a 21-Yeas-Old Male (x IS),, Deposition of Cementrun on th8 Roots cf Molar-

if orm Teeth in Males and Femal-es ,, , , , , , , *,, FIGUHE PAGE

12 Grotrth in Length of the Body of Iiialss arrd

Female~...~....lOda.e*....e*...... @ 13 Increase in Yelght of the Body ( the treights of 4 males and 6 females of unknown âge are taIren from Loughrey, 1955)...... 47

Grot~thin Lexgth of the Tu~ks...~~...... a..e 51 15 Growth of the Bacul~n...... ,...~~.~.~,~~.~~~% 16 Head and Shoulders of an Adult Male Walrus showing Epiderrnal Tubercles and Scars from

Tusk Inflicted Wounds...... a...... e. 59 17 Read of an Old Adult Male Walrus showing Worn Tusks and Vibri~sae...... ~~...~~~.~... 59 18 Dentition of the Full-Term Foetus A 11 (Teeth indicated by bracketed nunbers were not observed in the specirnens available, but were inferred from Fayls accouni of the Pacifie walrus) ...... 61 19 Percentage of Stomachs containing Fo~d...,~... 75 20 Development of the Testis (the specimens in

breeding condition are indicated by black dots)...... 81 21 Section through the Seminiferous Tubules of the Immature 6-~ear-~ldIdIale R 111 (x 600)...... 83 FIGURE

22 Section through the Zpididymal Epithefiwû

of the Immature 6-~ear-0ld Male A 111

( x 600)0~10ee~es01~010au~~*4*~.~re~*eeil~~~

23 Section through the Epid.idyrnal Epithelium of the Mature Male A 97 ( x 600).,...... ,.,,, 24 Section throggh a, Serniniferoias Tubule of the AduEt Male 1W IO4 taken on Eovember 30:

Type A ( x 600)~e.e**e*~*~~~~**OeesOOO~e8ee

25 Section through a Seminiferous Tubule of the Adult Male A 97, taken on June 17: Type B

( x 600)0~~*ee..e~**e4.e.~e~*s~eeee.~c.eeoe 26 Section through a Seminiferous Tubule of the Adult Male A 62, taken on September 18: Type

c ( x 600) ~O1e~e.O*~~e.LeLLO*oeee~~OB~Be~~O 27 Çeasona.1 Fluctuation in Dia.rneter of the Semin- iferous Tubules in Adult Males (the tira Specimens indicated by black dots are in an active state of Sperrniogene~is...,..~~~~ 28 Relation between Age of the Famale and Number of' Corpora. Lu-tea in the Ovarie~....~...,.~, 29 Section of the Corpus Luteum of the Pregnant Fernale A 42, taken on August 7 (x 600). .. ,. 30 Section of the Lâte Pregnancy Corpus Luteum of Female A 9, taken on May 26 (x-600),, . ,, 31 Section of the Regressing Corpus Luteum of Fernale A 43, taken on August 17 (a ~oo),.., ix

FIGURE PAGE

32 Section of a Corpus Luteut? Spuriun from the Barren Female A 77. taken on October 2 ( x 600) ...... 101 33 Growth of the Ernbryo and Placenta...... 104 34 Growth of the Hman Embryo (after Arey, 1954) . 105 35 Map of the Eastern Canadian Arctic ...... 118 LIST OF fiPPENDICES

APFELùD IX 1 Body and Tusk Length i.Ieasurûments of 83 Kale and 39 Female kfalrus of Kno.r\rn

Hge.9.8.~9DI..01.D0Ba~.0Bee(i~eeO(I~P~O~e~132

II Development of the Testis in Imrnature and Mature MaPese,.Be.~e0.0..0P~'10.~OeBe9Be136 III Development of Follicleç and Corpora Lutea in the Ovaries of 59 Atlantic ~~a~ruçO,..o.e.O.E..~BO(tea~~e~eaDD1.~O..Ol.Be138

IV Growth of the Hwnan Embryo ( after

Arey, 1954) ~~e~~e~~~.~.~~I)OasBBe~DOi)OOePOed145 V Cornparison of Mean Body Length and PIean External Tusk Longth in Plale Atlantic

and Pacif ic klalrus.. . -..a *. o. e.. *.. .. IL6 The Initial part ol the iabora tory work on t.rhfch this study Is based -+ras cxrried out An the Department of ZooEogy, McGi%7 Vni~ersity~I am most gsateful to Pro- fsssor J, Stanley for supplying labofatory fac3Pit2es3 and to Dr, Mu J, Dmbar for initiatfng the program of reseasch and offerhg much uselul adviee and criticlçn dwhg its cornpletion, Since April 1956 the work has been suppor-ted by the Flsheriec Research Board, Arctic Unit, ar,d 1 wiçh to thanlc Dr, H, D, Fisher and his staff for much valuable assis tance Y Research on the Atlnntlc walrus was begm by the Ffshrrles Research Board in 1953 as part of the generaX study of the marins resoxrces of northern -+ïrrters, I am gratefub to Dr, Duabas fur directhg the researeh initially and for designhg the tag used in rnarking expvrLmonts, Dr, E, H, Graingsr began the -kagging program at

Coats lslaad in 1954, and alsû made the f irst substantial co'ilecti.on of reproductive mate~ial, Further collections were made frorr! C uGuMeVe." Calamu&' during the psriod AugusU 1955 - Septernbei. 2956 and I am ir,debt;ed to Dr, Grainger for hfs valuable efforts in the field* Mr, 1, A, McLaren contributed speclmens from Hudson Strait, and made detailed analyses of Uheir stornach contents, 1 much appreclatu his help and advice throughout the study, and a%so bis crStLclsm of the manuscript, 1 wouïd aPso Like to thank Dr, Do V* EHlis for analyzing the collection of stornach contents from northern Hudson Bay and Dr. De E, Sergean$ for reading and correcting the zanuscrkptü The two Sumner seasons spent at Southampton Island were niade most pleasant by the friendliness and hospitality shown by the residents at the settlement: I4r. and Mrs. A. T. Swaffieid and Mr, and Mrs* R, Cruickshank of the Hudsonfs

Bay Company, and Mr. and Mrs, Je blhitford of th6 Department of Northern Affairs* 1 am pareicularly grateful to Father Z, Choque, O.M.I., for providing accommodation during this thme and for befng helpfu'l. in so mmy ways, At Igloolik, Mr. W. Calder, the Post Hanager of the Hudson's Bay Company, provided hospitaiity .r.rhich was

During the tbee çeasomf work, Eskimos were my constant travelling cornpanions, and withsut their help no collections could have been made, 1 have mucb pleasure in thanking Paniuk, Joe Curly, Angutialulr and Mikkitok of Southampton Island, and Kramanii; of Igloolik for t heir friendliness and co-operation in al1 phases of the fisld

WOP~,

For help In the Iaboratory, I wish to thank Mrso

P. 3. Thompson and fi, Re Szavay for preparhg histological sections, and Hiçs Berit Arnestad for drawing the diagrarns, Special thaulis are due to Mr, J, PoJ_lockof tl-xe

Department of Zoology for photo3raphing and preparing copies of the drawingç, The arduous task of typlng the m:inuscript was undeT.bake.n by Mrs. E, O'Brien whom 1 would also like to thank for her efforts. Finally 1 11ould .l:Eka to e:rpruss my gratitude -Go the Trustees of the McGill Carnegie Fuad and to the Fisheries Research Board for providing adequate finances to enable the progpam to be carried out, The ~ialrns,Qdobq~u? rt3srn=yp9 2s a cSrcrrnpol_ar species sf arctfc a~cisub-arc$-c wate~sauu is çsograph- ica1I.y fsolated Znto three or more mo~phologicalSydisticct groups, The Eastern Canadian Brctic and West Greenland group ranged as far south as Sable Island and the Gulf 02 St, La1,~ïencsIn hisboric ternes, bu.% tmres-tricted cornniercial exploitation led to a serious decline in nazibars and a withdrawal of the group to %he more northern an6 inaccessible parts of its range* The âdvent of the ~if?~cinto the Eslcimo ecoriony with consequené bras tef ul r;iethocis of hmtir~g caused further serious reductions in the walrus llerds and necessi- tuted the introduction of restric tlve 'htmiing measures, Iri 1931 a Depur kment of Fisheries Act was passed which limite6 the taking of waErus Lo Eskirno Tami43es and certain white resldents in the nor kl:l a~d,in addition, tha eicporting oJ raw, uz~,,rorlredivory T,faç torbidden,

Ir, the pos-t-war years th.9 increa.sed interest of the Governnznt in the economy of the native peosles has 7ed to the undertaking of hasic iaesearch into the naturai resogrces of the arcti.~, In 1952 the Department of Norlhern Afîalrs and National Resources initiated a preliminary two - year investigation into the present status of the walrus ir, nortf-lern Hudson Eay (Loughrey, 1955)~ ID 1953 members of Easteisrt Arctic Investigations aboard C,G.lii.7Pa" CaTanusft begar, a study of the walruç herds frequenting this ares as part of "cefr genera9 program of reseaïxk Snto the marine resources or" northern vaters (see Duribar, 19561,

In 1955 the presest author began a full time s$uSy of walruç Siology with financlal assistance from the McCiSl Carnegie Funâ. In 1956 the work %ras su-pported by the Fishertes Reseasch Board, Arctic Unit (formzrly Eastern Arctic Pn~resti~ations)with whom the author is now emgloyed,

Previous Work

The vast early literature was reviewed by Allen (1883) ln an exhâustive and auZhorilative aonognaph of th3 North Ameiican piïuiipeds, The first really important in- formation on the b3ology of the walrus was given by ChapskiL

(1936) on the population frequenting the Kara SeaY Belopolskii (19391, Freinan (1940) and Nikulin (1940) contributecl detalled analyses of the lffe history of the

Pacific walrus in the Chukchee Sea, and Vibe (1950) gave the most complete record of feeding habits, Unfortwato%y,

many of the conclusions of aeçe workers co~cernhgthe

problems of growth and sexual maturity were based on ageç assumed from frequency anzlyses of tusk and body Length measüremeilts. Pt is now known that body Sength is a very variable factor in several species of pinnipeds, and the

rcsults ûf the foregoing authors nust be vlewed with some reseivati~n~ A new methoci of age daterrcinatian in nianmals, with

special ~elerenceto pi,mipeds, w3s discovered by Scheffcr

(1950a) and Laws (1953~~)~and bcitil au th or^ vuggesxed Its possible application to the valrus, Mohr (1952) pointe6 out the significance of cernentwn layers in thu molariîor~teeth

as a possible guide to age, and B~ooks(195%) and Fay (1955) attempted ts apply the rnethod to the Pacific walrus, Brooks recognised the regu'iarity with which the cementurd layers were

forme&, but was unable to correlate thls with an annual cycle,

Fay determlned immature aga groups by analysing the frequency

distribution of external Yusk lengths and found no correlation bstween cernentum layers and age determined by this method, In mature males, however, there appeared to be a good correlation, and Fay vas able to offer a better interprezatlon of growth and age than had previously been given* The most recent study on the Atlantic walrus was a

preliminary investigation made by Loughrey (1955) on the population frequenting northern Hudson Bay.

Nomenclature

The early literature on the systernatics of the wairiss was reviewed by Allen (1880) who postulated the existence of iwo speciss in the genus Odobenus. Of recent authors, onfy G, M, Allen (1942) and Ande~son(1946) have supported Al:l.enls suggestion, whiLe Nikulin (1940) has assumed t1la-t the Atlantic and Pacffie fox-ms are of subspecific ra~konlyr namsly Odobenus rosrnarus sosmarus and &lobenus s~~~~usdiverz,?;lll&

Nikulin also refers Vo a theosy of Chagskii (1940) trho suggests that wairus Inhabi$ing the Eaptev and East Siberfan

Seas fora a separatc group, msrphologically distinct fron

. the Atlantic and Pacifie forrns. In the present work, it has been possible to com- pare rnate~ialfrom nûrthern Hudson Bay and northera Foxe Basin with Che data published by Fay (1955) and Chapskii (1936). Reference tu Table II shows that ths Bacific and Atlantic form are rnorphologlcally distinct, with the Kara

Sea wal~uscomprising an intesmediate group more akin to the barger Pacifie foim, Nothlng is lrno~~of the fourth group which inhabits the Laptev and East Siberian Seas* The truc relationships between the grazps will only be established when xheir morphometry has been studied

in nuch greater detail, buz until then the two subspecifîc

names in c~rrent usage appea? éo be acceptable. METHODS AND MATZRIALS

Field Localitieç

Nor-L'ilern.. H-ndsori. Bav (f ig 3), Fleld work in thiç areares hitiated in the stmrner of 1953 by rnembers of

C, Ge Me V, "~alanüs"under Dr, E, He Grahger, In the followlng year, worlr tqas continuecl on the tralrus census about Seahorse Point and Coats 1s land, and quantitative bottom sarnples were taken at selected points off the coast to provide data on walrus feeding, During late July and early A~~gus'c,Dr, Grainge~spent a period of three weeks sn

CoaLs Esland carrying out â preliminary tagging program and collectiag a series of specimens for study of the regroduc- tive cycle, Th?. author began hls field work at Southampton Islarld in Masch I9/;S, and was joined by the "Calanus" on August 14. The ship helped in collecting specirnens and tagg-

ing animals at Coats Island and Seahorse Point, and then left ' for lgl001ik on Septeinber 4, The üutho~f inished the 3-95 field season in mid-October and returned the following year in Eate May, remaining until October 27, InJalrus are occasionally taken a-t the edge of the fast Ice to the ssuth of the settlement in the spring rnonths, but the main hu.nting takes place in the fall, when -thsy hauP out on Land, The hauling-out sites or ugm are reoccupied 50 IO0

Scale: Nauticol Milas

Figure 1, Map of Southampton Island siiowing Position of

Uglj& and Limit of Winter Fast Ice, year afUer year, and they are groupvd closely en.ough on Bencâs and Coats Islands to provide botl; the ilunter and field wrker with â conveniently res tricted locale,

The southern coas tliiie of So~ichamnton1s land is mifor~lyflat and desolate and consists of loti raised Seaches of fragmented limostonu, The bays and indentations in the coast are very sh.al1ow and the fast ice is able to remain close to the shore until rnld-J~xly~ Strong curr.ents combined with high average wind specds keep the ice con- s tantly moving in Fisher and Evans S-traits, and the fast ice in South Bay is rarely. able to eextend south of a linn fron Ruia Point to Aative Point, Walrus Island (Akpatorardjuk) in Fisher Strait rises to 260 feet above sea level and is cornposed of large blocks of black basaltic rock, The coastline is steep and in certain years the Island is a favoured hauling-out grourd for as many as two thousand walrus (Manning, 19421, Tkiô featureless fLat lirnestone country fosms mos% of the coasiline of Coats Island (Alrpa.tord.juarli). In the northeast the Precambrian crystalline rocks rise to over 500 feet and provide a wvlcorne relief to the landscape, Beneas Island (Krekekta~~aluk)to the nosth of Coats Islarid forns a Zow lying outcrop of the Precambrian rocks, There are four =lit on these two islands (fige 1) and they are coaibed to -the Precambrian rocks. Halrus are no$ kno%$r~to frequent other places in this area, anci they never haxX otït un the Limestone beaches, The ecological factors affecting this choice of haullng-out sites will be discussed in a later section,

Northern Fo-e Basiq (figo 2) Ce Ge M, Veti~aLanus'' reached Iglooiik in October, 1955, and rema.ined fast in the Ice throughout the wlnter, During the follovring surnmer, work >ras conf ined to the northwestern region or" Foxe Basin, and the çhip was finally beached at Rovley Island in the fall, In the xilnter of 1955 and the spring of 1956, Dr, Grainger was able to make some collections of walrus material, and these were augmentvd in the surnmer by the efforts of several field parties froa the shipo Sn the sumrner of 1957 the authoris field base was located on Amitioke PenEnsula, about five miles narth of the srnall Eskimo comnunlty at

Tike~a(6BG 03'N, 82O 06'~~). Io July and August, the greatest concentrations

OP walrus are fomd in the pack 3ce to the east and northeast of thiç area, and the hünters from Tikera are generally more successful in seeuring their wlnte~meat susplies than their nearest relatives at Xringmiktorvik, In Segtember the wafrus appear to move north and tne hxrlters frorn Igloollk are able to make their best catches then. From October until May, when the fast ice extends al1 along the coast of Melville Peninsula and to the eas t of

Igloolik Island (fig, 21, special condftions are needed for O XI .-- ico i Scole' Nauticol Milss

Figure 2, Map of Foxe Basin showing Bathymetry and Limit of Winter Fast Ice. huinting to occur. In eas'c an6 soutlieasterly winds ths Foxe Basin gack closes in to the edge of the fast Lce along the coast, and the hunters are xben able to travel otxt onto the moving ice and look for walrus in the leads of open water, Frorn Amitioke Peninsula north~sardv to Igloolik the coast is forrned of featureless raised beaches of fragmented limestone, The two major indentations of Foster Bay and Parsy Bay retain unbruken fast ice until rate in July, and a narrow coastal strip of ice, seldom exceeding a mile in width, con- nects tlivrn, East of Igloolik Island the edge of the fast ice turns nostheastwards towards Sens Munk Island, WaErus are not generally found anywhere on land in

this region, though the Eskimos suggest that the$ corne ashore on South Coglit Island in the fall, At this time the island

is usuolly inaccessible from the mainland owhg to the formation of new ice,

At Southcttnpton Island in the spring months, the

huzrters haul their canoes and flat-boats acrosç the fast ice on South Bay and look for seals and walrus in the loose ice, The l.zirge 22 foot freight canoe fitted wi%h an outboard motor

is easily transported by dog sleàge, and rapid forays can be made away from the ice edge in fine weathcr, It is a frag2ie

%". %". craft, hoiraver, and the Eskimos exc$ise the greatest caution when harlting walrus Zn tha la te suinmer and faEl, motor whale- boats, trapboats and several fully decked 42 fooS Pet2rheâd boats ûre used for the long jotrrneys te the hauling-out sites, The autho~accompanied the Gskimos in Soth canoe and Peterhead boat, and supplemented these hmting trips with

several journeys in â whaïeboat belonging to the Fiskieries Research Board, Arctfc kit,

Zn northern Foxe BasIn, û similar whaleboat was used for the sumer Is work, In May, 1957, it was hauled to the edge of the fast ice to the east of IglooLik Island and sailed down to the camp site on Anitj-oke Peninsula, This journey was impeded by unusuaFly difficult ice conditions and litile hunting could be done,

Counts

At Coats and Bencas Islands during the sumer and fa11 months, counts were made at the u~1i-t:ancl also while travellïxi,g to and from suitable a:ichorages, On the re2a"cvely few fine days when work at sea was possible, walrus were found to be grouped close to each -a&*, and febi tsere seen along the coast, On severai occasions, most of the u1it were visited on one day, and a large proportion of trie wairus frequenting the area were probably accounted for in the observations, With practice , it became possible to distlnguish between adult maLes and fernales, but precise nwnbers of each sex could seldom be obtained ovriizg to their habit of lying so close together, CowCs made from the t'Calanusu in 1954 sug~estud

-l;hat; the to-ta1 population frequonting th2 Coats Island and Seahorse Point assa nwbered approxinately 3,000 animals (Dunbar, 1756) This figure was confirmed by an aerial census of the hauling-out sites maGe on Augüst 20, 1954, by Lougbey (1955). He was abls to fLy over al1 the ilnom

Uili, and observed an estirnatec! total of 2,900 animals, Limited local observations from otner areas have been made available through Re C, M, P. files, and some verbal reports have been received from Post Managers of the Hudson's Bay Company and Oblate Fâthers of the Roman Catholic Mission, The Atlantic Oceanographic Croup aboard

H. M, Co S, "Labrador" has contriSuteCl further observations from the shipls marine narnmal log,

The seasonal appearance of Ehe wnl.rus, particularly at the trûditional hauling-out sites In northern Huuson Bay and Hudson Strait, has led s9me obsnrvers to beliave that a

definite migration oecurs, The paucity of ariirnals in Lhe winter months has becn taken as parthal proof of süch a rnove- ment away from their summer hauts, but the lack of animals

seems to be more apparent than real, There is Pittle doubt that local movements do occur, but these are more probably in the nature of a dispersa1 as winter conditions set in,

CM.

