THESCIENTIFIC REPORTS
OF

THE WHALES RESEARCH INSTITUTE
No. 24

THE WHALES RESEARCH INSTITUTETOKYO· JAPANl Sci. Rep. Whales l·~~

NOVEMBER 1972

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SCIENTIFIC REPORTS
OF
THE WHALES RESEARCH INSTITUTE

No. 24

THE WHALES RESEARCH INSTITUTETOKYO, JAPANNOVEMBER 1972

THE WHALES RESEARCH INSTITUTE
1-3-1, ETCHUJIMA, KOTO-KU, TOKYO

THE SCIENTIFIC REPORTS OF THE WHALESRESEARCH INSTITUTE
CONTENTS OF NUMBER 24Page

OMURA, H.
An osteological study of the Cuvier's beaked whale, Ziphius carvirostris, in thenorthwest Pacific. . . . . . . . . . . . . . . . . . . . . . . . . .
NrsHIWAKI, M. and OauRo, N.
Catch of the Cuvier's beaked whale off Japan in recent years. . . . . . . . 35
NrsHIWAKI, M., KASUYA, T., KuREHA, K. and OauRo, N.
Further comments on Mesoplodon ginkgodens. . . . . . . . . . . . . . . . . 43
KASUYA, T.
Growth and reproduction of Stenella caeruleoalba based on the age determination
by means of dentinal growth layers.
. . . . . . . . . . . . . . . . . . 57
KASUYA, T. and OauRo, N.
A new tagging method of dolphins. . . . . . . . . . . . . . . . . . . . 81
KASUYA, T.
Some informations on the growth of the Ganges dolphin with a comment on
the Indus dolphin. . . . . . . . . . . . . . . . . . . . . . . . . . . 87
KASUYA, T. and ANINUL HAQUE, A. K. M.
Some informations on the distribution of the Ganges dolphin. . . . .
109
TsuYUKI, H. and !TOH, S.
Fatty acid component of various blubber oils of Ganges river dolphin.
117
NAITO, Y. and NrsHIWAKI, M.
The growth of two species of the harbour seals in the waters arround Hokkaido. 127
lcHIHARA, T. and YosHIDA, K.
Diving depth of northern fur seals in feeding hours. . . . . . . . . . . . 145

AN OSTEOLOGICAL STUDY OF THE CUVIER'S BEAKEDWHALE, ,ZIPHIUS CAVIROSTRIS, IN THE NORTHWEST
PACIFICHIDEO OMURAABSTRACT

Skulls and postcranial skeletons of :(,iphius cavirostris were studied for eleven
specimens, mostly stranded on the sandy beach of Japan. Some distinctions
between the adult male and female and/or juvenile are noted in the skull measurements. The fusiform tooth and the massive mesorostral bone with posterior
truncation in the male will be completed after the attainment of the physicalmaturity. The total number of the vertebrae is 46-47, and not differs fromthat of the other oceans. The proportional development of bones of skull aswell as the vertebrae according to the growth of whale body is also studied insome extent.

INTRODUCTION
The Cuvier's beaked whale or the goose-beaked whale, Ziphius cavirostris, distributes
in all temperate and tropical seas (Rice and Scheffer, 1968). In the North Pacific,
strandings of this species were reported from the coast of western North America by
various authors (for example Hubbs, 1946) and these are well summarized andstudied of its seasonality by Mitchell ( 1968), which contains records of 41 strandings.
These strandings range between Alaska and the tip of Baja California. From theCentral Pacific also strandings were reported from Hawaii (Richards, 1952) andMidway Islands (Galbreath, 1963).
In the north west Pacific two large skulls were found on the coast of Kamchatka
in 1951 (Tomilin, 1957). The only place where this whale is regularly hunted is on
the coast of Japan (Backus and Schevill, 1961), but as yet no comprehensive study
has been published (Mitchell and Houck, 1967). Hitherto only two papers were
published (Ogawa, 1936-37; Omura et al. 1955).
Strandings of Ziphius cavirostris are not uncommon also on the coast of Ja pan.
These are reported in local newspaper articles, and when the strandings had occured
near to Tokyo the staff of the Whales Research Institute have endeavored to collectsamples of these animals. Thus from 10 individuals skulls and sometimes with postcranial skeletons have been collected. Once someone of the institute made a study ofthese bones, but he could not finish it before he moved to the other research laboratory
where he is not able to continue the study of this kind.
I have investigated the material again, stimulated by the situation mentioned
above, and they are now reported in this paper. To my regret the data on the exact
time, place, body length, sex, and other particulars of the animals are missing, but ifl
Sci. Rep. Whales Res. Inst.,
No. 24, 1972, J-34.

2

OMURA

correctly remember most of them had stranded on the sandy beach of Sagami Bay atdifferent times and not in mass. One animal which stranded on the coast of Tokyo
Bay is also included. In any case all of them were collected from several places nearto Tokyo.
Buckus and Schevill ( 1961) write "Japanese whalers and cetologists seem not
yet to have recorded their observations of the living animal-a thing we may all lookforward to." On this problem I am not able to contribute anything in this paper yet.
MATERIAL

The skeletons used in this study are as follows:
ZC2. Very young specimen. Skull, right mandible, vertebrae, scapulae, 12
pairs of chevron bones, a pair of pelvic bones, fragments of ribs, a part of sternum
are preserved.
ZCl 1. Juvenile specimen. All bones except those of the flippers and pelvic
bone are preserved.
ZC12. Adult but suspicious of its sex. Nearly all bones are preserved as in thecase of ZCll, but each rib was cut into several pieces by saw, possibly just after
the stranding by spectators.
ZC6. Only skull and mandibles are preserved.
ZC3. Possively young adult female. Nearly all bones are preserved as in thecase of ZCl 1.
ZC7. Juvenile specimen. Nearly all bones are preserved as in the case of
ZCll, but each rib was cut into several pieces by saw.
ZC4. Only skull, mandibles, ribs and stermum are preserved.
ZC8. Possibly adult male. Only skull and mandibles are preserved.
ZCl. Possibly adult female. Nearly all bones are preserved as in the case of
ZCll.
ZClO. Possibly adult female. Nearly all bones are preserved as in the case of
ZCll.
TWMl. Adult male. Skull and mandibles. This specimen does not belong
to our collection. This whale was taken off Taiji on some day and the skull is being
kept at the Taiji Whale Museum.
SKULL

Diagnosis. According to Moore (1968) the diagnostic characters of the skull ofZiphius are as follows:
1. Where the premaxillary bones ascend posteriorly on either side of thesuperior nares and terminate, their anterior faces are oriented mesially a small but
obvious amount from directly forward.
2. The combined breadth of the nasal bones is greatest anteriorly and where
the right nasal is out on contact with the right premaxillary bone.
3. When the skull is upright and the long axis of the beak is horizontal, in
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

CUVIER'S BEAKED WHALE

3lateral view the nasal bones both project somewhat farther anteriorly from thesynvertex of the skull than do the up-curled posterior ends of the premaxillary bones.
Further, in his key to the living genera of the beaked whales by characters of theskull he separates Ziphius from Berardius in the character that when the posterior
aspect of the skull is viewed from a point aligned with the long axis of the rostrum,and from a distance of at least two meters, in the former the synvertex of it is completely occuluded by the supraoccipital, or so little of the synvertex shows that the
profiles of both descending sides are not seen to become sheer, whereas in the latterthe profile of the synvertex projects above the supraoccipital as a slightly asymmetrical
block with sheer sides.
The eleven slulls of Ziphius I examined are all in agreement with the above
descriptions (Plates I-V).
Adulthood and sex. As already stated the data on sex and body length of thespecimens are lacking. But in Ziphius the adult male can be distinguished fromthe adult female and juvenile by the presence of the prenarial basin, prominent
mesorostral bone, and by the size and eruption from the gum of the tooth (True,
1910; Fraser, 1942; Moore, 1968). Further, it is common practice among mammalogists to regard a mammal as morphologically adult when the epiphyses have become so fused to the centrum of each of the vertebrae that their sutures are obliterated(Moore, 1968). Using these criteria I have tried to determine the adulthood and sexof the specimens. In the following the specimens are arranged in the order of theirskull length.
ZC2. (Pl. I, Fig. 1) The skull length is 590 mm and evidently from a young
animal. Bones of the skull articulated each other very loosely and the sutures between them are open. Mesorostral ossification is not developed at all and no
prenarial basin present. This specimen has 47 vertebrae and none of the epiphyses
has become fused to its centrum. Further, from 7th up to and including 15th vertebra, the bones consisted of the spinous and transverse processes are not united to thebodies of the centra. In 5th, 6th, 16th, and l 7th vertebra they are united to theircentra, but sutures are still visible. Sex is not known.
ZCl 1. (Pl. I, Fig. 2; Pl. III, Fig. 1) The skull length is 707 mm and also
evidently from a juvenile animal. In this specimen too the mesorostral ossificationis undeveloped and no prenarial basin is present. The sutures of the each bone of theskull are visible. It has 46 vertebrae and none of the epiphyses is united to its
centrum.
ZC12. (Pl. I, Fig. 3; Pl. III, Fig. 3) The skull length is 811 mm and it looks
like to be from an adult male, because there present the prenarial basin distinctly as
shown in Pl I, Fig. 3. The mesorostral bone is developed, but it does not rise beyond
the level of the premaxillaries. It begins about 10 cm from the tip of the rostrum as anarrow ridge, and it increases its height and width towards the middle of the rostrum,and then depressed gradually, and not abruptly, to the prenarial basin. At the middle part of the beak the width of the ridge is about 18 mm and about 10 mm below
the level of the premaxillaries.
Fraser (1942) reports a case that the mesorostral is prominently developed with
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

4

OMURA

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No.2
4
,1
9
7
2
.

CUVIERSBEAKEDWHALE

5

c
r
i
te
r
i
o
no
ffema
l
es
e
x
. As
l
i
gh
twearo
rf
r
a
c
t
u
r
eo
ft
h
et
e
e
t
hi
nt
h
es
pecimenZC1
2
a
r
enots
u
r
et
h
a
tt
h
e
s
ea
r
ecausedbynaturalo
rbydamagedur
i
ngo
raf
te
rt
h
ema
c
er
a・
t
i
on. I
ft
h
e
s
ea
r
ec
a
u
s
e
dbyna
t
u
r
alwearthi
ss
pecimeni
spos
si
b
l
yfromanadultmale,n
o
t
w
i
t
hs
t
a
n
d
i
n
go
ft
he
i
rs
l
e
nde
rs
ha
p
e
. I
tr
e
s
emble
st
ot
h
es
pecimenr
epor
t
ed
d
u
l
t"m
a
l
e
,Garrynamonie,SouthUi
s
t
,1
9
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5
.4
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8.
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)
,
i
nwhichbyFraser（ Younga
oneoft
h
et
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thh
a
saf
r
a
c
t
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r
e
dt
i
pbutt
heo
t
h
e
ri
sc
o
m
p
l
e
t
e
,andt
h
eg
r
e
a
t
e
st
diamet
e
r
e
s
pe
ct
iv
e
l
y
. Ast
ot
h
eme
s
o
r
o
st
r
alhes
t
a
t
e
s"The
oft
h
e
s
et
e
e
t
ha
r
e1
5and1
4m mr
me
s
or
o
s
t
r
a
li
swelde
ve
l
oped.
.
.,b
u
ti
nt
her
e
g
i
o
nwher
e
,i
nt
h
et
y
p
i
c
alo
l
dmal
e
,
t
h
eme
s
o
r
o
s
t
r
a
li
ss
udde
n
l
ydepre
s
s
ed
,t
h
a
toft
heSouthUistspecimendi
psdowni
na
h
isr
e
s
p
e
c
tt
o
ot
hes
pe
cime
n
g
r
a
d
u
a
ls
l
opet
ot
h
ef
l
o
o
roft
hep
r
e
n
a
r
ialbas
i
n"
. Int
ZCI
2 resemblestotheSouth Ui
s
ts
pe
ci
m
e
n
,a
ss
t
a
t
e
da
l
r
e
ady. Ia
s
sume
dt
h
i
s
s
peciment
obeanadul
tmal
ei
nt
hel
a
t
eranal
y
s
i
so
ft
h
es
k
u
l
lproportions.
Anothe
ronef
e
a
t
u
r
eo
fs
omei
n
t
e
r
e
s
toft
h
iss
pe
cime
ni
st
h
eunus
ua
lde
v
e
l
o
p
‑
t
ebra(
1
s
tl
u
r
山 a
r)
me
n
tofs
omeoft
h
ev
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rt
e
b
r
a
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. Thepo
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toft
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7
t
h問 r
andt
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n
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8
t
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er
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br
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r
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r
r
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g
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lyde
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a
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ro
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r
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lbodyt
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er
ep
r
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s
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n
tani
r
r
e
g
u
l
a
rpi
t(
F
i
g
.2
)
. S山 habnorm‑
al
i
t
yi
sa
l
s
o found between 29th v
er
tebr
a(
2nd c
a
u
d
a
l)and 30
t
hv
er
t
eb
r
a(
3
r
d
cau
d
a
l)
. Thesea
r
epo
s
si
b
l
yduet
os
omep
a
tho
l
o
g
i
c
a
lc
aus
e
,buti
ti
sn
o
tc
e
r
t
a
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町e
ctt
ot
hegrowthoft
h
es
k
u
l
lan
dt
het
e
et
h
.
t
h
a
tt
h
e
s
eabn
o
r
m
a
l
i
t
yhadanyE

F
ig
.2
. l
7
t
ha
n
dl
8
t
hv
e
r
t
e
b
r
a
eo
ft
h
eS
p
e
ci
m
e
nZC1
2.
Le
f
t
:P
o
s
t
e
r
i
o
rv
i
e
wo
ft
h
el
7
t
hv
e
r
t
e
b
r
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.
e
r
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o
rv
i
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wo
f
t
h
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8
t
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b
r
a(
s
pi
n
o
u
sp
r
o
c
e
s
sp
a
r
tl
yb
r
o
k
e
n
)
.
R
ig
h
t・Ant
ZC6.(
P
l
.I
,F
i
g
.4
;P
l
.IV
,F
i
g
.I
) Thes
k
u
l
li
sl
a
r
g
e
rt
hant
h
ef
o
r
e
g
o
i
n
gs
p
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‑
mena
ndmea
s
u
r
e
s81
9m mi
nl
e
n
g
t
h,butits
eemst
obefromayoungeranimal
. The
s
u
t
u
r
e
sbetweenbone
so
ft
h
es
k
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r
evi
s
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e
. Theme
s
o
r
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tr
a
lbonei
sund
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v
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ped
andt
h
ecanalisempty. Thep
r
e
n
a
r
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lba
s
ini
sunde
v
el
o
p
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d
. Alo
ft
hev
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r
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il
ea
n
ima
l
.
andt
e
et
ha
r
el
a
ck
ing,butpres
umably仕omajuv
ZC3.(
P
l
.I
I
I,F
i
g
.4
;P
l
.I
V,F
i
g
.3) Thes
kull
e
n
g
thi
s823mm. Themeso‑rostr
albonei
sdeve
l
o
p
e
d
,buti
t
ss
u
p
e
r
i
o
rf
a
c
ei
sbelowt
hel
e
v
e
lo
fprema
xi
l
la
r
i
e
sby
S
c
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/
1
. Whale
sRe
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2.

＇

6

OMURA

about 5 mm towards the middle part of the rostrum, and then depressed graduallyand finally ends just after the region where, in the premaxillaries, the foramina aresituated. It is separated from the anterior end of the bony ethmoid, the vertical faceof which is tuberculated, and rests on the vomer. The sutures between premaxillaries and the maxillaries are visible in most parts. No prenarial basin is developed.
This specimen has 46 vertebrae and all of the epiphyses are fused to their centra,
but in the dorsal vertebrae sutures are still visible, especially in the posterior part ofeach vertebra. It is possible that this specimen is of an adult, at least semi-adult,
female, though the teeth are lacking. The length and the breadth of the mandibularalveoli are 17 and 12 mm in the right and 18 and 12 mm in the left.
ZC7. (Pl. II, Fig. 1; Pl. III, Fig. 2) The skull length is 826 mm. There is a
low ridge which runs antero-posteriorly on the superior surface of the vomer, which
begins about 4 cm posterior from the tip of the vomer and ends after the level of thepremaxillary foramina. The prenarial basin is undeveloped and the premaxillaries,
maxillaries, and the vomer articulate loosely. The anterior end of the bony ethmoid
rests on the flattened part of the vomer.
This specimen has 4 7 vertebrae and the epiphyses are not fused to their centra,
but separated, except a few vertebrae in the cervical and caudal vertebrae. Accordingly, it is possible that this specimen came from a juvenile animal.
TWMl. (Pl. V, Figs. 1 and 2) The skull is 837 mm in length and evidently
from an adult male. The mesorostral bone is developed conspicuously and its
superior surface rises over the level of the premaxillaries. It extends from the tip ofthe beak posteriorly and at a point, 92 mm from the tip, it is truncated abruptly. At
this point the bone is 55 mm wide and 50 mm thick. On either sides of the middle
part of the mesorostral there are a groove of about 3 cm deep which separates it fromthe ridge of the premaxillaries. The prenarial basin is also developed conspicuously
and the skull itself is well ossified.
The teeth are massive, and fusiform in shape. Their measurements are given in
Table 3.
ZC4. (Pl. II, Fig. 2) The skull is 844 mm in length and not well ossified.
The mesorostral is undeveloped and the canal is empty. The prenarial basin is undeveloped and the right premaxillary is nearly flat at this region. The beak is slender, and it seems that the specimen is of a female. None of the vertebrae and teeth
has been preserved.
ZC8. (Pl. IV, Fig. 2; Pl. VII, Fig. 2) The skull is 886 mm in length andrather heavy. Most of the sutures of the articulating bones are visible, but that ofthe vomer and premaxillaries is not clear. The mesorostral bone is developed as aridge of about 5 mm width. It begins at the tip of the vomer or about 10 cm posterior to the tip of the beak and ends at just after the line connecting the premaxillary
foramina, and then depressed. The superior face of the mesorostral is about 5 mm
below the level of the premaxillaries. The inner part of the right and left premaxillaries are steeply depressed at the prenarial portion and forms the basin, together
with the depressed part of the mesorostral. The teeth are lacking, but the alveoli of
the both mandibular teeth are large, and measures about 20 mm width and 28 mm
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

CUVIER'S BEAKED WHALE
TABLE I.
Measurement
no.
I

2
3
4

5
6

7
8
9

10
11
12
13
14
15
16
17
18
19
20
21

22
23
24
26
27
29
30
31
32
33

34
35
36
37
38
39
40

41
42
43
44

45
AB-!eft*AB-right*

SKULL MEASUREMENTS OF :(/PHIUS CAVIROSTRISIN NORTHWEST PACIFIC. (in mm)

zc 2 zc 11 zc 12 zc 6
juv.

ad. 6

zc 3

juv.

juv.

ad. ""

590
313
413
444
272
283
501
372
383
525
463
282
106
89
83
72
328
320
300
215
130
42
76
67
52
48
135
120
119
47
188
140
79
41
61
81
290
64
75
29
118

707
386
514
555
345
368
603
465
458
626
566
369
105
120
98
87
378
381
357
248
127
50
88
53
67
66
157
143
144
56
250
192
103
58
84
104
355
68
101
36
138
190

811
460
581+
611 +
390
440
689
531
534
717
623
419
144
127
98
86
471
468
433
261
170
66
102
55
69
63
177
174
177
54
288
224
97
64
91
107
367

819
472
616
667
394
429
730
560
582
745
675
437
141
121
119
105
448
449
439
258
139
48
95
52
77
73
183
164
168
48
305
233
109
62
90
112
402
91
106
45
150
234
20
50
54

823
459
630+
630+
415
427
701
550
546
743
645
435
154
131
123

172
0

53
55

0

50
54

92

137
59
133
203
0
55

* Greatest length of auditory bulla.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

7

Ill

477
476
462
250
!39
50
91
52
63
61
163
157
164
46
283
215
105
68
76
124
411
105
118
50
140
226
0

ZC 7 TWM I ZC 4
juv.
ad. 6
""

ZC 8 ZC I
ad. ~ ad. ""

826
487
637
676
400
456
738
577
569
744
663
435
128
137
108
95
463
454
447
261
139
51
96
50
67
50
166
158
160
52
291
222
93

886
499
659
694
425
469
774
588
575
794
698
462
142
128
116
105
502+
451+
499
311
148+

119

837
475
651
687
413
438
742
573
557
753
654
444
128
117
120
106
486
476
456
300
141
54
95
55
87
69
210
207
212
68
285
244
98
104
119
118
430
65
155

48
122
260

116
313

66
88

102
382
80

0

0

50
55

54

844
489
636
675
399
467
747
591
585
767
680
454
135
129
100
94
448
445
437
271
129
53
87
54
60
52
166
154
156
55
312
226
IOI
57
85
106
388
83
107
45
131
198
0
54
57

74
67
202
193
204
68
305
248
125
83
103
115
455
91
147
66
168
250
35

891
503
661
695
435
450
766
589
578
801
690
451
143
130
110
99
517
507
486
322
165
69
60+
75
66
181
176
178
71
310
246
110
74
99
Ill

427
96
126
51
158
255
0
57
60

ZCIO
ad. <:jl

921
517
728
764
470
458
769
609
587
821
701
490
138
149
130
124
522
517
498
340
161+

73
65
185
182
187
66

332
275
125
84
91
132
453
96
125
53
142
268
0
53
57

8

OMURA

length, whereas in the specimen ZClO, which is thought to be an adult female, thecorresponding figures are 14 and 20 mm respectively.
All of the vertebrae of this specimen are lacking, but it is probable that this skull
was obtained from an adult male.
ZC 1. (Pl. II, Fig. 3) The skull is 891 mm in length and well ossified, especially in the region of the beak. A very low and narrow ridge is present on the vomer,
even the highest part of which lying over 10 mm below the level of the premaxillaries.
No prenarial basin is developed. The mandibles of this specimen is lacking, butboth teeth have been secured, of which measurements are given in Table 3. They
are slender and resembles in shape to those of the specimen ZC12 and the root is completely closed in the both teeth.
In this specimen the number of the vertebrae is 4 7 and all of the epiphyses are socompletely fused to their centra that the sutures are obliterated.
In conclusion above it may possibly be concluded that this specimen is from anadult female.
ZClO. (Pl. II, Fig. 4; Pl. VII, Figs. 1 and 2) The skull is 921 mm in lengthand this is the largest skull among my collection. It exhibit characters of an adultfemale. The mesorostral bone is less developed and there is a low and narrow ridge
which runs from the tip of the vomer, about 10 cm from the tip of the rostrum, posteriorly to the prenarial region where the anterior end of the bony ethmoid rests. The
height of the ridge is about 5 mm at the highest part and well below the level of thepremaxillaries. No prenarial basin is developed. The broadened part of the rightpremaxillary is nearly flat, except the extreme outer part where a ridge is formed.
This specimen has 47 vertebrae and all of the epiphyses are so entirely fused thatthe sutures are obliterated. No tooth was left from this specimen, but the size of themandibular alveoli is small as stated already. Accordingly this specimen is possibly
from an adult female.
Skull proportions. The measurements of each skull are shown in Table 1 in actual
length in mm. The measurement numbers are those used by Moore (1963) andfollowed by Mitchell and Houck ( 1967) and Mitchell ( 1968). These are as follows:

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

Descriptions of measurements provided in Table 1.
Greatest length of skull.
Greatest length of rostrum, tip of beak to line connecting apices of antorbital
notches.
Tip of rostrum to posterior margin of pterygoid nearest mid-sagittal plane.
Tip of rostrum to most posterior extension of wing of pterygoid.
Tip of rostrum to most anterior extension of pterygoid.
Tip ofrostrum to most posterior extension of maxillaries between the pterygoidson the palate.
Tip of rostrum to most posterior extension of maxillary plate.
Tip of rostrum to anterior margin of superior nares.
Tip of rostrum to most anterior point on premaxillary crest (i.e. to anterior tip
of nasals).
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

CUVIER'S BEAKED WHALE

10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
26.
27.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.

9

Tip of rostrum to most posterior extension of temporal fossa.
Tip of rostrum to most posterior extension of lateral tip of left premaxillarycrest.
Tip of rostrum to most anterior extension of pterygoid sinus.
Greatest length of temporal fossa.
Greatest length of orbit.
Greatest length of right nasal on vertex of skull.
Length of nasal suture.
Greatest breadth of skull across postorbital processes of frontals.
Greatest breadth of skull across zygomatic processes of squamosals.
Greatest breadth of skull across centers of orbits.
Least breadth of skull across posterior margins of temporal fossae.
Greatest span of occipital condyles.
Greatest width of an occipital condyle.
Greatest length of an occipital condyle.
Greatest breadth of foramen magnum.
Greatest breadth of nasals on vertex.
Least distance between premaxillary crests.
Greatest span of premaxillary crests.
Least width (strictly transverse) of premaxillae where they narrow opposite
superior nares.
Greatest width of premaxillae anterior to place of measurement no. 30.
Width of premaxillae at midlength of rostrum.
Width of rostrum in apices of antorbital notches.
Width of rostrum in apices of prominential notches.
Greatest width of rostrum at midlength of rostrum.
Greatest depth of rostrum at midlength of rostrum.
Greatest transverse width of superior nares.
Greatest inside width of inferior nares, at apices of pterygoid notches, on thepterygoids.
Height of skull. Distance between vertex of skull and most ventral point on
pterygoids.
Greatest width of temporal fossa approximately at right angle to greatest length.
Least distance between main or anterior maxillary foramina.
Least distance between premaxillary foramina.
Distance from posterior margin of left maxillary foramen to most anterior extension of left maxillary prominence.
Greatest length of vomer visible at surface of palate.
Amount added to skull length because of breakage of occipital condyle.

The measurement number 45 of Moore is "Amount added to beak because of
breakage'', but it is slightly changed. In the present specimen some skulls were cut
open of their supraoccipital bones triangularly by saw in order to extract brain for
the anatomical study at the Department of Anatomy, Faculty of Medicine, UniSci. Rep. Whales Res. Inst.,

No. 24, 1972.

10

OMURA

versity of Tokyo. Most of them were so carefully cut that the occipital condyles
were not damaged, but in the specimens ZC6 and ZC8 their tips were slightly cut
down. Accordingly I have estimated the lost length, comparing them with otherspecimens.
Mitchell and Houck (1967) have studied some of the differences between thelarge male and female skulls on the one hand and the juvenile male skull on the other.
I have tried to find out the difference in the skull proportion, if any, which separates
%

CV

58

56

•

54 52

•

•

•
••
•

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.,
""
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d'

0

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78

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d'
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76
74

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70

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68

f-

66

f-

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700

800

900

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1000

SKULL LENGTH (mm)Fig. 3. Skull proportion of <:,iphius cavirostris in the North Pacific. Closed circle indicates specimens from the northwest Pacific, and open circle those from the northeast Pacific. Presumed adult males are denoted by male symbol. Numeral incircle in each figure indicates measurement number described in the text.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

CUVIER'S BEAKED WHALE

11

the adult male from the adult female and/or juvenile as well as the proportionalchange according to growth of the skull. I have calculated the percentage figures
against the skull length of the measurements and then plotted them in the order ofskull length (Fig. 3). In Fig. 3 I also included two skulls reported by Ogawa (193637). One of these skulls is the smallest which measures 445 mm in length, and ob%
14

f-

... "

@

•

12 r

•

"

10 f-

62 f-

P"

••.