Figure 3* Stainless Steel Tag used in marking Walrus, waber frûm a aotor ~rhalaboât, The îolLowinç silrrtrnur, rnost of the animnls were tagged cn the Land at %te &0,1:_C on the east coast 0% Coats Island, and. -i;his vras foi~-cdto be the simplest rnethod,

115 animals have bszn niarlrec! so far, but 170 Te- coveries have Deen reported, Since the Eskimos at Coral Harbour are weLl acquainted with the work, the effective- ness of the method is open to doubt, Tt seems probable that many of the tags must eithzr âall out, or ùe rubbed off when the animal5 are hauPed out on the ice op land, Perhaps the most effective rnethod uf marking would be by capturing calwss and attaching metai straps to -their flippers (ses Brooli-s, 1954)~brit this would necessitate diverting the attentiorl of the tem-porarily bereaved L"err,ay~vs, A possible soPutlon woixiG be -l;o im- rnobilize the fernale by use of a sui-lably adrninistereci alka2oi.d drug, a method whlch hzs proved successful in -~hcnianagernvn* of some ïa rger te~restrial ri;ammaIs (Crockf ord et al, , 1957), Such a -t,ecluliqüe aight alloi? both the cow and valf te be tagged a-nd result in a?- overall saving of mu.ch ti.me and effort,

Materials Collected

The pressnt series of specirnens conprises samples of 104 male and 72 femahe walrt~ç, Of these, 48 maies and 50 fernales were taken in n~rthernHudson Bay, Hudson Stsait and F~obishe~Bay, and the reinaining 56 males and 22 fernales from no~thernFoxe Easin (see Appendix 21, Lowerp jaws, molariforni teeth and -Lusks raieru collected to p~ovldedaiia on agei~g,and ~iiloleslcu3.l~ were taken when possible, These were dried in the wind after remcval of the braio and most of the flesh, The stomachs of most specirnens were examined for foad contents, and whole or sub-sarnples were washed in sea water and preserved in 10 percen-b formalin, In male specimens, the testes were weighed after removal of the epididymis and measured to the nearest miElf- rnelre, A 2 cm, slice from the centre of the testis and epididymis was rernoved and preserved in Bouin's fluid or 10 peicent formalino Xt was îomd that Bouin's fluid was better than formalin as a fixative for testis material çincs there was less distortion of the tubules ancl the histological. re- çults vere better, Bacula were collecteci, and were skimed and then wind dried, In the female specimens the reproductive tract was usually removed entire and examincd at leisure while the hunters were butcilering khe carcasse The sites of oLc? pla- cental scars were noted, and embrÿos were collected and stored in 10 percent formalin or 60 percent alcohol, The body wall and cranium of larger foetuses were slit to alLov pene- tration of the preservative, Ovaries were preserved whole in Bouin's fluid or 10 percect formalin and, when tlme permitted, samples a.f uterlne nucosa and vagina were collected, Pieces of mamrnary gland were taken fsom u fer? inrtture fernalés, Samples were either placed in. separate numbered

jars, o~ israpped in squares of muslin wfth an appropsiats label and packed together in larger ja~s, Ectoparasites and skin saniples were collected to-

gether alid preserved in Bt30ilZrrss fluide A complete intesti- na1 tract was presesved in 10 percent fornal-ln for study of parasitic Acanthocephala, During the fall hun-iloag at Coâts Island in 1956, 11 male and 8 fernale walïus were weighed, The larger anlmals were eut into seven or ej-ght pieces during the butcher-

Ing and each piece WELS hoisted on the boon, to which was

attached a 500 pound CliatilLon ice balance, CompPate sets of body rneasure~neiltswere talcen or* as many anlmals as possible, These, togethar with detailed

skull measurements, will be used in a later taxonomie study, The standard length (direct, nose to tip of tail) and extes-

na1 tusk leng-th are Liie only mea,surerrrlenGs of importance 2;o the present study,

Treatment of Muterials

Sections of nlolariiorrn teeth, several mlllirnetrês thick, were eut with a 3 inch diameter jeweller Ys saw, These were &round dom to a thlckness of approxicna.l;ely 100 ,q with the appartus describeci by Ffsiier and 14aclre~zie(1951;), The sections, both transverse and longitudinal, were examlned under a bhocular microscope in relFlocteà and refracted light, An optical micrometer vas used to measure the width of incremental zones in both the dentine and cernentum, Small segments of tusk sections were examined in a similar way, Stomach conxents were identified to species as far as possible, and numbers of each organism were counted and tabu- latede Small pieces of teatis and epididymis were embedded in paraffin wax and sectioned at 8 to 10~The sections trere stained trith Delafieldis Haemataxylin and alcoholic Eosin, and were examined for stages of spnrmatogenesis, Average diameters of testls and epididymis tubules Fiers obtairied w%th a.n ogtical ~icrometer~ Bacula and skulls were cleaned and degreased by boiling in a strong solution of caustic conmercial floor cleanes, Preserved ovaries were sliced into sections 3 or 4 mm. thick and examined for developing folElcles and corpora lutea of rscent and former pregnancies, SxalZ gieces of corpora lutea and developing follicles were embedded, sectiooed at 8 to los, and stained in Delafipldts Eiaematoxylin and Eosin, Samples of dried didphragm muscle were sent to the Department of Health, Toronto, for analysis of trichinosis infection. RaticmL explui ta tion of a stock of wild animals demands a knowledge of population dynaniics, anci this irr

turn must be based on a study of individualç of kriox.ni age if consurvation is to Se practisnd to the greatest advantage,

Numerous methods have been utllised to determine the ages of particu.lar anbals, but felcr have beon precise enough to enable more than rûugh generalisations about groït~thand mort- ality to be made, Eodv Icn'cth i.ieasürern»lCs, P~rhapsthe most oobvious

indicator of age in any ~.nlrnalis the body length, and this neastirement has been used as th2 standard paranieter of grov~th in most species exaained, Freiman (l9bO) vas able to measure about 800 walrus and attempted to separate age groups in both sexes, The frequency distribution of nose-tail lengths in

the male revealed six distinct peaks at 145, 195, 250> 2909

305 and 350 CD,, and. Freirnan conclildc?d that these represented five immature year groups and a sixth adult group, Al1 the older anirnals were incluàed in tlie latter group since variations of size with age were obscured by individual variabil- i-ty, The females mre represented by distinct peaks at lit-5,

195, 2ZSp 255> and 285 cm,, which Freiman interpreted as four rlrn~natüreyear groups and the adult animals, In the szries of specimens frox the Eastern Canadiaa Arcklc, rneasurements of body length were avai7crbi9 for 9k males and 66 females, Analysis of these dâiô (figo k)

SI~O~TSthat only %lie firs-L twc year groups can be clistin- guished with any csrtaintg, asd at greater ages, Sndivia- ual variabllliy rnasks variabion with age, Chapskii (1936) has reacl-ied a si!nilas eo~iclusiontrom his analysis of data collecteci in the Kara Sea, Fay (1955) has pointed out that an analysis of frequency distributions is only valid when the samples are obtained within a short space of tirne, Since Freirnanls material was collected between the rnonths of une- and Octobar, his interpretation of the data is open to question, Even if sarnpling rnethods are adequate, there is good reason for doubting the value of iength frequency analyses in de- termining al1 but the youngest age classes, Thus, in a detailed stuuy of the southern elcphant seal, Mirouana -- nina, Laws (1953S) analysed the frequency distribu-tiori of nose-tail lengths of 260 males and 142 females, but was unablr; to distiriguish with cer-tainty more -khan the first tw~age groups in the fernale and the îirs-t ti-lree in the male, Though the early grouss were apparently distinct, the ages from the teeth Selied the Eength frequency groupings, and shor~edthat there was an extensive overlap, Perhaps a fri~therargument agains t such analyses is the diff iculty in rneasuring a pinniped accurately, The variation in length depending on the position in wilich the animal is lying when examhed, and perhaps also on seâsonal Figwe 4, Frequeneg hafysis of Body I,ength Measwemsnts in anches, (BXack and white areas on the histo- gram repressnt speclrnens Xrom Budssn Bay an& Foxe Basfna aesp~ctfvefy,) f'atness, must influence the results to some extent. For thls

season the mecisu.rements recorde6 in Figure 4 were grouped in class intervals of îive Inches, If age groii.pç are to be establishecl from linear mea-

~~rernniitswith any degsee or" certainty, then sanpling should be adequate, and meusurements accnrate within small Iirnits, The latter condition can be çatisî~~edby measurements of tusks in both sexes, and further data can Re acquired from the bacula (penls bones) of the males, Tusk and bacu1~1~mmea.surenentss. Analysis of such data yields no mor.e precise inforrnat.ion than can be obtained from body-length measu-rements- Chapçkii (1936)? usfng external tuçk length and length of the baculum, was able to confirm only -Che age groupings determiriud f'ron the body measurements, Beîopolskli (1939) wtiliçed only tuslr lengths in kiis analysis of spximens collected from the Bering andChukchee Seas, but unfortunately he ignoïed the very real semal dimorphism and lu.mped male and femal-e snmples together, Fay (1955) has arialysed a series of 128 male tusks of the Pacifie walrus co'llected within a- period of six t~eeks during the summer, and Sas grouped the Sengths into four initial classes, These he interprets as the first four years of gro:~~.LLh,and atternpt;~to justify his conclusions by seeking Eskirno opinion, Fay states that "the Gambell men readily elassify specimens up to four years of age on the basis of OEL (observe6 externa1 tusk length), and thelr concepts of these are approximately as indicated in (the frequency analysis 1, " Moreover, correspo~~dlngbody L~ngthç:xlso agme vritk~the

first foar age grc>ups c1ete:rmicsecl Ï:tao!n :';'reirna.n1s body--l.jr,gth

data, Certniniy, Zskirnos wi71 readiiy cla-ssify an

animal's a.ge b~hcnasked to do so, but théi~kriowledga is

not basecl on any souriü crrlteri-., excep?; in the yo~mgestage classes considered, CaXves, yearlings and two--year-olds are ea.sLIy recognised fron -t;heir associüti.on with the cow, but after that distinction is lest and age classilication becornes merely a matter of opinion and nothing more, Un-

fortunately, the interpretation of the tusk length frequency gr ou pi ni;^ also a-ppears to be a matter of opinion, and the present author feels that the "series of ~easonablypromin-

ent modes" described by Fay has littLe basis Ln fa.ct,

Fay analyse8 a sampl-e of 107 fernale tusks in the

same wzy, but the frequ.ency histograrn shor.ar?d no modal regu-

larity camparable to the rnales , EIowever , Eslrirno opinion lJas used again to est;a,blish the first four year classes,

and these a,greed closely with those depictecl by Freina-n, Fay also fourld that baculum leng-th was a crude guide to age, but bras of no furtheï nelp in dis tinguishkng age classes, This is in agree~untwlth th2 present author's findings for specircens from the Eastern Canadian Arctic, Claws, Plekhanov (1933) suggested that the conspicuous and regular bands on the cl-aws of several species of phocids could be used to deterrnine the ages of individual seaxs, Recently, McLaren (in press) has been able to es- tabllsii thu vali.ri.it2; cf the n!etbod in -the ïlngeil sca?.., P~Ioc::~

)yjyjis~J3fiik7 5y ~ompa~kighkle n.ttro.bt.r of barrùs on the cla~~rsvitln

"ce age deterrnined f~~ii%nc;iv!;iental zones in the dentine of the caxli-rie teeth* In the presefiLb study claws were collected during routine examination of specimens, but no more than three visible bands were ever found, Fay (1955) fozmd a similar number of banus on the claws of the Pacific walrus, and suggestec! that the frcquei~cy$rith wliich animals haul out and move about on the ice (and laila) leads to attrition of the clatrs by breakage and Fiear. Tee-th. The most important method of age determin- atian applicable to the ~irhi~ediais that discovered independently by Scheffer (LqSOa) and Laws (1953a). Çcheffer found that visible growth ridges on the canine teeth or the northern fur seal, Gq'l_lorhinu.s urç SIE, correspondcd in number with the know age ir, years, determinecl from branding and tagging experiments , Laws s-tudied the s otrthern elephant seal and found that the marked periudç of fastlng and f ceding which this amimal undergoes were ref lectûci, in a differential deposition of dentine, visible rnacroscopically au alternate opaque and translucent bands In cross-sections of the canime teeth. Root ridges were also present on the canine teeth, and these could be correlated with the bands the dentine, It was found that one ridge was formed each year, as in the nor-thern fur seal. Fislies (195'11) and McLaren (in ~ress)have applied the me-thods to the harp soal, PI~oc:c?-~'~o~~snr~~~c!&, ar1.d the ringeu scaL respectively, though in these tt~ospecles root ridges are not present on the canine teeth arid only the dent- inal annuli can be used, Brooks (1953) anc' Fay (1955) have studîed the problenls of grtik~-i;hin the tusks and -mol-arxiform teeth of the Pacifie walrus 2nd have Îoilnd the olekhods of SchefCer and Laws to be partly applicable, at least to the males,

Application of Methods to the Atlantic Walrus

The limited value of measurements of 5he body, tuslcs and baculuri! has been pointeci out in the previous section, and no additional usefuL data can be obtained from the claws, Apart from the value of thc numbers of corpora lutea in the ovaries as a rough indicator of age in the fcmale, the teeth provide the only acc~raternethod of deter?~inlngthe age of 1ndlvidua.l animals , The peculiarities of the dentition are discussed in a later section, and here only the lorm of the tusks (mod- ified canines) and rnnLarlform teeth (Incisors, lower canines and post-canines) need be explained-, Tusks. In the full-term foetus, A Il, talcen on 1.iay 26, the tuçk is a hollow cone of Cientirle 42 rml. long, with an enamel cap measuring 32 mm, from tip -ko "notch"; a few milfi- metres of the root are covered with a 2 mm. layer of cementum (figo 5'). The whole of the tooth is erzibedded in the alveolus at birth, and eruption does not occur until later in July and FI enarne; €3 cernent a çeconcjory (pu.'lp) dentine a dentine

mm.

Figure 5. Cornparison of Tusk Growth in a Foetal, Year Old and Adnlt Male WaLruse - Augrist- Lnitial g~o:\rthIs rapiu, a.13.d i.s wel.2. shoern in Fig1rr.e

6, in wilich the foet;a?- tu.sk 2s c:ornpa.red t,riti~the tus!;s of calves, yearlings, and t:;ro and three yea-r 01-ds, S'cale clra~r-

ings of +he tusks have beqn superirnposed, and the position of

the guni Line in rela-tion to each speclrne~iis indi-cated by appropriate rna.rks, The gut line for the foetal tootfi is not

fncluded since it appears belo~irthe level of the tip. By Octobe-r 7 (A 130), the tusk is 72 inme Long axid projects 21 mrn, from the alveoliis, In the second year -the

tusk has increased i-n length up to 13 cm, by August 7 (A 41), and projects 4 cm, from the alveoluss Both the yearlings

A 41 and il 109 are ea..çily distingtiished from the cal~resby

appearance alone, but their age can be corifirmed when the reproductive history of the motlier is Irnol~ïn, for pa.r.turient

cows do not beccme rcimpregnated un-kil the f'ollo~ringbreeding season. Thus -the imrnatu.re male A 10, rorlnd in cornpa.ny with

the gravid fenlale d 9 on biay 26, has evldently jilst reached the end of its second year, Its tusks am noticeably larger than those of other yearlings and project much fu~tllerfrom the alveolu.~, There is a lit-tle clistal wear on the tusks, su-ggesting that the animal has only recently begrcn tu feed

in the adult mamer, The only other specimen with tusks of comparable length is female A 76 taken on Septenber 19, Sllght wear has occurred at tne tips of the tu-sks, suggesting that the animal has been feelling independently for only a short while, Its body size confirrns that it Is in its third year, The ages of the two otkier fi.îii71cî.ture sp?cimens shom

in Figure 6 are more difficult to asçess if tusli length alone is used, but both are tentatively placed in the groi~p'three years plusf, The tusks of A 37 show more weaJ8 than those of A 10, an6 the enamel cap is almoçt obiiteruted, While body size is littPe greater than that of A 10, the greater Pength of the tusks and the larger molariforrn teeth suggest that the animal belongs to a later age group, The age of A 37 is confirmed by examination of the cementum layers in the molariform teeth (see p. 3619 but the same mekhod brhen applied to A 113 shotrs that thiç specimen is five years old, We may conclude, therefore, that tusk lerigth

iç only reliable as an indlcator of age up to two years in the

female, and two or possibly téaree years in th2 male, The marner in whick; the dentine is laid dom is illusirated diagramatically in Figure 5, The odontobias ts

lining the pulp cavity glve rise to regular incrernental layers,

resembling ihin truncated cones, As the tusk elongates, the more distal portion of the pulp cavity becornes filled with secondary dentine. Zn yo~mganimals the puip cavity is large, but in very old animals it becornes aEmost entlrely obliterated, At birth, the hypercalcified foetal dentine is replaced by dentine of more normal appearance, the change being readily visible in macroscopic sections of the tusk, In the few immature animals examined, the dentine fs fairly unifarm

in texture and bears only faintly discernible microscopic --- relative position ol gum line Figure 6. Cornparison of Male and Fernale Tusk Lengths in the Firsé Three Years of ûrowth, (The nwnkgr a$ the root of eacIi -tixsk is the s'Au series field nurnber, The assurned tusk length at the end of each year is Pndicated by an appropriate mark), strinti~nswhich probably reflect changes in calciun metabo- lism asscvia-ted with feeding, These rnicroscopic striations are fo~ndIn adult dentine, and are overlaid by a larger- scale pactern, particuZe~Iyin th$ maless When Light is reflected at a suftable angle fron the poliskied surface of a tusk section, the pattern fs revealed as a series of faintly mârked zones consfstïng of darker, hypercalcified dentine ~

Melville Bay in June during their spring migration have ernpty stoixachs, and real feeding does not cornmence at the moll-uçc banks about Sauriders Island, northwest of Tnule, wrtil early July, Fay (1953) has fomà thzt root ridges on the tusks of the Pacific walrus ara formed in spring and this fs coincident with the breeding season as well as the middle oi' the migratory period, Anirnals following different migratory routes along the Siberian and ASaskan coasts, where Îeeduig habits may be expected to differ, have tusks which are indistlnguish- able. These j-n turn do not differ from the tusks of an adult male, apparently fro9 the herd resident in Bristol Bay. From these observations, Fay concludes that each ridge represents a breeding season with presumably a period of fastj-ng, and each Intarveriing layer the rernainder of the yearss growth, Insuff lsient factiial data on feedhg habits in the wihter and spring months are avallablc for Foxe Basin and

Hudson Bay, axid it can only be assumed that rnatura males artd fernales are fasthg for part of that tirne* Examination of a smaLl ssries of male tusks showing \sel1 defined root rldges indicates that ridge formation haç just been conpl-sted in ear3.y Jus, artd tktat throughout the smxrner and fall, grotrth is rapld, Even in immature anirnals therc appears to be a period of reduced growth durinç the winter and spring, and visual estimates from the tusks illustrated in Figure 6 show that during the five months June to October, the rate of growth 5s nearly Ixice as much as It is durhng the remalnder of the yecir, Ridges are no% formed on the tusk roots of in- mature aninzls since the rate of growtli, even in winter and spring, is relatively fast. Thus in the flrst year, the tusk may Iengthen by 6 cm,, but this rate of bcreasz declines as maturity is reached, The youngest mature males show only faintly rnarked grorrrth ridges , and the ma-xlmurn distance spart in any specirnen is 3,5 cm. In the oldest rnales, "ce root ridge interval. rnay beconie as srna11 a.s 0,5 cm, There can be little doubt from this cornparison and the foregclng obsvrva- tions that rldgs fornat?ion does occur in the sprlng, and that the distance between the root ridges does represent a yeargs growth, The tusk is firrnly fixed in the alveolus by the 3Lt perlodontal, fibres which penetl-a te the cen:erit;um Îrom the surrounding periodontal rnernb~ûne, Sections of tusk roots froa ~attlremales and 2sniains reveal -thai; 'the cemeritum is divided into well defir'ed concentrj.~3-ayers (fig, 8b) Each layer consistç of a darker inner band of hypercalciîiéd cernenturn which gradually merges into a transliicent oeitar Sand, The transition between the layers is abrupt and Is of ten emphas ised by the distrlbutlon of cementnblas t lacimae, Sections of old male tusks with welL defined root ridges show that the transLilcen-t; zones in the cernentum are formed at the end of the period of slow spring growth. The onset of rapid suminer grovth after breeding is accompanied by an increase in the nmber of cernentoblasts and apparent hypercalcification, which results in a marked da.rlr zone being foraad. The distrnctlon between spring and sumaer growth is more pronouiced irl older animals , particu7-3rly males, The cemuatunt layers are narrower where they overlie the root ridges, and. this tends to sinooth out the external contours of the tusk !fig. 8b), In ~oldweatfiered tuslcs from which the cementum has becorne exfoliated, the roo$ ridges are most conspicuous (fig, 8a),

---Molariforrn teeth* In the full-term foetus A 11, the incisors , molars anci lower canine teath are short, ho11011 colles of dentine, 10 to 15 mm, ?rom root to tip, and capped by a large enamel cromls, tliere is little or no cementua, By the end of the first surnrner, the teeth have lengthened to 16 - 25 rnrn., and thecementum averages 0-38 m. in thickriess (A 130). Figure 8 a. Illustration of the Root Ridges on an oLd Male Tusk after exfoliation of the Cementun,

i year

1.0 cm. I J

Figure 8 b, The Dentine and Cementun Layers on the Tusk Root in Loagitudbal Section. In the J->blrlingA 134 most of the teeth arc lonjo- than

25 mx,, and in the two year old A 76 thcy averp.go 2t -Leas% 35 mm, in length. At this ago the layer of cemuntilm lzas increas~:~itn 1,O nm, in thickness, The teeth increase in leilgkh b;; the addition of hol.10:~-tïuncated cones of dentlne which are sometimes visible externally as shallow ridgcs (fig. 9); internally the dentine layers are sirnilar to those fouiid in the roots of adult male tusks, As the tooth lengthens, the pulp becomes filled with secondary dentine, until finally the whole pulp cavity is obllterated. Closure is a variable factor and may occur belore or after maturity is reached, This is shown most rnolariform clearly in the 1ongitudLrial.sectim of a tooth -1 from femaln A 46, which is pregaant for the first or second tima 31i (f ig. 91, ITYnen destine deposition finally ceasus, the cernentrrm I beconvs continuous over the base of the tooth, and sli~htex- 1 F trusion froa the socket continues to oecur. Exambation of the conplote dentition fron several Immature and aduPt anirnals shows that the samv relative amount of cernentum is laid down on each tooth and tusk. In the first I sunimer cem3ritu.n is even in appearance, but in the follobring spriag a lighter zone may be laid dobm (A 134)- In the immature male A 10, which is nearly two years old, the lighter zone separating the cementuin into -ho nearly equal laye~sis not clearly defined in al1 parts of the sections exarnined, wilich indicates that the processos underlying cementum deposi- tlon are not regular as yet. In the three year old A 37, the Figure 9, Longitudinal Section of the Lowes MoEkr Too-kh of a 7-Year-07d Fernale (x 3,S):c = cenontua, d = dentine, pc = pulp cavity, sd = seconda~ydentine.

Figure 10. Part of a Transverse Section of ths Lower Molar Tooth of a 21-Year-Old Male ( x 15), amual gro~~thincrements in the dentine are plainly indicated hy ridges, and each ridgs 1s accornpanied by a translucent band of cementum, the innarmost of which is not as well defined as the outer two, In adult animals, especially old males, the cementum is separated into more clearly defined layers, wide bands of darker cernenturn al- ternating with narrow translucent bands; the nurnber of bands is constant for al1 the teuth in one dentition, The bands are much more sharply defined than those found on the tusk roots, and this is attributed to the corn- parative Sack of periodontal fibres* In the tusk cementum, the large nurabers of fibres and their psriodic readjustment to tusk growth give the cementum layers an uneven contour which sometimes complicates interpretation, Conparison of the tusks and molariform teeth in individual old males shows that the narrow translucent zones of cementum are laid dokm at the same tirne of year. It may be assumed that the spring months are times of moderate feeding, for the translucent cementum Is evidently hgpo- calcilied. This is shown by the exfoliation which occurs in teeth exposed to the 'tlreather for long periods, for the cementum separates off into layers which break along the narrow zones. The first formed layers are wide and they becorne progressively narrower as their number increases; there is no indication, in the males at least, that deposition of cementum $ver ceases. bhen the wicith of cenenturn layers is plot-ted agains t the assumed age in yoarç , ail expononti.a.1 gro?,~$l?, curve is obtained (figo Xi), and 'cl* bearç a satisîac.torÿ relation to the stralght 7ine representing- the rate of deposition of cementu In the first tvo years, Thus it js assumed that after the second year, one well Jefined layer of cvmentrrm is laid dovm annually, and this continiles throtrgkiout the life of the animal, In the Pacific walrus, Fay (1955, fige 31) tes-bsd the relationship between tusic. length and nuniber of ceinentum layers and concluded that the layers were as good indicators of age as tusk lengthsg in fact they were probably better in later years. However, in the earlier age groups, there appeared to be no correhation of age with the number of iayess, and Fay assuned that depssltion of cementum was irregular in the first six to seven years, This certainly does not apply to the Atlantic walrus, for the foregotng analysis shows that there is a good correlation between age and we1L defined cementum layers at al1 ages after two years,

In -view of the doubtful basis on which Fay '3 lirst four year classes were erected and the more subjective nature of his analysis, it is impossible to make any direct cornparison between the estirnateci gror.:rth rates of the two forms, Ho:?- ever, if it is assumeci that cementogenesis is similar in both the Atlantic and the Pacific walrus, than linear measurernents cari be compared directly. Such mea.suremen-ts have been ex- tracted from Figure 31 in Fayfs report and they are tabulated in Appendix V; the values are necessarily ôpprûxirnate since they are cierived from a mean curve, Similar values are aZso recorded for the Atlantic walrus and the signifieance of these measurements Is discussed in the section on growth, The cementum layers on the tusk root cannot be used for deterrnlning aga since they represent only part of the anfmaL9s life history, En general, even fewer years of life are represented by the root ridges, but Ln some tusks an appsox- lnate estimation of age can be made by plotting the distance between the ridges and then extrapolatulg the curve exponenti- ally to the lirnit of the tusk, ihen distal Wear is accounted for, an estimation is arrived at which closely agrees with the age determined from the cementum layers fn the molariform teeth, Determination of apv in the fernale, Growth of the tusks in the Semale follows a basic pattern similar to thaS of the male, but certain differences occur which yender interpretation of the chronology of dentine and cementum deposition difficult, Few adult tusks bear growth ridges on the roots, and when present they are rarely well defined, Cementuïn deposition on the root is irregular, and it has not been poss2.bl.e to correlate defbite layers with the rfdges, as in the male, However, on a91 tusk roots sectioned, the number of cementum layers increases hi a regular manner from the open end to the gum line, and this suggests that deposition occurs exactly as in the male, Xn the molariform teeth, the cementum has a slightly less praportionate bulk than in the male, and race of dcposi-

tion ûppears to be more irregular, Banding of the cementm

occurs In a91 animals older than ~WOyears) but in only a Sew specimens does the pattern approach th-t of the males in cl-arity and regularity of deposition (fige iO), it would appear that in both males and females the same seasonal influence regulates cementum deposition, but this may be some- tirnes over-shadowed by the phyçiologlcal demands of pregnancy and the long lactation period, In the fernale Pacifie walrus, Fay (3955) has found that éhe relationship between the observed externa1 tusk length and the number of cementun layers Pn the molariform teeth a.pppars to be radically different from that in the nales, and may have Sittle or no practical application in detcrrnining age, Kowever, observations on the

Atlantic walrus show that tus4 Iength ln the fernales as very

variablu owing to rapid Wear and breakage and is of less value In deterrnining age than the cementun Layers, In Figure l.1, the width of cementum 'I.ayers is plotted against assumed age in yearç, and normal exponential growth curves result, Conparison with the îimiting cusves for the adult males shows that the cementum Sayers in the fernale are generally ncirrower, and. this is entirefy as exgected whea the maximum çize of the âdult animals fs considered, In some speciwens oZde~than %en years, the outer-

most incremental Eayers are very narrow, and age interpreta-

tkon becomes difficuli, The ages of ths oldes animals re-

. corded Sn Figures 12 and 14 and in Appendix 1 shsuld -the~efora Width of cemontuns in mm

Fignre 11. Depoçition of Cementum on the Roots of Molariform Teeth in Males and Fernales, be regardefi as minimal,

GROWTH

The Maiv

Body Leneth, No new-born calves are avàilable in the series of specimens from Hudson Bay and Fox& Basin, but the foetus A 11, taken on May 26, was evidently full-term and its body Sength of 47 inches may be considered to repre-

sent that of the new-born anhal, The body length of caEves taken in fi-ugust a,nd September averages 56 inches, and thls compares closely wlth measurernentç of the Paclfric walrrrs (Fay, ~955). The increase of body size with age is secorded as

a scatter dlag-am in Figure 32, The speciniens collectecl in northern Foxe Basln Irese mcasured along the ventral curvo of the body arid the ~esultingfigures have been decrea.sed. by ten

percent to make them comparable tg the Hudson Bay specimens trl-rich trere measured in a direct line from nose to tail; this correction factor 1s ari average figurs deterrnined from the measurements of 81 female and 13 male walrus from Southampton

Islande The average growth curves were sketched in by eye trith guidance from a series of regression lines calculc3ted from the method of least squares, Growth in length ceases between 20 and 25 years when a.n average niaxirnwn size of 120 Inches has been attained, The figure shows that walrus from Foxe Basin tend to Age in years

Figure 12. Growth in Lengih of the Body of Males and Fernales be larger in average size than those fron northhcrn Hudson Bay, a fact which has long bsen known ta the Eskimos of Southampton Island, This sfgnfffcant size dlfference may well result from a clifference in feedPng çince the Foxe Bôsin shallo;~sare evidsntlg an abandant source of food, and the little evldence avai.lable on dls-tribrrtion and migration s-trggests that discrets breeding populations ars also represented, The Pacifie walrus is slightily larger than either of these two Sorms, and grorqs to a me~mbody Xength of 135 - 140 hches (f-ay, 1955; Freirnan, 1940)~ Since those measurements were al1 taken aLong the ventral curve oî the body, they must be decraased by %en prcent to make them comparable to tha s-tandard lengths of HudscmnBay and Foxe Basin speci.rnens, The final ad jus ted mean value of 12lt inches reveals a slight bu.t probahly reaL dlfference in overall Zength, Cornparison of gsotrth rates In irnmatu~eAtlantic and PaciSic walruç is difi'i- cult since zgeing tecknfques differ, but some assessrnent of changes in the adults may be made If lengths are considered only in relation to the number of cementu.n Layers in the molariform teeth* The data in Appendix V then show tbat ai'ter the eighth layer is forxed, the Baciîic walrus grâdually gains a slight ascendancy in size. lncrease in wei~hta The few data available from welghings are set out graphically En Figure 13 and a mean curve has been fitted by eye to the points; the data suggeçt that SI-oar.grarith continues thr~ughoutIifs, Since no new-born calf vas taken, the weight O@ the full-term foetus A 11 is included for eomparison. The dismembesed animals were weighed with a 500 pomd sp~ingbalance (accuracy approximately plus or minus ten po~~icls)and no allosliai.ïice was made for hoss or blood, No detailed weights of interna1 organç were recorded, and the figures set out in Table I are taken from LougPirey

(1955) 9

Werlghts of Various L~.tesnalStruc-tures of an AduZ",MaSe Atlantic Ilalrus (Loughrey, 1955)~

dj tructwe IrleighC fn Percent of total pounds bûd weigh% !208 E pouxlds )

Skin and blubber

Stomach, spleen, pancreaç 76 and intestine .. -- --

- - @ O --r--- C -P------J - / I / /' 0 O O I 0 Q -0- -- O 1 0 -0- -- - O / Q ------O------/' ----_ O f R O /+-- O ' @-- /' I i

@ - mule o - fernale

Ar- 17i: I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 overage 20 unknown hge in yearç Figure 13, Increase in Wefght of the Body (the weights of 4 males and 6 fernales of unknown age are taken f rom Lougkirey, 1955), The maximum weight recorcled is approx.i.iïiately 2600 pouncls (1-ess bl-ood) , but es timated wclghts of otiiqr. specimenc;, and visual observations of body size in very 1-argv males, sirggest that 3000 pou-nds mûy be reached occasionally, The maximum weight of the Pacific walrus recorded by Fay (1955) is 2800 poux~ds. ---Grovth of tusks, Although the walrus of northern Foxe Basin appear to be slightly larger on the average than those %aken in northern Hudson Bay (fige 121, there is little evidence of a difference in tusk size, However, when these two populations are together cornpared with the Pacific walrus, a great disparity in tusk size is shom, and serves to confirm the that two morphologically well-defined exist, view groups l The values of external tusk length are set out in Appendix V, trith the nuiber of cementum 1ayer.s In the molariform teeth forming the basis of cornparison, At five yea.rs of age there is little difference in tusk length, but after this the values begin to diverge, At twenty years, the tusk of the Atlantic walrus has almos "seased to lengtlien, indicating tht distal Wear is becoming equal to the annual increment of dentlne at the root. In the Pacific walruç, the growth rate does not show any appreciable change until after twelve cementum layers have beên laid do+m, Hotrever, grow%h still continues at a greater rate than in the Atlantic \ralsus, and does not appear to cease untir at least thirty cernentum layers have been added to the teeth,

---..Growth of the baculum, Bacula were first prepared by boiling in a strong caustlc soap solution anrl tben Left to

dry in a warm room for several weeks, The ~eightsand length measuremgnts of 40 specimens in the prescnt collection have been plotted in Figure ly and the curves show that tliere is no sudden increase in the rate of growth at maturity, as In several species of piiocids (Fisher, 1954; Law , l953b; McLaren in press), The strongly sigrnoid gro~rthrecorded in the Pacific walrus (Fay, 1955) is not apparent in the specimens examinecl,

The Fernale

Throughout lactation, growth of the calf is maIn- tained at a rapid rate, and little decrease is shotrn unLi1 nutr5tional independence is gaincd, In the third year, a marked change in rate occurs and the male and female growth curves Segin to diverge. At 20 years, the adult Êemale attains x maxlrn~~nlaverage size of 102 inches and weighs approxirnately 1680 pounds,

Difference in the body and tusk growth rates of the Atlzntic and Pacif ic fernales cannct be evaluated since Fay (19E;S) ;$as unable to correla-te age with cementum layers at any stage of the life hlstory, Only the oldest adult animals can be compared and these show that a slightly larger slze is attained in the Pacific walrus. Ths the average maximum body length is 108 inches (corrected) and the weight 1700 pounds ; these measurements dif fer significantly f rom thoss of the male,

Tuslc grorrrth in the female Atlantic walrus iç slightly sl-ower than in the malvs, After twelve years, correlation of tusk length and age is usually impossible since rapid w5ar and breakage of the narrower tuslr leads to very variable measurernents; thus in Figure 14, two sixteen-year-old feniales are sko;-m which have -kusks shorter than one of' the six year olds, The maximum tusk length recorded is 14 inches, and Fay gives 18.5 inches for the fernale Pacific walrus, This small difference may indicate that the fenales are less divergent in tus!< characteristics than the males, though ft could result fr~ma size limit imposed by gïeater wear and easier breakage in the fernales of both forms, 116ni.3-e the male tusk is also exposed to strong wear, its greater thicliness keeps the effect to a minimum and allows growth to occur mtil late 1 in lifee I 3

Semal Dimorphism

The marked difference batween the sexes in tusk and body lengths and total treight are sumrnarised in Table 11 . Eody length data for the Pacific walrus are taken from Fay (1955, 2ig. 2l), and the measurements have been d~creased by ten percent to give approximate direct nose-tail lengths. The body length data of the Kara Sea walrus are those given by Chapskii (1936) and are evidently direct nose-tail length measurernents The tusk measurements indicated are the mean lengths at sexual maturity, and body measu.rements are the maximum averôge lengths of adult animals, The ratio of male to female c,"

/ I

o Hudson Bey Foxe Basin

O 2 6 8 1 O 12 14 16 18 20 25 30 35

Age in years Figure 14 GrowPh in Lcngth of the Tusks. TABLE II

Comparative Semal. Dimorphism iri the iJalsus

Tusk length Body length Male body size in in as percent inches inche s of fernale

M F M F Length Weight - PAC IFIC 11 Be5 12% 1.08 120 150 Ee CANADA 7 5; 120 102 3-20 3.50 KkLSt SXA 90 8 1.25 120 - body siza for the Pacifie walrus is taken from Fayis data ancl repsesents average values fsom several authorities, The grega~ioushabits and narkvd huddling behaviour

of the walr~lsare simiJar in some respects to "the bshaviour 03" .bile poLygyrhsus harem breedtr-s sueh as the northerr~fur seal and the southern elephant seal, Ho~iever,harem breeding is charac.kerEsed by dominance hierarehies in which snxual select-

ion for size and flghting abiiity In the males Is actively maintained, Compara bive f lgures for the polygynous specieç (P'ay, 1955) shov that male body length varies from 130 - 165 percent of the feinale, and weighg from 380 - 500 percent, The figures for the different grouys of the kralrus set out

in Table IJ: bclicate that, &hile sexual di~~orphismfias oc-

curseà, it is not pronovaced enough to sugges-b a polygv~nous habit.