58 f-

..

f-

•

54 f-

•

f-

•

42 f-

@

~

38

~

•

d'

•

36 f34 f32

•

•'

•

44 f-

40

0

•

0

52 f50

0

@

60 f-

56

<:J

•
•
•• •

"

•

.•• •

f-

• •

fi'

0

fi'

•

30 500

600

700

800

900

SKULL LENGTH (mm)Fig, 3. Continued.

tained from a female of 247.6 cm long, taken off Shiogamashi, Miyagi-ken. The
other skull is the largest and measures 956 mm in length, obtained from a 590 cm
long male at Taiji. I also included, for the sake of comparison between skulls fromthe northwest and northeast Pacific, a skull reported by Hubbs (1946), of which
length is 716 mm and obtained from an immature female, and two skulls reported by
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

12

OMURA

Mitchell and Houck (1967). The skull length of their specimens are 907 mm (HSC57-1) and 923 mm (HSC 59-3), and the former is from a male and the latter from afemale. Both are presumed to be adult in their report. Further, Mitchell (1968)
reports measurements of skulls of northeast Pacific, but they are not cited in Fig. 3,
mainly due to the unknown sex and maturity.
%
22 f-

®

•

"'

20 r
0

18

• l:i'

f--

""

16

•

10

f--

8

f--

•

~

..9\~

6 -

®

10

10

f--

8

f--

6

~

26 f--

.,•

••

®

I

<J 0

. ..d.
....• " .
••

•

•

8 -

•

•

•o

b'

0

..

@

I
I

24 f--

•

22
20

0

•

I-'

I

I

I

500

600

700

..
0

I

f--

I

d'

[

:· • •I

800

900

SKULL LENGTH (mm)Fig, 3. Continued.

In this figure the skulls of the northwest Pacific are marked by closed circle andthose from the northeast Pacific by open circle. The skulls presumed to be adultmale are so marked with symbol, and others without symbol. As to the specimens of
the other authors I calculated the percentage figures from their measurements.
As seen in this figure there are a wide range of variation and it seems that the inSci. Rep. Whales Res. Inst.,

No. 24, 1972.

CUVIER'S BEAKED WHALE

13

dividual difference is much greater than the difference by sexes. But in some characters the presumed adult male is separated from the others. These measurements are
the following:
30. Least width (strictly transverse) of premaxillae where they narrow opposite
superior nares.
%0
fi'

®

24

..

22

•

20

26 r-

fi'

.•

•

•

®

0

• •

rl'

24 rfi'22 r20

fi'

8 r-

<@

•

0

••
•

•

•

~

• •
•

.r

•

... •
d'

6 r-

•

rl' ••

30

~

®

28

~

..
.,• .,

26

~

••

•

24 r-

4~

2

fi"

0

••
•

kl'.

•

I

0

•

•

'.@

•

•

rl'

••

0

rl' ••

• rl'

• d'

•

0

I

4-

@

..

2-

....• .• •

0
8-

•

•
500

600

•
"

700

d'

..

0

•

800

900

SKULL LENGTH (mm)Fig, 3. Continued.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

OMURA14

31. Greatest width of premaxillae anterior to place of measurement no. 30.
41. Least distance between main or anterior maxillary foramina.
42. Least distance between premaxillary foramina.
And also in the following measurements the presumed adult male shows greater
value than the others with a few exceptions.
29. Greatest span of premaxillary crest.
36. Greatest depth of rostrum at midlength of rostrum.
Most of the above characters concern to the width of the premaxillae and it is

%

0

4 '-

®

i

i

!

!

i

0

"

.•

•

2-

~

•

•

-; kf

•

•

8

4

52

®

~·

••

•

8

•

•
•

•
0

46

ri'

@

"'

6 f-

"'

••

•
8

•

•

•

d'

•

0

ti'

,f rf
0

• •

ri'

.

••••

• ~

-~

• ~

@

6

•

••

-

•

4-

d'eo

ti'

.. "

I

(@)

..

•

•

•

50

48

..

0

rf

•
10

8

6

•
•

A. BULLALENGTH(LEFT)

500

600

700

800

"

900

SKULL LENGTH(mm)Fig, 3. Continued.
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

CUVIER'S BEAKED WHALE

15

possible that in the adult male the width of the premaxillae posterior to the midlength of the rostrum is greater than in females and juvenile animals. It is also possible that in the adult male the depth of the rostrum increases with age and in the oldaged male the greatest depth of rostrum at its midlength is very conspicuous.
The absolute length of the whale body is no good criterion of maturity in
Ziphius cavirostris (Mitchell and Houck, 1967) and this is also applied to the skull
length, as suggested by the present material. But in Fig. 3 there are suggested some
general trend of the proportional changes in some of the measurements. They can begrouped in the following three categories:
1) The proportion increases with the growth of the body or age.
2. Greatest length of rostrum, tip of beak to line connecting apices of antorbital
notches.
3. Tip of rostrum to posterior margin of pterygoid nearest mid-sagittal plane.
18. Greatest breadth of skull across zygomatic processes of squamosals.
29. Greatest span of premaxillary crests. Male.
30. Least width (strictly transverse) of premaxillae where they narrow opposite
superior nares. Male.
31. Greatest width of premaxillae anterior to place of measurement no. 30.
Male.
34. Width of rostrum in apices of prominential notches.
36. Greatest depth of rostrum at midlength of rostrum. Male.
41. Least distance between main or anterior maxillary foramina. Male.
42. Least distance between premaxillary foramina. Male.
2) Practically no proportional change is observed with age.
10. Tip of rostrum to most posterior extension of temporal fossa.
13. Greatest length of temporal fossa.
16. Length of nasal sutures.
26. Greatest breadth of nasals on vertex.
27. Least distance between premaxillary crests.
32. Width of premaxillae at midlength of rostrum.
35. Greatest width of rostrum at midlength of rostrum.
37. Greatest transverse width of superior nares.
38. Greatest inside width of inferior nares, at apices of pterygoid notches, on
the pterygoids.
3) The proportion decreases with age.
21. Greatest span of occipital condyles.
24. Greatest breadth of foramen magnum.
Addition. Greatest length of auditory bulla.
The last mentioned measurement, greatest length of auditory bulla, is not included in the Moore's measurements, but I added this measurement in Table 1,
following after Mitchell and Houck (1967).
In conclusion above the length of the rostrum becomes larger proportionallywith age, and it becomes more wider at the base, but not at its midlength. The
proportional breadth of the skull is also becomes wider with age.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

OMURA

16

TABLE2. COMPARISON OF SKULL MEASUREMENTS BETWEEN ADULT MALE
AND OTHERS, EXPRESSED AS PERCENTAGE OF SKULL LENGTH.
Measurement
no.
2
3
4
5
6
7
8
9
10
11

12
13
14
15
16
17
18
19
20
21
22
23
24
26
27
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
AB**-left
AB**-right

Adult female and/or juvenile*

Presumed adult male
Number

Range

Mean

Number

Range

Mean

3
2
2
3
3
3
3
3
3
3
3
3
3
3
3
2
2
3
3
2
2
2
2
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
2
3
3

56.32-56.75
74.38-77. 78
78.33-82.08
47.97-49.34
52.33-54.25
84.96-88.65
65.47-68.46
64.90-66.55
88.41--89.96
76.82-78. 78
51.66-53.05
15.35-17.76
13.92-15.66
12.08-14.34
10.60-12.66
58.06-58.08
56.87-57.71
53.39-56.32
32.18-35.84
16.85-20.96
6.45- 8.14
11.41-12.58
6.57- 6.78
8.35-10.39
7.56- 8.24
21.82-25.09
41.45-24.73
21.82-25.33
6.66- 8.12
34.05-35.51
27.62-29.15
11.71-14.11
7.89-12.43
11.22-14.22
12.98-14.10
45.25-51.37
7.77-11.34
16.59-18.52
7.27- 7.45
13.86-18.96
25.03-37.40

56.60
76.08
80.21
48.47
53.17
86.99
66.77
65.76
89.33
77.91
52.28
16.38
14.68
13.17
11.70
58.07
57.29
54.73
34.37
18.91
7.30
12.00
6.68
9.08
7.86
23.24
22.65
23.39
7.48
34.66
28.25
12.59
9.90
12.36
13.41
49.32
9.79
17.33
7.36
16.41
30.22
6.45
6.78

6
5
5
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
5
5
4
4
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
5
5

55. 77-58.96
74.19-79.04
78.00--82.95
47.27-51.03
49.73-55.33
83.50-89.35
66.11-70.02
63.74-71.06
89.14-90.96
76.11--82.42
50.62-53. 79
14.98-18.71
14.59-16.59
11.85-14.95
11.11-13.49
53.08-58.02
52.73-57.84
51. 78-56.14
30.38-36.92
15.28-18.52
5.86- 7.74
10.31-11.62
6.05- 6.35
7.11- 9.40
6.05- 8.91
19.67-22.34
18.25-20.02
18.48-20.51
5.59- 7.97
34.39-37.24
26.12-29.86
11.26-13.57
6.75- 9.12
9.23-11.11
12.35-15.06
45.97-49.94
9.69-12.76
12.68-14.41
5.33- 6.08
14.77-18.32
23.46-31.48
5.75- 6.40
6.19- 6.75

57.15
76.18
80.84
49.02
52.51
86.94
67.89
67.37
90.21
79.20
52.75
16.41
15.56
13.48
12.25
56.08
55.56
54.04
33.11
16.90
6.43
11.15
6.28
8.10
7.17
20.39
19.33
19.76
6.57
35.78
17.62
12.54
8.00
10.32
13.41
48.06
10.76
13.68
5.70
16.46
28.12
6.14
6.58

* Exclude smaller skulls than 800 mm in length.
* * Greatest length of auditory bulla.

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

17

CUVIER'S BEAKED WHALE

The temporal fossa, nasals, superior and inferior nares retain their size in porportion to their skull length, but the occipital condyles and the tympanic bulla growvery little with age, and hence their proportional sizes decrease with the growth of theskull.
Distinctions of adult male were already mentioned. One interesting feature
among the measurements is the difference in the lengths of the right and left auditory
bullae. In the seven skulls in which both bullae were retained, the right bulla isalways greater than the left (see Table 1). In the skulls reported by Mitchell andHouck ( 1967) also the right bulla is longer than the left in two skulls with both bullae(HSC 57-2, HSC 59-3). It is not clear, however, whether or not this is related tosome physiological matter such as difference in hearing between right and left ears inthis species.
In Fig. 3 most of the measurements are shown in proportion to the skull length,
but they do not cover all measurements. In Table 2 all measurements arearranged as percentages of skull length, separately by the presumed adult male andadult female and/or juvenile of my specimens. Of course more material, especiallyfor the adult male, is needed for the tabulation of such nature. I present here
this table, therefore, only for reference.
Further, I compared the proportions of the skull of the northwest Pacificspecimens to those of the northeast Pacific specimens as reported by Mitchell andHouck (1967) and Mitchell (1968). They are partly included in Fig. 3. If all of thematerial from the northeast Pacific are plotted in Fig. 3 it shows more wide individual
variation, and none of the difference between the specimens from the east and west
North Pacific. But in the measurement no. 8, tip of rostrum to anterior margin of
superior nares, some distinction is noted in which my measurement showing always
smaller value, though this is not included in Fig. 3. It may possible, however, this is
TABLE 3.
Measurement
no.

a

b
c
d
e
f

MEASUREMENTS OF MANDIBLES AND TEETH OF Z,IPHIUS
CAVIROSTRIS IN NORTHWEST PACIFIC.

ZC 2 ZC 11 ZC 12

ZC 6

ZC 3

ZC 7 TWM 1 ZC 4

494
91
8S
261
101
24

718
1S8
139
397
134
40
416

737
1S6
138
391
138
49
443

730
162
170
393
136
3S
403

g
h

60S
108
111
330
120
38
374

j
k
m

*

Only teeth were saved.

** Tip erased.
Sci. Rep. Whales Res. Inst.,
No. 21, 1972.

710
134
130
341
lSO
4S
423
49
46
11
11

10
10

7S3
1S3
140
420
139
49
434
48**
36**
21
22
lS
lS

737
1S7
160
413
137
46
422

ZC 8 ZC 1* ZC 10

777
171
186
417
160

808
14S
170
4Sl
1S6
48
488

so
474
S2
SS
11

12
10
9

18

OMURA

due to the difference in the method of measurement, because this is rather difficult todefine and in the light of good agreement in the other measurements. I have notplaced, therefore, much importance on this measurement.
In Table 3 measurements of mandibles and teeth are shown. It is regrettablethat the teeth are lacking in most of the specimens and more mention on mandibles
and teeth may not be needed here. The measurement number are as follows:

a.
b.
c.
d.
e.
f.
g.
h.
i.

J·
k.
1.
m.

Descriptions of measurements of mandibles provided in Table 3.
Greatest length of right dentary bone.
Greatest length of right dentary to posterior end of symphysis.
Greatest length of right dentary to posterior border of mental foramen.
Greatest length of right dentary to anteromedial margin of mandibular
vacuity.
Height at coronoid process.
Breadth of symphysis at posterior margin of mandibular alveoli.
Breadth of jaws across mandibular condyles.
Total length of tooth-left.
Total length of tooth-right.
Greatest diameter of tooth-left.
Greatest diameter of tooth-right.
Diameter at right angle to greatest diameter-left.
Diameter at right angle to greatest diameter-right.
VERTEBRAE(Pl. VI)

Complete sets of the vertebrae of Z,iphius cavirostris in the northwest Pacific weresecured from seven individuals. In some specimens the spinous and transverse
processes, and sometimes the vertebral body too, were cut by saw just after the
stranding by spectators. But still they are in such condition that they could be restored. Thus there is no difficulty in counting of their number and take measurements.
The vertebral formulae of each specimen are shown in Table 4. As seen fromthis table the total number of vertebrae is 46-47: cervical 7, dorsal 9-10, lumbar
TABLE 4.

VERTEBRAL FORMULA OF :{,IPHIUS CAVIROSTRIS INNORTHWEST PACIFIC.

Specimen

CervicalDorsalLumbarCaudal

Total

zc 2
zc 11
zc 12
zc 3
zc 7
zc
zc 10

7
7
7
7
7
7
7

10

10

9
9
9
9

10

20
20
20
20
21
20
20

47
46
47
46
47
47
47

10
10

11
10
10
10
10

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

19

CUVIER'S BEAKED WHALE

10-11, and caudal 20-21. True (1910) gives a table in which the vertebral formulaefor eight specimens are shown, including those reported by the other authors. In
his table the vertebral numbers are: cervical 7, dorsal 9-10, lumbar 9-11, caudal
19-20, and the total 46, excepting the specimens with question and the one which has
49 vertebrae, the Argentine specimen. But he comments " In the figures of theArgentine specimen the last ten caudals are practically without characters, and it isperhaps allowable to question whether the terminal two or three were not added tomake an even taper to the end of the column. If such be not the case, this specimen
had more vertebrae than any other ". It can be concluded, therefore, that in thevertebral count there is no distinct character which separates ,Ziphius cavirostris of thenorthwest Pacific from the other oceans.

6.0
5.6
,I'

5.2

/

/

4.8
4.4
4.0
3.6

--

3.2
2.8 2.4
2.0
1. 6-----o---__,.

--L----..------ Ca---,..
VERTEBRAE

Fig. 4. Ratio of greatest height against height of centrum in each vertebra in dorsal,
lumbar, and caudal vertebrae of Ziphius cavirostris in the northwest Pacific.

The measurements of vertebrae of the seven specimens are shown in Appendix
Table with some notes of observations. Since the vertebrae were secured from thevery young, juvenile, and adult animals it is possible to investigate the change in size
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

OMURA20

of vertebrae according to the growth of the whale body.
In Fig. 4 are shown the ratios of the greatest height against the height of thecentrum in each vertebra for the specimens ZC2 (very young), ZCI l (juvenile), and
ZC 1 (adult). This figure may demonstrate the relative height of the spinous process,and its change according to the age. As seen in this figure the relative height of the
spinous processes becomes larger with growth, especially in the dorsal vertebrae,
except the lst dorsal.
In Fig. 5 are shown the ratios of the greatest breadth of each vertebra against its
centrum breadth separately for the three specimens. This figure shows the relative
growth of the transverse processes according to age, at least of those in the lumbar andcaudal regions. It is of some interest to note that in the dorsal vertebrae the lengthof the transverse processes increase gradually, but in the 3rd vertebra anterior to the

G.B.jB.C~------------------------,
3.6
3.2
2.8
2.4
2.0
1.6
1.2

...,.__ _ _ D~~~-ea~~~~VERTEBRAE
Fig. 5. Ratio of greatest breadth against breadth of centrum in each vertebra indorsal, lumbar, and caudal vertebrae of .(iphius cavirostris in the northwest Pacific.

last it shows practically no relative growth and the value itself is very low, and afterthat vertebra they grow increasingly until the first lumbar where the value is greatest.
This is partly due to the fact that in the dorsal vertebrae the transeverse processes are
not situated at the level of the center of the centrum, but at more superior position,and in the 3rd vertebra anterior to the last they present at the highest position among
the dorsal vertebrae. As seen in the Appendix Table the greatest breadth of thisvertebra is always smaller than in the neighboring vertebrae.
Omura (1971) reports that in the baleen whales the long distant migrating
species and fast swimmers have more developed vertebrae in the posterior portion of
the lumbar and in the anterior portion of the caudal regions than in the other species.
For the :(,iphius cavirostris I also calculated the mean length of each centrum, using theSci. Rep. Whales Res. Inst.,

No. 24, 1972.

CUVIER'S BEAKED WHALE

21

same following formula:Mean length=~ axbxc
where a, b, and c are the breadth, height and length of the centrum
respectively.
The calculated lengths are shown in Fig. 6 for the specimens ZC2, ZCll, ZC7(larger juvenile than ZCll), and ZCl. This figure denotes that in this species thevertebrae in the posterior portion of the lumbar and in the anterior portion of thecaudal regions become larger with the growth of the body. This fact is presumed tobe applied to the other species of whales too.
In the Ziphius cavirostris the first several cervicals are fused into a mass. Among
seven specimens four vertebrae, namely the atlas, axis, the 3rd, and the 4th cervicals
are fused in five specimens, and the remainders are three and six, as noted in Appendix Table.
140

120

--

ZC I

ZC7

~100
I
f-

~ ::~::~ZC2
40

20

Comparison of mean length of each vertebra in four specimens of :(,iphiuscavirostris in the northwest Pacific.

Fig. 6.

OTHER BONES

Rib. A complete set of ribs was obtained only from the specimen ZC3, and even inthis specimen the last three (right side) and four (left side) ribs were cut into two or
three fragments. The broken parts were restored and the measurements were madeof their straight length, and the results are shown in Table 5.
Scapula (Pl. VII, Fig. 3) The scapula is fan shaped and the acromion is welldeveloped with broadened distal end. The coracoid is also developed. From six
specimens the scapulae were secured and their measurements are shown in Table 6.
The other bones e.g. sternum, hyoid, chevrons were also secured from some of thespecimens, but they are mostly fragmental and have less value to report here, but theSci. Rep. Whales Res. Inst.,
No. 24, 1972.

2
2

OMURA
TABLE5. STRAIGHTLENGTHOfRIBS OfTHESPECIMEN ZC3.
(
i
nm m)
Ribnu
m
er
ι
F
q
4
ー
0
3
A
D
Tb

Right

Lef
t

Ribnumber

Right

L
e
f
t

453
614
698
755
770

435
595
693
753
763

6
7
8
9

7
5
3
745
7
10
630

745
740
710
635

TABLE6. MEASURE
孔1ENTSOfSCA
PULAE OF:()PHIUSCAVIROSTRISIN NORTHWE
ST PACIFIC. (
i
nm m)
Ri
ght

l
ef
t

Specimen

zc2
I
ZC I
zc 12
zc 3
zc7
zc 10

Br
ea
d
t
h

Hei
gh
t

1
95
256
367
384
358
4
12

1
3
9
1
8
0
246
264
237
286

Br
ea
dt
h
1
98
256
3
6
1
379+*
356
408

He
i
g
ht
1
4
1
1
8
0
256
271
237
283

* Tipb
r
o
k
e
n
.

f
i
g
.7. Sternumo
fthespecimenZC3
.

s
‑
t
e
rnumo
ft
hes
pecimenZC3i
scomplete(
F
i
g.
7
)
.I
ti
sc
ons
i
s
t
e
do
ff
i
ves
e
g
ment
sand
巴r
a
l
ll
engt
hi
s796m mandt
heg
r
e
a
t
e
s
tb
r
e
a
d
t
hoft
h
ef
i
r
s
ts
e
g
menti
s289mm.
t
heov
DISCUSSION
Amonge
l
e
ve
ns
k
u
l
lsIi
n
v
e
st
i
g
a
t
e
dt
hemo
s
ti
n
te
r
e
s
t
i
ngonei
st
h巴 s
pe
cime
nZC1
2
.
AsIh
a
v
ea
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No.2
4
,197
2
.

CUVIER'S BEAKED WHALE

23

Fig. 3. As already mentioned, in the measurement number 29 (Greatest span ofpremaxillary crests) and 36 (Greatest depth of rostrum at midlength of rostrum) the
adult male shows greater value than the others with a few exceptions, and thisspecimen is included among the exceptions in the both measurements. It is probablethat the span ofpremaxillary crests and the depth ofrostrum at midlength ofrostrum
will increase with age. The oldest male among my specimens is TWMI, next to thesmallest in Fig. 3, judged from the well developed mesorostral bone with posterior
truncation as well as the presence of the massive and fusiform teeth. This specimen
shows far greater value in the both measurements than in the specimen ZC12. The
teeth of the specimen ZC12 are slender and cylindrical in shape with closed roots.
It is true that this specimen has already attained the physical maturity, but allevidences suggest that this specimen is not an old animal. Fraser (1942) describes" the massive fusiform teeth are indication of a late phase in the animal's life ", and it
is possible that the passage from the cylindrical to the fusiform shape in the tooth ofthe male is brought about after the attainment of the physical maturity, but subject
to the individual variation.
It is also suggested from the material used in this study that the development of
the mesorostral bone is continued after the attainment of the physical maturity andthe massive mesorostral with the posterior truncation in the male is completed with
old age.
In seven specimens the mesorostral bone is recognized in varying degree ofdevelopment, from mere a low ridge on the upper surface of the vomer (ZC7) to awell developed bone with posterior truncation (TWMl). These material confirms
the finding by Fraser (1942) that the mesorostral ossification is demonstrably a development of the vomer, and not an ossification of the cartilaginous ethmoid.
On the other points I have already discussed in the foregoing chapters.
ACKNOWLEDGMENTS

My sincere thanks are due to Dr. Edward Mitchell of the Arctic Biological Station,
Fisheries Research Board of Canada, who stimulated and encouraged me for the
study of this species and kindly sent me a xeroxed copy of the very valuable literatureon the skull of this species by Kernan (1918). I also express my gratitude to Dr.
Richard G. Van Gelder of the American Museum of Natural History who sent me an
original copy of the Kernan's paper, which contains many excellent photographs ofbones of the skull, upon request from Dr. Mitchell.
REFERENCES
BAcKus, R.H. and W. E. ScHEVILL, 1961.

The stranding of a Cuvier's beaked whale (:(Jphius cavirostris) in
Rhode Island, U. S. A. Norsk Hvalfangst-Tid., 50(5): 177-181.
FRASER, F. C., 1942. The mesorostral ossification of Z,iphius cavirostris. Proc. Z,ool. Soc. London., (B) 112: 2130.
GALBREATH, E. C., 1963. Three beaked whales stranded on the Midway Islands, Central Pacific Ocean.
J. Mamm., 44: 422-423.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

24

OMURA

HARMER, S. F., 1927. Report on the cetacea stranded on the British coasts from 1913 to 1926. Brit. Mus.
(Nat. Hist.), 10: 1-91.
HUBBS, C. L., 1946. First records of two beaked whales, Mesoplodon bowdoini and ,::Z,iphius cavirostris, from the
Pacific coast of the United States. J. Mamm., 27: 242-255.
KERNAN, J. D., 1918. The skull of ZJPhius cavirostris. Bull. Am. Mus. Nat. Hist., 38: 349-394.
MITCHELL, E., 1968. Northeast Pacific stranding distribution and seasonality of Cuvier's beaked whale
Z,iphius cavirostris. Canadian J. Z,ool., 46: 265-279.
MITCHELL, E., and W.J. HoucK, 1967. Cuvier's beaked whale (Z,iphius cavirostris) stranded in northern
California. J. Fish. Res. Bd. Canada., 24(12): 2503-2513.
MOORE, J.C., 1963. Recognizing certain species of beaked whales of the Pacific Ocean. Am. Mid. Natur.,70(2) : 396--428.
MOORE, J. C., 1968. Relations among the living genera of beaked whales with classifications, diagnoses andkeys. Fieldiana: Z,oology., 53(4): 209-298.
OGAWA, T., 1936-37. Hompo no Hakujira ni kansuru Keu'kyu (Studien uber die Zahnwale in Japan).
Shokubutsu oyobi Dobutsu (Botany and Z,oology)., 4: 1159-1171, 1337-1344, 1495-1504, 1685-1694, 18371844, 2017-2024, 5: 25-34, 409--416, 591-598.
OMURA, H., 1971. A comparison of the size of vertebrae among some species of the baleen whales with specialreference to whale movements. Sci. Rep. Whales Res. Inst., 23: 61-69.
OMURA, H., K. FUJINO, and S. KIMURA, 1955. Beaked whale Berardius bairdi ofJapan, with notes on Z,iphiuscarvirostris. Sci. Rep. Whales Res. Inst., 10: 89-132.
RrcE, D. W. and V. B. SCHEFFER, 1968. A list of the marine mammals of the world. U.S. Fish and Wildlife
Ser. Spee. Sci. Rep. Fisheries., 579: 1-16.
RICHARDS, L. P., 1952. Cuvier's beaked whale from Hawaii. J. Mamm., 33: 255.
TOMILIN, A. G., 1957. Cetacea. Mammals of the U.S. S. R. and adjacent countries (ed. S. I. Ognev) IX.
English translation, Jersalem 1967, 717 pp.
TRUE, F. W., 1910. An account of the beaked whales of the family Ziphiidae in the collection of the U.S.
National Museum. Bull. U. S. Nat. Mus., 73. 89 pp.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

CUVIER'S BEAKED WHALE

25

APPENDIX TABLE. MEASUREMENTS OF VERTEBRAE OF :(,lPHIUS
CAVIROSTRIS IN NORTHWEST PACIFIC. (in mm)

1. Specimen ZC 2
Serialno.

Vertebral
no.

c l
2

2

3
4

3
4
5
6
7

5
6
7

8
9
10
11
12
13
14
15
16
17

DI

18
19

2
3
4

5
6
7
8
9
10

20

L I
2
3

21

4

22

5
6
7
8
9
10

23
24

25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43

Ca 1

2
3
4
5
6
7

8
9

10
11
12

13
14
15

16

Greatest
breadth
168 )
136
88
79

72
75
84
124
150
149
141
131
122
117
107
128
158
171
164+
174
167
177
159+

172
174
181
183
169+
175
163
153
143

131
118
103
87

GreatestheightCentrum
Notes
Breadth151*

Height88*

165

Length
}

60

64
60
63
75

51

6

50
50

15
14
17

66
61

53

55

205

51
52
54
61

49
47
48
49
51
53
53

216

72

55

225
233
241
245
248
246+
254
249
245+
245

77

57
61
63

121
139
142
165
176
180
185
187
193
195
197+

233
229
224
211
196
180

163
148

130
113
93
70

54

50

76
74
78
78

77

52

50

66
67
69

79
81
84
85

72

88
85
87
85
85
81
81
82
80
75
66

75
75
76
75
75
76
78
76
78

63
58
51
48
42

75
76

77

77
74
65
54
43

36
31

24
34
41
49
52
56
60
64
67
70

* Articulating face.
Very young specimen.
All of the epiphyses are notfused to their centra.
First 4 cervicals united
into a mass, but only
partly.
In vertebrae up to andincluding 8th dorsal
the centra are notfused with a mass ofprocesses, but separarated. In 9th dorsal
these are fused, but
sutures are visible.
lOth dorsal and thereafter completely fused.