...... ----The calf, Tiiere is llttle uifference in extemal appeaîance between the full.-ts:m foet~:s A 5.1 and -the two- month-old calf A 39, and. the foklowdng d-scription Zs considered applicable to -the nelrrly born a'nimal,

The skin 3.5 slate gray in colsur, particularly wéien wet, and Es covered with a coat of short silver-gray hair fsom

5 to 10 mm, length (the preclss colour 1s hard to descrLbe, In f leld notes it is given as "asb-blond"). This ha%r covering evidently corresponds to the embryonic pelage f lariugo) cf Age in years Figure 15. Grosth of the Baeulum. phocids, for it has been fovnd in f'oetuses of i;he i'a2ific walrus taken in November and Decernber (Fay, in litt, ), Nikulin (1940) ka.s described. tiie appearance of sixty calves

taken in Ju-ne and July, and s taCes that during that time an intensive loss of embryonic hair was occurring, Most of the later calves were bald, but Idilrulin gives no indication of tihen the first hair coat was forrned, Xn the calves taken from nortliern Hudson Bay in the summer and fall, it is apparent that the natal pelage has been replaced by a thinner coat of shorter and stiffer hairs, 1 to 2 mm, long, The urnbilical cord is probably lost shostly after birth, and the navel scar is healed at the end of three rnonths, Tne upper canine teeth do not pierce the gums until two rnonths after birth, and by late October they may attain a length of 2 cm, The mystacia?.. bris-tles are short and inwardly curved, the longest attaining a length of 5 cm, in a two-month-old calf, Both fore and hind limbs are proportionately large. ---Irnmatuwe males and -_Semales, There is evidence that an annual moult occurs in the sumrner rnonths (see p, 76) and the old hair, which has by thiç tirne reached a Length of 2 cm, and has attained. a reddish-brown colour, is shed, and a ne~r and sparser coat of silver-gray hair develops, The skin colour is stilf a slate-gray, but the patchiness of the hair adclç a brownish tinge to the overa-ll colour, Animals which have been hauled out on ice or land for a long time may ba stained a

Light brown colour with faecal matter, and this may be partly res ponsible for the final. colour of' the rnoülting kiair , Scars are i~suallysmall in nunlber and appear to resul-t froro. worinds caused by sharp edges of' ice or tusks of other animals. Occasionally, heavy scarring occurs and a possible explanation has been suggested by Soper (lqklt), A yotmg (probably first yea.r) nale was taken on October 24 at Cape Dorset and the whole of the back was covered with small circular wounds and shallow scratches, "The Eskimos were of the opinion that its mother had died, whereupon the orphan had been bullied and abused, until it was frlghtened and discour- aged, and had left the herd to shift as best it could in soli- tude". It is impossible to d istinguisln the sexes of immature animals up to threz or four years of age when ob- serving them from a distance, but older sub-adults can usually Se accurately sexed if a clear view of the head is obtained. The broader muzzle and thicker tusks of the male are apparent, and the tusks of the fernale are often sha-rply pointed as a result of theis more rapid antero-lateral wear, The adu.3.t fernale, The oldest îemales are usually heavily scarred along the back and about the neck, and it is ass~medthat many of the wounds are received from the male during c~pulatiori~This is knot~rn to ba a characteristic feature of mating in the northcrn elephant seal, uro~m~a anzustirostris, (Bartholomew, 1952) and the southern elephant seal (Laws, 1956a and personal observation)- Occasional individuals are observed with a prono~mcedcrom of whitish scar tissue, and this may resuLt from the forceful method commonly used to keep open breathing holes in young ice, Similar scarring occurs on the heads of the males, aad also on the heads of some old bearded seals, Constant abrasion on ice and rocks results in the underside of the body becon- ing alinost pink in col-our, and an overall mottled eLfect Is produced which is very difficult ta descriùe adequ-ateiy, The tusks may become almost as long as those of the males in a few individuals, but their slender structure usually results in more rapid wear and a sharply pointed profile. The greater degree of twist and curvature may alrnost cause them to Soin or even overlap at the tips, if wea;l.has been minimal, The vibrissae are longer than those of the male, the lateral ones attaining a length of 10 - 12 cm,

The adult--.- male, The thick powerful tusks and broad mrrzzle atoonce distinguish the adult male, and tbesr chaqacleristics are most prcnovnced in old age, At sexual maturity, the neck, chest and shoulders become covered with large epidermal tubercles. These are hard, white, fibrous protuberances up to 8 cm, across and 4 to 5 cm, thick, and tbey are undoubtedly a secondary semal character (Nikulin, 1940; Fay, 1355). In the Pacific wal~us,the skin is much thicker (Fay, in litt,) and the protuberances in the neck region may reach a thickness of 7 cm, (Brooks, 19541, The lumpiness of the skin about the shoulders, and the development of powerful neck muscles to move the heavy skull, give the male a characteristic depth in outline which is unniis- takeable, Thet-berc/&increase in size during life, and in old age the skin o.ver tlie rieclc and shoulders assuntes a pronounced pinkish-white mottled appearance (fig. 16). Scars from tusk inflicted womds add to the overaI.1 blotchlness, and this may account for the "albino" males wliich are sometimes reported (Brooks, 1954). The hair covering is sparser in old anirnals and rarely exceeds 1 cm* in length, Most of the coloür changes associated with increasing age can be attributed to the skin, for moulting hair is usually a reddish- brown colour and the new hair a silver-gray, However, some individuals have light golden-brom hair, and this may result from a missed moult and siibsequent fadinç of the retained hair,

This Is Itno~rnto occur occasionally in the southern elephant seal (Laws, 1956%) and may glso explain the straw-coloured crabeater seals , Lobod-on ca~cinopha~ussometimes observed (personal observation). The mys ta&l bristles becorne worn with advancing age (fig. 17), the more medial ones sonetines becoming flush with the skine Theye seems little doubt that the wvar can be attributad to the constant friction Involved in feeding. Mahr (1940) is obviously mistaken in implying that the animals with short whiskerç taken in European waters In the 20th century are immature. They were most probably old males.

Deciduou~and~ern&n_cnt tteeth. Only two complete young skulls and an additional.lower jaiu are available for Fig. 16, Head and Shoulders of an Adult Male Walrus showing Epidermal Scarsw and Tubercles from Tusk Inflicted Womds.

aa.4 ~i~,17, Head of annBdu1t Male Walrus showing Worn Tuskâ and Vi.brissae, examination (foetus A 11; calf t13; calf W2), The deciduous dentition appears to be: and this may be reduced by prenatal resorptlon (fige 18)- Fay

(1955) identified a fourth upper prernolar, but this has not been found in the two skulJ-s available, The full set of successional teeth is present at birth, but does not bôgin to erupt witil the calf is two or three months old, The formula observed is:

Fay has found that the second and third lower incisor and the second Lotrer niolas are present, giving a complete formula of

Al1 the data relating to the adult dentition ax-e sum~xarisedin Table III, Many of the skulls examined were fourd at oSd Eslriino camp sites, and usually most or al1 of the teeth were missing, Tlzus in some of the slcu11s the presence of &he norrnally vestigialteeth was not directly observed, but it was inferred from the development of the alveolus. Although na slrull was observed with Inore than t~tm tusks , rare specimens are known in which a second tusk is developed on one side. Figure 18, Dentition of the Full-Term Foetus A 11, (Teeéh indicated by bracketed numbers were n~tobservad in the speclmens avallable, but were hferred

from Fay8s account of -the Pacif-lc Wa7rus (1955) TABLE III Observed Variations in the Denti tion

Incisors Canine Pos t-canines

------.------Sex O 12 O L :- 012345

L1 278 14 R1 269 UPPER

The figures in the top line refer to the ntxrnber of teeth of each type present, and not to the position in the skull, The figures Ln the body of the Table are nmber of specimens examined, Frorn Table III it will be seen that the sec0n.d and thircl lower incisor, and the first upper and second lo~rer molar usually remain vestigfal and may becone resorbed, while the second upper inclsor, the fourth upper preinolar and the first lower molar occur fn up to 26 percent of the skulls

The normal adult dentition may be considered as:

ILCIPm3 O l 3 -Tooth Wear. Most of tlie apical wear of the molariform teeth results from occlilsa1 abrasion, though some is undoubtedly caused by the tcngue and opposing gingival tissue, Fay (1955) has pointed out that sand arid grave1 are of'ten found in stomachs and observed about holes in the winter ice trilese clam shells have becn spat out, and he assumes that much of the abrasion resulks Prom the ingestion of this material while feeding, This view appears to be confirmed hy molariform testh fron the Atlantic walrus, for close inspection of the opposing surfaces reveals that many bear minu-te pittings and scratchings, I~iost tuslc wear is alitero-lateral, and is unldoilbted2y associated with the rnethod of fecding. In mature anima-1-s of both sexes, shallow media1 depressions are ofteil observed he- low the level of the guin-line and thsse are evid.exitly caused by somo rnouth activity (fige 7). Fay has found that in the males, the distance betrreen tile depressions is equival-?lit So the root ridçe intervals, alid in very old animals only a broad deep trough is iound. The fernales often show series of tiidnly spaced deeper troughs as >:el1 as the sliallor~depressions, and

Pay has associated these wlth an enormous increase i~tfeeding during lactation. The evidence for these assumptions is that the distances between the deepeçt troughs are comparable to the total tusk length increments (Absolute Total Length) between pregizancies. Though few tusks are available in the series of specimens from Hudson Bay and Foxe Basin, the pattern of medial tusk wear in the male agrees with that found in tne Paclfic walrus, but no valid deductions can be made from the female material. The depressions evidently result from a periodicity in growth, and this probably depends ultirnately on seasonal changes in feeding habits, The wear appears to be caused by the lateral moveinents of the lobrer Jaw during fecding, for the skln of the outer lip 1s very rou.gh to the touch, However,

Fay (1955) quotes Eskirno opinion h hi ch favours the possible exprrlsion of materials (presurnably >rater and food detritus) fron the nouth, though this would appear to occur too infre- quently to result in such mas. Furtheï distal weas a.nd fracture may rcsult from the use of the tuslcs while haullng out onto ice or rocks, Though this pattern of behavlom- has resulted in many cont$oversial statements in thil literature, it lias becn observed frequently enough by the author to suggest that it is a potent cause of tusk wear, Fighting, or mere exchange of blows between indi- vicluals in a disturbed herd is cornrnon, but it is doubtlul trlletrier the tusks suÎfer much in such encownters. Food preferences

The lactation period of the walrus probabl-y lasts for trso years in the najority of animals, and may be ex- terxied into the third year if the adult femâle does not give birth to another calf, The stoaachs of calves and yearling animals talren in northern Hudson Bay were always empty or contained only milk, alid "cis is in agreement with the observations of other authors, Nikulin (1940) records the finàing of milk in the stomachs of 2 two-year- old animals, and quotes a sirnilar observation of Freiman (1940) who found both milk and the remains of molluscs in a two yrar old, The adult mode of feeding is assumed to begin in the third year, since dlstal tusk wear 3s first apparent then. However, Brooks (1954) has suggested that the immature animal remains wi-th the cow, and Ray rely upon her to rake up its food, The adult walrus feeds almost exclusively on the nollilscs which form the greater part of the Hacoma calcaria cozrnunity (Vibe , 19501, thûugh amielids , crus taceans, ho?-O- thurians and tunicates rnay be eaten occasionally (Table IV), Foraging depths range froro 15 to 80 metres, and the walrus is rarely found ove- water deeper than this, TABLE IV

Food OrganFsms taken from Stomach Contents

Areas of Occurrerice A - Bencas Island and nortl-ieastern Coats Island (12 stomaciiç ), B - Seahorse Point, Southampton Island (2 stornachs) C - East of Cape Dorset, Hudson Strait (1 stomach). D - Loks Land, Frobisher Bay (1 stomach). E - Nosth7.?estern Foxe Basin (3 stomachs). Foods narked with an asterisk could not be identified further than the groups recorded, ------~\JO* No . of No, Areas Food species of s tomachs tirnes of organisins containing dominant occurrence organisms

Palecypods (siphons )* 22lt 7 A, E

Shell fragments * 4 A Mya truncata 2193 14 8 A,B,D,E Cardi1.3 spp, 221 ? 1 A,B,E Saxicava-grctica 3 50 EO 2 A,B,E Astarte borealis 58 1 33 Pecte~sp, 140 4 2 A Holotnuroidea

-Thzonidium sp. 14 5 A9B9C7E Gastropoda * 19 2 B9E OpercuLa * 2 53 4 I A,B,C,Z Buccinum spe 50 2 GD Siph0 spo Decapoda * Eggs * Paguridae * Eu~a~urusKrë~erj- Hippolytidae

Eualus sp, 1s opoda

Ascidiacea *

------Prianulus caudatus-- Squid beaks * Fish otoliths *

~las~aAi~s~U-skinand blubher 2 lb, 1 Vibe has siiown from a detailed qualitative and quantitative survey of the, wairus bariks of northwes-tern Greenland that th? two species of Carc1iu.m are most frequently eaten at depths from 15 to 35 m., and aiid

Saxica~rn,from depths between lt-O and 80 m.. Since the latter two bivalves are cominon in the botkom fauna at the shalloi~rer depths, it is evident that the walrus selects the larger species by foraging over large areas of' the bottom, At greater depths, Car.diurn are scarce, and few are found in stomach contents. Vibe suggests that this partly results from the minimal feeding time available; expediency is necessary, and the kralrus forages over as litkle of the bottom as poss ible, No similar data are available for Foxe Basin, but

one Eskimo (~ramanik)has conf irrned that Cardiu-tn is generally more abundônt in stornachs of animals taken at Amitioke Penin- sula, ~rherehunting is usually done in shallow water. East of Kringmiktorvik, where huting talces place over dee~er water, the siphons of lys and h~icava.form the principal food elements , In the Pacific walrus the sexes appear to show diî1'es- ences in feeding habits, for Brooks (1954) has found that the males seem to select m, Clinocardium and Molrad&, bwhile the fernales and immature animals favour the smaller molluscs, -Astarte and Macona,

During local dispersals and more pronounced migratory - movements, walrus may pass over less suitable foraging grounds in which molluscs a:.c rlot domiriant, It is tkien that the other benthonic organisms already referred to play an important part in feeding (Table IV), It was formerly balieved that the walrus was partly vegetarian in diet (Allen, 18801, but no signiflcant aniounts of plant material have been found i.n any stomach contents ex- arninvd, Brooks (1954) has noted that the food is often covered with algal slime and suggests that it may play a nutritional role in supplying vitamins ,

Vethod of Feeding

The follorci.ng observations on feeding largely confirrn the excellent account given by Vibe (1950)~ In adult animals, most tusk wear is antero-lateral, Wnen considered togeth-er wlth the vibrissal wear, this strongly suggests that the t~alrusforages in sand and mud by standing on

its head and rotating its tusks frorn sicic to side in the su.b- strate, Adult animals with a broken tusk, os one mlssing from a congenital defect, are sometimes seen but they appear to feed normally, Brooks (1954) has observed an ~ldand appasently healthy male with both tusks absent, which suggests that the mystacial pads may still be efiective in food gathering, Though the vibrissae must be to some estent tactile and of some use vinen feeding occurs at depths below the limit of vision, they are neverthvless worn very short as the animal grows older, and perhaps becorne of limftcd use then, In spite of the broad rnuzzle, the lips are probably very sensitive and able to select the food organisns required, The great breadth and deptl-1 of the rnolariforrn teeth was long considereG Vo hs an adaptation for crushing the hard- stielled molluscs on which the aia al rus f eeds (Cobb, 1933) e This vie;;point seerned to follo'szr logically from the knovm fact that nypercementosis in hurfian teeth results from increased occl~isal stress, However , the hooded seal (Cvs to~horaCS-is tata) exhib- its a high degree of hypercementosis, though it is evident from the pelagic nature of this species that the diet must consist of relatively soft-bodied food organisrns such as fish, squids or crustacea, which would require little crushing. Fay (1955) has found that al1 sizes af teeth, irrespective of function, have corresponding arnounts of cenentum, and suggesb that hypercementosis results from an o~rerallpliysiological fmctfon related to tusk growth, rather than from a purely mechanical compressiont The strong Wear on the molariform teeth may then be esplained by normal occlusal abrasion aided by the srnall particles of grit and sand taken in with the food, + The walrus is able to select not only small individual food items, but can readiby separate the more edible parts of thern. Thus the species Serri-oes, Cardiun, Clinocardium, )lacoma and Astarte are represented by the feet alone, while only the siphons of and Saxicava are taken. Since other parts of the bivalves are rarely included in the stomach contents, the walrus must remove the fleshy feet and siplions by squeezing thern off with the opposing anterior surfaces of the upper and lower jaws, Illhere is good svidence that the fect of &~~-G~;PI_s~ (~ardiu.rn)groen1.ii11cIicun~ are cornpa.ratively s1o'r.r in re tracting, for MikuPich (1949) has fo~sndtizat they are extensively eaten by a small fis11 (Pleurograrnmi*. a.zonu.s), clos3ly related to the greenlings* After the foot has been removed, the clam dies, and the rest of the body is tnen eaten. 1%may be concluded that the walrus is also capable of rernoving the feet before tkiey have had time to contract into the shell, This is probably not the only method of feeding,

for Vibe (1950) has observed that quantitics of intact and connected bivalve shells aie sometimes fouid about the breathing holes of the tralrus in thin ice, From tkiis evidence, he st~gges-tsthat the aninal is able to sizck out the soft parts of the bivalve before squeezing off the siphons, Gastropods such as gucci19~and hermit crabs (-rida%) are also eaten, but no shell fragments are fouid in the stornach contents. Vibe notes that Buccinw has a thin shall which is of ten open at the top, and suggests that the soft body of the gastropod is easily sucked out, There seems little doubt that the herrnit .crabs are removed

in 2 similar fashion since their soft bodies are more nxrnerous in the stornach contents than the anterior thoracic segments and large appendages, In only one species, Pecten, in which the adductor muscle alone is renioved, is it nost likell- t1ia-i; the tihole shell is crushed, In this instance, both shell fragments and the softer body parts are probably sepasated by the tongue bef ore expulsione

Aberrant Diets

Chapskii (1936) and Nikulin(l~40)record the only two observations of stornach contents whicki were largely corn- posecl of fisb. In each case, only the polar cod (Boreo~adils saida) was represented. The record of otoliths in one alrus rus stomach from Cape Dorset (Table IV) indicates that the fish- eating habit is probcLbly resorted to iflien the normal rnolluscs are In short supply, Furtner indirect evidence is availablr fron the intestine of an adult male A 127, which contained a large nlmber of' Acanthocephala of a species normally infest- ing fish as a second internediate host (Dr, Paul Montreuil, verb, comm.)* Fragments of the skin and blubber of several species of pinnipeds and cetaceans are occasionally found in stomach contents, The ringed seal is most often represented, but the bearded seal, hooded seal, narwhal (Monodon monoceros), white trhale (Delphina~t-cru-s le~~easand bowhead wkiale (Balaena pysticet-~-ç)have al1 been reported, In the series of specirnens from the Eastern Canadian krctic only one stomach out of 35 contained pieces of ringed seal as food, The rancid nature of the blubSer suggesteè that the food had been dead for a long time before being eaten, However not al1 food of this sort is carrion, for numerous and well substantiated accounts show that certain adult walrus actively prey on seals, These adult animals are rogues, for the 2skimos from northern Hudson Bay and Foxe Basln state that they are al].. rnales vihich are soli:ta.ry 8.t the tims of capture, The causes of the carnivorou-s habit aïe obscure, AccordFng to Fay (7955>>the Alaskan natives say that the rogues are orphaned Young t\rhich never learned to feed on the bottom, but this ignores the fact that only males becorne rogues. It is not kno.im whether seal meat is eaten to the exclusion of other foods, but the tusks, yellowed with greasc and often heavily scratched, suggest that tbis is so, Such a diet is paralleled only by that of the polar hear (I?a_-arctos maritirnus), and it is of interest to note that the liver of rogues is regarded as unfit to eat by the Eskimos. Roclahl (1949) has described hypervitarninosis A in polar bear liver and its toxic elfects on human heings, and thls m2y explain the E:sklraoç ' distas te of rngue r+lalrus Ilver,

Fas ting

The wri.tings of earlier authors concerning the ha.ulkng-out habits of the Atlantic walrus have been weJ.1 surnmarized by Allen (18801, and Nikulin (1947) and Fay (1955) have contributed detailed studies or the Pacifie walrus, From these accounts, it appears tnat at al1 times from April to Dece:r,ber, and probably throughout the whole year, the walrus hauls out onto land or ice during periods of fine weather and remains relatively inactive between feeding excursions, Allen (1880), in quoting 2n account of ShuPdham ~rrittenin 1775, states that during the spring, 1ra1r.u~af; the 1-Iagdalen Islands used to rernain ashore for periods as long as fourteen days provided the ~reatlierwas fair. Fay (1955) has observed tl-iat during 1;i'ovember and December tl-ic Pacific vralrus may remain on shore at Big Dionede Island for as long as a ~jreek, and Nikulinls account (1947) gives five days as the maximum time. At Coats and Bencas Islands, the present autilor fou-nd

that walrus did not rernain ashore for longer than six days, owing to the frequency of ba.d weatkrer, Though feeding appears to be intermittent at al1 tirnes of the year, it is proùably more intensive during winter, OP 111 stomacl~sexarnined in the field, only 35 contained food of any sort. During the period Su-ly to Oc Lober, slightly more fernales tban males have food in their stonachs (f ig. 19), but the difference is not significant, No observations have been made in th$ spring months during the breeding season, and it has been assumed that feeding is then st a minimum, particularly In the males.

A few stomachs containino small quantities of stones have been found, but there is no correlation of these trith absence of food, The stones may satisîy hunger pangs occasionally (see Latrs , 1956a ) but the sniall aniounts sxralloered suggest that they are accidently ingested with the food, 9 3 4 5 17 5

%O ' O 59) PeireenP stomechs wi4h food

Figure 19, Pescen.tage ûf Sksmachs conAi;artningFood, The calf is born with a coat of soft, fine, silver- gray hair, 5 to 10 mm, in length, dccording to Nikulin (19401, this eabryonic pelage is shed soon after birth and by the end of July most calves are devoid of hair, In

August the netr coat begins to form and by the end of the first year attains a length of 6 mm, (See Table VI. In succeeding years an amual moult occurs in the surnr,ler rnonths, though it is a much more variable and prolonged process than the moult of phocids, The new hair covering is a silver-bloncl colc>ur tlllen dry ancl accovnts for the many light-coloured individuals seen in the fa11 and early spring. In the slJrflTiierrnonths the old hair is a reddish-bïown colour and can easily be pulled out. During periods when the animal is hauled out, sheddins of the old hair is aided by friction of the skin on the rocks or ice, and by deliberate scratching, At tr~eu~lit, this rnoulted hair falls between -the rocks and filLs the cracks 1.1ith a dense felt, Mohr (1952) ha.s prnsented evidence for an anrlual renewal of the vibrissae, but it has been impossible to confirm her observations, Examination of the mystacial pads of the specimens recorded in Table V shows that there is an even gradation of wear, and this suggests that the vibrissae are retained throughout life, In individuals with short vibrissae, the length appears to result from wear alone rather than re- placement. TABLE V

%BE MOULT

When old and ne11 hair are present, "fastfîand "pulling" refer to the old liair only, A full hair coat is iiidicated by the syrnbols XXXXXe A dash indicütes "no observation recorded" ; a blank neans "no thing observed",

Field Date S ex Age Length Amount Fast Length Amount No. of old or of new ha lr Pulllng Ilair in rm in mm.

A 11 26 May M O 5 - 10 xxxxx f

A 40 6 Aug P/! 10 12 xxxxx P

A 42 7 Aug F 10 12-18 xxxx P - - ALlO 10 Aug F 20 12 xx - 6 - 12 xa Al11 12 Aug M 6 10 xxx P 2 - A112 13 Aug F 9 6-12 xx:c A 43 17 Aug F - - xxx P 3-6 -

A 45 20 Aug M 21 12 x p 3 -12 xxx A 46 20 Aug F 7 32 xxx - 3 x TAULE IJ (Continued) - A 113 21 Bug F 3 - - 6-12 xxxx A 48 22 Aug F 15 - - 1 - 10 XX A 114 22 Aug M 20 6 - 12 xxxx A 115 22 AU.^ F 10 - x 6 - 12 xxx A 116 23 Aug 14 4 6 xxxx A 151 2 Sep M - 18 xx 2 - 17 xxx rl. 152 2 Sep M - 10-13 - 2 - ù 118 10 Sep M 1 6 xxxx A 1x9 10 Sep F' 15 - x 6 - 12 xxxx A 61- 18 Sep M 2 6-12 - A 72 23 Sep F 16 h. 78 2 Oct F 6 a 79 2 Oct F 6 12 x A 80 4 Oct F 10 A 81 5 Oct F 4 ~127 60ct M 15 12 x

K 129 7 oct M 6 12 xxx 6 x

A 131 7 Oct M 3 12 -

A 132 7 Oct F 20 - X - - XXXX A 133 7 Oct F 23 - X - - XXXX A 136 10 OC^ F 11 - xxx - - XX THE 9.lAIiE RE PRODUCTIVE CYCLE

Most of the male material available frox the

Eas terri Canadial1 .ArcCie is no% representative of the brecd- Png season. E'ortunütely, -,r'ay ily791 has ~eenable to co1lec-I; a sufficior,tl,y large satnple of =ale Facific icralsus in the late sprlng months, and the reprocluctivv cycle cün thus be establishecï with some accuracy,

Perhaps the best crite~ionof rnaturity in the male is the presence OS sperin in both tne ~eminife~oustu-bules and tne epididyrnis, and this can only be demonstsated effect- ively by his tological examination of preserved rnaturi.al.

Gross changes in the size of the genitalia aie ktio5rn.. to occur at maturity in several other pinaipeds, and bacula and tees tes of "ce milrus have been exarnii~ed to see if sirûilar increased growt'n occirrs. Grotrth of the baeulyil and tes cise li)isile:i- (lg54) has found that in the hasp seal, the maturation of the gonads is accornpanied by an increased rat2 of gkowth of the baculurn and testes in the eiglith year. A similar acceleration of growth in these organs at rnaturity has been recorded in both the ringed seal (I.lcLaren, in press) a,nd the southern elepiiant seal (Laws, 19~6b), In the northern fur seal the baculum and testes develop fairly s teadlly throu~hoiltlife (Scileffer, 1950b) and do rlot show any accelerated gro~rthdiring lrite ado- lesceneen Fay (1955) haç silovrrl tha t s Leady developinent of these organs OcciiTS Sn the Pacifie walrus, and this agrees with the findings of the present author for the Atl-aritic . walrus (îigs, 15 and 201, lit-st ol=qgy of t hc CES t is a~1_d~e~-iii&rn-i-g The initial groi~~tiiof the seminiferous tubules is rapid, and' in yearling animais they becoma packed closely together and form tne bulk of tire testis, Each tubule consists of a basal layer of xndifferentj-ated cells , with speraatogenic cells scattered. througho-(1-1; the central cytoplasmic syncytiun, This appearance is rnaintained until the end of the second year, vhen the layer of cells adjacent to the base- ment rnvinbrâne becornes clearly differentiated into Sertoli cells aiid sperrnatogcilia, The loose syncytiun contains large nunbers of spermatocytes with res ting nuelei and pale cyto-

In the next three years, this pieture of s-beady grokrth is rnaintained, The n~wiberof sparmatogonis in the basal layer increases s teadily, and the spermatocytes becone much larger and fill most of the tubul-e, In the tt~ospeci- sens talcen in their seveath year, the spermatocytes have become more peripheral in distribution, and a fetr tubules have patent lumina, Active ce11 division is observed in many spermatocytes, up to four layers of cells being forned above the basal layer of spermatogonia and Sertoli cells Age in yeors

Figure 20, Davelopment, of the T~ettis((S~ecinens in bresding condition are indicated by b9âck d~-ks)~ (f iQo 21) There is spcrrnatii? fornation in a. si:iall nuniber of tubules, but no sperrnin are p~esent~In later age groilps the testis tubules show the featusss typical of post-oestrus adults, rqi-th large lumina, sloughccl spzrrna tids 3r,d spermatoc y {;es, and giant cells, In the epiclidymi.~, there is the samc picture of steady developmori,-L up to the time of mztusity, The low, cuboidal epithelial cells lengt'rien into ta11 colu3nar cells in the yearling animal, In the third jear, a brush border of long cilia develops, and lohing of the epithelium occurs in the following year, There is no secretory activity at this stage. The fifth yea.r aniqal shows little fur%iier develop- meizt, thougi.ï there is soma cellular detritus in the duct, In the seventh yen, maxy of the ta11 eells bvar terminal vacîl- olês in the cytoplasrn, indicatihg the ùeginniag of a pilase of secretory activity (figo 221, In older animals tliû apithel.ia1 cells are more heavily vacuolated, and secretion is i~rssentin somû sections of the duc* (fig, 231, There is a grea"uer- anio-mt of cellular detritus consisting mainly of wiiole and fragmented spermatidç and spernatocytes , The condition of the seniniferous tubules and epi-

Ciidpis in the six-year-old anirnalç clearly iridicates tha-t rnaturity is reached in that year* However, a larger sample of specimens might well reveal a range in the ages of maturity, with a peak age of six or possiblg seven years, Figure 21, Section through the Seminiferous Tübules

of the Inlmature 6-~ear-016Male A 1-11 ( x 600).

Figure 22, Section through the Eplclidymal- Epithelium of

the Imature 6-Year-Old Male A 111 ( x 6001,

Figure 23. Section tkirou.gh the Epididyn'd Epithelium of

the Mature Ilale A 97 ( x 600)~

Figure 24, Section through Seminiferous Tubule of the

Adult Male IW 10 "caken on Noveuiber. 30: Type A

( x 6OO),

Figure 25, Section 'chrough a Seminiferous Tubille of the Adult Male A 97 taken on Surle 17: Type B

( x 600).

Figure 26. Section through a Seminiferous Tubule of the

Adult 1vfal.e A 62 talcen on Septzrnber 18: Type C ( x 600)-

The Testicizlar CyeLe in the Aduli; liale -

Tlze nost complote a.ccoun-t of the testlcular cycle

In a. mature phniped has besn glven bg Law (1956b) in 2 paper on the physiolo~yof reproduction of the southern elepilant seal. He recognhed sîven phases of tubule activity, .. and these have bren descïibed in great detaif,,, - For the prusent study, it vas found ti-iat tubules could be divided more suitably into three easily recognisable types, depending on their state of activity. These types are es follovs: (8) - Sertoli cells elongated with maturing sper- rnia atti~ciledto tlrieir free ends; small lumina (fig,24), (3) - Sertoli cells uithdraiun toirards the basal layer, with columns of spermatids and speraatocytes occupying most of the epitheliun; no spernia visible; large Lumina containing sloughed spermatids, and rnultinucleated giant cells formed îrom the fusion of spermatids cr spermatocytes (fig. ZS), (C) - Only a few spernatoeytes remain, together vith a peripheral layer of spermatogonia and Sertoli cells, In a few tubules the latter terninate in an apparent cytoplasmic syn- cytium ~dzichf ills most of the centre (fie* 26.1, Th-state of development of the testes in the adult

,,Y -> a_ male 'iç surnlarised in Appendix 11, the ttlree tubule -types being given in the order of frequency of occurrence. There is

sliçht evidence of a seasonal variation in the diameter of the sîminiferous tubules and this is illustrated in Figure 27.

blhen additional specimens can be ob"t2ned -from the vinter montils 5 , .-,, :" c ,. .% ' ,'$ * ,- - . -Sv ,,- * < -; *-..'t ,',. * . .- the t~:i)~r~vswi13. probably show a triore prorioilrlced cycli.::nl. f luc Lu::. Lion tilari i.3 sugges ted by tiiz gra-pli.

Cilroiîol-ogy of Ev-ezts in the Adult 2,Ii*Le

Al thouglrl orzly triro spec imens of tiïe iltlaiitiç imlrus have bezn fomd in an ac-bive s tate of sperrniogenesis (f ig, 27), the larger amou.nt of data on the Pacifj-c tialrizs collectecl by

Fay (1955) iias enabled. the aniïual cycle of the aciu1.t [nale to be fixed ;lit11 some certainty,

Fay f ouild ti-iat bettreeii April 20 and June 8, 911 percent of the 5 to 10 year olds and 16.5 percent of the older an.im.1~t:ere f ecund, Tile s eininif erous tubules of the ap;,ar - ently non-breeding olcler rnales vert? f oulrd to contain abu.iidailt Sertoli cells, i~:l;icli Fay suggested ii~igiitbe associated trith s terility, Tkieie is no sugges tioi~of a co:.i;)a:ra.tive sterilbty t~it1-rage in the Atlantic :tra,lrus, 201-ma-Lure ciales i~pto 28 years of age show normal pos-t-0estiu.s ciianges in. the testis,

It seerns niglily probable tha.t Fay has misidentLlied tîlese normal post-oes tru-s ciialzges (partic;.il:irly type C ) asd that al1 iiis adlxlt maL~-tsare eitiler se;ci~allyactive or beginili.iig to enCer the quiesceilt pnase, His cornparis on beti~~esnthe t;~o2ge groups niay 7;reLl mezn tlnat tire olds3r males terniiiate -ti~breeding sehson earlier and more abruptly.

Sitlce al1 -the kitlailtic vialrus taken in JUZICo~e poçt-- oestrus aclultç, the sessoii of ruL nlay ùê assurnef-1to eiii.cl abox~-t;

r 1 the rnicli-ile or encl of i?Iay, -i?iirour;i-;oii t -the sirrri.?ci r:io;i.t;lrs , the Figure 27. Seasonal FLuctiiatioo ie Diameter of the Sembiferous

Tubules in Adult Malcs (the two spccimens indicated by black dots are in. an active state of sperorniogenesiç. tilbiiles reniain in phase 13, A Bew mny snter phase C, but this never becornes a genaral condition, even as lüte as the end of Oztober, Ry lste November the tubules are once again in a state of active spermiogenesis, Fay (in litte) has canfirmed this early commencement oL rub and its contiin~ationinto mld- winter, and cites the fol_lor.ring specirnens as evidence: "A 16-. year-old mule taken on Ro.vember 28 had much spermcttogenic activity in the testes, and the epididyrnal tubes were packed with sperms, Two 8 year olds, one taken December 6 and the other Jarzuary 26, trere in the same condition* %.ro 6 year olds (Novembz* 6 and December 12) appear to bc in the early stages of spsrnatogenesis, but no sperms are present and the epididy- mides con-bain only slollghed spermatids and some half-Geveloped spermia", This Long period of rut is comparable with that of the southern sea lion (Otarla byr0ni.3)~though the seasonal limits are not so well defined in that specles (Hamilton, 1933). There is good evidence from the reproductive cycle of the female that breeding occurs only in the months of April, May and June, and observations of copulation in the Pacifie bralrus suggest that this is so, Thus Broolrs (1951;) states that ma-tlng occurs on the ice in April and the first part of May in -the

Bering Sea and 1s occasionally observed in asring Strait in late May and early June, There 3s also one observation of copulation at Point Bar~owin early July, The onLy evidence available ïrom the Eastorn Cünadian Arctic is from northesn Fcxe Rasin, In April the walrus are in the no~thernpart of their tesritosy, and matins hns hesr~SQP~ on rare occasio~~sby Eskimo hunters frorn Içloa3_11i. There is no record of copillation occurring in the water, tlicugh this is probably quite frequent, The short breedi~igseason is probably litnitcd by the ovarian cycle of the femalo and the rnarked gregaxious behav3.o~and seAuilal segragation of the iierds, These factors are considered in greater detail in the section dealing with the chïonology of events in the female (see ~~108).