74
76
78
82
85
89
92
94
97
98
99
98
95
92
89
86
83} Transverse processes im80
perfectly perforated
78
71
Transverse processes dis65
appear.

52
41
34
31
27

Spinous process disappears.

Continued ...
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

OMURA

26

APPENDIX TABLE.
Serialno.

Vertebral
no.

44
45
46
47

17
18
19
20

Greatest
breadthGreatestheightContinued.
Centrum

Breadth
35
30
22
16

Height25
19
13
9

Length

Notes

24
19
15
13

2. Specimen zc 11
Vertebral
no.

1
2
3
4
5
6
7

c1

8
9
10
11
12
13
14
15
16

D 1
2
3
4
5
6
7
8
9

166
178
173
154
144
135
129
152
211

199
226
243
252
256
269
270
275
285

70
61
59
59
69
69
74
88

17
18
19
20
21
22
23
24
25
26

L 1
2
3
4
5
6
7
8
9
10

253
254
250
248
248
245
243
236
231
231

290
293
302
315
323
328
331
335
329
324

87
84
85
87
89
89
90
98
95
97

27
28
29
30
31
32
33
34

Ca 1
2
3
4
5
6
7
8

232
229
213
194
179
159
139
119

319
317
295
281
254
236
209
190

2
3
4
5
6
7

Greatest
breadthCentrum

Serial
no.

203)
181
Ill
83
79
87
101

Greatestheight

Notes
Height

73
68
68
91

60
58
58
54

72

56
53
51
51
51
54
55
56
61

29
39
49
59
64
69
75
82
87

62
64

81
88
87
88

91
96
99
101
106
109
111
119
124
127

89
96
95
95
93
92
94
94

129
129
124
121
114
110
108
105

88*

176
133
145
137

LengthBreadth
134*

98
IOI

103
104
102
103
101
103

72
72

75
77

)

69
17
17
19

* Articulating face.
Juvenile. All of the epiphyses are not fused totheir cen tra.
First 4 cervicals united
into a mass, but the
4th fused only at the
tip of spinous process.

Transverse processes imperfectly perforated.
Continued ...

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

CUVIER'S BEAKED WHALE

Serialno.

Vertebral
no.

35

9

36
37
38
39
40
41
42
43
44
45
46

10
11
12
13
14
15
16
17
18
19
20

27

APPENDIX TABLE.

Continued.

Greatest
breadthGreatestheightCentrum
BreadthHeightLength

101

163

98

94

99

138
112
82

90
83
76
69
62
55
46
38
31
25
20

94
90
78
62
51
45
38
31
23
15
10

94
84
65
48
40
37
32
29
21
20
15

Notes
Left transverse process
perforated.
Transverse processes disappear.
Spinous process disappears.

3. Specimen ZC 12Greatest
breadthCentrum

Serialno.

Vertebral
no.

1
2
3

c 1

4
5
6

4
5
6

7

7

131

190

115

69

25

8
9
10
11
12
13
14
15
16

D 1
2
3
4
5
6
7
8
9

219
236
242
230
211
204
200
265
345

293
351
363
351+
340+
382
285
395
405

92
82
79
75
75
75
81
88
94

69
66
63
61
64
67
68
69
75

41
56
70
82
90
94
102
110
120

17
18
19
20
21
22
23

L 1
2
3
4
5
6
7

389
385+
365
389
355+
368
282+

434
425+
455
453
459
443+
470

95
114
100
103
105
107
108

78
109
93
96
98
104
106

138
133
137
143
147
150
157

Greatestheight

}

2
3

Notes
Breadth163*

HeightLength

94*

220

300

135
162
167
172

81

83

* Articulating face.
Adult. All of the epiphyses are completely
fused to their centra.
First 6 cervicals are united, but the 6th fused
only at the inferior
part of the body.
Spinous processes are
fused in l-4th, andothers free.

Facets for articulation
for ribs present.
Posterior portion of the
lst and anterior partion of the 2nd lumbar developed extraordinary and a pit
present at the center ofboth centra.
Continued ...

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

OMURA

28

APPENDIX TABLE.

Continued.
Centrum

Serialno.

Vertebralno.

Greatest
breadthGreatestheightBreadthHeightLength

24
25
26
27

8
9
10
II

346+
260+
288+
300

473
477
479
485

110
117
119
115

109
116
118
123

163
157+
175
179

28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47

Ca I
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

305
292
262
215+
231
200
173
149
125

467
472
431
401
375
332
295
263
227
192
144
101

115
119
131
125
128
127
123
118
117
106
96
88
82
77
68
56
49
41
37
24

118
126
121
115
115
118
119
118
120
118
105
91
79
67
58
47
37
29
28
13

180
175 } Centra developed extra158+
ordinally as in the case160of the lst and 2nd
151
lumbars.
140135 } Transverse processes im124
perfectly perforated.
115
T.p. perforated.
106
T.p. disappear.
83
62
53
Spinous process disap51
pears.
43
39
35
31
28
22

GreatestheightNotes

4. Specimen ZC3Serialno.

Vertebralno.

Greatest
breadth

I
2
3
4

C I
2
3
4

250
203
133
111

5
6
7

5
6
7

90
97
107

8
9
10
11
12
13
14

D 1
2
3
4
5
6
7

187
207
195
180
176
179
166

)

Centrum
Notes
BreadthHeight

143*

86*

197

Length

) 81

80

71

151
181
207

78
78
106

71
73
76

18
22
27

283
346
353
359
364
367
374

73
76
66
64
64
66
69

71
68
61
60
60
61
62

44
57
67
78
85
91
98

* Articulating face.
Adult. All of the epiphyses are fused totheir centra but linea
epiphysialis are visible
up to 7th caudal.
First 4 cervicals united,
but the 4th fused onlyat spinous and lefttransverse processes.

Continued •••Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

29

CUVIER'S BEAKED WHALE

Serialno.

Vertebralno.

APPENDIX TABLE.

Continued.

Greatest
breadthGreatestheightCentrum
Notes
BreadthHeightLength

15
16

8
9

210
279

384
392

74
79

64
65

104
112

17
18
19
20
21
22
23
24
25
26

L 1

353
360
355
360
357
352
340
320
318
313

409
424
440
451
455
460
458
453
444
444

82
84
85
86
89
91
94
98
102
103

73
78
82
85
86
91
97
99
101
103

119
124
128
131
136
144
150
157
164
167

27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46

Ca 1

321
322
302
267
242
212
187
156
118
98

433
416
410
379
347
318
287
257
225
189
158
109

105
106
109
111
114
114
112
111
108
96
90
80
78
69
69
56
50
38
33
25

106
106
104
107
104
105
105
105
103
101
98
87
75
58
52
46
36
27
18
11

168
168
164
157
149
146
141
136
125
115
100
69
56
51
47
43
38
32
29
21

2
3
4
5
6
7
8
9
10
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

Transverse processes perforated.

Transverse processes disappear.
Spinous process disappears.

5. Specimen zc 7
Greatest
breadthGreatestheight

2
3

} 220

} 206

4
5
6
7

110
96
93
138

Serialno.

Vertebral
no.

1
2
3

c 1

4
5
6
7

135
162
155
181

Centrum
Notes
BreadthHeight134*

90*

Length

} 71
83

70

77

71
71
73
71

74
73
72

20
20
22
28

* Articulating face.
Juvenile. Epiphyses are
only fused to their centra in 4-5 cervicals
and 11-17 caudals.
First 3 cervicals are united into a mass as wellas their spinous processes.
Continued ...

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

30

OMURA
APPENDIX TABLE.

Continued.
Centrum

Serialno.

Vertebralno.

Greatest
breadthGreatestheightBreadthHeightLength

8
9
10
11
12
13
14
15
16

D 1
2
3
4
5
6
7
8
9

186
190
182
176
180
174
144
237
285

263
316
328
333
331
349
347
356
358

71
73
74
76
69
71
75
85
89

65
61
59
60
60
64
68
69
73

45
58
69
79
84
91
96
106
111

17
18
19
20
21
22
23
24
25
26

L l

289
299
295
292+
298
290
281
267
268
265

373
386
402
413
412
430
428
429
423
419

91
93
96
96
98
99
103
106
109
107

80
87
89
90
93
99
99
102
99
102

116
119
124
128
127
134
139
144
152
155

27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47

Ca I

261
253
237
214
198
179
164
135
108

409
384
381
359
327
304
274
244
240
181
145
98

107
108

103
104
100
100
100
102
104
103
105
105
103
90
75
63
54
47
38
28
20
14
9

157
155
150
143
137
131
128
123
119
108
94

2
3
4
5
6
7
8
9
10
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

Notes

Ill

113
110
108
108
110
105
93
86
84
77

-

70
65
58
48
39
32
26
20

Articulating facet for ribpresent.

Transverse processes perforated imperfectly.
Transverse processes disappear.

71

56
48
45
41
39
34
30
25
17

Spinous process
appears.

dis-Continued .•.

Sci. Rep. Whales Res. Inst.,

No. 24, 1972

CUVIER'S BEAKED WHALE

6.

APPENDIX TABLE.

Continued.

GreatestheightCentrum

31

Specimen ZC 1
Serialno.

Vertebralno.

Greatest
breadth

2
3
4

C 1
2
3
4

279
240
191
124

) 236

5
6
7

5
6
7

IOI
99
170

8
9
10

DI
2
3
4
5
6
7
8
9
10

II

12
13
14
15
16
17
18

19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43

Notes
LengthBreadth164*

Height

87

72

150
178
224

81
79
92

73
73
76

25
24
26

187
226
237
242
219
222
195+
174
282
328

230
318
362
380
379
397
408
418
421
422

87
78
74
71
72
76
78
91
91
102

75
74
70
67
66
68
69
71
73
82

36
52
67
78
88
93
IOI
112
121
129

L I
2
3
4
5
6
7
8
9
10

360
360
354
347
336
330
323
312
303
298

439
457
470
478

JOO
IOI
!03
107
108
109
113
118
121
125

80
89
93
93
101
106
110
113
114
120

138
146
149
153
158
164
173
185
185
189

Ca I
2
3
4
5
6
7
8
9
10

300
298
285
261
239
220
195
161
129

124
127
131
130
129
130
127
123
115
108
100
92
80
72
65
47

119
122
118
117
114
118
123
117
117
115
109
93
71
56
50
43

192
183
177
168
162
153
147
143
134
121
96
65
53
50
48
44

II

12
13
14
15
16

488
492
489
490
483
483
472
441
404

283
243
213
177
141

) 83

* Articulating face.
Adult. All of the epiphyses are fused totheir centra completely.
First 4 cervicals fused
into a mass, including
spinous processes.

Transverse processes perforated.
processes
Transverse
disappear.
Spinous process disappears.

Continued ...
Sci. Rep. Whales Res. Inst.,.No. 24, 1972.

OMURA

32

Serialno.

Vertebral
no.

44
45
46
47

17
18
19
20

Greatest
breadthAPPENDIX TABLE.

Continued.

GreatestheightCentrum
Notes
BreadthHeightLength

42
37
31
27

33
25
27
10

39
34
27
22

7. Specimen zc 10
Serialno.

Vertebralno.

Greatest
breadthGreatestheight

c1
2
3
4
5
6
7

2
3
4
5
6
7

8
9
10
11
12
13
14
15
16
17

DI

) 257

Centrum
Notes
BreadthHeight

163*

100*

79
74
76
80

18
19
25

) 178

Length

) 87

95
107
120

147+
209
195

90
87
85
112

2
3
4
5
6
7
8
9
10

203
236
239
230
218
201
183
189
283
345

273
326
358
372
385
398
405
442
419
437

94
94
93
73
74
76
81
92
95
100

79
72
67
69
66
68
70
68
71
74

40
56
70
83
93
98
105
116
121
130

18
19
20
21
22
23
24
25
26
27

L 1
2
3
4
5
6
7
8
9
10

372
356
356
353
343
334
325
311
308
315

449
459
469
477
484
486
491
489
485
479

102
104
105
106
108
108
111
114
119
122

83
91
95
97
105
108
111
117
118
120

136
142
144
147
153
158
167
175
179
180

28
29
30
31
32
33
34
35

Ca 1
2
3
4
5
6
7
8

310
288
265
253
240
217
193
155

475
459
431
399
369
332
303
272

130
134
131
137
136
135
136
135

127
132
126
123
123
126
121
122

181
177
168
159
152
147
145
141

* Articulating face.
Adult. All of the epiphyses are fused totheir centra completely.
First 4 cervicals fused into mass.

·-·---

Continued ...

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

33

CUVIER'S BEAKED WHALE

Serialno.

Vertebral
no.

36

9

37
38
39
40
41
42
43
44
45
46
47

10
11
12
13
14
15
16
17
18
19
20

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

APPENDIX TABLE.

Continued.

Greatest
breadthGreatestheightCentrum

128

Notes
BreadthHeightLength

240

123

124

131

207
159
106

110
102
93
82
75
69
61
55
46
40
31

124
115
97
79
67
61
53
45
32
23
16

123
102
67
54
50
45
44
42
35
28
21

Transverse processes perforated.
Transverse processes disappear.
Spinous process disappears.

OMURA

34

EXPLANATION OF PLATESPLATE I
Superior view of skulls of Z,iphius cavirostris in the northwest Pacific.
Fig. I. Specimen ZC 2. Skull length 590 mm. Very young. Sex unknown.
Fig. 2. Specimen ZC 11. Skull length 707 mm. Juvenile. Sex unknown.
Fig. 3. Specimen ZC 12. Skull length 811 mm. Adult male.
Fig. 4. Specimen ZC 6. Skull length 819 mm. Juvenile. Sex unknown.
PLATE II
Superior view of skulls of Z,iphius cavirostris in the northwest Pacific.
Fig. I. Specimen ZC 7. Skull length 826 mm. Juvenile. Sex unknown.
Fig. 2. Specimen ZC 4. Skull length 844 mm. Female.
Fig. 3. Specimen ZC I. Skull length 891 mm. Adult female.
Fig. 4. Specimen ZC 10. Skull length 921 mm. Adult female.
PLATE III
Fig. 1.
Fig. 2.
Fig. 3.
Fig. 4.

Inferior view of skull of Z,iphius cavirostris in the northwest Pacific. Specimen ZC 11.
Inferior view of skull of Z,iphius cavirostris in the northwest Pacific. Specimen ZC 7.
Posterior view of skull of Z,iphius cavirostris in the northwest Pacific. Specimen ZC 12.
Posterior view of skull of Z,iphius cavirostris in the northwest Pacific. Specimen ZC 3.
PLATE IV

Lateral view of skull of Z,iphius cavirostris in the northwest Pacific.
Fig. I. Specimen ZC 6. Skull length 819 mm. Juvenile. Sex unknown.
Fig. 2. Specimen ZC 8. Skull length 886 mm. Adult male.
Fig. 3. Specimen ZC 3. Skull length 823 mm. Adult female.
PLATE V
Skull of Z,iphius cavirostris in the northwest Pacific. Specimen TWM I. Skull length 837 mm.
Old adult male.
Fig. I. Lateral view.
Fig. 2. Anterior view, showing prenarial basin and a part ofmesorostral bone.
PLATE VI
Vertebrae of Ziphius cavirostris in the northwest Pacific.
Fig. 1. Cervical and dorsal vertebrae.
Fig. 2. Lumbar vertebrae.
Fig. 3. Caudal vertebrae.

Specimen ZC 3.

PLATE VII
Fig. 1.
Fig. 2.

Fig. 3.

Mandible of Z,iphius cavirostris in the northwest Pacific. Specimen ZC 10.
female. Lateral view.
Mandibles of Z,iphius cavirostris in the northwest Pacific.
Left: Specimen ZC 8. Adult male.
Right: Specimen ZC 10. Adult female.
Scapulae of Ziphius cavirostris in the northwest Pacific. Specimen ZC 3.

Adult

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

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rJSv ~ 日I吋OCATCH OF THE CUVIER'S BEAKED WHALES OFF JAPANIN RECENT YEARSMASAHARU NISHIWAKI* AND NOBUO OGURO*ABSTRACTWe analysed Cuvier's beaked whales (.<)phius cavirostris) caught off the coastof Japan between 1965-70. In most cases they were caught in waters deeper
than 1000 m. They eat food abounding in the surrounding waters. 70% of
189 whales were males. This tendency was the same every year, and was also
reported by Omura et al. (1955). 87 % of the whales caught were mature, andthe average body length of both sexes was larger than between 1948-52. Ifan
annual quota of 30-50 animals were to be observed, this probably would notendanger the ,Ziphius stock in the western North Pacific.

The ' smaller whale ' whaling industry of Japan has been catching a considerable
number of Cuvier's beaked whales (Ziphius cavirostris) along with Minke whales(Balaenoptera acutorostrata) and Baird's beaked whales (Berardius bairdi). Omura et al.
(1955) reported on the Cuvier's beaked whale caught off the coast of Japan between
1948-52. The total catch during that period was 85. Ziphius is the least valuable ofthe three to the whaling industry, and hence there is less pressure on it than on theother two. It is evident that coastal whaling operations have diminished and thenumber of catcher boats have decreased in recent years. There must, therefore,
have been some change in the different relative rates of catch of Ziphius and the othertwo species, while the total catch has been decreasing. Our discussion here concerns Ziphius caught between 1965-70. The data was extracted from the report by
the Fisheries Agency of the Japanese Government on the harvest of the smaller whales
during 1965-70.
ANALYSIS OF CATCH

The areas of the whaling operation and the precise positions of catch are shown in
Fig. 1. The coastal waters are divided in the same way as by Omura et al. (1955).
Ziphius whales has been taken in each of the seven areas except for VI, in which,nevertheless, Omura et al. has some catch records. The catch positions are mostly on
the 1000 m contour or in deeper waters, and are most abundant in areas I and II.
The catches are particularly numerous in Area I on account of the indented coastline
and the concomitant meandering 1000 m contour.
Table 1 and Fig. 2 show the size distribution of the whales caught. Table 2
indicates the monthly catch in each area. The total catch was 189, of which 132
were males (70%) and 57 were females (30%). This rate is almost the same as re-* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972, 35-41.

36

NISHIWAKI AND OGURO\OKHOTSK SEA' \I'

45'Nt--~~~~~~~~~~--~~,~-r~~~--\

AREA N

I

I

I

"

o I

\.

HOKKAIDO

AREAV/--- ____' \ .....

\\.... ,,/'\Q)

AREAill

1C!:.=

SEA of JAPAN

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\~

\~

','°'ov\

40'Ni-~~~~~~~~~~~~~7,_,.,.

I£:

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,,,,,,.- .... I

tO
tO, .....

I
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[.

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.
.. ...
..... :·:,,,:;·.::·'I

I

AREA VI

I
I

[~
/

/,,,

/'/I'

,, ....

,,,.,,."""'

I

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/'

/ ' 'I
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'

I

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PACIFIC OCEAN

I

/

I
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35'N

/

'·
/~-­

..

AREA I

135'E
Fig. 1.

140'E

145'E

Position of catch of <:_iphius cavirostris off Japan, 1965-1970.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

CATCH OF THE CUVIER'S BEAKED WHALE
TABLE I.

Month

37

NUMBER OF CATCH OF Z,IPHIUS AVIROSTRIS ACCORDING TO
THE MONTHS AND AREAS, 1965-1970.
Area I

Area II

Area IV

Area VII

Total~,.-"--.

,.---_~~

Male Female

Male Female

Male Female

Male Female

Male Female

2
18
11

Jan.
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Total

6
4
10
7
4
2
0
65

0
10
8
0
2
2

2

0

2

0
1
3
12
8
20
7
54

3
6
6
3
41

0
4
1
2
3
4
16

1
2

0
0

3

0

2

0

3
3

0
0

5
18
13
10
7
2
15
19
12
22
8
132

*
*

0
0

10

2
10
8
0
2
2
0
7
7
8
6
5
57

* A sex unidentified individual is excluded.
40

__II=

~

.!::

Male
Female

30

...,

..c:

llO

::I

ro

c..>
I/)

~

ro
..c:

20

3:

....0
....
Q)

..c

E

::I

z

10

13

14

15

16

17

18

19

20

21

22

23

Body length in feetFig. 2.

Size distribution of Z,iphius cavirostris caught, 1965-1970.

ported by Omura et al. The catch in each area was as follows: in area I 106 werecaught, 70 in II, 3 in IIland 12 (including 2 individuals of unidentified sex) in VII.
In Area I, 64 were caught between Jan-June and 42 between Aug-Dec, while area II,
64 of the year's total of 70 were caught between Aug-Dec. In area IV only 3 werecaught between May-June, while in area VII records are scattered throughout theSci. Rep. Whales Res. Inst.,
No. 24, 1972.

NISHIWAKI AND OGURO

38

TABLE 2. AVERAGE BODY LENGTH AND SEX RATIO OF Z/PHIUS
CAVIROSTRIS CAUGHT DIVIDED BY AREAS AND MONTHS, 1965-1970.
Area I

Area II

Male

FemaleJan.-June
Average length
Sex ratio

20.1
65.5

19.8
34.4

Aug.-Dec.
Average length
Sex ratio

18.9
54.8

18.l
45.2

Male

Female

19.5
74.1

19.1
21.9

first six months of the year.
The whales caught in the above mentioned periods are presented in Table 2
together with the average body length of both sexes and the sex ratio. According toabove mentioned data, the abundant catch in Area I between Feb-May may consistof adult males going north to chase after adult females. The whales caught inArea I in the other months may be younger males searching for food. The abundantcatch in Area II between Aug-Dec seems to consist of males migrating south, some ofthem possibly in the company of adult females.
SIZE DISTRIBUTIONAs seen in Fig. 2 and Table 3, the greatest body lengths of all the individuals caught
were 23 feet for males and 22 feet for females. The most common body length forboth sexes was 20 feet, while most of the catch was in the length range 18-21 feet.
There are four species of Mesoplodon in the western North Pacific: M. stejnegeri,
M. densirostris, M. ginkgodens and M. carlhubbsi. We found some suggestions of
TABLE 3.
Body
lengthin feet
13
14
15
16
17
18
19
20
21
22
23
Total
Sex ratio
Maturity

SIZE DISTRIBUTION OF Z,IPHIUS CAVIROSTRIS CAUGHT, 1965-1970.
NumberMale

Number

Percentage
Total

6
9
17
17
45
30
7

4
3
10
10
18
8
2

*10
12
27
27
*63
38
9

132
69.8

57
30.2

189
100.0

Male

Female

Total

1.8
1.8

0.5
0.5

7.0
5.3
17.5
17.5
31.6
14.0
3.5

4.5
6.8
12.9
12.9
34.1
22.7
5.3
0.8
100.0

100.0

5.3
6.4
14.3
14.3
33.3
20.1
4.8
0.5
100.0

88.6

84.2

87.3

* A sex unidentified individual is excluded.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

CATCH OF THE CUVIER'S BEAKED WHALE
TABLE 4.
Areal
Year

---~

Male Female
1965
1966
1967
1968
1969
1970
Total

14
10
19
9
4
9
65

39

ANNUAL CATCH OF Z,IPHIUS CAVIROSTRIS AND THEIR SEXRATIO ACCORDING TO AREAS, 1965-1970.
Area II,.-.____,

Area IV

Area VII~~..-"'----.

Male Female

Male Female

Male Female

Male Female

Male

Female

47
17
29
21
9
9
132

78.3
63.0
64.4
72.4
69.2
60.0
69.8

21.7
37.0
35.6
27.6
30.8
40.0
30.2

7
8
12
6
2
6
41

28
6
7
10
3

6
2
4
2
2

3

54

16

3

0

0

2
l
3
2
2

*O

10

0

0
0
0
0

Total

13
JO
16
8
4
6
57

Sex ratio~* Two sex unidentified individuals are excluded.
Mesoplodon in the discarded bones around the whaling stations where ,Ziphius areprocessed, but there has been no report of Mesoplodon being caught by these companies. Therefore, the data in Fig. 2 for ,Ziphius may include some Mesoplodon, but
the percentage of the latter is so small that it could exert no significant effect on the
figures.
The catch for each year is indicated in Table 4. Although the total catch of,Ziphius has been decreasing year by year, this may be partly due to reduced hunting
effort rather than to an actual population decrease.
FOOD

The stomach contents varied according to the area in which the animals werecaught, as shown in Fig. 3. The food found in the stomachs of the animals from
Area I consisted mainly of deep-sea fish, but that from animals in Areas II and VII
was exclusively squid. There was no food report from Area V. Therefore, deep-sea
fish must have been the main food in waters deeper than 1OOO m, while squid must be
the main food in the shallower waters. As seen in Fig. 3, deep-sea fish were often
found in the animals from Area I all through the year, but squid was sometimes
found in Area II from Nov-Jan. This evidence suggests that the whales may eat
whatever fish are abundant in the waters where they happen to be.
CONCLUSION

Our analysis suggests that Cuvier's beaked whale (,Ziphius cavirostris) has been beingcaught throughout the year, abundant harvests being taken in Feb., Sept. and Nov.
The greatest body length in our sample is 23 feet (male) and 22 feet (female).
The data also suggest that the majority of ,Ziphius whale were caught in waters deeper
than 1000 m. The variety of food in the stomachs examined shows that the ,Ziphius
whales, like other smaller whales, eats the food most common in its surrounding
waters. Both sexes of ,Ziphius seem to be about 18 feet in body length when theyattain sexual maturity. 87% of the whales caught were mature, and the average
Sci. Rep. Whales Res. Inst.,
No. 21, 1972.