TIB FEifALE REPRODUCTIVX CYCLE

Sexual 3Ia turity Freinian (1940) vas unable to Cti~t~ngurtshmore than five age groupings in his fsequency analysis of body and tusk mensuremonts of the female Pacifie walrus, and from thris a-nd other data he concluded that sexual matuurity was âttained at tnree or four years of age, Fay (1955) adopted a siailar method of age glaoupLng arld supposed that the majority of females were first impregnateed trhen four os five years old, The present study, based on more objective methods of age determination, shot~sthat there is probably a wides variation in the ages of females ovulating for tlze first tirne. This is not a unique occurrence in the Pinnipeclia., for Fisher (1954) has shobm tliat in the harp seal, the female may become mature between the ages of three and eight yenrs with a peak at six yearse Similarly McLaren (ln press) has found that the ringed seal becornes semrally rnaturc from four to çsven years of age, with a peak again at six years,

Otrul-ation --.in nu1lS~aro:~ls------fernales, ----- Macroscoplcal,ly visible lollicLes do not occur until the feaale is five years old, -though lu.rthrr specimens wouLd probably indicate lollicular developxerit a t an ezlrlier age, The irnmzture appearance of the gonads is still found in one of the seventh year fv~fialeshe~~~vve~, and this may posslbly extend ta later age groups, The female is considerecl Go be semally matuïe when one of -the follicles has ripened and liberated itç oTmn with the f crXation of a corpirç lirteu7i 2% the site of oymlation.

If concep-Lion f olloi<~sovula.tion, the corpus lil.teum pe~sis ts throughout pregnancy, and then degenerates intoafibrous corpus albicans after t.he bir-th of the calf, Regressioz~rnay be gradua1 ovel- a peiiod of years until the corpus albicans is finally reduced to a sna.11 dense $;nite scar, When conception doeç not occu-r, the corpus luteuq evidently regrcsses moi-e quiclily and rnay reaell a small clianieter in a relatively short time, It is su-spected that the resul-tlng coypora albicantia rnay not persfst for more than several years (sec p.lC2 1. Rzes at_-fis v~ltion~ Only four mature fernales xith a single corpus luteum in the ovarieç have been collected, and the condition of tiieir reproductive tracts sbior~s tliat tliey have not borne young bef ore. Two are f ive year. ol& (Il$43, 90

IW 48), one is a six year 01-2 (A78) and the other is a. nine

year old (A112), axid eacti one has ovulated too late in the season for impregnatlon to occur, The formation of corpora liitea trithout çubsequent

conception (coroosa 111tea _caspyïia) is not unique arnong -the

Plnnipedia, for McLareil (in press) has fomd that at least thirty percent of ringed sealç ovulating for the first time do not conceive. He suggests that the unseasonal ovulations may reflect a polyoestrus cycle in the yomg fernales, and the regular cycle only beco~nesfixed by the advent of full ~natur~ty,This probably explains conditions in the walrus, thoughthere is no evidence of more than one corpus luteeum being produced in a year, The twelve females with two corpora lutea (inclu-ding corpora albicantia) in the ovaries show a varaed reproductive sta,i;e, Al1 have borne Young, alrd four are de-

finitelg pregnant for the second time (A9, ~lt-2,AllO, Al20). The data are set out in Table VI with tiie corpora lutea separated bto two colurms representing the assumed first and second ovul.ations, In the first column, a corpus luteum of pregnancy (corpus 1.te~unverum) is only indicated wkn there is definite evidence of an old placenta, or when the female is accompanied by a yearling or two-year-old culf, The ages in the final column have been adjusted to correspond with these assumed f irst ovixlations , the minimum age diff erence Deing allowed r~henthe history of the assunecl first ovulation

is LI nkrlor,m ...... , ...... -...... (-1 1- )i 2 <: 3- ,L..>L>L~,--P , C3 CT of' ~cT~z,?..c~ 7;:; f(]lj.,@>-~s:'14' - natl~-r~z~ rluli:i_p.n;.-n:j.s; - ~~c~~I;,:I,~~~~- bûrren j 'c ' - , -- .l. 1 . .,' .

' y ' -., 7,,.;*. ... 7-:..,AL --,>,,-,1'/ LCLL .LLL>,:>4- ,.>,, ,, r: . 1.1.t3; ;;)iat; the hi-s-tory of' t;ile

-..f' .-i. . .(, -. .::. .[, <>T!?.i.!-Z i;j.<)l: j.2; ;..:,.yjl<~-!o\rJ;,> The wide range of ages and the lack of a definite Peak .Zn the age distribiltion si~ggeststlrat the older ani:na.ls have undergone ovulations which aye 110 longer recordcd In the ovarieç Until more specirnenç have been examined, i-L is diffj- cult to assign an age at which the majority of females attain scxual rnaturity, but a figure of seven years may be adopted provisionally,

Birth Rate

In order to arrive at an unbiased estimate of the birth rate, only those adult îenales can be considered which were not de1ibera.tely selected to reprvsent a certain phase of the seproclucti.ve cycle, The total nu1.1ber of mature fernales from Foxe Basin and northern' Hudson Bay 2s 31, and of these 9 are pregnarit, This represents a birth rate of 0,29 calves per mature fernale per year, but there is lit%Le doubt that the value is an underes tirnate. During most of the year there is niarked segregation of the sexes, and occasional groups of old femaies are found, One such group, containing several old barren fema.les, is included In the Foxe Basin ca-tch, and this has resulted in the low figure for the birth rate,

At Southampton Island the walrus usually hâul out at the u.glit in the summer and fall, and the sexes appear to mix together quite freely, Seventeen females were collected in the fa11 hunting, and six were pregnan?;, giving a birth rate of O,JS, This figure is considered to be more representatlve, and will be used in. pr2f erence to the lobrer valu.e, Accordi.ng to Frej.rnaxl s

(lgl-i-0) da ka, -tlie crude biï.i;bir.nte il? the Pri.cif ic walrus is between 0,37 (Tab3.e 3,) and 0.4-3 ('L'able 2), and Broo1:s (195%) has found' a value of Oe33* Both Chapskii (1936) and Loughrey

(195'5) give a iligher figura of 0,S, but this Is evidently based on çsrlns of szlected animals,

The birth rat3 indicates that the reproductive cycle is basically bienniai, but a varying numùer of mj-sçed pregnanc- les, partic~ilarlyin older anirnnls, leads to calf prodiiction. more neaily once in every three years,

The Ovarian Cycle

Ovaries wcre preparcd for macroscoplc examinatio~ by cuttlng thern into longitudinal sJices 2 - 3 mm, thick with a sha.rp long-biaded pncke t knif e, Follicles were classif ied into size gsoups by setting â pair oî divlde~-sa% 3 and 6 mm, and applying %lien to the longest diameters, Larger follicles were measurect in two planes and listed iriedFvidua.lly (see Appendix III), Selected parts of follicles and corpûra lutsa trere embedded in paralf in wax, sectionvd ctt 8 fi and stained in Delaf ield !s Haernatoxyiln and Eosin,

---DeveLopnieni;,of - the Îollic1es and ovul.atio~, In al1 the phocids and otariids so far invus tigatecl, the developing embryo remains in the blastocyst stage for several months before implanting in the uterine mucosa and unde~goingnormal developmen-t, In the Odobenidae, however, deveiLopment; is diruci-;, .:!xi6 no delay jil imp1antat;ion occurs (Fay, 19.551, This

has been confirmed in the series of specimens collectecl from

Hudson Uay and Foxe Eaçin, and the different pattern of deve-

lopnent :i-s reflected In the cycle of foll-icular activity, Enders, Pearson and ~earçon(1946) nave found that

in the northern fur seal, tiie corpus luteurn of pregnancy sup- pressvs foxLicular grokrth in that ovary throughout the devûlop- ment of the embryo until several rnonths after pal-turition, In the other o-i7ary, tliere is a progressive devolopment of follicles during pregnancy, until they become numerous at parturi- tiono In the val-rus the overall suppression of folliculation during pregnancy is clear, but there is a lirnited activity, particularly In the ov2ry containing the corpus luteume The specimens sugzest that follicula-ro devolopment is by no means a.n even process, and females taken In Augus% may have ovaries with no follicles larger than 3 mm., or as many as 16 in one

orary (A 46?. The fact that the females taken earliest (id$! 7) and latest (A 82) in the season show no developnvnt of follicles, suggesis tl-iat the peak in Augv-st is real (A lt-6) and would continue to be slio~mby a larger nuniber of -specimens, The picture of development in later pregnancy is uncertain for th? ovaries of the only female with a full-term foetus are in a losr stato of follicular activity, Thcre is no evidence of renewed folliculai activity and subsequent ovulation in the period during and after parturition, though Pay (1955) has observed this in 2 (9 percent) oui; of 23 post-parturn fetnales exami.ned, Such foll.icular develop- nient is evidently abnormal, for no newly pregnant fernales wlth calves have ever been fo'~u.?.d, This colz-i;inu.edsir.ppres$ion of ovar1a.n activSty ic the period following birth of the caff is in :narked contr::st to conditions four,d in the ma jority cd? phocjds and otarilds, where a new phase of follicular proliferation results in post.-partun oestrus and a n.ew pregnancy (Fisher, 1954; La~is,1956b; McLaren in press; Rand, 195%)- From Jv.ly to Octsber, after the birth of%h~câlf the efîect of th2 corpus luteum has declined, There is a renewal of follicular activity, which is mainly confined to the non-pregnancy ovary, bu.% this is once again markedly unevela, i?urnbers of fol-ljcLes Larger thctn 3nine fluctuate between on2 and twenty nine, the larges5 folLlcle attaining a mean diameter of 10 mm, Therr is no evidence that development be- yond this stage occu-rs at this time, for mrnora ll~.teaso~,~. have not been recorded fr~mfemaleç with calvc?s, In the îollowing spring a small proportj-on of females ovu.late and are l~pregnatedbefore the males go out of f ema.les rut. The r~rna.iningnsL1or.f a variecl s-tcite of f-ollicul.ar activity throughou't the sumrner and fa11 months , and- in al1 but four specimens, ( A 121, W 14, Di 38, IW 39) ovulation has occurred with the formation of a GorDus lu-teum sou.rium, In IW 38 and 39, there are numerous follicles over 3 mm, in diarileter, and at least one Iriealthy 8 mm, follicle in each pair of ovaries, Most of the follicles are atretic, but the usu-al type of cystic atresia has not occurred, Insteüd the cavity of each follicle ilas becornt' invadeS! by a markecl prolifera tion of theca lutein tell-s, The resulting body bears a, close resêmblance to the ~P-IJS111Le~1ii1 atseZ;i.ct~.m described by i\la;tirnow and Bloc~m (13li-8) for the h~lriianSemale, Luteiilised follicles are fotind in the barren adult female 1 121, and in an immature f?male 1T;ui 25, both of wiiich seern capable of ovulating soono Mc~arvn(1958) has recorded similar large follicles in the ovaries of an immature' six-year-old bearded seal, and concludes that they almost certainly reflect the hormonal state of maturity, It seems reasonable to assume that in the valrus such follicles indicate impending ovulations, though it nust be pointed out that this is probably an abnormal de- veloprnent, The mechanism by whi-ch follicu1a"Lion is suppresssd in the year foll~wingthe birth of the calf is uIh:nown, The onlj other pinrliped in which a biennial reproduc-tive cycle occurs is the bearded seal, but in that species ovulation I appears to follow the birth of the pup, However, ovulation i is deiayed mitil the males are out of rut, and only cornora 111-tea suuria are f ormed (McLaren, 19581, Ho specimens are available for the winter and srring months, but Fay (in litt,) gives details of a barren female taken on December 4, in which five follicles greater than 5 mm, l in average diameter are present in the ovaries, The la-rgest i follicle is 11 mm. in dianeter, which suggests that ovulation miçht occur within a few weckso Since conceptions do not appear to tak~place in the winter and spring months when the males arn kriown to be sexlial.1-gr üci;i.~rc, t;here nlust be sorn-t

of .foc-tive barrkev to copul.ai;iori, Perhaps segregatj-on of the

sexes, wi-iici; :Ls knotm. to occur a-L oiher seztsons of the yecir,

rnay be the lirnlting f':cS-nr,

Tire raplcl olzset of post-partuni oestrus iil those plio- cids and otarl3.d~with an anriual breeding eycle tends to effect an alternation in function of the ovaries, though tnis is never coaplete (see Laws, 1956b; McLaren, in press; Rafid, 1954-1. Where the corpris lu-teum persis-ts as a fibrous corpus albicüns throughout succecding pregnancies, the àlter- na%ion in function may be easily shown by the balance of corpora lutea in right and left ovaries, Thus in those pairs .of ovaries in h hi ch the nurnùers of corpora liitea are the same,

or differ by only one, the alternation is perfect, This occurs in 73 percent (33) of the walrus examined, and a further 15

percent (6) S~O~Ta ciifference of only two corpora lutea,,

---The c o-r19-5;~~-1~~~935~The final development c>f the follicle and its transforma-Lion into a corDus 1uteu.m are not represented lin the liini-tod collec.i;ion of mï-terial. availabla,

A ripening follicle, 10 mm, in diam~ker,is preseni in the right ovary of the barren feinale IN l+5 taken on August 5, and may well represent the initial stage Pn the development of a corDus hlteun s ~11rit1-2.This is the larges t healthy f ollicle recordeci, thougf~.a cystic fo1licl.e 29 Km, in size is present in the ri,-;ht ovary of the barren fernale fl 125 kaken on Septem- ber 27, Since there is no evidvnce to suggest that cystic follicles reach a grzater sizctl~anhcalthy follicles, it is h I fi n .-. fi & Tr-i I I 1 I I 1 I 1 1 1 1 I I I 1 I i I I 1 1 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 over age 20 undeterm:ner? Age in years Figu~e28, Relation beDdeen Age of the FernaLe and Nuber of.Corpora Lutea in the Ovaries, assuri,~d -kiicti; 29 ,[fiI more riea~lyrepreçeats the average dia- met?? at ovulati.ona This Iç ~uppo:~tedby the occu.rrencv of

30 an, f ollicEes in the Poclîlc walrus (Fay, 1955). nihere 1s probably little differencc in the size ol

the :ripe %oJ_licXeand the c0rpv.s li~teurn~~ihich wili S~JO~form,

'i'i1i.s is in rnarkvd contrast -Lo conditj-ons Ln the Phocldae in wklich th? mature foliicle üttains only 65 percent of the dla- mzter of the fully grown corpus luteum (Fisher, 1954; Laws, 1956b; IiScLaren, in press), In this farnily, howevei-, the corpus 1ut~:~mis rriaintained a.t a small size until linplanta-Lion of th5 enbryo tiiieli final rapid gro~rthoccurse

After collapse of the follicle, luteinisation iç rzpid, and aaxiniuiii developmer~tof the corpus luteum is attained at soae time before August 3 (W 71, There is some suggestion that a slo\

*LO partu~ltion~but this may be the reçult of sampling erros, At this tirne, the gl.a,nd shows degenerative cilanges vrhich are sinilar 50 those found in rnos-b other speciss of pinnipeds, There is great variation in the sizes of corpora li~teatalçeri in Augu-st which might indicate a. bricle spread .in the dates of concep-i;iong Hor.~ever, the structure of the glands is similar and the size clifference probably results from indfvid- ual variation in follfcular size at ovulation, A$ this stage, the luteal cclLs are oval or polygonal, 20 - 40 8 in diameter, with large eccentric pale-staining riuclei (fige 29); up to 20 percene contjin one or more clvar vacuoles which may be large 2:.ou:;ii to iili nos t of the cell. iicording to L,u\is (1456ù ) , similai vacu.oles in tiie luteal cells of -the sou-khern eizphant :;sa1 contairi 1i.r;oi.d material, ari~3ar.rison (1911-8) has en- rhaçised the poi~i;that they are sot necessarily indicative

of degenvratlon, but probably repi2sunt a resting period

2rrring ti~ses tablis@rzlvnt of the pl-rtcenta, In late prvgnzncy, signç of degeneration nave already appeared (fis. 30). A few luteal cells have enla.rged to 55

--i~t diameter and mos-t show perip!l?ral vacuolation and shrinkage,

T77 ne anount of flbrouç interstitizil tissue is increased and the

111. Leal cells becorne suparated into stnall groups , -- 1\10 specimens are availzkle for the early post-partum

?eriod, but by early July the corsus Eutsurn has regressed by

noarly a third of its size (SD 14?) 2nd there is a great in-

clsase in fibrous tissue, The lu;sôl cells are mostly frag- xented, alid the spaces which they r^or=erly occupied are being invaded by cords of interstitial snlls from the perlphery of

the gland (figo 31). Regression Fs agparently maintained for a nuinber of years following partiinition, and the fibrous corpus albic<~nsgradually shrijnlcs to a. coapsc-t white scar, The corpora âlbicdntîa rollect in the ovaries, and as rnany as fourteen have been foucl in one old female (fig. 28). Sertraz (1940) has suggested that the corpora albicantia Ln ;:eddeil and crabeater seal ovaries persist for the life of the individual animals, and Harrison, Ma%thews and Roberts (195'2) have agreed with his obser-~ations,thougn they state

that there is no definite evidencz that the corpora albicantia Figure 29, Section of the Corpus Luteum of the Pregnant

I1e!nal.e :L taken 0x1 4.ug.i;l.ç t 7 ( x 600 ) ,

Figure 30, Section of th2 late Fregnancy Corpus Luteurn of Fernale B 9 takeri on May 26 ( x 600)-

Figure 31e Section of the Regressing Corpus Luteum of

Female A 43 taken on Au.gu.st 17 ( x 600 ),

Figure 32. Section of a (;orQus Lute.txrn S~usniu,mfrom the

Carren Fernale A 77, talcen on October 2 ( x 600 ),

do not disappear, More recent worl: on the '/iec-ldell seal

(Plansfield, in press ) su;;gests that their retention is. variable, and Fisher (1954) has çIriom -tiiat iri the harp seal, the corpora albicantia remaln visjble for on17 about five years in animals up to twenty years, In the adult walrus, the corpora albicantia in each ovary can be arranged in a descending order of size, with a minimal value of 2,5 mm,, The smaller corpora alblcantia are always accompanied by several larger ones and tlriis indicates that regression is gradua1 over a period of years,

Th6 rate of regression is not constant hovever, for in corgora 111tea suuria, fibrous connective tissue 1s p~orly developed (îig, 32) and the resulting corpora alblcantiâ prohably reach the minimal diameter in a relatively short

Cime, Histologisal examination shows that the process is only quantitatively different froa the regression of normal corpora lutea of pregnancy, and the resulting corpus albicans doûs not difier in any way except in size,