NISHIWAKI AND OGURO40•

OKHOTSK SEA

Deep-sea fishes

45°N

N

o Squid

SEA of JAPAN0

PACIFIC OCEAN
0
0
0

0 0

0

II

35°N

135°E

Fig. 3.

140°E

145°E

Position of catch of <:,iphius cavirotris with stomach contents, 1965-1970.

body length of both sexes from this data are greater than those in the data of Omura
et al.
Considering that the number of new whaling boats has been decreasing conSci. Rep. Whales Res. Inst.,
No. 24, 1972.

CATCH OF THE CUVIER'S BEAKED WHALE

41

tinually, possibly, if the population remains in its apparently stable condition as atpresent, this industry may not endanger the Z,iphius stock. Our estimate of apermissable quota, based on Omura's paper and the consistency of the average bodylength over the years is in the region of 30-50 animals, regardless of age or sex.
ACKNOWLEDGEMENT

We are greateful to the members of the Whaling Administration Section of theFisheries Agency for allowing their data to be used in this report.
We would also like to thank the stuff members of the Biology of Fisheries
Resources Division of the Ocean Research Institute, the University of Tokyo and
Mr. T. Kubota of the Fuji Suisan Co. for their helpful advice.
REFERENCES
HoucK, W.J., 1958. Cuvier's beaked whale from northern California. J. Mamm., 39(2): 308-309.
NrsmwAKr, M., 1965. Whales and Pinnipeds. Univ. of Tokyo Press, Tokyo, 439 pp. (in Japanese).
NrsmwAKI, M. and N. OGuRo, 1971. Baird's beaked whales caught on the coast ofJapan in recent 10 years.
Sci. Rep. Whales Res. Inst., 23: 111-122.
OMURA, H., K. FUJINO and S. KIMURA, 1955. Beaked Whale Berardius bairdi of Japan, with notes on Ziphiuscavirostris. Sci. Rep. W'ales Res. Inst., 10: 89-132.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

FURTHERCOMMENTSON M ESOPLODON GI
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.

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ig
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I
NT RODUC
TION

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e
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e
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pe
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‑
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44

NISHIWAKI, KASUYA, KUREHA AND OGURO

offemale M. stejnegeri. Moreover, from the photograph taken by an onlooker at thetime of stranding, the animal bore few scars on the body surface. The intact bodywas only witnessed by local people and fishermen.
We are presenting here the results of our examination of two animals identified
to be M. ginkgodens, one of which was washed ashore at Kamakura in 1968 and theother near Ito in 1971.

YELLOW SEA

SEA of JAPAN0
EAST CHINA SEACHINAPROPER ~..._~"?"':>t~~ June 26, 1963

r!J

"'

(!

I

\

OKINAWA

><

~lung

<1

"0~

<;

TAl~AN Aug. 10, 1968~

oshiungrn populated area

~hima

x

\

35'N

PACIFIC OCEAN

Jan. 27, 1962

Fig. 2.

The stranded or captured positions of Mesoplodon ginkgodens.

Besides, there was one more specimen of M. ginkgodens occured at Choshi City,
Chiba Prefecture. A newspaper reported a strange whale stranded on the beach on
March 13, 1968. We rushed at the spot but Mr. Mitsuyoshi Aoki of the Tokai
University had collected it already. Two of us were allowed to study on it together
and we identified it to be a M. ginkgodens. On this specimen, however, will be
published in other paper. Therefore we only add in Fig. 2 the location and the dateof stranding.
In addition, we have three informations on the specimens of M. ginkgodens from
Taiwan waters. Mr. Hung-chia Yang of the Taiwan Fisheries Research InstituteSci. Rep. Whales Res. Inst.,

No. 24, 1972.

FURTHER COMMENTS ON MESOPLODON GINKGODENS

45

collected them. One of them appears in " Geiken Tsushin " (Yang, 1964) andother two will be published by him in near future. He kindly communicated to us.
The occurrence of eight isolated individuals of M. ginkgodens stranded on the
coast of Japan and captured in Taiwan waters, among them, six were found withinrecent 10 years, suggests that this species may not be so rare in the western part of
the North Pacific as has been supposed. Since groups of this animal have not beenreported, the social structure of this species is still obscure; possibly they often travelsoli tarily.
The locality of those eight specimens are shown in the map in Fig. 2.
MATERIALS

One of our specimens (TK 242) was stranded on the beach at Kamakura, Kanagawa
Prefecture, in Aug. 23, 1968. Since local people mistook it for a specimen of the commonly eaten ,Ziphius cavirostris, the flesh had been removed, and the skeleton together
with the intact head had eventually been discarded on the beach. Quite by chance,
Dr. Masayuki Nakajima of the Enoshima Marineland came across the skeleton.
He made some external measurements at once and reported it to us. The bodylength was estimated by reconstructing the vertebrae, and the external measurementsof the head were taken. Afterwards we also examined the bones osteologically.
The other specimen (TK 366) was washed ashore near Ito City, Shizuoka Prefecture, in July 28, 1971. It was found by a fisherman, taken to Ito fish market andsold. Mr. Akio Tamura of the Ito Aquarium happened to see it, however, and since
he immediately recognised it to be M. ginkgodens, he rang one of us up. We measured
the external body proportions, dissected it, and weighed its inner organs, and afterwards examined the skeleton osteologically.
EXTERNAL APPEARANCE

Since we received the Ito specimen intact, we were able to examine the external
aspect of the body in detail and photographed it. However, as in the case of the
Kamakura specimen, the information we could obtain from Dr. M. Nakajima wasthat the animal was a male.
As we mentioned before, the lack of scarring on the body surface of the Oiso
specimen was one of the reasons that there had been some doubt as to its male
identity. However, the Ito specimen, which was certainly a male, also bore very few
scars. It may be that M. ginkgodens males are so little scarred on account of theirincompletely erupted teeth. Their fighting can not remain much scars on their skin.
On the ventral surface of the Ito specimen there were many scars from parasitic infections, but most of these had healed.
The external body measurements of both specimens are compared with those of
the Oiso (type) specimen in Table 1. The comparison indicates no differences ofany taxonomic significance among the three specimens. In both the new specimens
the dorsal fin shows definite undulations (Fig. 3), and the tail fluke has no notch but
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

46

NL
SHL
W A KI,KASUYA, KUREHA AND OGUROTABLE I
. EXTERNAL MEASUREMENTSOFMESOPLODONGINKGODENS
Oiso
specime
n
−
−
−
、
ー
ー
ー
ー
ー
ー
町
、
。。
cm
I
. BodyL
ength
472.
0
2. He
a
d
,o
c
c
i
p
i
t
alco
nc
l
y
l
e
st
ot
h
et
i
pof
snou
t
8
0
.
0
3
. ー ，greates
twidth(
o
ppo
s
i
t
et
ot
h
ee
y
e
s
)
4
3
.
0
4. P
r
o
je
c
t
i
o
no
ft
h
elowerj
ewbeyondt
he
snout
2
.
5
5. Tipoft
hel
o
w
e
rjawt
ot
h
et
e
e
t
h
2
0
.
5
6
. Tipoft
hel
o
w
e
rj
awt
ot
h
eapexo
ft
e
et
h
4
0
.
0
7
. Tipoft
helowerjawt
ot
hecent
ero
fe
y
e
5
1
.
0
8
. Tipofthelowerjawt
ot
h
ebl
owho
l
e
4
9
.
0
9
. Breadthoftheblowhole
8.
0
1
0
. D
i
s
t
a
n
c
eb
e
t
w
e
e
1a
p
i
c
e
sofbo
t
ht
e
e
t
h
1
1
.
5
1
1. F
l
i
p
p
e
r
,a
x
i
l
l
at
ot
het
i
p
33.
0
1
2
. F
l
i
p
p
e
r
,a
n
t
e
r
i
o
ri
ns
e
r
t
i
o
nt
ot
h
et
i
p
51
.
0
1
3
. f
l
i
p
p
e
r
,greates
twidth
1
3
.
0
1
1
2
.
0
1
4
. T
a
i
lf
l
u
k
e
s
,t
o
t
a
lspread
1
5
. T
a
i
lf
l
u
k
e
s
,middlep
o
i
n
toft
h
ehi
nder
margint
ot
h
et
i
p(
average)
5
7
.
5
1
6
. He
i
g
h
tofd
o
r
s
al日n
i
pofd
o
r
s
a
lf
i
n
L
7
. Le
n
g
t
hfromtailnotchtot
t
oanus
1
8
.
1
9
.
t
ou
m
b
i
l
icus

、

1
0
0

Kamakura
specimen
，
−
＂
、
ー
ー
ー
ー
ー
『
，
cm
%

cm

。，
。

470

1
0
0

4
7
7
.
0

1
0
0

1
.0
21
.5
3
7
.
0
51
.
0
4
8
.
0

0
.
2
4
.
8
7
.
9
1
0
.
9
1
0
.
2

1
.3
2
3
.
9

0
.
3
5
.
0

5
7
.
4
5
3
.
8

1
2
.
0
1
1
.
3

3
2
.
0
5
0
.
0
1
4
.
0

6
.
8
1
0
.
6
3.
0

1
1
.
9
4
1
.
2
54.
0
1
5
.
4
1
1
9

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

1
9
.
0

44

2
1
.
4
1
5
8
1
3
9
21
8

4
.
8
3
3
.
1
2
9
.
l
4
5
.
7

I
t
o
specimen

1
6
.
9
9.
1
0.
5
4
.
3
8
.
5
1
0
.
8
1
0
.
4
1
.
7
2
.4
7
.
0
1
0.
8
28
2
3
.
7
目

1
2
.2
目

F
i
g
,3
. D
o
r
s
a
lf
i
no
fM.g
i
1
1
k
g
o
d
e
1
1
s
,I
t
os
p
e
cime
n
.

F
i
g
.4
. Tai
l日u
k
e
so
fJ
¥
I
I
.gi
1
1
k
g
o
d
e
1
1
s
,I
t
os
p
e
c
i
m
e
n
.

S
c
i.Rψ
.WhalesRes
.I
n
s
t
.
,
No.2
4
,197
2
.

FURTHERCOMME~TS ON M E
SOPLODONGINKGODENS

47

i
t
sp
o
s
t
e
r
i
o
ri
sal
i
t
t
lesw
o
l
l
e
n(
F
i
g
.4)
. TheOisos
pecimenal
s
ol
a
c
k
e
dt
h
et
a
i
lf
l
u
k
e
n
o
t
c
h
. Thel
e
f
tf
l
i
p
￡
e
roft
h
eI
t
os
pecimenwasphotographedanditsphalang
e
a
l
bone
sa
r
es
howni
nF
i
g
.5
.

F
i
g
.5
. L
e
f
tf
l
i
p
p
e
randphalangealbon
e
so
fl
v
l
.g
i
n
k
g
o
d
e
n
s
,I
t
os
pe
cimen.

INNERORGANS
F
i
g
.6i
saphotographoft
h
eL
e
f
ts
i
d
eviewofexpo
s
edi
n
n
e
ror
ga
n
si
nt
h
ebodyc
a
v
it
yof
I
t
os
pecimen. vVe found no unu
s
u
a
lf
e
a
t
u
r
ei
nt
he
m,i
nge
ne
r
a
l
, asorgansofa
toothedwhale. Butac
o
n
s
i
d
e
r
a
b
l
ehypertrophyi
ss
eeni
nt
h
es
p
l
e
e
n
. V
l
/
ecann
o
t
t
e
l
lwhe
t
h
e
ri
ti
sanormalsizeor ap
a
t
h
o
l
o
g
i
cphenomenoncaused bys
trand
ed
＇
i
p
h
i
u
sc
a
v
i
r
o
s
tr
i
swhi
c
h ha
st
h
e
s
t
r
e
s
s
. Althought
h
i
ss
p
e
ci
e
si
sac
lo
s
er
e
l
a
t
i
v
eofと
s
tomach with m
u
l
t
i
p
l
ecompartme
n
t
s
,t
hes
tomach s
e
eni
nt
h
i
ss
pecimen was ofdolphintype. Thekydneyislocatedcomparativel
y pos
t
e
r
i
o
r
l
y and t
hehe
a
r
ti
s
l
a
r
g
e
ri
np
r
o
p
o
r
t
i
o
nthant
ot
h
o
s
ei
no
t
h
e
rtoothedwhales.
Weightofeachorgani
si
n
d
i
c
a
t
e
di
nTable2.
Sci.Rψ
.Hlhal
e
sRe
s
.I
n
s
t
.
..

λ匂.2
4
,1972
.

:
¥I
SH
l¥
V
A
K
I
, KASUYA,KUREHA A:¥DOGURO

48

F
i
g
.6
. I
n
n
c
ro
r
g
a
nsof1
¥
l
..
l
!
i
l
l
k
g
o
d
e
n
s
.I
tos
p
e
c
i
m
e
n
,s
h
o
wi
ngt
h
ei
rs
h
a
p
ea
n
dp
o
s
i
t
i
o
n
.
TABLEl:. WE
I
GHTOF I
NTER:¥IALORGA:¥SOFMESOPLODON
GI
NKGOD
ENS
.IT
O SPECI
l
'
v
l
E
:
¥
I(
i
n Kg
)
R
. 1
0
.80
L. 1
0.
7
0

Lung
He
a
r
l
I
r
ac
h
e
aa
n
dE
s
o
p
h
a
g
u
s
St
oma
c
h＇》
I
nt
e
s
t
in
c
2
>
i'vlc~cn tcrium

.
'
i.
60
1
.
9
0
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.
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.
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7
8
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20
ト01

L
iv
er
Spl
e
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n
I
) I
nc
l
u
d
cs
t
omac
hc
on
t
e
nt
s
,

Pa
nc
r
e
a
sa
n
dOmcntum
2.
15
C
o
r
p
u
ss
u
p
r
a
r
c
n
al
c
L
. 0.
010
K
i
dn
e
y
R
. 8.40
L
.

U
r
i
n
a
r
yb
l
a
d
d
c
1
D旧 p
h
r
a
g
m
Te
s
t
i
s
O
t
h
e
r
s

7
.
2
0
0.
1
3
0
2
.
4
0
R
. 0.130
L. 0.140
2.
29

2
) 1
6m i
nl
e
ngt
h
.

Thet
e
s
t
iswei
gh
tsoft
heI
t
os
pe
cimenwere140g(left)and1
30g(
r
i
ght
)
. Theseweight
sareunus
u
a
l
lys
mal
lcompared with thosefrom otherwhale
sofsi
milars
i
z
e
.
Ho
wever
,wear
enotyetabl
et
ot
el
li
ft
heconditionofthisanimalwastyp
i
c
a
lor
pat
hological. Theperi
f
eralt
is
suei
nt
het
e
st
iswasinthepuber
t
ys
tag
e
,maturet
is
sue
ands
permbeingfoundon
lyaroundt
heampullaoft
hevasdeferens. Unfortunatelytherehavebeen nopr
ev
iousde
s
cr
i
p
t
i
o
n
softheM
e
s
o
p
l
o
d
o
nt
e
s
t
iswi
thwhi
c
ht
ocom‑
pareourf
i
n
d
i
ng
s.
OSTEOLOGICALEXAMINATIO
Tabl
e3compare
st
hcs
k
u
l
ldimensi
onsofthet
hr
ees
pec
imensinordert
ode
t
e
ctany
d
i
f
f
e
r
enc
e
sbetweent
heOis
o(
type
)s
pec
imenandt
heothertwo. Howeve
人 apa
r
t
S
c
i.Re
p.W
h
a
l
e
sRe
s
.i
n
s
t
.
,

No.2
4
,1
9
7
2
.

FURTHER COMMENTS ON MESOPLODON GINKGODENSTABLE 3.

SKULL DIMENSIONS OF MESOPLODON GINKGODENS

Total (condylo-basal) length
Length of rostrum (median)
Breadth of rostrum at base
Breadth of rostrum at middle
Depth of rostrum at middle
Breadth of premaxillae at middle ofrostrum
7. Breadth ofpremaxillae opposite premaxillary foramina
8. Length of nasal suture line
9. Distance from tip of rostrum to anterior
end of vomer visible on palate
10. Distance from tip of rostrum to anterior
margin of superior nares
11. Greatest breadth across zygomatic processes of squamosal
12. Breadth across posterior margins of ternporal fossae
13. Length of tympanic boneL.
R.
14. Breadth of occipital condyles
15. Breadth of foramen magnum
16. Height, vertex to inferior border ofpterygoidsL.
17. Length of mandibleR.
18. Length of symphysis
19. Distance from anterior end of mandible L.
to anterior end of alveolusR.
20. Distance from anterior end of mandible L.
R.
to posterior end of alveolusL.
21. Depth between angle and coronoid
R.
processL.
22. Length of toothR.
L.
23. Breadth of tooth at cervix (anteroR.
posterior)L.
24. Breadth of tooth (transverse)
R.
I.
2.
3.
4.
5.
6.

49

Oiso
specimen

Kamakura
specimenItospecimen,------..

~,------..

percemtage
mmto thelengthpercentage
mm to thelength

779
476
208
64
54

100
61.1 *
26.7*
8.2
6.9

716
426
201
63

47

6.0

69
48

8.9
6.2*

56
48

160

20.5

578

mm

percentage
to thelength

762
456
215
59
47

100
60.2
28.2
7.8
6.2

47

6.2

7.8
6.7

77
54

10.2
7.0

140

19.6

207

27.3

74.2

499

69.7

547

72.2

357

45.7*

350

48.9

363

47.9

218
41
42
126
47

28.0
5.3
5.4
16.2
6.0

200
41
43
111
38

27.9
5.7
6.0
15.5
5.3

227
45
46
117
40

29.8
5.9
6.1
15.4
5.3

293
666
672
184
180
183
277
282
121
122
91
92
99
99
16
16

37.6
85.5
86.3
23.6
23.1
23.5
35.6
36.2
15.5
15.7
11.2
11.6
12.7
12.7
2.1
2.1

277
621
621
162
193
199
226
229
110
Ill

38.7
86.7
86.7
22.6
27.0
27.8
31.6
32.0
15.4
15.5

66

9.2

303
640
642
179
211
213
302
300
114
115
81
79
83

56
11
11

7.8
1.5
1.5

40.0
84.5
84.7
23.6
27.9
28.l
39.9
39.6
15.0
15.2
10.7
10.4
11.0
10.2
2.1
2.1

100
59.6
28.1
8.8

77
16
16

* The figures have been changed from formerly published data (Nishiwaki and Kamiya, 1958).

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

50

NISHIWAKI, KASUYA, KUREHA AND OGUROTABLE 4.

NumberDIMENSIONS OF THE VERTEBRAE

Ito specimen

Kamakura specimenofvertebrae

c.

D.

L.

Ca.

lst
2nd*
3rd
4th
5th
6th
7th

(1)

53

(2)

131

(3)

183

(1)

33

(2)

(3)

(4)

(5)

124

135
118

42

52

110

104
136

82
88
95
128

14
14
15
20

95
106
120
158

92
92
88
124

42
41
43
47

39
42
43
47

25
38
50
58
65
71
78
85
89
95

183
237
262
271
281
290
303
313
321
322

156
166
163
158
157
156
154
109
197
266

26
32
49
57
62
67
73
79
85
92

198
244
266
279
280
283
295
299
306
319

159
169
171
164
164
162
156
154
175
233

48
51
53
52
53
54
50
49
48
46

57
56
53
53
51
47

lst
2nd
3rd
4th
5th
6th
7th
8th
9th
lOth
!Ith

101
104
108
111
115
118
123
131
134
138
142

334
348
360
366
375

289
293
296
296
291
283
276
266
261
261
262

97
102
107
111
115
119
124
129
134
138
142

327
337
355
361
367

275

45
43
42
43
42
43

lst
2nd
3rd
4th
5th
6th
7th

140
133
127
122
116
109

346
325
307
287
257
232
203

8th

101
94
89
75
54

257
241
223
204
181
147
121
98
(83)
(78)
(78)
(75)
(70)

381
362
341
313
281
247
224
190
166
141

(46)

143
142
130
123
115
107
100
95
90
83
69
50
40
37
36
35

51
48
43

269
257
235
218
196
169
143
117
97
82
76
76
70
62
54
50

(43)

32

33

44

16
16
17
19

100
104

lst
2nd
3rd
4th
5th
6th
7th
8th
9th
!Oth

9th
!Oth
!Ith
12th
13th
14th
15th
16th
17th

106

372
377

379
379
368
354

172

148
119
(86)
(75)

44

(60)

39
37
36

(50)
(45)
(37)
(30)

32

(55)

(51)

372

379
390
395
395
386

113

78
61

277

286
291
294
294
294
293
286
277
272

40

44
40

34
32
32
32
32
32
31
31
29

34
30
30
28

23

23

18
15

18
15
14

12
11

10
10
7
6

3

24
22

21

14

14
12
10
8
9
7
6
4

Continued ...
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

FURTHER COMMENTS ON MESOPLODON GINKGODENSTABLE 4.

51

Continued.

Numberofvertebrae

Kamakura specimen_________,,

I to specimen

(1)

(2)

(3)

(1)

(2)

(3)

18th
19th
20th

28
24
22

25
19
16

37
29
26

29
24

28
22
17

36
30
26

8

8

11

10

12

*

(4)

(5)

34

2lth

(!)=Length of body at center
C7+DIO+Lll +Ca21 =49(2)=Total height at anterior* fused(3)=Breadth between ends of transverse processes(4)=Greatest height of neural canal(5)=Greatest breadth of neural canalfrom some minor individual differences, there was no distinct disparity.
There are various controversial criteria for defining the rostrum base. We
chose to adopt the method of Moore (1963) who has carried out the most detailed examination of the Mesoplodon skull to date. The measurements of the Oiso specimen
according to this method are a little different from those we published originally(Nishiwaki and Kamiya, 1958). The figures in Table 3 which have been changed
accordingly are indicated by an asterisk.
The vertebral dimensions of two new specimens are shown in Table 4.
The rib collections from the Oiso and Kamakura specimens were not complete,
but we presumed the complete number of the thoracic vertebrae to be ten from theshape and condition of the remaining ribs and attached vertebral bones. The rib
measurements oflto specimen are shown in Table 5. The Ito specimen was the firstone which we collected with a complete rib cage, and many of its ribs on both sides
had been broken and healed, as seen in the Plate VIII.
The number of lumbar vertebrae were 10 in the Oiso skeleton and 11 in theother two. This difference may only be due to difficulties in identifying the chevronbones, which are sometimes very small or not ossified, and then missed when the
TABLE 5.
Number
of
rib

Left

1
2
3
4
5
6
7
8
9
10

320
449
518
567
587
589
602
606
559
508

DIMENSIONS OF RIBS OF MESOPLODON GINKGODENS,ITO SPECIMEN (in mm).
Along visceral border

Breadth at middle

Right

Left

Right

Left

Right

313
453
535
583
592
595
618
614
578
506

435
580
678
732
745
745
742
705
648
568

445
587
682
743
741
746
746
695
638
545

54
44
34
31
29
30
30
28
27
18

54
43
33
31
30
29
30
28
26
18

Straight length,,-------'

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

,,,.------

52

NISHIWAKI, KAS
UYA,KUREHA A N
D OGURObonesa
r
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O+L 11十 Ca2
1=49
C7十 D l
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54

NISHIWAKI, KASUYA, KUREHA AND OGURODIMENSIONS OF CHEVRON BONES OF MESOPLODONGINKGODENS, ITO SPECIMEN (in mm).

TABLE 6.
Number ofchevron
R
L
2
3
4
5

6
7
8
9
10
11

R
L
R

Greatest length(antero-posterior)Greatest breadthGreatest height(supero-inferior)

54
57

79
92
102
89
83
88
74
60
24
24
18

55

49
49
49
49
51
45
37

49
51
118
132
116
97
80
62
42
29
19
14
10

Kamiya, 1969) attributed to M. stejnegeri was ascribed to M. carlhubbsi by Moore(1963) on the basis of several skull features including the controversial maxillarycrest. The Akita speciemn (Nishiwaki, 1962) originally considered to be a M.
bowdoini, was reidentified to be M. stlljnegeri by Moore ( 1963), using similar criteria
and viewing from the point of distributed area. While we are in agreement with theresult of his identification, we consider that there will still remain some question on thevalidity of the morphology of maxillary crest as the specific character.
SUMMARY

1. We examined two similar specimen of toothed whale stranded in Sagami
Bay, one of which was at Kamakura in 1968 and the other near Ito in 1971.
2. Their external proportions were little different from those of the Oiso (type)specimen.
3. There were no distinct osteological differences between these two and the
Oiso (type) specimen.
4. The vertebral formula of the two specimens is as follows:
C 7+D lO+L ll+Ca 21=49
5.

The phalangeal formula for Ito specimen is as follows:
I: 1, II: 7, III: 6, 1\1: 5, \T: 4

6. We considered the two specimens to be M. ginkgodens.
7. The Oiso specimen (NSMT-M8744) is kept in the National Museum, while
the Kamakura (TK 242) and Ito specimens (TK 366) are kept in the Taiji whale
museum and the Ocean Research Institute of the University of Tokyo respectively.

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

FURTHER COMMENTS ON MESOPLODON GINKGODENS55ACKNOWLEDGEMENT
We wish to express our sincere gratitude to Dr. Masayuki Nakajima of the Enoshima
Marineland and Mr. Akio Tamura of the Ito Aquarium who keenly noticed therarely occurred individuals of M. ginkgodens and informed us.
We acknowledge the kindness of Mr. Hung-chia Yang of the Taiwan Fisheries
Research Institute who informed us the catch position of the Taiwan specimens of
M. ginkgodens.
Our sincere thanks are also due to Mr. Mitsuyoshi Aoki of the Tokai University
who informed us the data of the Choshi specimen.
We indebted deeply to Dr. Yoshinori Imaizumi of the National Science Museum
for his contribution toward our re-examination on Oiso (type) specimen in theMuseum.
REFERENCES
AoKI, M., 1972. Personal communication on the study of M. ginkgodens, Choshi specimen.
MooRE, J.C., 1963. Recognizing certain species of beaked whales of the Pacific Ocean. Amer. Midland
Naturalis., 70(2) : 396-428.
NisHIWAKI, M., 1962. Mesoplodon bowdoini stranded at Akita Beach, Sea of.Japan. Sci. Rep. Whales Res. Inst.,
16: 61-78.
NISHIWAKI, M. and T. KAMIYA., 1958. A beaked whale Mesoplodon stranded at Oiso Beach, Japan. Sci. Rep.
Whales Res. Inst., 13 : 53-83.
NisHIWAKI, M. and T. KAMIYA, 1959. Mesoplodon stljnegeri from the coast of Japan. Sci. Rep. Whales Res.
Inst., 14 : 35-48.
NISHIMURA, S. and M. NJSHIWAKI, 1964. Records of the beaked whale Mesoplodon from the.Japan Sea. Pub.
Seto Marine Bio. Lab., 12(4): 51-62.
YANG, HUNG-CHIA, 1964. Cetacean species found in Taiwan waters and whaling in Taiwan. Geiken Tsushin,
157: 113-122. (in Japanese).
YANG, HuNG-CHIA, 1972. Personal communication for catch of Mesoplodon species in Taiwan waters.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

56

NISHIWAKI, KASUYA, KUREHA AND OGUROEXPLANATION OF THE PLATESPLATE I

I. Right lateral aspect of Mesoplodon ginkgodens, Ito specimen.
2. Ventral aspect of Mesoplodon ginkgodens, Ito specimen.
3. Left side head of MesojJlodon ginkgodens, Ito specimen
4. Dorsal view of the snout of Mesoplodon ginkgodens, Ito specimen, showing the apices of teeth.
PLATE II
Dorsal view of the skulls of Mesoplodon ginkgodens, Oiso (Type), Kamakura and I to specimens(top to bottom).
PLATE III
Ventral view of the skulls of Mesoplodon ginkgodens, Oiso (Type), Kamakura and I to specimens(top to bottom).
PLATE IV
Lateral view of the skulls of Mesoplodon ginkgodens, Oiso (Type), Kamakura and Ito specimens(top to bottom).
PLATE V
Dorsal view of mandibles of Mesoplodon ginkgodens, Oiso (Type), Kamakura and Ito specimens(top to bottom).
PLATE VI
Left lateral view of vertebral column of Mesoplodon ginkgodens, Kamakura specimen, cervicals
and thoracics, lumbars and caudals (top to bottom).
PLATE VII
Left leteral view of vertebral column of Mesoplodon ginkgodens, Ito specimen, cervicals andthoracics, lumbars and caudals (top to bottom).
PLATE VIII
Ventral view of rib cage with sternums of Mesoplodon ginkgodens, Kamakura specimen.
PLATE IX
Dorsal view of rib cage of Mesoplodon ginkgodens, Ito specimen.
PLATE X
Inner-lateral view and ventral view of right side tooth of A1esoplodon ginkgodens, Oiso (Type),
Kamakura and Ito specimens (top to bottom).

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

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GROWTH AND REPRODUCTION OF STENELLA CAERULEOALBA BASED ON THE AGE DETERMINATION BY MEANS OF DENTINAL GROWTH
LAYERSTOSHIO KASUYA*ABSTRACT

Growth and reproduction of Stene/la caeruleoalba caught on the Pacific coastof Japan in October to January were studied based on the annual growthlayers in dentine. The mating seasons are in May and June, and in November
and December. Calves are born after 12 months gestation at 100 cm in bodylength. They attain sexual maturity at 9 years at the lengths 212 cm infemales and 220 cm in males, and physical maturity at 14 to 15 years at thelengths 222 cm in females and 236 cm in males. Lactation lasts about 1.5
years. Mean reproductive cycle is about 3 years or slightly less. Oestrous
females assemble to form a school, which is retained at least for one reproductive cycle but can join with the schools in other growth and reproductive
stages of both sexes.

INTRODUCTION
The dolphin fishing was formerly operated in the several villages along the coast of
the Izu Peninsula, which situates in the Pacific coast of Ja pan (Japanese Fisheries
Bureau 1900). But in most of these places this fishing was abolished before the world
war II.
Though, until few years ago Arari on the west coast of the Izu Peninsula
operated this fishing for Stenella caeruleoalba (Meyen, 1833) and other delphinids inspring season (Nishiwaki and Yagi 1953, Nishiwaki et al. 1965), the operation haverecently ceased. At present, only Futo and Kawana on the east coast are cooperatively operating this fishing with several speed boats.
The fishing season for these two villages usually starts in the middle of Octoberand closes in December, but few catches have been made in January and early October. The catches are mostly Stenella caeruleoalba with occasional catch of Stenella
attenuata and other delphinids (Tobayama 1969). According to the private communication of Mr. N. Miyazaki, the mean annual catch of Stenella caeruleoalba in theboth villages is about 4980 individuals in recent 3 seasons from 1968-'69 to 1970-'71,
when the catch was regulated by the fishermen to control the market price.
The schools of Stenella caeruleoalba are found mostly in the waters off the south
east to north coast of Oshima Island, and then chased into the Kawana harbor or
the Futo harbor (Tobayama 1969). There are few catches in the west coast of the* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972, 57-79.

58

KASUYAisland. As shown in Fig. 1, there is a strong inflow of warm water in the south east
entrance of the Sagami Bay. The migration of this species in the Sagami Bay and its
south east entrance seems to be related with this current.
This study was intended to obtain some informations on the growth andreproduction of Stenella caeruleoalba as a base of the population study.
141°E'--'~..J_...LJ....~.1..---'-----'=--=---'-~"'--'-----''---'---J.~"'--'-~'---'--'34°N

Fig. 1. Map showing the geography around Sagami Bay with the position of sightingof this species in Nov. 1971 (cross) and in Nov. 1970 (triangle). The surface
isothermal line is based on the observation in November 1971. Dotted line indicates 200 m line of the depth. A indicates Arari, F Futo, K Kawana, and otherwhite circles the position where dolphin fishing was formerly operated.

MATERIALS AND METHOD

Most of the materials used in this report were obtained from the 4 schools, schools
A, B, F, and Gin Table 1, processed at Kawana or Futo in 1967, '68, and '70.
School A, captured on 15 Nov. 1968 and processed at Futo, contained 1680 individuals, and 406 individuals were studied randomly. They were composed ofnewborn calves, juvenile, and mature individuals of both sexes, but lacking in thecalves from 110 cm to 140 cm in body length. Fetuses from 5 cm to 105 cm in bodylength were observed.
School B was caught on 16 Nov. 1968 and processed at Kawana. Among 319
dolphins constituted this school, 318 were studied. This school was composed ofjuvenile and mature individuals of both sexes ranging from 160 cm to 255 cm in bodylength, with an exception of a calf of 100 cm. No pregnant female was observed.
School F, caught on 26 Nov. 1967 and processed on 28 Nov. at Kawana, wascomposed of about 3,300 individuals, among which only 146 were studied randomly.
They were composed of newborn calves, juvenile and adult individuals ranging in
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH AND REPRODUCTION OF A STENELLATABLE I.

School
no.
A
B

c
D
E
F
G
H
ll

SOME INFORMATIONS ON THE SCHOOL COMPOSITION OF
STENELLA CAERULEOALBA

No.!) Sex ratio
No.
(male,
caught studied

%)

1,680
319
330
256
2.000
3.300
330
101

59

406
318
38
256
125
150
84
58
22

Ratio in mature female (%)

31.3
56.0

p
4 J.12)
0

34.0
41.7

2.0
23.3

p&l

r

Immaturity
in females
(%)

47.7
89.5

0.5
0

10.7
10.5

18.1
86.2

80.4
63.3

0
0

17.6
13.3

47.4
31.3

Fetus not included. 2 l 3 recently ovulated nonpregnant females included.
ing.
R resting. P&L pregnant and simultaneously lactating.

Date killed

16, 18, 22 Nov. '68
17 Nov. '68
21 Oct. '70
2 Dec. '70
22 Nov. '70
28 Nov. '67
14 Oct. '70
4 Oct. '71
19 Nov. '69
P pregnant.

L lactat--------·------··-----------------------80

n

70

'°
tll

:::J

60

"O

:~ 50

I

'O

11

s 40
0

... 30
QJ

-E 20
:::J

z 10
op...i.,.um..--~-...ai.mllm....-!J.,."-"lmlll.,.,L...Wlllmll...ll-

100

125

200
150
175
Body length in cm

225

250

Fig. 2. Body length frequency of the materials used in this study, schools A, B, F and
G are combined. Black indicates male and white female.

body length from 95 cm to 255 cm. But the dolphins of 150 cm to 195 cm were
scarce. Only three fetuses were observed.
School G was captured on 12 Oct. 1970, and processed and studied on 14 Oct.
Among 330 individuals constituted this school 84 individuals were studied randomly.
They were composed of juvenile calves ranging from 100 cm to 130 cm and from 165
cm to 200 cm, and adult individuals of both sexes ranging from 210 cm to 260 cm inbody length. Few fetuses were observed.
The body length was measured in each 1 cm interval in a straight line from thetip of upper jaw to the bottom of the notch of the tail flukes by two persons with atape measure. When the length was analized, each body lengths were grouped into
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

60

KASUYAthe nearest 5 cm.
The mammary gland was observed in the field and classified into lactating andnon-lactating. Ovaries were collected from all the adult females and from most of
the immature females, and fixed with 10% formalin solution. The number of corpora albicantia and lutea was counted in the laboratory slicing the ovary into about 1
to 2 mm thickness. The both testis were collected from all the males and preservedwith same manner as used for ovaries. The weight was measured in the laboratory.
When a corpus luteum was observed in the ovary, the uterus was carefully searched
for small embryo.
Several teeth were collected with a hammer and a chisel usually from thecentral part of the upper tooth row, and fixed with 10% formalin solution.
For preparing the tooth for age determination, at first the connective tissue wasremoved with nife, then its half side was ground off perpendiculary with stones ofvarious granule. The polished surface was glued on a plastic board with synthetic
resin, then the other side was polished with the same manner to a thickness from 50
to 70 µ. The growth layers in dentine were observed under transmitted light withbinocular microscope ( X 20- X 50).
Other than the materials obtained from the schools A, B, F, and G, some tooth
samples and biological data collected at Kawana, Futo, and Taiji (33°35'N,
135°55'£) were presented by Dr. S. Ohsumi and Dr. K. Hirose. They are used inanalizing the growth curve. The informations on the body lengths of the fetuses
and juvenile calves of the schools C, D, E, and H were offered by Mr. N. Miyazaki,
and those of school I by Dr. K. Hirose. These body length frequencies are usedin analizing the reproduction of this species.
AGE DETERMINATION
The dentinal growth layers are used in this study as the age characteristics of Stenella
caeruleoalba. In the dentine of this species, as shown in Pls. I and II, there are observed the layers of opaque and translucent dentine arranged alternately. Though,the thickness of the layer varies at the positions on a tooth, the thickest is the layer
formed in the fetal stage. This fetal layer is usually composed of a opaque dentine.
But sometimes there are observed one or two faint laminated structure, on which no
study was conducted. Probably this will be a reflection of the physiological conditions of the mother which have affected the formation of the laminated dentine of themother. Though there is a neonatal line between the fetal dentine and the postnatal
dentine, this structure is inconspicuous in this species than in the sperm whale(Ohsumi et al 1963).
The structure, the thickness and translucency, of the postnatal dentine boundedon the neonatal line is variable between the animals. This will be related with thedate of birth and the season when the alternation of the opaque and translucent
layers occurs. There are usually observed one or two faint translucent layers in the
thick opaque layer accumulated just after the birth. But this fine structure was not
used for age determination, because it was not expected to show the annual accumulaSci. Rep. Whales Res. Inst.,
No. 21, 1972

GROWTH AND REPRODUCTION OF A STENELLA

61

tion cycle.
The thickness of the postnatal layers decreases with the age of accumulation,
especially the 7th or 8th and the latter layers are thinner. The dentine ofabout 15thor latter layers is composed of poorly calcified secondary dentine as in the case of
Globicephala melaena (Sergeant 1962). It is possible to read the laminations in thissecondary dentine with slight difficulty.
Though the boundary of opaque and translucent layers is usually not clear,
there is no indication to consider that there is significant difference of the thickness
between two layers.
Fig. 3 shows the seasonal change of the conditions of the newest dentinal growthlayer in the tooth with 13 or less layers, in which the layer is not too thin to makethe accurate observation. It is expected, from Fig. 3, that the alternation of dentinal
layer from the opaque to the translucent occurs in from November to December.

80

>.
u

60

c

QI

5- 40
QI

Lt

0 .
Oct.

.. ·.·.·.·.·.·.·.·.·. . . . . . . . ..

DecemberJan.
MonthFig. 3. The condition of the newest dentinal layers. The marks indicate thin opaquelayer, thick opaque layer, thin translucent layer, and thick translucent layer (fromtop to bottom). The numbers at the top indicate the sample size. The dates of thekill are grouped into the lst, 2nd, and 3rd decade of month.

NovemberIn this study it is presumed that the opaque layer is accumulated in summer
and the translucent in winter as in the case of Physeter catodon (Ohsumi et al 1963),
Tursiops truncatus (Sergeant 1959), and Globicephala melaena (Sergeant 1962).
For determining the age of the dolphins, it was tentatively assumed that theopaque and translucent layers indicate the growth in 6 months respectively. And
in the animals with the number of opaque layers 5 or less, the age was determined toeach nearest 1/4 years considering the conditions and thickness of the oldest (formed
just after birth) and the newest layer, in the animals with between 6 and 10 layers tonearest 1/2 years, and in the animals with more than 10 layers the number of the opaque layers was used as the approximate age of the animal.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

62

KASUYAGROWTH

Lengths and length frequencies
The length frequencies show characteristic features in each schools. This isconsidered to be resulted from the schooling behavior related with the maturity andreproductive cycle. Descriptions of the length frequencies of each schools areroughly made in the chapter of Materials and Method, and some discussions in thechapter of Reproduction.
When schools A, B, F, and G are combined, the smallest individual is found in
the length group of 95 cm, the largest female in 245, and the largest male in 260(Fig. 2). The highest frequency of the adult female is in the length group of 225 cm,
and that of male probably in 240 cm. The length of the adult mal~ seems to exceeds that of the female about 15 cm (see Growth curve).
No significant difference of length frequency between both sexes is observed in
the animal smaller than 175 cm.
250

.t:..

• •

'6i

I

=t •

c:

~

>-

-g 150

en

100
0

5

10

15

20

25

Age in year
Fig. 4. The mean growth curve of the female. One dentinal layer corresponds to one
year. Closed circle indicates immature female, open circle mature, and cross unknown. For explanation see text.

Growth curve
The relation between body length and the age in 218 females is shown in Fig. 4.
The growth is characteristic in the rapid increase of the length in the first 2 years.
The increase of the body length seems to stop at the age of 14 or 15 years. This age isconsidered to mean the time when most of the female individuals attain the physicalmaturity. As the mean body length of the 36 females at the age of 16 years or more isSci. Rep. Whales Res. Inst.,

No. 24, 1972.

GROWTH AND REPRODUCTION OF A STENELLA

63

222.4 cm, it is considered that the mean maximum body length attained by the female
is approximately 222 cm. The age of oldest female was 26 years.
The mean growth curve shown by a solid line in Fig. 4 was drawn by eye, considering the mean body lengths in each ages. Based on this growth curve and themean body length at birth obtained separately, it was tried to adapt the Bertalanffy's
growth formula, L(t) =a(l-e.-fit), using Walford's finite differences diagram. But
it was impossible to adapt single growth formula for the mean growth curve of thefemale. For the growth of the first 2.5 years, the formula with the constances a=
192.2, a=-0. 7350, and /3= 1.1384 fits perfectly. The growth curve at the age of 2.5
years or more can be calculated from the above diagram, the mean final length 222.4
cm, and L(2.5) = 186.8 of the former formula. This gives the constances a=222.4,
a=-1.1813, and /3=0.2601, which is shown by the dotted line at the top in Fig. 4.
These two formulae can be considered to represent approximately the mean growth
curve of the female Stenella caeruleoalba. But the fittness of the latter formula is notgood for the ages between 6 and 12 years. Another formula which fits better only tothose ages is shown by the constances a=219.l, a= -1.3026, /3=0.2445, and shownby the dotted line at the bottom in Fig. 4.

..

250

E
u

•

I

.

•

•

I

. .
--- --- ----- -------- --- ------- -:

200

.s
.c
c

°'
~

>.

-g 150
CJ

0

5

15

10
Age

in

20

25

year

Fig. 5. The mean growth curve of the male. Solid line is drawn for male by eye.
Dotted line is the female growth curve shown by the solid line in Fig. 4.

The relation between body length and age in 191 males is shown in Fig. 5. Theline was drawn by eye. In the younger individuals the growth of the male is samewith that of the female. The difference of the body length between both sexes appears at about 6th year. After this age the growth is rapid and attaines the approximale length 230 cm at the age of 13 years. This rapid growth will probably
related with the attainment of the sexual maturity, and resembles with that of theSci. Rep. Whales Res. Inst.,
No. 24, 1972.

KASUYA

64

male Physeter catodon (Nishiwaki et al 1958). But the growth does not continue so long
period as the sperm whale. The physical maturity is considered from the growth
curve to be attained at 14 or 15th year as in the case of the female. The mean bodylength of the males of 16 or more years old is 235.9 cm or approximately 236 cm,
which is considered to be the mean maximum body length attained by the male.
This length is 14 cm larger than that of the female, which coincides with the value
expected from the body length frequency.
The age of the oldest male was 25 years.

Mean body length at birth
Because of the scarecity of the samples, the body length at birth was obtained
combining the both sexes. This will not give erroneous result because there is observed no sexual dimorphism in the body length of the younger individuals.
The mean body length at birth was calculated from the body length frequenciesof the large fetus and newborn calf. The data from the 4 schools, A, B, F and G wereused for this purpose. The body lengths were grouped into each nearest 5 cm units.
The largest fetus and the smallest calf were found in the length groups of 105 cm and95 cm respectively. So the length frequencies in the length groups between 90 cm
and 110 cm are considered here.
The numbers of calves and fetuses in the above range are 17 and 73 respectively,
and the frequencies of both categories are equal in the length group 105 cm (Table 2).
But there is a wide discrepancy between the total numbers of fetus and calf. As thecause of this phemomenon, it is possible to expect two reasons. One is related withthe method of fishing in which a school of dolphins is chased for several hours to be
driven into the harbor, during this chase some of newborn calves may be lost. The
other less probable cause is the difference of the schooling behavior or segregation of
the newborn calf and the mother.
TABLE 2.

BODY LENGTH FREQUENCIES OF FETUSES AND CALVES

Body length
(cm)

Futus
(no.)

Calf
(no.)

Fetus
(%)

Calf
(%)

% of calf(corrected)

90
95
100
105
110
Total

15
27
27
4
0
73

0

20.50
36.99
36.99
5.48
0
100

0
5.88
47.06
29.41
17.65
100

0
13.72
55.99
84.29
100
50.00

8
5
3
17

Though the correctness of these possible presumptions are not proved in thisstudy, the length frequencies were corrected to equalize the total numbers offetus andcalf. Then the ratios of the calf and the fetus were calculated in each length groups(Table 2). From this corrected percentage of the calf, the regression line y=
5.411 x-490.3 is obtained by the method of least squares, where y is the frequency ofthe calf in percentage and x is the body length in cm. The mean body length atbirth, 99.8 cm, is obtained from this formula as the body length corresponding to theSci. Rep. Whales Res. Inst.,
No. 24, 1972.

65

GROWTH AND REPRODUCTION OF A STENELLA

frequency of 50% (Fig. 6). But when the accuracy of the measurement is considered, it is better to say that the mean body length at birth is 100 cm.

•

iii 100
;:J

"C

:~

"C

80

.f
...c 60
0

.!l
~

Cl>
c 40

....0

Cl>
Ol

20

111
.....

c

Cl>

...

u

Ol
Ol

0
95
100
105
Body length in cm

90

Cl>

0.

Fig. 6.

110

Mean body length at birth, for explanation see text.

Age at the attainment of sexual maturity
In Table 3 the females with corpus luteum or albicans were identified as attained
sexual maturity, and the animals of the age of 6.5, 7.5, 8.5, and 9.5 years were
included into the age groups of 6, 7, 8, and 9 years respectively (see Materials andMethod). The oldest immature female and the youngest mature female were foundin the age groups of 10 years and 8 years respectively. As the materials are very few,
and the ratio of the mature individual fluctuates too wide to obtain the regressionline, another method was used to estimate the mean age at the attainment of sexual
maturity.
At first step, the percentages of mature and immature animals were calculated ineach age groups, then those of the immature animals were added from the older age
groups to the younger, and those of the mature from the younger to the older. These
accumulated percentages are shown in Fig. 7. The mean age of the female at theTABLE 3.

AGE FREQUENCIES OF IMMATURE AND MATUREANIMALS OF BOTH SEXES
No. of females

No. of males

Age
6
7
8
9
10
II
12
Total

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

immature

matureimmature

mature

2
2
8

0
0

8
8
4

0

0
0
14

4
2
3
7
17

I
2
0
24

0
2
2
5
I

11

66

KASUYAattainment of the sexual maturity is obtained in the figure as the point where twolines cross. This gives the age 8.8 years.
-..!
0

Males

.!:: 140
>c:

u

~100

O"'

Cll
.....

-0
Cll

.....

60

..!!!

::J

N

§ 20
u

u
<t

0)

7

8

9

10
7
11 6
Age in year

8

Fig. 7. Mean age at the attainment of sexual maturity.
quency of mature individual, and cross the immature.

9

10

11

12

Circle indicates the fre-

300
200
~100
u

~ 80

0

:c: 60Cl"Qi

3: L.0 -------------------------------------20•i... ·i180•:•
-lo •!!i••.+•w•!•w•".,. •!- •

200

..
220

240

Body length in cm
Fig. 8. Relation between body length and the weight of both testis. Dotted line indicates the mean weight at the attainment of sexual maturity used in this study.

Another estimation can be obtained from the relation between age and numberof ovulations (Fig. 14), as the age when the number of ovulation is 1.0. The mean
age of the female at the attainment of sexual maturity obtained by this method is
8.9 years. These two figures coincide well.
Fig. 8 shows the relation between body length and the combined weight of bothtestes. Hirose and Nishiwaki (1971) showed with similar materials used in this study
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH AND REPRODUCTION OF A STENELLA

67

that the testes of more than 40 g are mature. Though they did not give the mean
weight of testis at the attainment of sexual maturity, it is considered to be between
30 g and 40 g. In the present study the testis with 35 g or more in combined weight
were considered to be sexually mature.
In the males, the oldest immature animal and the youngest mature were foundin the age of 11 and 7 years respectively. The mean age of the male at the attainment of sexual maturity, obtained by the same procedure used in the female, is 9.2
years (Fig. 7).
At present there is no reason to consider that the difference of the ages of theboth sexes at the attainment of sexual maturity is significant. And the best estimation for both sexes seems to be the age of 9 years.
The mean body lengths at the age of9 years obtained on the mean growth curveare 212 cm for fem ale, and 219 cm for male.
100.--~~~~~~~~~~~~~~--::::.--.~--wi

Fern ale

75
50 ----------------------E'-;;'!-

u'

25

N'

~·

c

~

N1

0

190

220

210

200

.......~-=---.i]ioo~~~~~~~~~~~~~~~~~~
m
Male
~

75
50 - - - - - - - - - - - - - - - - - -,

•
I

E:

25
200

210

220

230

Body length in cm
Fig. 9. The body lengths where 50% of individuals are sexually mature.
drawn by eye.

Lines areBody length at the attainment ef sexual maturity
The ranges between the largest immature individual and the smallest mature
are from 190 cm to 220 cm for females, and from 200 cm to 240 cm for males.
The mean body length at the attainment of the sexual maturity was obtained
directly from the ratio of the matured individuals in each length groups.
Fig. 9 is based on the 640 immature females and 604 mature females, and 53
immature males and 46 mature males. On the regression lines in Fig. 9, the length
where 50% of individuals are sexually mature is 212 cm for females, and 220 cm for
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

68

KASUYA

males. These figures coincide well with those obtained from the mean age at theattainment of sexual maturity and the mean growth curve.
REPRODUCTION

Sex ratio
Table 4 shows the sex ratios in 4 schools caught at Kawana or Futo, and that of
TABLE 4. SEX RATIO IN PRENATAL AND POSTNATAL INDIVIDUALS,SHOWN BY THE NUMBER OF FEMALES PER 100 MALES
Prenatal
SchoolPostnatal~

male

femalemale

femaletotal

sex ratio

A
B
F

53
0

G

4
0
58
100

53
0
1
3
0
57
98.2

127
178
51
35
51
442
100

279
140
99
48
40
606
137.1

406
319
150
83
91
1,048

219.6
78.6
194.1
172.9
78.4
137.1

Taiji specimens
Total no.
Sex ratio

160 II
140

5 120
c

100 - - - - -

-c 80

L:.

OI

II

~

>-

-0
0

60

£I)

40
20
0

/

IV

v

VI VII VIII IX

x

XI

XII

III

II

Month
Fig. 10. Body length frequency of the fetus (solid line) and juvenile calf (dottedline). One month interval means 15 individuals. The growth curve of the fetus
was drawn presuming 12 month of gestation, and that of calf is based on the growthformula. I is started on the lst ofJune and II on the lst of December. The school
D, F, E, I, B (right side, no fetus) and A (left side), C, G, and Hare plotted against
the date of the catch (from right to left). A school in May is cited from Nishiwaki
and Yagi (1953).
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

GROWTH AND REPRODUCTION OF A STENELLA

69

the catch off Taiji in January 1969. The ratio is shown by the number of females
per 100 males. The Taiji specimens were caught with hand harpoons from various
schools and studied by Dr. K. Hirose.
These data show that the sex ratio of the postnatal individuals varies in eachschools. This will probably be related with the characteristic schooling behavior
concerning the sexual conditions of the animal, and will not show the real sex ratio in
the population. The number of both sexes in fetuses is considered to be nearly equal,
and no uneven sex ratio is suggested.

40 A
2060 ········•···•·
B
40
20

20

11

Fig. 11. Frequency of the date of birth of the one year or younger individuals of both
sexes calculated with the growth formula. Square with smaller dots indicates theindividuals born 12 months prior to the date of catch. The numbers in the rightindicate the sample size, and the vertical rod the date of catch.

Parturition season
As there are observed many full termed fetuses and newborn calves in theschools caught in November and December (Fig. 10), this season seems to be at least apart of one of the parturition seasons of Stenella caeruleoalba.
Fig. 11 shows the frequency of the parturition infered with the growth formula,
the date of catch, and the body length of juvenile calf of 165 cm or less which isconsidered to contain one year old calves and all the younger individuals. It isseen in this figure that, though some parturitions may occur in any season of the year,
this species have two peaks of parturition one in May and June, and the other in
November and December. In this figure, the autumn peaks is smaller than thespring peak. But it will not be necessary to think that the autumn peak is smaller
than the other, because the frequency of the date of birth infered from the length
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

KASUYA

70

and date of kill with fetal growth curve shows the reversal pattern (Fig. 12).

32
106

4
6

28
3

7

20
20

226

10
06;.;;;;:~~~~~iZ21:!:m:m~mlli~~~~~~

IV

V

VI

VII VIII JX

X

XI

XII

II

Ill

Month
Fig. 12. Frequency of the expected date of birth calculated with the growth curve of
fetus. Square with smaller dots indicates the fetuses expected to have been born 12month after the date of catch. The numbers at the right indicate the sample size,
and the vertical rod date of catch.