Irnplaiitation and Growth of the Embryo

Since no free blastocysts or recently implanted em- bryos have been recorded in the ~aterialfrom the Eastern Sanadian Hrctic, data irom the Kara and Bering Seas (see Fay, 1955) have been used in cornpiring the composite growth curve shown in Figure 33, It 5s clear that foetal lengths recorded from al1 three areas do not differ significantly, and the çame curve ha5 been fitLed $0 al.:. th? data. In.ii-)l-ai~-t;,?tiorl evider-ii;l.y occurs about the rniddlc of I4ay on tile avera,;e, and iiiis !!s conf irrned b;; tiie f o:iloa~~ingcal-ci.ilaticns, Development of the embryo is assumvd to para-ll-el that in hurnans ? and a direc-t coiiiparison mcly bc maue by dratxring a curve of equivalent foetal lengths (see Fay, 1955). This is illustra-Led ir, Figure 3lt, and -the nuiiierieal data îrom which it is derived (Arey, 1951~)are listed. in Appendi:~ IV, In order to calculate the average ges tation period, it is necessary to assume a n;ean birth date, Since the foetus A 11, taken on May 26, was near Ïull-tem, this date may be used as a converiien.t be.glmiingO This may be sonewhat late, howevër, foT Fay has obsesved- tha-t full-term foetuses are rare in the experience of Eskimo hunters in Bering Strait in late E4ay and early June,

The lengths of eleven foetuses and the corresponding gestation periods calculated are set out in Table VII, The average ges-tatiirl period is 376 days, but this is probably a sliglit underes tirnate since measurements were talsen from em- bryos ~~rhichhad shru-nk during preserva-tion, H bette^ figure perhaps is 380 clays , wilich gives a mem conception date of May 11, Fay assumed a mearl birth da-te of May 14 anci Ïound t2rat the calculated mezn gestation period was 366 dsys, h&en allo;\r=- aace is made f~rthe difi'erence :irz average birth dates chosen, the results do not appear to dlfi'er significantly, O r, 0 / .-- / /' c'3 ,'@ / #' I'

/ 0'0 '/ /' / / 1 /' / / i- / /' r / /' "" / / / / - / / / /' X /' - \r A O // / - / /O @ ei ci E-Cariada O/ / %@O s Kara Serd o,~z G-3 @x X placenio 0 ...MO0

T=-L r 1 i 1 I I I î" M cd J h S O N O l J F I M A 1W

Figue 33, Gro'~+rthof the Eab~y~and Placenta, Calculatnd Average Ces tation Period derivcd f rom leng ths of ELeven Foetuses

(a) The length of' the full-teru oeb-il:; A 11 is II(; cnt, (b) Tnis is derived directly fron the curve irl Fizure 21, (c) Ti19 birth date is tzlien .ris flay 26,

----.- 6 3 Aug ~LI-.5 296 390 1.i 7 3 Ailg 21,5 296 374 6 Aug 22,5 293 376 A ri-2 7 Aug 23,O 292 380 A 110 10 tiug 24. O 289 330 W 14- 11 iaug 234' 288 374 w 46 20 Aug 28,O 279 387

A 119 10 Sep 33*5 2 58 379

A 120 1-0 Sep 30,O 2 58 369 A 80 4 Oc-t; 3Se0 23Lt 360 A 82 5 Oct 3790 233 369 Average gestation period 376 days Percent gestation completsd

Figure 34, Growth of the Hman Embryo (after Aregr, 19541, Rirth and csre of the Young

r.,ine3 rmge ol' foeta1 ieng ths in.dicates t1ia.t parturition extends o;icr a periocl of about %\IO montl~s,whicii is cornparabXe to conditions in the Piloci.(i*a-ei~~aws, ~y~oa)7 *Y/' anci iiie Otariidae (Rand, 195Lt.), Occasional ~mseasonalbirths ocrur in -these fanlilies and are also characteristic of thc Odobenidau, Ti~us Fay (1955) records a calf of not less tiïaa ttro rnonths taken on I'.:a;i 13, which vas regarded as a curiosity by the liunter who captured it, Perhaps the most notable exzrnple is that cited b'r Freuchen (1935) >:ho records cl. cor$ \$alrus with a new- born calf eau-ght in Frozen SFralt (see fig. 11, on January 31; an Sskirno 2lso caug~hta sirnilar-calf' from which the urnbilical cor6 nad not yet beeïi shed, SucIl untimely births probably result; in a great disacivan.tage for the calf, in spite of the solicitous care of the CQI~, â:?d it Ls doub-tful if rnany new- born young can survive at this early seûson,

The apsearalice of tlie cal- ii:li.s been described on page53, and evidence for tkx excèptiool.-rally long lactation psriod is givên in the svvtinn on nutri~tion. Numerous a.& well documented accounts of' ihe bahaviour of cow and calf are availabla in the 1-iteratxre (see Allen, 1880; Fay, 1955). and nend not be considered héi.e in dst;r.il. Hhat should be stiessed,

Lio:.rever, are the strong tics I?el;i,:è~>:l uother and young wlrlich are

OZ great survival value wnere the reproductive potential is so lor~, Great pro-tee-tion is ai'-forded during the critical period berore weaning, and the calf or yearl.irig iç able to learn both swim:ning and fceding tecanlques whllv rernainlng in close contact v;i tn the col.;. Tlie par-Licvlar pïl ti,ern of bcrLavioi.zr in :.rbiclr t;he Young animal clings to the ri?other. is very strik- ing, and even a two-year-old aiiin~alhas beec seen to ride the back of an adult male in this -r.lay, Strong social ties link the brceding Semales with the Young and immature animals (Freiman, 1,q1k0> and help to provide even greater measilres of protection. There seernsllo reason to doubt that orphaned young are adopted by other fe-

al es, though this kias not been definitely observed in the specimens taken from the Eas tarn Canadian krc tic, Qnly one calf is produced at birth and the process has been accurately describefi by Ryder (lq5lt) in Fayls accol~rltof the Pacific 1ra1ru.s (1955'); it does not Cliffer appociably from pa.rturition observed in other species of p-jnnipeds (Laws, 1956a; Mansfield, in press 1, Twins have 1 never been recorcled, and accosding to Fay, "none of the Alaskan natives contactecle,.had knowledge of this phenornenon Male calves appear to outnurnber females at birth,: and

Brooks (1954) ha, recorckd a seex ratio of 1.2 'co 1 in 274 calves examined,

Chronology of Events in the Adult Fernale

The calculatvd average gestation periocl of 380 days shows that developmvnt of the ernbrji-O begins in mid-May at a 'cime ~rîlenthe males are still in rut. It is highly likely,

1. In a recent report, translatecl by Pay, P.C. NikuZin records the finding of two pregnant females trith twill foetuses. See i-likulin, p ,Ge, Tikilookeanskii n-i. Isçl~edovatels!-ziiInst, Rybnogo KizoziaiLva i 0l;eanograLii IzvestÜa. 39: 353 theref ore, that the blastocys-i; irriplarits: in the ul;er.iis on1.y a short tirne after matint;, Observations by native hunters in Foxe Basin, and by Brocks (1-354) iri the Rering Sea, corifirm that copulation occurs at this time of year, Ya~turi-Liontakes place approxin~atelytwo weclcs later in the following spring, and is f0110r.1ed by sexuül quiescence in the m&j3sity of females, When post-partun oestrus does occur (see p. 941, ovulation is probably de- layed untll the males are out of rut, for no pregnant females with calves have ever been f ound, Increased f ollicular activity in the foll.owing spring results in the developmerlt of ripa follieles, but only a small proportion of females manage to o.m~latebefûre the bïeedirlg season is over, The remainder avulate later in the sumner with the d-eveZopment of GzLnora lu.tva s~.1u&zZ, There is na indication that fernales rernain barren for a third. year follo~ringtilt? b5~thof the calf, and it is assumed that they ovulate sufficiently easly in the ncxt season for impregnation to occur, Fay (195'5) has suggested that the initial pregnancies are biennial and. that a progressive delay in the timv of o~mla- tion reçults in a series of missed pregnancies in the ten to fifteen-year-old animals. A similar pattern of reproduction may occur in the Atlarltic ~ralrus,tiiough the evidence suggests that barrenness is mainly confirieci to 'cile older ariirnals, The smal2 nurriber of u~iseasoxlalbirths suiggests that ovulations are rare in the winter and early spring, It aay ba arguel tint wintel. bir.$hs are rnore cornmon than is supposed arid are offset by a high ca.lf moïtalTty, but examination of the ovaries tails to reveal any indication of this, Senility has been observed in some old seals (Laws, 1356b; McLaren, in press), Sut the olciest valrus specimens availaùle show that normal ovarian function may continue to a late age, The social ties between adult females and the yomg and immature animals are evidently stsong enough to cause a general segsegat&on of the sexes throt~ghoutkhe year (Fay, l955), The gravid female may seek an isolated floe away from the main hesd when calving is inninent (A 9 on May 26), but obâevva,tion suggests that she soon retuïns to the other animals once her calf is born., Though old males occur in these groups of adult females and young, their presence does no% imply a polygynous social struci;ureg rather, the very nature of the habitat suggests that brerding Is promiscuous, The morphological evidence for the formaLion of discrete populations has been discusseci in the sectiori on growth, and the data are surnrnasized in Table II, Though the ma.rl;ed differences in tusk length and resulting facial proportions between the Atlantic and Pacifie forms may be regarded as er~aractersof sübspecific rarik, the stcitus of the Kara Sea walrus is uncertain* It has long been supposed that the walrus inhabiting the shores of northeastern North America, Greenland, Spi-tzbergen, Franz Josef Land and northwestern Asia ~epresenta uniform stock, distinct from -the Pacific walrus, but the sumrnary of morphologieal characters indicates that this is not SOj rathe*,i-t would appear that the Euro-Aslatic walrus is more akin to the Pacific walrus, and the Eas tern Canadian Arctlc population is dis tlnc t from either of these stocks, hat te ver the relationships, it is clear that the Paclfic and eastern North kirneriean forns have been separated for a long period of tirne, RecentLy, Davies (1958) has reviekred the distribution of tlrie northern pintiipeds and snggests that the sepration of

O, r. divereens and 0, P. sosmarus dates from the penultimate or an earlier glacial maximum in the Pleistocene, This irnplies that effective mingling of the stoclcs did not occur during the ice-free period preceding the last glaciation, a fcrct which Davieç finds hard to explain in view of the imminence of contact along the Siberian shelf of the present day, Hoi<~ever,Davies açsurjies that t;he Euro-.i&siatic ?'ral.rilç 1s cl-ose%yr.c:lated to the eastcrn North Anierican st~c!i.and rern~ii-nsdistririet from the Pacif ic valrus, If we accept the rnorpkiological etridence ancl adopt the alternative view that the ~.ialr~isof the Kara Sea is little different from the Facific l;ralrms, ttien the pat-tern of spuciation is mort: en.sily -aidzrs.t;ood, I~icieed, the geographical evidence alone suggests that this is the more probable development, Wlthin the proposed subspecies & r. rosmarus which occupies the Eastern Canadian Arctic, some slight different- iation in body form has taken place, This suggests that isolated breeding populations occur, a view that is supported by Loixghrey's detailed discussion of the geograpliical distribution in this region (19551, The formation of such discrete grou-ps can only be full-y appreciüted whzn the ecological factors eff ecting distribution are full-y unc1er.s tood, Vibe (1550) has given the mes t detailed accotrni; of thûse so far, and the follo~ringobservations are included to supplemexlt his WOIILL~

Relation to the Land

The numeïous accounts of walrus hunting in the past four centuries abound trith descriptions of the terrestrial habits of the animal, for it was at the hau-ling-out sites on the land that the principal killings were effected, The evidence suggests that the rfalrus was essentially 2 sedentary aninzal wlirre abwdant feeding areas occurred, alid macle use of

ice when it appeared, rather than seeking it out in definite migratory movements, In places sucri as Sable Island a~Cithe

Magdal.en Islands, t~ilerath@ spring ~nonthswerc of ten ice-froc,

tne breeding cows took to the land to hear their yomg (Allen,

1880). In the early surnrier, the hariling-out sitcs remainecl

populated, evidently by mernbers of both sexes, In the higher latitudes of Bear Island and Spitz- bergen, walrus xrere round ashore in large numbers in July and

Aügust wnen there was lbttle pack ice about, and they pre- stmably freqiiented the land until the onset of winter conditions, TBus the land haul-out seemed to result directly from lack of ice, and could occu-r from as early as hpril until late Octobor, Observations on the wairus in nortl-iern Hudson 3a.y coi?i^irm this psttern of behavioiir, for anirnals are no%

fourid on the land until laLe July, ~ihenmos t; of tlie ice has

left the arca between Southampton and Coats Islands. Eviderice from the behaviour of the Pacifie walrus sugges ts that this species is more activcly migratory (Brooks,

19541, though Mikulin (1947) shobrs conclusively that sedentary populations do occur where food organisms are plentifL?l, ,Wal- rus remain in these areas of abundant food at least throughout the whole sumrner, and haul out on skiore at established si-tes, LWith the appearance of drifting ice, they forsake the shore and use the ice for resting as long as it is present in the snallow water zonet']. Nikulin stresses the fact that walrus are not adapted to pelagic life llke some other pinnipeds and -. tiiereforn 1 "cerrriot mainta in thernïeloes in tlie open i.iaiel* for long periods of tirne without resting on the ice or on siiore" -A] The val-rus is marlcedly gregarious when hauled out on the land, and large 'podsg of closely packed animals arc formed.

At llalrus Island, in Fisher Si;ra.it, an estimated maximum of

1,000 anirnals has been observed in the fa13 (M. P. Carrick, persona1 communicztion), and further observa Lions quoted by Allen (1860) show that as many as 7 - 8,000 were seen a.t the lechouries' on the Magdalen Islands in the late eighteenth century, îJikulin (1947) records that in 1937 - 389 mass settle- nents of 2 - 3,000 anlmals were observed at four places on Wrangel1 Island, and In 1941, 8,000 were seen at the hauling- out ground at Inchovyn on the Chdrotsk Peninsula, Similas settlements , but nümbering only 500 animals , have been observed by Chapskii (1936) on IJovaya Zenilya . The physical nature of the hauling-out sites at the present time is partly dspendent on the presence of man, In forner times gently shelving sand bars and wide sand or shingle beacnes were cornmonly used, and localised population pressure often forced -the animals to move inland, These sites were probaùly the most favoured, for the walrus has poor abllity to rnove on land. Tnese past records also show that bays with high bordering headlands were most frequently usecl, and Fay

(1955) has suggested that high promontories associated with hauling-out sites in the Bering Sea may serve as landmarks for coastal navigation, In that region, aniuals will haul out on anything fïom bouldvïs to turf, and Nikulin (1941-)records that svme of the sites may chanj;e.from year to yeaï, In ilor-ti?errt Hudson Eay, the walrus is never knotm to na111 01.i-l; on the l-irzes-borie beaches, arid the uUare re- strictecl to $ho rocks of the Precambrian shield., Each III&..& is sitüated on a promontory or small 5sl.et, and the dip of the rocks a,llows d.eep vater to be reached a little way from shore, iilhen disturbed, the aniraals are able to enter the >rater very qulckly and reach a safe depth in the initial. plunge from the rocks, The same u~litare used year after yezr, ~Iiichindicates that the walrus are able to idontify tbem eosily from the water, Weatficr conditions play a la.rge part in deterniin- ing rzauling-out behaviour and it haç been foud that the

U.I. on Bencas and Coats Islands are on1.y frequented whea the wind is offshore a.nd not too strong, In liigh wifids fron any quarter, or when the sea is breaking on the rocks and covering them trith spray, r3ralrus desert the land and seek more slieltered bays, This miivement to calmer waters invariaSLy leads them to one of the otkier u-~lit,

Nikulin (19.7) has fomd a similar correlation between rough seas a~donshore winds anci the hauling-out habits of -the Tacific walrus,

Relation to Sea Ice

\ken drifting ice appears in shallow waters during tne suinmzr and fall, the walsus dessr ts ihe land and hauls out on t1;e floes (Nikulin, 1947'; Lou-ghïey, 1955) At Southsmp ton lsland this occurs par ticularly along the coas ts of Bell 13eninstila, an6 the 2r;I-i-P; in thls area are no% so îrequently occupied as those on Bencas, Coa ts and ilalrus

Islands , In the fall young ice forms In the bays and along th2 coasts, and the walrus maintains breathing holes by breakïng through thls thin layer with its head, This habit has been described by Jchansen ( 1910 and probably accorzri-ts for the pronsunced patch of scar tissue which some adults bear on the croim* As the new Ice thickens, the breathing holes beqome more difflcult to naintain, until flnalLy the walrus is forced -to retreat -lo open water at the edge of the fast ice, VlSe (1950) bas shown tha.t when the Sce edge extends begond the outer limits of the mollusc banks in certain areas of northwes t Greenland, the tralrus popula Lion disperses to more accessible feedlng grounds, There seems Zittle doubt tkat similar local movenznts during the'winter and spring occur throttghout inos t of the Eastern Canadian Arctic, Loughrey (1955) quotes observations from numerous sources which tend to support the hypothesis that the majoslty of walrus populations are local and se!;.cntary. In view of the ecological relationships discussed by Vibe, this seems a more reasonabl-e assurnption than tiilb i2,!stula Lion of extensive migrations, Tk.2 interac-Lion of ssasonal ice rnovements with the locatlon of suitable foraging gruwlds does not comple.l;ul-y-explain the patclïy distribution of the walrus a% the present

-tirne, a.rici other factors sccn as laclr of popul~itl.o~ipressure and th5 eff ec ts of hui-11.m preda tion rni.rst be involwed,, I!OWSTTC"~ tkese can onLy be efi'ectivsly assessed whcn more data bccome availablt.,

Local Movements and Migrations

In Foxe Basin, optirnal, conditions appear -to bc met witli, for feeding sha.llows are extensive and ice is abundant a11 the gear round- Walrus do not appear to i'sequent the southvrn part of the basïn wiiere deptbs ars gseater than fifty fatliorns (set? fige 21, which indicates that this papu- lation is ef fectivvly isolated f ioin the Soilthainpton I,.;l..aml group, The extensive migratlolis pos tulated by Freuchen (1935) czppear to have little basis in fact, for the walrus is ob-viou.sly perfectly adap%ed to existence arnongst the wintor ice in this reg3.0~1- In western Hudson Bay, (sec fige 351, there is a small popu,lation along the coast from Eskirno PoinC to Wager

Bay, arid recent Re Ce M. ;De gatne reports (1956, 1957) s~lgpest that the numbeïs are inareasing. Former phlLt are now being reoccupiecl (soe Eorsgkrey, Iqt;S), and observations indiciate that tlze herds rernai~in .the area throuçhout the winter, Fe11 walrus have been seen in recent years south a.l_ong ---

Figure 35. Map of the Eas tesn Canadian Arctic, the c~jastas far as Cape Henrietta Maria, though a t that point, ovor one thousand a~inialsihrere seen riaule6 sut in the sum-iey of 1955 (see Loughrey, 19551, The bathyrnetry in. this area suggests that thls herd n1a.y be associated with others fowid about the Belcher and Sleeper Islarids to the northeast, Little Is known of this group, bu% z scarclty of animais along the northeast coast of Hudson Bay points

to its being û resident population, At the western end of Hudson Strait, in the late çwnqer and fall, walrus evidently remafn on the ice coming do~

along the no'th side of Hudson Strait u_ritil the Middle

Savage Islands (620 08'N, 670 SSi3!) are reached, A recent

report by i, G, Cooch (in litt,) indicates. tha-b several hmUe7-

dred valrus am founcl about these islands from October qntiZ F~iay, After this $ilne their dis-tribution 1s unknown, -though the Eskimos state that they move trestwards to~rard.~Hudson Bay, Prom Hudson Strait northwards to Home Bay, but ex- cluding most of Cumberland Sound, the coastal waters probably

fora natural reserves at the present tirne, for li~itedhunting oiit groi!!ï4 vas at Paci:LzF 9 ji;c;t sc~::i;ti of' I:lri.Loj,irig Isl29d. on kllc

eas -ter11 Ba.f.t'Ln Island coclst;, and B~tili~ri~?(.1_*3!+-) ~.'s~~rii~ .th;lt

one c cnpîriy took over f otr't- tiiousand s1ri.n~per y2:i.r- Rccordiiig

to recent i3ç1,;irno opiniori (FI, N. Anclers:?:n, fri litf;,1, ti-1er.e is a large resident breeding population in thls area, and several.