Mating season
Many small embryos are observed in the females caught in November andDecember (Figs. 10 and 13). In these figures the smallest length group includes theembryos smaller than 2.5 cm, which range is a half of the width of the length range of
5 cm applied to larger fetuses. Accordingly the height of the frequency of the smallest
group must be doubled to compare the relative abundance with that of the larger
length groups. Then it reveals that the relative abundance of the fetuses of2.5 cm orless in body length is higher than that of the next length group.
This will indicate that the beginning of the mating season is at slightly prior to
November, and the newly impregnated females are still increasing in November andDecember. Accordingly it is reasonable to consider that one of the mating seasons is
in November and December. As this season coincides with the autumn parturitionseason, another mating season in May and June is expected. This is supported by
the existance of small embryos, 10 fetuses under 10 cm, in a school caught in May at
Arari (Nishiwaki and Yagi 1953, reffered in Fig. 10 of this report).
Length of gestation
As the sampling period is restricted to October, November, and early December,
it is impossible to follow the seasonal increase of the body length of the fetuses to preSci. Rep. Whales Res. Inst.,

No. 24, 1972.

GROWTH AND REPRODUCTION OF A STENELLA

71

sume the gestation period and the growth of fetus.
But it can be presumed from the seasons of mating and parturition, and bodylength frequency of the fetus. As mentioned above, both peaks of mating andparturition are in spring and autumn with the interval of6 months, then the approximate length of gestation must be a multiple of 6 months. On the other hand, there
are observed three peaks in the fetal length frequency in autumn season (Fig. 13).
80
C/I

<11
::J

-0

>

60 -1.0

0

-0.5

0.5

1.0

-0

.!:

...

QI

.0

E 20
::J

z

0

20

40

60

BO

100

120

140

160

180

200

Body length in cm
Fig. 13. Body length frequency of the fetus (dotted area) and juvenile calf (whitearea) in the catch of October to December. Figures at the top indicate approximate
age shown by the year from the birth. Schools A to I are combined.

The smallest peak is composed of the newly impregnated fetuses, the largest of the fulltermed fetuses, and the median of the fetuses impregnated in the preceding season.
If the length of gestation period is 18 months or more, there must be observed 4 ormore peaks, which is inconsistent with the above observation. Accordingly thegestation period of Stenella caeruleoalba is presumed to be about 12 months.
The mean fetal growth curve in Fig. 10 is drawn based on the above gestation
period using the method of Laws (1959). 0.13 X Gestation period is tentatively usedhere for Lt 0 of Laws (1959), which is the time when the extended straight line of the
fetal growth cuts the axis of time. The starts of gestation are put at the lst ofDecember (growth curve I) and at the lst ofJune (growth curve II). The growth curve of
the calf is based on the growth formula.
Fig. 12 shows the frequency of the date of birth infered with the fetal growth
curve, from the length frequency of the fetus and the date of kill. There are twoparturition seasons one in June and the other in November and December. This
result coincides well with the parturition frequency obtained independently (Fig. 11).
It is interesting that the shapes of the autumn parturition peak in Fig. 12 and that ofspring parturition peak in Fig. 11 are similar and the highest peaks are in December
and June respectively. This will indicate that the frequency of parturition is slightly
higher in December and June than in the preceding months, and will support thecorrectness of the presumed gestation period of 12 months.
For the comparison, the frequency of parturition was calculated on the asSci. Rep. Whales Res. Inst.,
No. 24, 1972.

72

KASUYA

sumption of the gestation of 11 months and that of 13 months. When 11 months
gestation and 0.18 X Gestation period for Lt 0 are assumed, the spring parturition peakis in April. And when gestation of 13 months and 0.13 X Gestation period for Lt 0
are assumed, the spring peak is in the range from April to June with the highest in
May. These results do not fit to that obtained from the length frequencies of thejuvenile calves.

Length of lactation
In this study the direct information indicating the length of suckling period was
not obtained, because no stomach content was studied. But it is expected that thecalf starts feeding on food before the age of0.5 year, because most of the teeth except
those in the anterior and posterior regions of the tooth row have erupted in all theindividuals of that age.
The length oflactation was estimated from the number oflactating females andthat of juvenile individuals caught together. There are observed several peaks inthe body length frequencies of each schools. The peaks of the younger individuals
are considered to represent the individuals born in some particular parturitionseasons, and their approximate age can be presumed from the body length at themode of frequency. The peak at 100 cm (schools A, B, and F) is considered to becomposed of individuals born in the autumn season when they were caught, and thatat 165 cm (schools A and B) is of the dolphins about 1 year old. The peaks at 120 cm(school F) and at 115 cm (school G) will have been born about 1/4 year before thecatch, and that at 140 cm about 1 /2 year before, and that at 170 cm about 1 1/4
years before the catch.
TABLE 5. LENGTH FREQUENCIES OF THE JUVENILE INDIVIDUALS,
THEIR APPROXIMATE AGE, AND NUMBER OF LACTATINGFEMALES.
Length frequency (cm)School
A

B

F

G

Range

Mode

Age

Number100-105
145-170
175-190200100160-170
175-21522095-1 JO
115-125130-145
160-175
185100-130
165---180
195-

JOO
165
185

0
I
2
7+
0

5
23
7
244

100
165
200
105
120
140
170
115
170

2, 2+
0
1/4
1/2
I 1/4
4+
1/4
I 1/4
4+

Number oflactating females
94

17
14
245
60
9
15
46
3
77
II
7
54

41

19

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

GROWTH AND REPRODUCTION OF A STENELLA73

The number of the lactating females nearly coincides with that of calves
younger than I l /4 years old (schools B and G). The number of 2 years and older
calves caught together with the lactating females is very few comparing with thatof the younger individuals.
The school A was caught on 15 Nov. 1968, and the members were killed on 16,
18, and 22 Nov. when I had a chance to study some of them, but I had no chance tostudy many dead individuals picked up daily from the harbor and sold. The ratio of
the suckling calf may have been higher in these dead individuals which I missed to
study. This will be the reason of the low frequency of the juvenile calves in thesample compared with the lactating females. The quite reverse case is found in theschool F. This school was caught on 26 Nov. 1967, and I studied on 28 Nov. only thecarcases of the dolphins which had died in the water and picked up. In this school,
the number of juvenile calves is higher than that of the lactating females. But evenin these schools, A and F, it can be suggested that the 2 years old calves are rarely
accompanied by the lactating mother.
The lactating females are devided into two groups by the size of the largest
corpus albicans (Hirose et al 1970). The Futo school and Kawana school in Hirose
et al (1970) correspond to the school A and B of Table 1 respectively. Probably thelactating females with larger corpus albicans, which is few in number, will be themothers of newborn calves, and those with the smaller the mothers of the calves of theages from 1.0 to 1 1/4 years old.
As the conclusion of above discussions, it can be said that lactation lasts at least
for 1 1/4 years, and probably for about 1.5 years as in the case of Tursiops truncatus(Tabolga and Essapian 1957, Nakajima et al 1963), but rarely for 2.0years. The calves
which have started feeding on food by the age of about 0.5 year, will continue to take
both food and milk until the age of about 1.5 years.

Female reproductive cycle
As the females lactating and simultaneously pregnant are very rare in the catchand the recently ovulated non pregnant 3 females were not lactating (Table 1),
most of the fem ale seems not to ovulate in the period of lactation.
Between schools, there is wide variation of the ratio of the resting females, inwhich all the mature females other than the pregnant or lactating are included. But
it may be approximately between 10.5 and 17 .6 % of the total number of the mature
females (Table 1). If this ratio is compared with the total of the length of gestation(1 year) and length of lactation (about 1.5 years and surely more than 11/ 4 years), theaverage resting period of between 0.29 and 0.53 year (in case of 1.5 years lactation), or
between 0.26 and 0.48 years (in case ofless probable 11 / 4 years lactation) is obtained.
Accordingly the probable mean reproductive cycle of the female is presumed to
be about 3 years or slightly less (gestation 1, lactation 1.5, resting from 0.3 to 0.5year). This means that some females are impregnated in the same mating season
when they have weaned the calves, and most of the females in the next mating season.
In this species the corpus albicans probably remain in the ovary all through its
life (Fig. 14). The mean annual accumulation rate of the corpus albicans and luteum
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

KASUYA

74

is 0.69, and the lowest and the highest accumulation rates are 0.25 and 1.6 respectively. To explain the mean accumulation rate and the mean reproductive cycle, there
must be expected about two ovulations in one reproductive cycle (Table 6). But as
indicated by the lowest accumulation rate, there must be few females which stayanoestrus for 3 years after giving birth to the calves and show the reproductive cycleof 4 years.

15

1.6 /year

Ill

c
0

~10
:J

V:0.69X-5.16

>
0

.....
0

5

0

z

/year

..

. ::::.
4

6

8 10 12 14 16 18 20 22 24 26
Age in year

Fig. 14. Relation between age and the number of corpora albicantia and luteum.
The regression line is calculated by the method of least squares, and the highest andlowest ranges are drawn by eye.
TABLE 6. MEAN ANNUAL OVULATION RATE CALCULATED FROM THE ASSUMEDREPRODUCTIVE CYCLE AND NUMBER OF OVULATIONS IN A CYCLE.
Number of ovulations

Pregnant(year)

Lactating(year)

Resting(year)

Repreductive
cycle(year)

2

3

4

5

6

1
I

1.25
1.25
1.25
1.25

0
0.26
0.48
1.75

2.25
2.51
2.73
4.00

0.44
0.40
0.37
0.25

0.89
0.80
0.73
0.50

1.33
1.20
1.10
0.75

1.59
1.47
1.00

1.25

1.50

1.50
1.50
1.50
1.50

0
0.29
0.53
1.50

2.50
2.79
3.03
4.00

0.40
0.36
0.33
0.25

0.80
0.72
0.66
0.50

1.20
1.08
0.99
0.75

1.60
1.43
1.32
1.00

1.25

1.50

Reproductive cycle and school
Fig. 15 shows the frequencies of the date of conception infered with the mean
growth curves of fetus and juvenile individual. The materials include all the fetus
and the calves smaller than 165 cm in body length. It is sure in the preceeding discussion that these calves are still accompanied by the mother. The frequencies ofconception calculated from the calves are shown by white area, and those calculated
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

GROWTH AND REPRODUCTION OF A STENELLA

75

from the fetuses are shown by dotted area. The height of the highest peaks of theboth frequencies in each schools are modified to be equal.
When schools are seen from the date of the conception of the fet us, the schools
are grouped into two patterns. One includes the schools in which the fetuses aremostly composed of the autumn fetus (fertilized in autumn mating season), and theother the schools in which the fetuses are mostly composed of the spring fetus. The
schools A, C, D, E, G, and H belong to the former, and school I to the latter. Because of the scarecity of materials it is impossible to classify the school F. The school
B did not contain the pregnant female.

XII

Ill

V!

IX

XII

Ill

VJ

IX

XII

Month
Fig. 15. Frequency of the date of conception of the fetus and calf smaller than 165 cm
in body length, calculated by the growth curve. Figures at the top indicate theapproximate age of samples at the time of catch. Dotted area indicates the fetuses
and the white area calves. For further explanation see text.

Similar classification is possible by the date of conception of the juvenile calves.
The calves in schools A and B are mostly composed of the autumn calf (fertilized
and born in the autumn season), and those of the schools C, D, E, and F are mostly
composed of spring calf. The school G shows the intermediate pattern.
There is observed various combinations between the fertilized date of calves
and that offetuses in the same school. In the school B only calves are observed, in theschool A autumn calves and autumn fetuses are observed in one year interval, in theschool C mostly spring calves and autumn fetuses in half year interval, in the schools
D and E spring calves and autumn fetuses with about 1.5 year interval. In theschool F the sample of fetus is too few to conclude, but probably it belongs to thesame type with the school D. In the school G the larger fet uses and smaller calves
seems to belong to one continuous mating season which slightly deviates from theSci. Rep. Wahels Res. Inst.,

No. 24, 1972.

76

KASUYA

typical mating season, and there is also observed few fertilizations in half year intervals at both sides of the main peak. In the schools H and I, there is observed no
calves smaller than 190 cm and 205 cm respectively. These observation lead me tothe following hypothesis on the behavior of the mature female.
The oestrous females may assemble together in a mating season, and will be impregnated. This stage is observed in the schools Hand I. The school thus formed
is expected to be the base of other complicated schools, when seen only from the sideof mature females. This connection of the females will be retained through theperiod oflactation and at least untill the next oestrous cycle. This stage is seen in theschool B. Then the females will reconstruct the school in accordance with the stageof the reproductive cycle. This is the reason why there is observed a peculiarity ofthe season of the conception of calf or fetus in each schools. All the other schools
may have been formed as the result of sporadic annexation of the schools of pregnant
females and that of lactating females in various stage of reproductive cycle. No
special affinity between the original schools related with the size of calf and that offetus is expected. The annexation between the lactating schools, or between the
pregnant schools is not denied.
The schooling behaviors of the immature individuals of both sexes and of mature
males are not well studied. If the males of 220 cm or more in body length aretentatively classified into mature, the numbers of mature males in the schools A, B, F,
and G are 93, 41, 11, and 18, or 64.1 %, 242%, 21.6%, and 54.6% of mature females(212 cm or more in length) respectively. It is considered that numerous mature
males are found together with the mature females. There is an example of the school
composed of immature individuals. This school, composed of about 600 individuals,
was caught on 14 Dec. 1971, and random investigation was made on 303 animals byme and Mr. N. Miyazaki. Among these dolphins, all the 66 females were sexually
immature and only 6 males in 237 males had testes weighed more than mean testes
weight at the attainment of sexual maturity applied in this study.
Though there are observed many spring calves and autumn fetuses, the numberof spring fetus is scarce in the present materials (Fig. 13). This may suggest thepresence of the segregation of females related with the reproductive cycle. But
further confirmation is needed on this problem.
DISCUSSION
There have been published two contrary opinions on the accumulation rate of thedentinal growth layers. Sergeant (1959, 1962) showed on Tursiops truncatus andGlobicephala melaena that one opaque and one clear (translucent) layer are accumulated
annually, and that the former in summer and the latter in winter. Similar conclusion was obtained on Physeter catodon by Ohsumi et al (1963), But Gambell andGrzegorzewska (1967) on Physeter catodon, Brodie (1969, 1971) on Delphinapterus leucas,
and Kleinenberg and Klevezal (1962, cited in Brodie 1969) on Delphinus delphis considered that two layers are accumulated annually.
However, as indicated by Sergeant (1962), Ohsumi et al (1963), and Brodie
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

GROWTH AND REPRODUCTION OF A STENELLA

77(1969) there are observed several fine layers in one dentinal growth layer. Especiallyin case of the young sperm whale, one growth layer ofOhsumi et al (1963) is usuallycomposed of two parallel layers. Similar one or two vague layers are also observedin the lst layer of Stenella caeruleoalba.
I consider that the above mentioned contravention on the accumulation rateof dentinal layers may be mostly caused by the different interpretation of the finestructure of the layer. It will be most necessary, at present, to establish the standards
suited for each species, and then define the accumulation rates in each species.
According to the observation on the several western Pacific Tursiops truncatusborn in an aquarium, the body lengths at the ages of0.5, 1.0, and 2.0 years are 133 °/o,
155 %, and 185 % of the length at birth respectively (Nakajima et al 1963). In the
Atlantic T. truncatus, the similar figure at the age of 7 or 8 months is 160 % (Essapian1953). These figures coincide well with the growth of Stenella caeruleoalba presumed
in this study, and suggest the correctness of my interpretation of the dentinal growthlayers.
In Stenella caeruleoalba, the sexual maturity is attained in the 9th year in both
sexes as in the case of Physeter catodon (Nishiwaki et al 1958, Ohsumi et al 1963). But in
Globicephala melaena (Sergeant 1962) and Delphinapterus leucas (Brodie 1971), the mean
age of the female at the attainment of sexual maturity is from 4 to 6 years, which isabout half of that of the male. Further study is desired to have a conclusion if thisresult reflects the real growth of these species, or simply resulted from the different
interpretation of the dentinal layers.
The mating season of Stenella caeruleoalba is peculiar in the possession of bimodal
peaks. In the northern species, Physeter catodon has a mating season in April (Ohsumi1965), Delphinapterus leucas in April and May (Laws 1959, Brodie 1971), Globicephalamelaena in April and May (Sergeant 1962), Phocoena phocoena in from July to August(Laws 1959, Fisher 1970, M!llhl-Hansen 1954). The mating seasons of the former 3
species nearly coincides with the spring peak of Stenella caeruleoalba, but the mating
season of Phocoena phocoena situates in the summer, or at the intermediate season of thespring and autumn peaks of Stenella caeruleoalba.
With the relation of the various lengths of gestation period, the parturitionseasons are in August in northern Plryseter catodon (Ohsumi 1965), in June (Laws
1959) or in July and August (Brodie 1971) in Delphinapterus leucas, in August in
Globicephala melaena (Sergeant 1962), and in July (Laws 1959) or in June and July(Fisher 1970) in Phocoena phocoena.
These informations are obtained, with one exception of Plryseter catodon, from thespecies in colder waters. In these species the mating season and the length of gestation will have been adapted to put the parturition season in the northern summer orlate spring, when the environment is better for newborn calves. However, Stenella
caeruleoalba is considered to distribute, in the western Pacific, in warmer waters (Kasuya 1971, Kasuya and Oguro 1972), and not to migrate north of the northern boundary of the Japan current. Therefore it will not be an important factor for this species
to give birth to the calves in summer season. This will have a relation with theexistance of the two parturition season in Stenella caeruleoalba.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

78

KASUYA

Tursiops truncatus in captivity had the gestation period of about 12 months andnursing period of 18 months (Tavolga and Essapian 1957), or nursing period of 16months (Nakajima et al 1963). These figures show good coincidence with that obtained in Stenella caeruleoalba.
Ohsumi (1971) reported a hypothesis on the structure of the school of Physetercatodon. There are several structural differences between the school of Stenella
caeruleoalba and that of P. catodon. One is the continuity of the members in the schoolof mature female of Physeter catodon. If this exists in the school of Stenella caeruleoalba,
it is reasonable to expect the spring fetus and autumn fetus in same frequency in one
school. This was not observed in the present study and the continuity, in thestrict sense, of the members in nursing school can not be expected in Stenella caeruleoalba. Other characteristic features of the school of Stenella caeruleoalba are thelarger size of the school and the larger number of the mature males found together
with the mature females. The juvenile school is observed in Stenella caeruleoalba as in
the cases of Physeter catodon (Ohsumi 1971) and Globicephala melaena (Sergeant 1962).
Perrin (1969) considered the between-school differences in coloration detectedin Stenella grajfmani to suggest the generic entities of the school of this species. This isinconsistent with the informations on the schooling behavior of Stenella caeruleoalba
obtained in this study.
ACKNOWLEDGMENTS

Sincere thanks are due to Dr. S. Ohsumi of The Far Seas Fisheries Research Laboratory, Dr. K. Hirose and Mr. N. Miyazaki of The Ocean Research Institute, University of Tokyo, who offered the tooth samples and many biological informations.
Dr. T. Kajihara and Dr. M. Nishiwaki of The Ocean Research Institute areacknowledged for their cocperation and the valuable suggestions.
REFERENCES
BRODIE, P. F., 1969. Mandibular layering in Delphinapterus leucas and age determination. Nature, 221:956-958.
BRODIE, P. F., 1971. A reconsideration of aspect of growth, reproduction, and behavior of the white whale(Delphinapterus leucas), with reference to the Cumberland Sound, Baffin Island, population. J. Fish. Res.
Board of Canada, 28(9): 1309-1318.
EssAPIAN, F. S., 1953. The birth and growth of a porpoise. Natural History, 62 (9) : 392-399.
FISHER, H. D., 1970. Reproduction in the common porpoise (Phocoena phocoena) of the North Atlantic. J.
:(ool., 161 : 471-486.
GAMBELL, R., and C. GRZEGORZEWSKA, 1967. The rate oflamina formation in sperm whale teeth. Norsk
Hvalfangst-tid., 56(6): 117-121.
HIROSE, K., T. KAsuvA, T. KAZIHARA, and M. NISHIWAKI, 1970. Biological study of the corpus luteum andthe corpus albicans of blue white dolphin (Stenella caeruleoalba). J. Mamm. Soc. Japan. 5(1): 33-39.
HIROSE, K., and M. NrsHIWAKI, 1971. Biological study on the testis ofblue white dolphin, Stenella caeruleoalba.
J. Mamm. Soc. Japan, 5(3): 91-98.
JAPANESE FISHERIES BUREAU, 1900. Nikon suisan hosaishi (Fishing in Japan). Suisan Shoin, Tokyo. vol. 1, pp.
424. (injapanese).
KASUYA, T., and N. OauRo, 1972. A new tagging method of dolphins. Sci. Rep. Whales Res. Inst., 23: 81-85.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH AND REPRODUCTION OF A STENELLA

79

LAws, R. M., 1959. The foetal growth of whales with special refference to the fin whale Balaenoptera physalus
L. Discovery Rep., 29: 281-308.
M0HL-HANSEN, U., 1954. Investigations on reproduction and growth of the porpoise (Phocoena phocoena L.)from the Baltic. Vidensk. Medd. fra Dansk naturh. Faren., 116: 369-396.
NAKAJIMA, M., K. TAKAHASHI, M. 0GURA, and K. SAWAURA, 1963. On the growth of infants of the small
size toothed whales. J. Jap. Ass. <:,ool. Gardens and Aquarium, 5(1): 16-22. (in Japanese).
NISHIWAKI, M., T. HIBIYA, and S. 0HSUMI (KIMURA), 1958. Age study of sperm whale based on reading of
tooth laminations. Sci. Rep. Whales Res. Inst., 13: 135-153.
NISHIWAKI, M., M. NAKAJIMA, and T. KAMIYA, 1965. A rare species of dolphin (Stenella attenuata) from Arari,Japan. Sci. Rep. Whales Res. Inst., 19: 53-64.
NISHIWAKI, M., and T. YAGI, 1953. On the growth of teeth in a dolphin (Prodelphinus caeruleoalba) (I). Sci.
Rep. Whales Res. Inst., 8: 133-146.
OHSUMI, S., 1965. Reproduction of the sperm whale in the northwest Pacific. Sci. Rep. Whales Res. Inst., 19:

1-35.
OHSUMI, S., 1971.

Some investigations on the school structure of sperm whale. Sci. Rep. Whales Res. Inst., 23:
1-25.
OHSUMI, S., T. KASUYA, and M. NrnHIWAKI, 1963. The accumulation rate of dentinal growth layers in the
maxillary tooth of the sperm whale. Sci. Rep. Whales Res. Inst., 17: 15-35.
PERRIN, W. F., 1969. Color pattern of the eastern Pacific spotted porpoise Stenella graffmani Lonnberg(Cetacea, Delphinidae). <:,oologica, 54(4): 135-151.
SERGEANT, D. E., 1959. Age determination in odontoceti whales from dentinal growth layers. Norsk
Hvaifangst-tid., 48(6) : 273-288.
SERGEANT, D. E., 1962. The biology of the pilot or pothead whale Globicephala melaena (Trail) in Newfoundland waters. Bull. Fisheries Res. Board of Canada, 132: 1-84.
TABOLGA, M. C., and F. S. EssAPIAN, 1957. The behavior of the bottle-nosed dolphin (Tursiops truncatus):
mating, pregnancy, parturition, and mother-infant behavior. <:,oologica, 42(1): 11-31.
ToBAYAMA, T., 1969. School size and its fluctuation in the catch of Stenella caeruleoalba in Sagami Bay.
Geiken Tsushin, 217: 109-119. (in Japanese).

EXPLANATION OF PLATESIn all the figures the contrast is reversed, or translucent layer is seen dark and opaque layer light.
PLATE I
Fig. 1.
Fig. 2.
Fig. 3.

Thin ground section of tooth of 92 cm fetus.
Thin ground section of tooth of a female, 116 cm, 1/4 year.
Thin ground section of tooth of a female, 173 cm, l year.
PLATE II

Fig. 1.
Fig. 2.
Fig. 3.

Thin ground section of tooth of a female, 193 cm, 4 1/4 year.
Thin ground section of tooth ofa male, 216 cm, 13 year.
Thin ground section of tooth of a male, 221 cm, 25 year.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

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A NEW TAGGING METHOD OF DOLPHINSTOSHIO KASUYA* AND NOBUO OGURO*ABSTRACT

In order to establish a technique to tag the dolphins without disturbing or
destroying the school, tagging with bow and arrow was tried for dolphins whichcome to the bow of the ship. This method requires less skill in shooting and no
special handling of the ship. Though, in this method, more than half of thetags are wasted and the length of the time when the tag remains on the dolphin
is unknown, this method can be applied in the study of the short period movement of the schools.

INTRODUCTION

Dolphin fishing is operated at the several places on the Pacific coast of Japan.
In the northern area Phocoenoides and few other boreal species are caught with hand
harpoons. And in other area Stenella caeruleoalba, S. attenuata, and other severaldelphind species are caught both with hand harpoons and by driving a whole dolphinschool into a harbor.
The establishment of the tagging technique is desired to obtain the informations
on the migration and the schooling behavior of these species. Especially for thelatter purpose, tagging must be performed without destroying the school.
This experiment was intended to establish the method of tagging the dolphinsfrom a cruising vessel.
MATERIALS AND METHOD

The tags are of a type FH-69A (Floy Tag &Manufacturing, Inc., Seattle, Washington), and of the similar type used by Sergeant and Brodie (1969) for Delphinapterus
leucas, except for a clear vinyl tube which covers, in the present tags, the printed return address and the number. The size of the stainless steel head is 35 mm in lengthand 7 mm in width. The length of nylon string is 15 cm. The weight of tag is
about 3 g.
The arrow, applicator of the tag, is composed of three parts. The shaft is a
tube made of glass fiber, 36 cm in length and 7.4 mm in diameter, and furnished withno feather. The head is made of brass. Its anterior part is shaped of a flat disc
(15 mm in diameter, and 4 mm in thickness) to protect the dolphin from heavy injury,
and the posterior part is shaped of a rod (6 mm in diameter and 17 mm in length)
which is inserted into the shaft. A steel rod (70 mm in length and 3 mm in diameter)
is inserted into a hole at the center of the brass disc. This rod protrudes about
45 mm from the disc, to leave about 1.5 cm between the disc and head of the tag.

* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972, 81-85.

82

KASUYA A:¥"
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r
t
so
ft
hearrowa
r
ei
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t
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de
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c
hot
he
r
.
Andt
h
et
aghe
adi
ss
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nan
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t
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lr
o
dandt
hep
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cparti
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edont
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tw
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thap
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lpaperadhes
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et
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t
ht
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gi
sshota
tt
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bowo
ft
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i
pw
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r
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ow of80pound(36kg)power
.

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.

DOLPHIN TAGGING83

RESULT

Preliminary experiment
As the first step of preliminary experiment, three diameters of disc of the arrow
head, 15 mm, 20 mm, and 25 mm, were tried on a carcass of Stenella caeruleoalba laidin the air. The 15 mm disc was considered to be of enough size to protect the dolphin, and other experiments were made with 15 mm disc. This tag could efficiently
penetrate into the dead dolphin sunk in a tank about 15 cm beneath the surface of thewater, when shot at the distance of 5 m and at the angle of about 45°.
Other preliminary experiments were made on a school of Stenella caeruleoalba
kept alive in Kawana harbor, and on an alive Phocoenoides truei tied to a ship. In theformer case, two dolphins which had been swimming together were tagged and thisaccompaniment was observed for 7 hours until one tag, which hit on the hard tissue
just behind the blowhole and did not penetrate enough, dropped. Another individual was tagged on the throat and penetrated sufficient depth.
In the case of Phocoenoides, when the three parts of the arrow were not fixed butloosely inserted each other, the tag penetrated under the blubber of dorsal region.

Practical experiment
The result of tagging is shown in Table 3. Two tags, nos. 3 and 4, were shot at
the bow of the research vessel Tanseimaru (257 gross ton). Her height at bow andspeed at the time of tagging were 4.5 m and 10 knot respectively. 8 tags, from no.
31 to no. 45, were shot on the whale catcher Ryuhomaru no. 3 (429 gross ton), andthe height and speed were about 6 m and 4 knot respectively. 3 tags, nos. 54, 62
and 67, were shot on the research vessel Hayachinemaru (54 gross ton), and the heightand speed were 3 m and 8 knot respectively.
TABLE 1.

SOME INFORMATIONS ON TAGGED DOLPHINS
School Water.
tempersize
ature

Tag
no.

Date

Position

Species3

20 Nov. '71

35°23'N, 141°ll'E

Tursiosp sp.

13

17.5

4
31
34
35
40
41
42
43
45
62
?67
54

21 Nov. '71
19 Jan. '72

34°52'N, 141 °05'E
29°35'N, 140°38'E

S. caeruleoalba

2

20.0

100

19.8 }

School of small dolphins,
no mother and calf

20

19.8

Mother and calf observed

214)

Mother and calf observed

,,
,,
,,
,,

}

29°3l'N, 140°42'E
20°07'N, 141°1 l'E

) JOO

"
10 Feb. ,72

39°45'N, 142°17'E

Phocoenoides truei },,14 Mar. '72

39°0l'N, 142°17'E

Sci .Rep. Whales Res. Inst.,
No. 24, 1972.

13

9.4

6

6.3

Remarks
Other schools in short distance84

KASUYA AND OGURO

21 tags were wasted to tag the 13 dolphins. The number of tags hit is 38% of
the total number of tags shot.
At present (31 March 1972) no recovery is reported.
DISCUSSION
This method of tagging is aplicable for the dolphins which come to the bow of theship without any special technics both in shooting the arrow and in handling the ship,even on the ship with high bow. But it is difficult to tag the dolphins which do notcome to the bow, and requires special technics in the shooting and in handling the
ship.
Even in the former species, the difficulty differs between species. Phocoenoides
swims zigzag very actively at the bow, and considered to be one of the difficult species
to tag.
According to the experiment on the Ryuhomaru no. 3, tagging was easier at the
speed of 4 knot than the cruising speed 14 knot, because the dolphin stays longer on
the surface, But the suitable speed may vary between species, because too slow speed
does not usually attract the dolphin.
The two types of arrow head were tried. In one type, the three parts of thearrow were not fixed but loosely inserted into the holes each other. This type wastried on Phocoenoides. In other type the three parts were fixed each other, and triedon other species. There is no difference between two types in the shooting. The
tagged dolphins went out of sight, in both cases, with the arrow shaft on its body.
But we suppose that the shaft will have dropped within short period. Probably,
the former type will be better to expect earlier drop of the shaft.
The efficiency of the similar tag on Delphinapterus leucas was reported by Sergeantand Brodie (1969). And it is reported that similar tag had stayed on some delphinids
for several months (Evans et al 1972).
We consider that the present tagging method will be applicable in the study ofshort period movement of the dolphins.
ACKNOWLEDGEMENTS
This experiment was possible with the cooperation of the crews of the Hayachinemaru, the Ryuhomaru no. 3, and the Tanseimaru, and with that of Kawana Fishermen's Cooperative Union. Mr. T. Masaki of The Far Seas Fisheries ResearchLaboratory cooperated in tagging on the Ryuhomaru no. 3. Mr. S. Fujino of The
Ocean Research Institute, University of Tokyo, kindly prepared the applicators of
the tags. Prof. M. Nishiwaki gave us valuable informations on the tag. These
persons are acknowledged.

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

DOLPHIN TAGGING85

REFERENCES
EVANS, W. E., J. D. HALL, A. B. IRVINE, andJ. S. LEATHERWOOD, 1972. Methods for tagging small cetaceans.
Fisheries Bull., 70(1): 61-65.
NrsHIWAKI, M., M. NAKAJIMA, and T. ToBAYAMA, 1966. Preliminary experiments for dolphin marking.
Sci. Rep. Whales Res. Inst., 20: 101-107.
SERGEANT, D. E., and P. F. BRODIE, 1969. Tagging white whales in the Canadian Arctic. J. Fish. Res.
Board of Canada, 26(8): 2201-2205.

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

SOME INFORMATIONS ON THE GROWTH OF THE
GANGES DOLPHIN WITH A COMMENT ON THE
INDUS DOLPHINTOSHIO KASUYA *ABSTRACT

Following result was obtained in the study based on the 22 Ganges dolphins obtained in East Pakistan. Though the parturition season lasts long
period, there might be two peaks in early winter and in early summer. Calf isborn at small size compared with that of oceanic dolphins. The female grows
larger, but the weight is slightly smaller than the male of same body length,
which will be related with the larger length of the female snout. The sexualand physical maturity seems to be attained at the age of about 10 or less, andmore than 20 years respectively. The growth pattern of this species shows
peculiarities.
From some morphological differences, it is proposed to deal the Ganges
and Indus dolphins as two separate subspecies.

INTRODUCTION

When seen from the evolutional point of view, the freshwater dolphins or Platanistidae is a interesting group of toothed whales in the morphological primitivenessfound together with some specialization, and the restricted habitat.
Various authers have conducted the morphological and anatomical studies on
Platanista, especially Pilleri and his colleagues are conducting the study on Platanista
in various field of the biological science. They will throw light on the evolution of
Platanistidae.
Present study deals with the problems related with the growth and reproductionof Platanista, which will afford some of the fundamantal informations on the adaptation and specialization of the toothed whales.
MATERIALS

This study is based on the 22 individuals of the Ganges dolphin obtained or studied
by the Cetacean Research Expedition, University of Tokyo, directed by Prof. M.
Nishiwaki. These materials are shown in Table 1 together with some biologicalinformations. As shown in Fig. 1, all the present specimens were caught in East
Pakistan, present Bangladesh. Among these specimens, no. 14 is a fetus obtained at
the lower Meghna and preserved at East Pakistan Fish. Res. Inst. in Chandpur,
which external measurements were made by M. Nishiwaki, 5 were caught at the Kola
River a tributary of the Jamuna River in the north of Tistamukhghat, 11 at the* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972, 87-108.

KASUYA88
TABLE 1.

LIST OF MATERIALS USED IN THIS REPORT

Date of death

No.

Date of catch

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

12, x, 1969
12, x, 1969
- , VI, 1969
- , VI, 196923, VIII, 1969 23, VIII, 196930, XI, 196930, XI, 1969
20, X, 1969
20, x, 1969
20, XII, 1969
28, XII, 19696, I, 1970
6, I, 197012, I, 197012, I, 197012, I, 197012, I, 1970
19, I, 1970
19, I, 1970
26, I, 197027, I, 1970
26, I, 1970
26, I, 1970
1, II, 1970
1, II, 1970
27, VIII, 1967 27, VIII, 1967
26, I, 1970
9, IV, 1970

6
6
6
6
6

16

26, I, 1970~

1726, I, 197013, IV, 1970
2, VII, 1970

Sex

6
6
6
6
~

~

6
6
~
~

~

18
19
20
21

28, IV, 1970

28, IV, 1970-, v, 1970
7, v, 1970-, v, 1970
7, v, 1970

6
6

8, VI, 1970

8, VII, 1970~22

26, I, 197030, VII, 1970

6

~

Body
length
(cm)
105.0
100.5
115.0
171.5
110.0
117.0
113.0
121.5
117.5
200.0
113.0
115.0
115.0
27.0
114.0*
118.0
120.0*
120.5
120.0*
127.0
126.0
122.0
199.0
67.4*
76.0
122.0*
126.0

Body
weight(kg)

Position of capture
Sutiakhali, Brahmaputra

18.8

14.5

16.8

Kalir Bazar,
Begunbari,
Kewatkhali,
Khagdahar,
Jamalpur," MaghnaLalpur,Kola river
Bhairab Bazar, Meghna
Chandpur
Kola river

16.4
Kola river
17.0
Kola river
23.0
17.0
22.5
84.0
?7.3*
3.4

Dighirpur, Meghna
Bhairab Bazar, Meghna
E.P.A.U., Brahmaputra
Bhabakhali, Brahmaputra
Kola river

24.0* Measured at the time of capture.

Brahmaputra River, and 5 at the Meghna River near Bhairab Bazar.
One of the method used in catching these animals is the "Jagatber" usuallyoperated in dry season (Kasuya and Haque 1972). Specimens nos. 8, 9, 11, 15, 16,
17 and 22 were obtained by this method. Some of other specimens were caught withdrag net which instruments are shown in Pl. I, Fig. 2 in Kasuya and Haque (1972).
Specimens nos. 15, 16, 17, and 22 were transported to Japan and kept alive inan aquarium, The Kamogawa Sea World, for several months. No. 21 was kept
alive in a pond at Mymensingh for one month, then the carcass, together with nos.
18, 19, and 20, was transported to Japan by Prof. A. K. M. Aminul Haque.
AGE DETERMINATION AND GROWTH

Age characteristics
In this species, the growth layers are observed on both tooth and scapula.
On the scapula, there are observed several narrow translucent bands arranged
parallel with the contour of the dorsal edge. In the younger individuals less than 2
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

89

GROWTH OF THE GANGES DOLPHIN-- _.,.._ - - - _.....,

.,,,.

~

-

r- -,

," .... J,- - ..,,/

'

..,
\

I

''\

I I '
I I
\I
\
'-'

l

Fig. 1. Map of the Ganges and Brahmaputra River system showing the positions of
the catch of present specimens. Numbers in the map indicates the specimen number
in Table 1. (For Baria! read Barisal.)

years old, the band is clear and the number coincides with that of growth layers in
dentine and in cement. But, in the older individuals, the bands formed in theyounger stage become vague or disappear, because they are covered by the bone
tissue as the thickness of scapula increases.
In the cross section of the tooth, both in dentine and cement, there are observed
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

KASUYA

90

wider opaque layer and narrower translucent layer accumulated alternately (Pl. I).
As the number oflayers in dentine and cement nearly coincides, it is considered thatthey are formed in a same cycle. However, as the growth layers in dentine is moreregular in thickness and easily counted than the layers in cement, I concluded thatthe best age characteristics of Platanista is the dentinal growth layers, which is used in
the present study.
For preparing the tooth for age determination, a larger tooth removed from theanterior part of maxilary or mandibular tooth row was ground perpendicularly fromboth sides to the thickness of about 50 to 70 µ (Kasuya 1972).
For determining the age, the number of the opaque layers in dentine wascounted under the microscope. In the younger individuals, the age was determined
into the approximate l /4 year intervals considering the thickness of the first and last
opaque or translucent layers. The dentine formed in fetal stage, an opaque layer,
was not included. Several thin darker dentinal layers often observed in the layer oflate fetal stage or in the first postnatal opaque layer are not discussed here. In thisstudy, though the accumlation rate of the growth layers is not concluded, it is presumed from the consideration of the last layer (Table 2) that the translucent layer
TABLE 2. CONDITION OF THE NEWEST LAYERS IN DENTINE OF THE
GANGES DOLPHIN, SHOWING THE SEASONAL ALTERNATION OF
THE OPAQUE AND TRANSLUCENT LAYERS
OpaqueMonthTranslucent
Thin

3

January
April
May
June
.July
AugustOctoberNovember
December

TABLE 3.

Age

0.25
0.50
0.75
1.00
1.25
1.50
1.75
10
16

28

Thick

3

3

1

2

AGE OF THE GANGES DOLPHIN PRESUMED FROM THE
GROWTH LAYERS IN DENTINE
No. ofsamplesl2
9Range of bodylength, Sex76.0, ~
100.5, <!
105.0-110.0, ~ <!
113.0-117.5, ~ <!
122.0, <!
120.0, ~126.0, ~171.5, <!
200.0, <!
199.0, <!

Mean bodylength (cm)

107.5
116.2
} 122.7

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

91

GROWTH OF THE GANGES DOLPHIN(clear band) will be formed in winter and the opaque in summer as in the case of theoceanic dolphins (Sergeant 1959, '62, Kasuya 1972). The result of the age determination based on the growth layers in dentine is shown in Table 3.
The growth of the tooth of the Ganges dolphin has a peculiarity. Namely, theincrease of the length of tooth after the formation of the root, which is considered tobe finished at the 4th year after birth, is carried on by the accumulation of the thickcement layer (Pl. I). This type of growth is quite different from that observed in
the tusk like tooth of the sperm whale, but can be explained as a result of specialization of the tooth of delphinidae, where the accumulation of cement layer is thinner.
The accumulation of the dentinal layers continues after the formation of the root.
And even in the oldest individual, in which 28 dentinal layers are counted, there isobserved the space for more accumulation of dentine in the dental cavity.
120
E

u110
c
.c100
Ol

jj 90
~80
0
ro

70 ..... .

/60~~~~~-~~~~~~~~~~~~~~~~~~

12 1 2 3 l.

5 6 7 8 9 10 11 12 1 2 3 l.
Month

5 6 7

Fig. 2. Presumed mean growth curve of the Ganges dolphin. Closed circle indicates
male, open circle female, and cross marks the mean body length at the age of0.5, 1
and 1.5 year based on the growth layers in dentine. Circles connected with astraight line indicate the body length at the time of capture and that at death. The
dotted lines indicate the range of known largest fetus and smallest calf.

Growth in young stage
Among the present specimens, the youngest individual was 67.4 cm (No. 21) at
the time of capture. This individual is considered to be just after the birth. Anderson (1878) reported a fetus of 70.5 cm in body length. Therefore, at present, bodylength of the Ganges dolphin at the time of birth is presumed to be about 70 cm.
Besides the age determination data based on the dentinal layers, following informations on the growth of the Ganges dolphin were obtained. The specimen
no. 21 showed the growth of8.6 cm in body length while it was kept alive in a pondfor one month. And the 3 specimens in the 4 animals kept alive in an aquarium,
excluding one which had no increase of the length, showed the average growth of
I.I cm per a month (Table 1). Furthermore, the body length of the juvenile individuals shows a slight increase with the elapse of date of catch.
The growth curve of the Ganges dolphin, shown in Fig. 2, was drawn based on
the above informations. According to this curve the animal attains the body length
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

92

KASUYA

116 cm at one year after birth, or the increment of65.7% of the length at the birth.
As shown in Pl. II, only the anterior teeth of upper and lower jaws had slightly
erupted in the specimen no. 21. This will indicate that this animal was suckling at
the time of capture. Within a month when this animal was kept alive, however,anterior 16 pairs of tooth of the both jaws erupted. And the observation of thestomach of this animal showed that it had started the feeding on fish. All theother juvenile individuals ranging from 110 cm to 120 cm in body length, caught in
the river, had the food in the stomach and most of their teeth had already erupted.
And these individuals were considered not to be accompanied by the mother.
From these informations it is presumed that the calves born in the early winterstart feeding at 1 or 2 months after birth, and weaning will be accomplished by the
beginning of the dry season, or within one year after birth.

Sexual maturity
As shown in Table 4, all the individuals smaller than 130 cm in body length aresexually immature.
TABLE 4.

SEXUAL CONDITIONS OF THE GANGES DOLPHIN

Body length
(cm)

Sex

110.0-126.0
115.0-121.5
171.5
199.0
200.0

6
6
6
6

~

Sample
size
3
4

Age

<2
<2
10
28
16

Gonadsweight (g)0.4-1.6
6.7-7.5250
1110

Maturity
immature
immature
probably mature
maturematureA male specimen no. 20, 199 cm in body length, was identified sexually matureby the histological observation of the testis. Though the testes were too decomposed
for the histological observation, no. 20, 200 cm in body length, was considered fromthe weight of testes to have attained the sexual maturity. In the specimen no. 4,
the testes had decomposed too bad to weigh, but the size of the original testis waspresumed from the size of tunica to be a half or a third of that of no. 10. Then, theweight of the testes of this individual might have been from 40 to 140 g, which is far
heavier than those of immature animals, and suggests that this individual had probably attained the sexual maturity or puberty.
This presumption lead to the conclusion that the male Ganges dolphin may
attain the sexual maturity at about 10 or slightly less years as in the case of othertoothed whales (Kasuya 1972, Ohsumi et al 1963, Sergeant 1962), and at the bodylength about 170 cm or less.
There are 6 records of sexually mature females known to me (Anderson 1878,
Pilleri 1970), among which the smallest individual is 200 cm in body length. And
the largest immature female is 150 cm (Anderson loc. cit.). These informations
suggest that the sexual maturity will be attained between 150 cm and 200 cm. But as
the female seems to attain larger size, it will be better to consider that the femaleattains the sexual maturity between 170 and 200 cm in body length.
Sci. Rep. Whales Res. Inst.,.No. 2'1, 1972.

GROWTH OF THE GANGES DOLPHIN

93

Physical maturity
None of the present specimens had attained physical maturity. Table 5 shows
the relation between body length and the ankylose of vertebral epiphysis to the centrum observed after cleaning the skeleton. The anterior epiphysis ankyloses earlier
than the posterior one on the same vertebra. The epiphyses of the posterior thoracic
vertebrae seems to be the last which ankyloses to the centrum.
TABLE 5.

ANKYLOSE OF VERTEBRAL EPIPHYSES TO THE CENTRUM IN
THE MALE GANGES DOLPHIN1 »2 >No. of vertebrae 1 2-----_Cl
Speci- Body
men length Age
no.
10
20
4
13

3 4

5 6

7

8 9
Dl

10 11 12 13 14 15 16 17±± + + ++++++++ + ++++++++ + ± + ± + ± ± 199.0 28 +++++++ ++++++++ ±171.5 10 +++ ± ±±+126.0 1.75 +++--

200.0

16

18 19 20 21 22 23 24 25
Ll++++ + +++± +++ + ± +±++

1>

The upper lines indicate the anterior epiphyses, and the lower the posterior.
•> + indicates the ankylosed epiphysis, ± that ankylosed at small parts, and - free epiphysis.

The male specimens nos. 10 and 20 are physically immature in spite of the ageof 16 and 28 years old respectivily, which suggests that the growth of this species continues longer period than Stenella caeruleoalba (Kasuya 1972) and probably than
G!obicephala melaena (Sergeant 1962), as in the case of Physeter catodon (Nishiwaki et al
1958, Ohsumi et al 1965).
Anderson (1878) reported a physically mature 211 cm male, and the present
specimen no. 10 is supposed to may have attained the physical maturity within ashort period. These informations suggest that the body length of male at the attainment of physical maturity is between 200 and 210 cm.
In the present study, no physically mature female was obtained. The largest
male known to me is 211 cm in body length (Anderson Zoe. cit.), but there are several
records of female larger than this male, or 226, 238, 240 and 252 cm in body length(Anderson Zoe. cit., Pilleri 1970). Among these records the 238 cm female is physically immature but the 252 cm female is physically mature. Then the best estimation of the body length of the female at the attainment of physical maturity may, atpresent, be probably about 250 cm, which is larger than that of the male.
BREEDING SEASONIn the present study sufficient number offetus was not obtained to analize the breeding season. However, the dates of birth of the juvenile individuals were presumed
from the body length and date of catch, using the mean growth curve in Fig. 2. This
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

94

KASUYATABLE 6. DATE OF BIRTH OF JUVENILE INDIVIDUALS PRESUMED FROM THE
BODY LENGTH AND GROWTH CURVE, AND RECORDS OF LARGE FETUS
OF GANGES DOLPHIN.
Month
No. of birthl>
Large fetus 2 >
1
2

IX

x

XI

XII

I

II

III

3

2

2

3

2

3

IV

v

1

0

VI

2

> Calculated from present specimens.
> Cited from Anderson (1878).

resut shows that most of the juvenile individuals were born from October to Marchwith a center in December and January (Table 6). So, it is considered that thisseason is, at least, one of the parturition seasons of the Ganges dolphin, which coincides with the beginning of the dry season and with the winter season when most of
the dolphins in the small rivers move to the main streams (Kasuya and Haque 1972).
However, as indicated by specimen no. 21 of present study and four 25 cm fetuses in
December reported by Pilleri (1970), another peak of parturition in the beginning ofsummer season (Anderson 1878) can not be denied. Anyway it seems to be sure thatthe parturition of this species can occur at any season of the year, and the presumed
two peaks are not conspicuous.
If there are two peaks in the parturition season, one in the early winter and theother in the early summer, as in the case of Stenella coeruleoalba (Kasuya 1972), thegestation period may probably be about one year. And the 27 cm fetus in August(no. 14) might have been born in the former season and those reported by Pilleri(loc. cit.) in the latter. In this case, it must be presumed that the calves born in theearly summer would have left, accompanied by the mother, the small streams in
September when the water starts to decrease, and that some of the calves born about ayear before and newly weaned had failed to leave the small streams where most of thejuvenile specimens were obtained in the present expedition.
BODYWEIGHT
Fig. 3 shows the relation between body length and weight in the Ganges dolphin(circles) and the Indus dolphin (Cross marks), including 12 data cited from Pilleri(1970). As seen in Fig. 3, the body weight of the adult female is slightly smaller thanthat of the male of same body length, but there is no sexual difference in juvenile individuals. This will be related with the sexual dimorphism mentioned in the next
chapter.
The regression line, calculated by the method of least squares for all the femalesof the Ganges d0lfbin except the smallest specimen (no. 21) is shown by the formula
W =0.0003025 L2· 290 , where L means body length in cm and W body weight in kg.
The formula for the Ganges dolphin of adult males and the juveniles of both sexes
except no. 21 is shown by W=0.00002456 L 2 ·S 26 •The body weight of the smallest fem ale is smaller than the value expected fromthe formula, this will probably due to the unfavorable condition of the animal in theSci. Rep. Whales Res. Inst.,

No. 24, 1972.

GROWTH OF THE GANGES DOLPHIN

95-.I::.100Clc..!! 50>-"O0m
4 6 1020
40
Body weight in kg2

100 200

Fig. 3. Relation between body length and body weight in the Ganges dolphin.
Closed circle and solid line indicate male, and open circle and dotted line female.
Cross mark indicate the lndus dolphin reffered from Pilleri (1970). For explanation see text.
TABLE 7.
Specimen no.
Body length (cm)Sex
Body weight (kg)Weight of parts
Blubber
blubbertail flukes
Skeletonskullvertebraeribs
scapulaeflippersll
Skeletal muscle
vertebral, dorsal
vertebral, ventral
ma5seterothersInternal organs
Total

WEIGHT OF THE GANGES DOLPHIN

21
76.0

19
122.0

18
126.0

~

J

J

J

3.42

22.5

17.0

84.0

g

%

970

30.0

1,175
558
365
130
32
90
418
192
80

36.3
17.3
11.3
4.0
1.0
2.8
12.9
5.9
2.5

146
670
3,233

4.5
20.7
100.0

20
199.0

g

%

g

%

g

%

10,600
10,220
380
3,670
1,210
1,430
560
120
350
5,881
2,720
1,620
410
1,131
1,724
21,875

48.5
46.7
1.7
16.8
5.5
6.5
2.6
0.5
1.6
27.3
12.4
7.4
1.9
5.2
7.9
100.0

5,280
4,880
400
3,723
1,640
1,150
503
100
330
5,255
1,800
850
205
2,400
1,390
15,648

33.7
31.1
2.6
23.8
10.5
7.3
3.2
0.6
2.1
53.6
11.5
5.4
1.3
15.3
8.9
100.0

30,99029,1401,850
16,050
5,630
5,170
2,230
540
2,480
29,79011,4406,190
R. 71011,4509,578
86,408

35.9
33.7
2.1
18.6
6.5
6.0
2.6
0.6
2.9
34.5
13.2
7.2
0.8
13.2
11.0
100.0

1 > Including the blubber.

pond where this animal was kept alive to die.
Table 7 shows the proportional weight of organs of 4 Ganges dolphins. In thisspecies the weight of blubber occupies high percentage of from 30 to 48 % of bodyweight, and the internal organs do only from 8 to 20 %· The ratio of skeletal muscle,
which increases with the growth of the animal, is from 12 to 35 %of the body weight.
In the specimens nos. 18, 19 and 21, the total weight calculated by summing up
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

KASUYA

96

TABLE 8. THICKNESS OF BLUBBER MEASURED ON THE LATERAL LINE,
LOWER COLUMN INDICATES THE SOFT FATTY TISSUE BENEATH
THE DERMIS.
Specimen
Body length (cm)
Sex

21
76.0

7
113.0

6
117.0

9
117.5

8
121.5

19
122.0

20
199.0

10
200.0

<1

<1

<1

<1

<1

~

<1

<1

cm

% cm

% cm

0.5
0.6
Level of flipper
0.5
0.0
Level of dorsal fin 0.4
0.2
Level of umbilicus 0.5
0.3
Level of anus
0.3
0.1

0.7 1.2
0.8 2.0
0.7
0.0
0.5 2.5
0.3 0.0
0.7 1.5
0.4 1.0
0.4 1.0
0.1 0.0

Level of neck

1.1

1.8

% cm

% cm

% cm

1.0 0.9
3.0 2.6
1.1 0.9
1. 7 1.5

2.2

1.3

o.o

1.1

1.3
0.9
0.9
0.0

1.5 1.3 1.2 1.0 1.1 0.9
2.7 2.3 0.9 0.8 1.9 1.6
1.5 1.3 1.6 1.4 1.9 1.6
0.0 0.0 0.0 0.0 0.0 0.0% cm% cm %

2.0 1.0
0.5 0.3
1.1 2.5 1.3
0.9 1.5 0.8
1.8 0.9
0.8 0.4
2.2 1.1
0.8 0.4

1.5
3.3

0.8
1.7

3.2
0.0
1.8
2.0
2.5
0.0

1.6
0.0
0.9
1.0
1.3
0.0

the weight of each parts shows the decrease of from 2.7 to 8.2 %of the original weightweighed before dissection. However, in case of no. 20 which was dissected watering
to defrost, the summed weight showed the increase of 2.4%.
Table 8 shows the thickness of blubber measured on the lateral line. The
blubber of this species is characterized by the thick soft fatty layer beneath the harderconnective tissue which will probably correspond to the blubber observed in theoceanic cetacea.
RELATIVE GROWTH
All the measurements, except those of appendages and distances between ear, eyeand angle of gape, and the length of nasal slit, were made on a tape set in parallelwith the carcass. These measurements of the present specimens are tabulated inAppendix. The relative growth of the anterior region of the Ganges dolphin is shownin Figs. 4 and 5, and that of posterior region and appendages in Figs. 6-8 and Table 9.
Some important measurements are summarized in Fig. 9.
The length of head region is larger in adult females than in the males of corresponding body length. This is due to the larger length of the female rostrum assuggested by Anderson (1878), and will mean that after the growth of rostrum finished in the male the growth of this region continues in the female to attain about 20
cm larger length. This sexual dimorphism is presumed to come out at about 150 cm
in body len~th. .\s the position of the anterior insertion of flipper does not show thesexual difference, the length from center of eye to anterior insertion of flipper is considered to be slightly larger in adult males than in the females (Fig. 4, top). Though
the rostrum and mandible of juvenile Ganges dolphin is nearly straight, those tips ofolder individuals of both sexes are bended obliquely upward. This feature is wellshown in Pls. 39 and 40 of Anderson (1878).
The relations between body length and the dimensions of the posterior region,
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

97

GROWTH OF THE GANGES DOLPHIN

and those of appendages are shown by straight lines. The regression lines in Figs. 6-8
and " mean " in Table 9 are calculated for the Ganges dolphin by the method ofleastsquares. Among these measurements, those concerning the positions of umbilicus
and genital aperture show the sexual dimorphism. In the male, umbilicus situatesslightly anteriorly than it does in the females. This will be related with the extremely anterior situation of the male reproductive aperture, which situates very close to theumbilicus as in the case of Pontoporia blainvillei (Table 10). Though the measurement
is not recorded, it is clear that the male gential aperture of Inia opens near to the umbilicus same as Pontoporia and Platanista (Pilleri 1969, Fig. 3). So, it is presumed that
this character may be general in Platanistidae. But similar character is observed alsoin Physeter and Kogia.