..-.-a-u~ltt are i_uzo:m which are used year after ye;l.r, Reports fron

the R, C, 14, P, establishment at Cape Christian (1955, L957) indicato that val-rus are scarce from the north of Home Bay to Pond Xnlet, which suggests that the ~xtensfvemigration down

the Baffin Island coast postulated by Freuchen (1935) does not ozcur at the prssent tirne. A similar Eimited distribu- 51on of walrus is found along the Greenland coast, the animals occurring only between Sukkertoppen and Egedesminde (Allen,

191i2). This partial S.solation of the Eavis Strait herds fjiox

those further north in Baffin Bay may result fron lack of pop-

ulation pressure, for ihere 1s no iridiccltion that; the inter- vening coastai areas are unsuitable feeding growids, The herds frequenting Kane Basin in the samer and fa11 alntost ceriainly migrate south tl-irough Smith Sound and winter along the coasis of nortkdest Greenland (Vibe, 1950), and Ellvsrnere and Devon Islands (R. Ce M. P., 19541, This ~overnentis ernphasised by the narroiIn,?ss of Smith Sound, and paralleis on a srnall scale the channeled migratory strearn of

the Pacif lc walrus through Bering Strait, The nost dif9icult group to assvss is that found about Akpatok Island in the surnmey. According to Eskimo opinion these animals spond the rsinter off the Labrador coasB at Hebson (A, W, Fe Banfield, in litte) or in Davis Strait (Le M. Tuclc, In litt.), and ihen migrate into Hudson Stralt, reacfiing Akpatok Island by mid-July, In com~entingon the supposed migration, Tuck states that "wa7rus have not been recc-srded withln the viclnfty after the f'irst ~ieekor so of August, but thfs must be treated with caution as 1 was unable to barn of a single visit to %he islând by native hranaters during late Augus t onef2 Tuckgs comment is particularly apt since it il- lustrates the dangers of accepthg opinion, even cf apparently Irrioi.rlcdgeab3.e huntsrs, without due eonsidern-bien of al1 economic end ecologlcal factors involved, Tne nate rial examined consis ts of samples taken froa 45 n~alesand 53 fems1.e~ in northern Hudson Bay and 56 males and 22 females in northern Foxe Basin, Body and tusk length moasurements were analysed -to see if their frequency dis tributions sho~iedany modzl regularity equivalent to presumed year groups, Only the yearling and two-year-old animals could be distinguished by thls nethod, and further age classes were masked by in- divj.dual variation with age, The teeth were next examined with the objec-t of establishing the periodicity of the incremental layers in the dentine and cementuml No positive proof of their annual nature has been found, but it is highly probable that the layers are formed at the same season each year, A similar method has been used for the Pacific walruç by Fay (~955)~but only the adult males can be aged in this way, The nurnber of cementum rings in the imtnature males appeaB to be variable, h hi ch is surprishg 3n vierv of the regularity of their formation in the Atlantic walrus. If cementogenesis is equivalent in both the AtIantic and Pacifie forrns, then the ages assigned to irnnature Pacifie wa.lrus on the basis of frequency modes in the measurement of tuçk length are incorrect, In spite of these differences in age determination, it is apparent that the Pacific walrus is slightly larger in body size and much longer in tusk length at sexual maturity than the Atlantic walrus, Cornparison of these ~YJOforms with the walrus of' the Kara Sea S~OIJS that

the latter group Is more alcin %O the Pacifie walrus, Exarninatiori, of 69 skulls and 7;+ loi-rer jaws shows thaL the normal adult dentition is I 1/0 C i/l Pm 313, In addition, the second upper* incisor, the îourlh upper pre- molal. and the first 1-ower molar occur in up to 26 percent of the specimens, Stomach contents were anslysed and 22 food organisms recorded, The feet and siphons of sevesal species of pele- cypods form the dominant food, but other benthonic inverte- brates are eaten when these are scarce. Blubber and slrin of the ringed sea,l were taken from the stomach of one adult male, Feeding appears ts be an Irre,yular process a.t aLL times of the year, and there is no direct; eviclence of any prolonged periods of fasting correlated with the breed-ing season or the moultc The latter eveni occuru annually and 2s a more variable and prolonged process than the moult of phocids, The males becorne sexually mature when six years old and the testes show the typical facies of post-oestrus adults in the following summer and fall, There Ss no ac-

celerated growth of the testes and baculüm which character-

ises the onset of sexual niaturity in phocids, Only two adult males with sperm in the testis and epidldyrnis have been found and thesc indicate that the males are in rut from late November until at least the end of March, More extensive data on the reproductive cycle of the Pacific walrus show that the testes produce sperm from November until Tate Kay, and evidence from the fernale breeding cycle indicates that copulation occurs principally in April, May and Jlm-e, The fernale is considered to be sexually mature when the fisst ovulation occurs, Breeding maturity is not generally coincident with vexual rnaturlty, since only 30 percent of the nul7iparous females become irnpregnated at this time, The age at first ovulatiûn varies from 5 to perhaps 10 years, and it Is assumed that the majority of females ovulate Eor the first time when they are seven years old. The reproductive cycle is basically biennial, though missed pregnancies, particularly in the older animals, lead to calf production more nearly once in every three yeürs, The averase calf production is 0,35 per a-mnum, which Is not signif icantly dlf f erent from the estirnated birth rate of the Pacific walrus. In the year following the birth of the calf, folliculation is suppressed in the ovaries, and the female remains barren. In the following spring, only a few females become impregnated, the remainder ovulaking later. in the season,

Corgora lutea vera and s~uria-aresirnilar to those in other pinnipeds, and they regress to form easily recognisable dedse white scars, the corpora albicantia, TheLr rate of regression is variable, and some may eventually disappearg ho~rever, their number does give some indication of the past reproductive life of the individual fernale, II . . l.11~ 0.c O 01.a l: lt 1: , ,! hu!na:l c-nibryo and used tn calculate tiie avera:;e gestation period and average d3te of conceptlone No delay in implantation occurs, the ernbryo f orrning soon af ter ir~pregnatlonor1 May 1.1 (average da-ke) and being born at the end of )laye The calf remains protected by the fernale for two yesrs and does not appear 30 attain nutritional independence mtiL the end of that pzriod, Norphological evidence sho:~s that 5crii;hin the subspecies Qo r, rosmarus occupylng the Eastern Canadian Arctic, some slight diflerentiation of body form has taken place, This suggests that isolated breeding populations occur, and emphasises the Sedentary nature of the walrus, During the summer, when ice leaves the normal feedlng areas, walrus haul out on suitable rock outcrops, Promontories and srnaIl islets with clear descents to deep water are favoured, and the ânl- mals are quick to tai-ce to -the >rater wiien Clisturbed, Tkse

--ii&i,& are used year after year, except when ice remains In their viclnity during tne surnrner, Local weather conditions determine wnich ggI1l.A is used, the exposeù rocks boing aband- oned during onshore vinas and heavy seas, 3ce is al~jayspre- ferred as a resting place, anil local movements fl-uctuate as the pack moves with wind and cul-relit. The extensive migrations once postulüted have not been reliably observed, and they fail to take into account the walrusl adaptation to itç environment and its ability to ~rinterin areas where pack ice is extensive, Allen, Gall, 1942. Sxti~ctand va.rilsfling mamninls oL -the western herfiispnere witlx the marine specleç of al1 the oc eans ker. Coinrn, for Int erna.tiona1 T~!i.lde-i5-ypr--Lif e -?Pro tscti-on Spec Pub. II, Lancaster, Pa.. ,

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-_---a 1956 a, The elephant seal (Miroun~a9e~nin+ Linn, ). II, General, social and reproductive behaviour. Falkland, Islands Dependencies SUT~J~Y5cie R~Q,, 13: 88 pp. Law.;, fiut";, 1.956 b, The elephant seal (tfiro~~n~~a1eoni.- Linn,), 1 The physiology of reproduction, Fa]-klaficl 1sla.nds. -Dependencies Su.rvey SC~L~Repi ). 15: 66 pp,

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Manning, T.H. 1942, Remarks on the physiography, Eskirno and mam~nals of Southampton Island, Cane ceop* Je, 2k (1): 16 - 338

Mansfield, A.W, 1955, Eastern Arctic ffsheries investigations, 1947 - 55- Arctic, 8 (2): 133 - 13S9

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Ttle following anrtual reports are a. sel.ection of thoçe

submitted by "0" D-i_vision detaciments to the Ottawa, Keadquarters of the Royal Canadian Moun-Led Police on

Jtme 30 of each year, R,C,M,P, 199. Came conditions - Craig EIarbour, 59559 Il II Cape Christian,

1t li 19 56 * Ches terf ield,

1: li 19 57 0 Cap? Christian, 1957- t l 11 Chesterfield, Body and Tusk Length Measurernents of 83 Male and 39 Fernale

?,Tales are designated as eltnar innature - OXi or Mature - 'Mt, The classes of remales are as follotrs: '1' - immature; 'Mt - mature, nulliparous; 'P9 - pregnant; 'B - barren; 'cg - with calf; !yg - with yearling* Body length is the direct nosv-tail measurement ( IW series were measured along tire ventral ctirve of the body and have been corrected by deducting ten percent), Tusk length is measured In a straight line from tip to alveolar creçt; the longest diameter fs neasured at the gwn line,

A: Males

Field No, Date, Age, Cl-ass, Body Tuslc Tusk Leng th, Iength, Lolag diam. Inches, Inches.

A 10 26 ~IZY 2,o 3: 88 058 PA II. 26 May 0,O Foetus L.7 oeo 37 1 Bug 3*2 1 90 0*9 2 llug Ge2 1 56 - 6 Aug 1O,2 III 5-13 7 Aug 1.2 1 73 17 Aug 8,2 14 100 20 Aug 2i02 M 120 22 Aug 0.3 M 57 2 Sep 10~3 M 3.16 - 18 Sep 2~3 1 81 38 Sep 8.3 PI 98 18 Sep 9.3 M 105 18 Sep 16.3 M 103. 18 Sep 29~3 M 105 18 Sep 10.3 M 102 18 Sep 983 M 91 18 Sep 17.3 M 111 23 Sep 1503 M 122 23 Sep 15.3 M 11 5 17 Sep 083 1 55 Field No, Date. Age, Class. Body Tusk T~slc Length, Length, Long diam. Iric hes , Inches.

5 oct 17 YU 27 Jun 12 Aug 22 Aug 23 Aug 10 Sep 10 Sep 10 Sep 17 sep 6 Oct 6 Oct 7 oct 7 Oct 7 Oct 10 Oct 10 Oc-% 24 Sep 4 Oct 26 Qct 26 OC-t 30 Nov 22 Jun 10 Jul 10 Jul 10 Jul 30 Sul 30 JUI S aug 10 Aug 9 Aug 9 Aug 9 Aug 9 Aixg 9 Aug 9 Aug 9 Aug 9 Aug 9 Aug APPEIIDIX 1 ( continued )

- .--- , , Field No, Date, Age, Class, Body Tus 1s Tusk Length, Length, Long dian, Inches, Inches, -

~itr61 9 Aug k4.2 M 104 508 .L" 62 9 A% 7.2 M 104 9~3 - IW 63 9 Aug 7e2 - 123 9.3 - IN 64 22,2 M 1x9 13.0 - 1w 65 13.2 M 129 11,s w rw 66 9 Aug 14.2 M 114 9.5 P.) IN 70 10 Sep lle3 M 7.5 - IW 72 19 Sep 7.3 M 3-19 800 - r'rr 73 19 Sep 12,3 M 127 10,s Y 1t.1 74 19 Sep l4e3 M 113 10,O - ~m\i 75 19 Sep 19O 3 M 337 niu5 - rw 76 19 Sep 17~3 EI 136 15.8 .- Illr 77 24 Sep 12.3 M 117 13~0 - 1% 78 24 Sep 15.3 M 13l llal; - IN 79 2rl- Sep 903 - 121 9.5 .. IN 80 24 Sep 9-3 M 112 990 - \? 2 25 Ju1 0,2 1 45 010 .. 1.1 11 k Aug 12-2 H 118 10e5 ... W 13 li Aug 2,2 1 84 - ... S 2 31 Jul 31.2 M 111 9.0 - S 52 3 383 f 84- 305 - l s 54 3-03 9 69 le1 - S 55 2- Eg 2e3 9 81 1,O -

A 9 26 May . 8.0 PY A 13 27 May 20,O B A 38 2 Aug 9~2 .Bc A Lt2 7 Aug 8-2 PY A 46 20 ~ug 7.2 P A 48 22 Aug 13.2 Bc A 72 23 Sep 16,3 B A 73 17 Sep 7.3 Bc Field No, ~a-ke. Age, Classe Body TuçB Tusk Length, Length, Long diam, Inches. Xnchea,

- - ... A 75 19 Se2 17e3 BY 99 - - A 70 19 Sep 2e3 1 83 300 099 A 77 2 Oct 18,k B 102 10,O la% A 78 2 Oct 6,4 M 92 50 5 1,P A 79 2 Oct 6,4 I 83 Ete8 04 A 80 4 0c-t ao,4 P 92 6,a 103 A 81 5 Oct 3,4- 1 88 3 ,f+ 0,8 A 82 5 OC% 91*L; P 98 6,s' se5 A 83 Oct 11*4 BE 97 7,o 10 5 A 109 b Aug 1,2 I 72 5 0~6 A 118 xo Aug 93,2 Py 106 1 0 - 4, 112 13 Aug 902 M 94 k3 as A 113 21 Aug Fe2 1 92 303 es A 1-15 22 AU^ 512 , BC 103. 7.3 a,& A 119 SO Sep 94,3 .. P 105 883 le5 A 120 10 Sep 3-393 P 95 783 1,s A 12% 10 sep 13.3 B 96 7e3 105 A 3-25 27 S~P SS93 9 102 %0,0 - A 126 27 Sep i9,3 Be: 3-03 980 A 130 7 0c-k 0,4 i 59 0,6 0.4- A 132 7 C)ct 3.5e4- Bc 93 53 105 A 133 7 Qct 17& By 97 790 le5 APPENDIX 14:

1 Developraent of the Testifs Sn Zmnatu*.e and 'fatw~3 %les

FIsld E+~mSerse sAQseriss Prom Bencas and Coats Islands, 1955 62 6. 9kJP series from Coats 9s3anc9, 199-b. OIW8 svries from Foxe Bzisinp 1955 & 60 S 2 from Seahorse Point, Southampton Island,

Testis 2 Tubüle types as detailed on page 8b3 Diameters in microns . xxx indicates psesence of spern,

Tes tis tubules Epididymiis Field No, Date, Age , Types Diam, in

A II 26 May 39 2 Aug A= 49 22 Aug

A 3.0 26 May A 61. 18 Sep W 13 92 Aug Al35 J-0Oct

LI 3'7 '9 Aug 5s 9 AU~P A 123 90 Sep

A 97 17 Jun IW 62 9 Aug IW 72 13 SSP IW 6 26 OC^ irrî 58 9 Aug A 62 18 Sep APPENDIX II (continuedl

Tes tls tubules Epfdidymf ç Fieéd Mo, Date, Agz, Types Diam, in Diam, Sperm? order

IW 20 22 $un 9 * J. 58 B, C ' 68 O A 63 18 Sep 9.3 60 B 60 0 A 67 1.8 Sep 903 47 B 62 O Dr80 24Sep 9,3 5s B - - A 60 2 sep 903 - 3, C 71 8 331 5s 9 Aut; 1002 49 B, C 5s O Iw 54 53 Aug X0,2 52 Eh C 78 O 57 9 Aug 1O,2 44 C, B 88 O A66 P8Sep 10,3 39 Eh C 79 0

hl 91 b Aug 73 19 Sep LW 77 21; Sep A 84- 5 0c-t; IW 10 30 Nov

A64 18Sep 16.3 bot C, B 59 O A 68 18 Sep 17.3 55 CY 3 78 O

Y Et Oct 21,h 4s' B, C 60 O Development of Follicles and Corpora Lutea iri the Ovaries of 59 Atlûi~ticiialrus

The classes of females are as f0110~~rs:'Ir - ir;i,rnature; 'PZr - mature9 nulliparous; 'Pl - pregnant; ID1 - barren; 'cl - with calf; 'yt - with yearling. Follicles are classified as either atretic ( A ) or healthg ( B )* Measurements of larger follicles and corpora albicantia represent maximum an6 minimum diameters of the sections examined. Thus a follicle listed as "7.4' measurcs 7 mm. by 4 mm. Corpora lutea are measured along three diameters, Follicles rnarked with an asterisk are luteinised, APPENBIX III ( contimed )

APPENDIX II3 ( continued APPENDLX 111 ( continued )

Crovth of the Euman Emb~yo ( after A-rey, 3954 ),

1 Percent gestation cornplated No, 01" days Cr om-rump lengt'n in cm, + !F: <'?A. 2= M C;- O ci- X 2" @DOt3PZ .--,*Cq !-Jrn p VI LI *>& 0 ct- 02$, -la I-> n Y nCD 9J CD P. CD d-(D frJ 3 s t Ytj tiY v 0 d- CF '5-3 P. tir v2 "y b+) p.Q, - r- !U mQ6I?, 0 P CJ P -P O t-~ I-J PO ry t-J i-J 3 ci, 10 tlJ CA e F?H OJ r-3 a u10 5 k-, k-' c t-JG $g cq P- PO fj 9 3 2; Gg Gb xrJ3 Pd- t-'. 5 os Cd ('9 F: iri +'2 ta VJ Ct- kJ- d- 02 t+ t-' G g P. =r k-5 3 CD P. @q-=-.-7' P. $ tir Y * 9 4 0 n Os F9 O FJ Cs & WY li> 5 F ; a I pe