Tip of rostrum to angle of gape.

6i:----------A.

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

40

..

~ ~.
co·.~§

20____-·

~

0

·~

O

~·"""
I

50

I

0

I

I

100

150
200
Body length (cm)I

250

Fig. 4. Relative growth of the anterior region in Platanista. Circle indicates present
specimen of the Ganges dolphin, triangle the Ganges dolphin reffered from Anderson(1878) and Pilleri (1970), square the Indus dolphin reffered from Pilleri (1970).
The closed marks and solid line indicate male, and open marks and dotted line
female. Lines are drown by eye for the Ganges dolphin.

DISCUSSION ON THE GROWTH
Though, in the present study, no definite conclusion on the parturition season was
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

98

KASUYAobtained, the possibility was suggested to consider that Platanista has two parturitionseasons one in early winter and the other probably in early summer. Then, thebreeding season of this species seems to retain the same pattern as that of Stenella
caeruleoalba which is different from that of Physeter, Phocoena, or Delphinapterus (Kasuya1972).
Ohsumi (1966) showed an allometric relationship, B=0.532 M 0 · 916, between
mean body length at birth (B in m) and that offemale at the attainment of sexual
maturity (M in m) for Physeter, Beradius and several species of Delphinidae. If thisformula is applied for Platanista assuming B=0.70 (m), 135 cm is obtained as the
cm .... Tip of rostrum to nostril
40'"
....

20'"
Length of nasal slit/~··

Tip of rostrum to ear

oo"/

t;: 0

t-

20

0

•

E:.~~:'-e-··-4=--4'9-·-.--~- . - o - - · • o•i':.
tpt""

o

01--1-~--1~~L-~..l-~....L.-~-'-~-'-~--'-~--''--~"---t-...

Tip of rostrum to eye

4, ......

•• ----•, , ' lJ.

I

50

100

I

I

150

I

I

200

250

Body length (cm)Fig. 5.

Relative growth of the anterior region in Platanista.

For marks see Fig. 4.

female body length at the attainment of sexual maturity. However, this figure is too
smaller than the length obtanied in this study, even if it is compared with the smaller
sex or the male.
The increment of body length of Platanista in the first one year after the birth is
65. 7 % of the body length at birth. This is nearly same with the value seen in someDelphinidae species (Kasuya 1972), and it is considered that the growth pattern of
Platanista in the early stage of life retains presumable primitiveness as in the case of
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

GROWTH OF THE GANGES DOLPHIN

99

some Delphinidae species. Then it is considered that the augmentation of body size
may have happened in the later part of the growth as one of the specialization of
Platanista.
Accompanied with the augmentation of body length, the elongation of thegrowth period may have brought on as in the case of Plryseter. But these specialization of growth is considered to have been accomplished as a result of evolution occured independently of that of oceanic odontoceti. Though in the oceanic species
the secondary sexual characters as the tooth, or size or proportion of body develops
usually in the male with an exception of body length of some Ziphiids, in Platanista
cm Umbilicus to anus

• ._-

~~

-~------·-.
........-·v·~ . . . . . . . --- __20 ~:-ooo!;,•,...._ _._•_,,.,. .........

110 .•o- ----___..___ _ __ ___,__
_._

___..

......_/ .___/,,,~-o ..............

. ,'Tail notch to umbilicus •,'',:t/!!6
,'

,''

90

,''

,,,,''

70

,-'

..

Jtlr:! 0

•' ,,

,'

,o

•

••• ,'o• Et>' 0,' ,•' .··
,'

••

,'

.
a

D

:~~ 0•

,

50

,'

•

0

,,'
, o'

.·

,,·,·'

,•'

•

...

Tail notch to anus

Ill' 0/09•..-','..··/·

30..y.··_,·· ......
0,-~_:..

··· _10 -::i.:..:---"

50

0

.

•

_

••

~

•...!.o~~'!'!;J--Tail notch to ant. ins.
of tail fluke

100

150

200

250

Body length (cm)Fig. 6. Relative growth of the posterior region in Platanista. Lines are calculated for
the Ganges dolphin by the method ofleast squares. For other marks see Fig. 4.

the body length and the length of rostrum which are the prominent secondary sexual
characters develop in the female. In Ziphiidae, at least in Berardius bairdi and:(iphius cavirostris, the male is smaller than the female (Omura et al 1955).
Though Platanista resembles with Physeter and Kogia in the anterior situation ofgenital aperture, Platanista may have developed this character independently of theother two species.
It is concluded, from the above discussions, that the pattern of the growth obSci. Rep. Whales Res. Inst.,
No. 24, 1972.

100

KASUYAcm.--~~~~~~~~~~~~~~~~~~~~~~~~,

Gen;tal ape•tu.- to anus ~

30

20
10
100

~~·
... ··--·-- ---. --.p--<a.~---- --- --------· ----··----------·--·
Tail notch to genital aperture

80

.-·

60
40

20

50
Fig. 7.

cm

100

150
200
Body length (cm)

Relative growth of the posterior region in Platanista.

250

For marks see Fig. 6.

Tail notch to tip of dorsal fin

70
50
30

10
50

100

150

200

250

Body length (cm)Fig. 8. Relation between body length and length from tail notch to tip of dolsal fin.
For marks see Fig. 6.
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

101

GROWTH OF THE GANGES DOLPHINTABLE 9. COEFFICIENT OF THE REGRESSION LINES 3 > OF THE
PROPORTIONAL LENGTH OF THE GANGES DOLPHIN
Upper limit
Measurements

Sex

Length from tail notch to tip of dorsal fin•>to anus1 >to genital apertureI»•>

S?, erS?, er

~

a

"

5?

er

to umbilicus"1 »2 >

5?

er

"

b

Mean

Lower limit

~

~

a

b

a

b

0.357 4.5
0.395 -0.3
0.391 -2.7
0.527 3.5
0.561 -4.2
0.563 1.6

0.335 3.68
0.310 1.06
0.309 4.10
0.479 5.05
0.508 -1.49
0.530 1.93

0.328
1.9
0.266 -0.3
7.7
0.254
0.437
7.1
0.492 -2.4
0.472
6.0

0.058 2.9
0.216 -0.1
0.227 -2.7
0.247 -0.4

0.075 3.22
0.028 0.74
0.187 1.31
0.202 -2.59
0.217 0.23

0.014 -0.3
0.152
2.7
0.177 -1.8
0.254 -11.4

0.179 -0.1

0.166

0.145 -0.7

0.155 -2.2
0.134 -1.6
0.309 -4.6
0.170 -2.8
0.222 -2.6

0.121 -0.85
0.107 -1.51
0.235 -1.47
0.155 -3.77
0.215 -3.50

to anterior insertion of tailS?, erfluke
Length from anus to genital aperture 1 >5?

er
to umbilicusI>

5?

erDistance from anterior insertion of flipper to anterior distal tip 2 >S?, erDistance from axilla to posterior distal tip offlipper
S?, erWidth of flipper 1 »•>S?, erTotal spread of tail flukes 1 »2 >S?, erDistance from tip of to tail flike to tail notch 2 >S?, erto anterior insertion 5?, er(1970), 2 > Include Anderson (1878),
portional and body length shown in cm respectively.

1 > Include Pilleri

3

0.83

0.122
0.098
0.181
0.121
0.160

> Y=aX+b, where Y and X.indicate pro-

100

'Eu
.c

u,c 150

~

>-

"O

0

CD

200

250'--'--'----'---l.---''----'---...L--'-~fip'-'-•r_.__,__.____.'--"--"-'-~-'---'~'---'--'--'--"=---'~
50

100

Distance from tip of rostrum (cm)Fig. 9. Summary of Figs. 4-8, showing change of the relative positions of the externalorgans in the Ganges dolphin. Eye indicates center of eye, ear opening of ear,flipper anterior insertion of flipper, u umbilicus, g.a. genital aperture, d. fin dorsal
fin, anus center of anus, fluke anterior insertion of tail fluke, and t. notch tail notch(left to right). Dotted line is for female and solid line for male.
Sci. R.ep. Whales Res. Inst.,

No. 24, 1972.

-3.4
-2.5
-1.l
-2.3
-0.8

KASUYA102

TABLE 10. DISTANCE BETWEEN THE CENTERS OF GENITAL APERTURE
AND UMBILICUS, MEASURED ALONG THE BODY AXIS AND SHOWN
IN% OF BODY LENGTH
Male

Sex
Species

Platanista g. gangetica
Pontoporia blainvillei(Pilleri 1971)
Stenella attenuata(Nishiwaki et al 1965)
Feresa attenuata(Nishiwaki et al 1965)
Berardius bairdi(Omura et al 1955)
Physeter catodon(Matthews 1938)
Kogia simus(Kasuya et al unpbl.)

Female

N

Range

Mean

N

Range

Mean

12

0.8- 4.1

2.5

6

14.4-22.0

17.1

3

5.1- 7.7

6.0

4

13.0-14.8

13.8

3

17.7-19.2

18.3

4

20.6-25.2

23.4

6

10.5-14.3

12.4

7

12.9-19.4

16.4

20

21.3

5

24.8

60

7.6

8

20.8

7.0

served in Platanista gangetica might have originated from that which had scarcely
showed sexual dimorphism or augmentation of body size. From this hypotheticalprimitive growth pattern, that of recent delphinids and other oceanic toothed whales
may have derived. But, among recent toothed whales, the delphinids seems to haveattained the least modification in the growth pattern. This presumption is compatible with the morphological information on the growth of tooth (see Age determination).
TAXONOMICAL CONSIDERATION OF PLATANISTAIn Figs. 4-8, the proportional measurements of the Indus dolphin cited from Pilleri(1970) are also plotted. Though most of measurements are within the range of individual variation of the Ganges dolphin, the measurements concerning the length oftail show a significant difference between the dolphins from two river systems (Fig.
10, Table 11). Namely, when compared between the dolphins of nearly same bodylength, 118 cm, obtained from the two river systems, the length of tail is 6. 7 cm shorterin the Ganges dolphin than the Indus dolphin. This difference is too large to concider as individual variation or personal deviation of the measurement. There is also
observed a slight difference of the position of the anterior insertion of flipper between
the dolphins from two river systems, which seems to come from the difference of thelength from center of eye to anterior insertion of flipper (Fig. 4). But it can not be
concluded, at present, if the difference is significant or not.
Pilleri (1971) reported the osteological difference observed on the height of nasal
crest as a character to distinguish Platanista gangetica (Lebeck, 1801) and P. indi
Blyth, 1859.
According to Yamashita (1971), the strong Himalayan orogenic movement
started in the middle of Pleistocene, and is still continuing. He also indicated theSci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH OF THE GANGES DOLPHIN

4

103

I
I

1----:---t
,P\:
~2

I

,'

I

'

'

I

I
I

llS

I

:J

I

"CJ

>o

12

"CJ

c

-

16

14

20

18
I

0

I

~-----:-----~
I

Qi 4

I

.0

E
:J
z

,q
I
I

2

0

I

30

32

I

34

I

I

\
'
'

'

'

'

''

'

~--,',,,

36

38

40

Percentage of body length
Fig. 10. Frequency distributions of relative length from eye to anterior insertion offlipper (top), and that from tail notch to anus (bottom) in Platanista, showing themorphological differences between Platanista gangetica gangetica (closed circle andsolid line) and Platanista g. indi (open circle and dotted line). Vertical and horizontal
lines indicate the mean and the ranges of two standard errors in both sides of themean.
TABLE 11. SOME MEASUREMENTS SHOWING THE MORPHOLOGICALDIFFERENCE BETWEEN THE GANGES AND INDUS DOLPHINSSpeciesNo. of samples compared
Range and mean of body length (cm)Length from anus to tail notchrange and mean in cm
range and mean in percentage
Length from eye to flipper
range and mean in cm
range and mean in percentage

Ganges dolphin

Indus dolphinll

13110.0-126.0

117.2

6
108.0-126.0

118.3

33.5- 43.0
29.6- 36.8

37.6
32.l

38.0- 46.0
35.2- 40.7

44.3
37.4

15.0- 21.0
12.8- 18.6

18.3
15.7

16.0- 18.5
13.0- 15. 7

16.9
14.3

ll Pilleri, 1970

possibility that the upper streams of some river had shifted, during this period, to havea connection with another river. This kind of exchange of the drainage area may
have occurred between the Indus and the Ganges-Brahmaputra, which will haveoffered the chance for the Platanista to expand its habitat to another river, or to exSci. Rep. Whales Res. Inst.,

No. 24, 1972.

104

KASUYAchange the animal between connected two rivers. Anyway there will be no doubtthat Platanista in the two river systems had originated from the same origin, andgained some morphological differences as the result of the separate evolution.
In some species of Mysticeti (Nishiwaki and Kasuya 1970, Omura 1957, Omura
et al 1970), the characters of nasal or tail region seems to be the character where thedifferentiation occurs rapidly. Probably same presumption will be possible on
Platanista. And, in my opinion, the evidence is still insufficient to consider Platanista
gangetica and P. indi as two distinct species. The best way, at present, will be to deal
them as two subspecies, or Platanista gangetica gangetica and Platanista gangetica indi.
SUMMARY
By the consideration of the growth of the Ganges dolphin based on the 22 individuals
obtained in East Pakistan, the following results were obtained.
1. As the age characteristics, the growth layers in dentine is the best among
the three characteristics compared in this study.
2. The opaque layers in dentine is suggested to be formed in summer, and thetranslucent in winter.
3. One of the peak of parturition season is in December and January, and theother, probably in early summer.
4. The calf seems to be born at about 70 cm in body length, and attain the
body length of 116 cm in one year, and 123 cm in 1.5 years.
5. The calf probably start feeding at 1 or 2 month after birth, and weaning isaccomplished within one year.
6. The sexual maturity is supposed to be attained at the age of 10 or slightly
less, and the physical maturity, in the males, at the age more than 20 years.
7. The body weight of the adult female is slightly smaller than that of the maleof the same body length.
8. Sexual dimorphism is observed in the body length, length of rostrum,
positions of genital aperture and umbilicus, and perhaps in the position of flipper.
9. The growth pattern of Platanista seems to have originated from that probably had observed in primitive delphinids.
10. There is a clear difference of the length of tail between the Ganges dolphin
and the Indus dolphin. And it is proposed to deal them as separate subspecies.
ACKNOWLEDGEMENTGreatest thanks are due to Prof. A. K. M. Aminul Haque of the Bangladesh
Agricultural University, without his cooperation present study would not have beenaccomplished. The Kamogawa Sea World and all the members of the Cetacean
Research Expedition are also acknowledged for their help offered in East Pakistan
and in Japan.

Sci. Rep. Whales Res. Inst.,.No. 24, 1972.

GROWTH OF THE GANGES DOLPHINAPPENDIX I.
Specimen no.
Sex
From tip of upper jaw to:
1. tail notch (total length)
2. anterior end of nasal slit
3. angle of gape
4. center of eye
5. ear
6. anterior insertion of flipper
From tail notch to:
7. tip of dorsal fin
8. anterior insertion of tail fluke
9. center of anus
10. center of genital aperture
11. center of umbilicus
From angle of gape to:
12. center of eye
13. ear
From ear to:
14. eyeFlipper:
15. anterior insertion to anterior distal tip, straight
16. anterior insertion to anterior distal tip, along
curvature
17. axilla to posterior distal tip
18. greatest width
19. width at baseDorsal fin:
20. length of base
21. height
Tail fluke:
22. tip to tip (total spread)
23. tip to notch
24. tip to anterior insertion
Nasal slit:
25. length

Sci. Rep. Whales Res. Inst.,

EXTERNAL MEASUREMENTS

14

21

5

11

15

16

18

<;!

<;!

<;!

<;!

<;!

<;!

<;!

27.0 76.0 110.0 113.0 118.0 120.5 126.0
6.0 14.5 18.0 25.0 21.0 26.2 23.0
3.5 13.5 19.5 21.0 23.5 26.2 24.0
4.2 13.5 18.5 21.0 22.5 26.6 23.0
6.5 19.0 26.0 28.2 30.0 33.0 31.5
9.5 26.5 37.5 42.0 40.0 44.0 42.0
11.0 29.0 39.0 39.0 43.0 45.9 45.0
9.0 12.0 12.0 10.5 13.6 11.5
7.5 25.5 35.0 34.5 37.0 39.2 39.0
40.0 41.7 41.0
27.0 37.5
10.9 39.0 56.0 55.0 56.0 59.0 62.0
2.3
6.5

3.2
8.3

5.5

7.8

3.2

13.5

18.5

3.0
9.5
7.5

8.0

9.0

18.0

19.1

18.0

2.0
2.0

14.5 20.5 20.0 20.0
9.5 13.0 12.5 13.0
6.5 11.0 11.5 11.0
4.0
2.5

21.0
13.5
12.6

19.5
13.5
11.0
4.0

3.3
0.4

9.0
1.5

12.0
2.0

7.0
2.0

25.5
3.1

10.0
1.3

3.8
1.8
3.5

15.0 24.0
8.0 12.5
14.0 18.5

27.0
15.0

26.5 24.3 25.0
14.0 12.4 15.0
19.0 19.0 22.5

1.1

2.5

4.0

4.0

In nos. 1 to 11, length was measured in parallel with body axis.

No. 24, 1972.

105

4.5

18.0

2.5

4.5

5.8

106

KASUYAOF THE GANGES POLPHIN (cm).

17

2

1

<?

6

6

7
6

3

13

12

6

9

8

19

22

4

20

10

6

6

6

6

6

6

6

6

6

6

6

127.0 100.5 105.0 113.0 115.0 115.0 115.5 117.0 117.5 121.5 122.0 128.0 171.5 199.0 200.0
24.0 (16.3) 19.5 21.5 (17.0) 19.0 20.0 22.0 23.5 24.0 19.5 25.0 34.0 33.0
24.5 17.0 18.5 23.0 20.0 21.3 19.5 21.5 23.0 23.5 21.0 28.5 31.6 37.5 36.0
23.5 16.5 18.2 21.5 18.0 20.0 19.0 21.0 22.5 22.0 20.0 26.0 29.2 35.0 35.0
47.5 48.0
33.5
27.8 27.0 28.0 30.0 30.0 29.0 34.0
29.0
45.0 31.0 35.0 40.5 35.0 38.5 37.5 36.0 40.5 41.0 39.5 47.0 54.6 69.0 76.0
47.0 37.0 39.0 41.0 44.5 42.0
11.0 11.0 13.0 11.0 12.8 12.0
43.0 33.0 33.0 33.5 39.5 35.5
45.5 51.0 54.5 58.0 63.0 59.0
67.0 54.0 56.0 61.0 65.5 63.0
4.2
9.0

42.5 46.5 41.0 44.0 46.0
12.0 12.5 12.0 13.0 11.5
36.5 43.0 39.5 38.0 38.5
59.0 65.0 60.0 63.5 62.0
61.5 67.5 61.5 64.5 67.0

47.0 64.8 68.0 72.0
11.5 16.5 18.5 18.5
39.0 55.3 61.0 60.0
65.0
94.0 102.0
70.0
100.0 109.0

3.4
9.4

3.5
9.5

2. 7
9.5

3.0
9.3

3.5
9.5

3.0
9.5

3.5
9.0

4.5
14.0

6.0
16.0

9.0

7.5

8.0

8.0

8.0

8.8

8. 7

9.0

8.0

8.8

9.5

8.0

13.5

14.0

20.5

15.5

17.5

19.0

17.0

19.0

19.0

19.0

18.5

18.0

17.0 21.0

35.5

29.0

23.0
14.0
15.0

17.5
11.5
8.0
3.5

19.0 21.0
12.0 13.0
10.0 9.5
4.0
3.5

16.0
2.5

19.5 21.3 21.0 21.5
13.0 13.2 13.5 14.0
8.5 11.5 11.5 9.0
3.0
4.0
3.0
8.0
2.8

21.0
4.5

1.5

19.0
2.0

20.5 20.0
12.5 13.0
11.5 12.5
4.0
4.0

39.5 33.0
19.5 22.5
11.5 15.5 24.4 23.0 21.0
11.0 14.0 17.8 25.0 22.5
4.5
5.0 5.7
7.0
7.0

17.0
3.0

11.0
1.5

18.0
3.0

12.5
3.1

36.0
5.5

28.0 23.0 22.5 26.5
16.0 13.0 11.0 15.5
23.0
22.5

26.5
14.5

26.5 25.0 28.5 27.0 28.5 29.0 29.0
15.3 13.5 15.0 15.0
16.0 15.5
22.5 20.5 22.0 21.5 22.5 21.0 24.0

38.7

57.0 42.5
30.0 23.0
38.5 33.0

4.5

3.3

2.8

5.6

8.0

4.3

4.3

4.3

3.5

4.8

4.8

3.5

5.0

4.0

6.0

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH OF THE GANGES DOLPHIN107

REFERENCES
ANDERSON, J., 1878. Anatomical and ,Zoological researches comprising an account of the ,Zoological results of the two
expeditions to Westerm Yunnan in 1868 and 1875 and a monograph of the two cetacean genera, Platanista andOrcella, vol. I. Bernard Quaritch, London, 550 pp.
KASUYA, T., 1972. Crowth and reproduction of Stenella caeruleoalba based on the age determination bymeans of dentinal growth layers. Sci. Rep. Whales Res. Inst., 24: 57-79.
KASUYA, T., and A. K. M.A. HAQ.DE, 1972. Some informations on the distribution and seasonal movementof the Ganges dolphin.Sci. Rep. Whales Res. Inst., 24: 109-115.
MATTHEWS, H., 1938. The sperm whale, Physeter catodon. Discovery Rep., 17: 93-168.
NrnmwAKI, M., T. HIBIYA, and S. 0HSUMI (KIMURA), 1958. Age study of sperm whale based on reading of
tooth laminations. Sci. Rep. Whales Res. Inst., 13: 135-153.
NrnmwAKI, M., S. 0HSUMI, and Y. MAEDA, 1963. Change of form in the sperm whale accompanied withgrowth. Sci.Rep. WhalesRes.Inst., 17: 1-14.
NrsmwAKI, M. and T. KASUYA, 1970. Recent record ofgray whale in the adjacent waters of Japan and aconsideration on its migration. Sci. Rep. Whales Res. Inst., 22: 29-37.
0HSUMI, S. 1966. Allomorphosis between body length at sexual maturity and body length at birth in the
cetacea. J. Mamm. Soc. Japan, 3(1): 3-7.
0HSUMI, S., T. KAsUYA, and M. NISHIWAKI, 1963. The accumulation rate of dentinal growth layers in the
maxillary tooth of the sperm whale. Sci. Rep. Whales Res. Inst., 17: 15-35.
Ol>IURA, H., 1959. Bryde's whales from the coast ofJapan. Sci. Rep. Whales Res. Inst., 14: 1-33.
OMURA, H., K. FUJINO, and S. KIMURA, 1955. Beaked whale Berardius bairdi of Japan, with notes on ,Ziphiuscavirostris. Sci. Rep. Whales Res. Inst., 10: 89-132.
OMURA, H., T. lcHIHARA, and T. KASUYA, 1970. Osteology ofpigmy blue whale with additional information
on external and other characteristics. Sci. Rep. Whales Res. Inst., 22: 1-27.
PrLLERI, G., 1970. Observation on the behaviour of Platanistagangetica in the Indus and Brahmaputra Rivers.
Investigations on Cetacea, 2 : 27-60.
Pilleri, G., 1971. On the La Plata dolphin, Pontoporia blainvillei off the Uruguayan coast. Investigations on
Cetacea, 3(1) : 59-68.
PrLLERI, G., and GrnR, M., 1969. Zur Anatomic and Pathologie von Inia geoffrensis de Blainville 1817
(Cetacea, Susuidae) aus dem Beni, Bolivien. Investigations on Cetacea, 1 : 94-108.
PrLLERI, G., and GrnR, M., 1971. Differences observed in the skull of Platanista indi and gangetica. Investigations on Cetacea, 3(1): 13-21.
SERGEANT, D. E., 1962. The biology of the pilot whale or pothead whale Globicephala melaena (Trail) m
Newfoundland waters. Bull. Fish. Res. Board of Canada, 132: 1-84.
YAMASHITA, N., 1971. The history of Himalayas. Science (inJapan), 41(4): 221-230. (inJapanese).

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

108

KASUYA

EXPLANATION OF PLATESPLATE I
Ground thin section of the teeth of Ganges dolphin, translucent layers are shown black andopaque layers white.
Fig. 1. Specimen no. 20, male, body length 199 cm, number of growth layers 28.
Fig. 2. Specimen no. 4, male, body length 171.5 cm, number of growth layers 10.
Fig. 3. Specimen no. 18, female, body length 126.0 cm, number of growth layers 1 3/4.
PLATE II
Ganges dolphin, no. 21, female, body length 67.4 cm. Photographed at the time of capture. Anterior most one or two pairs of teeth started to erupt, and hairs are observed on theboth jaws.
PLATE III
Ganges dolphin, no. 7, male, body length 113 cm. In fresh condition the colouration 1s
pale brown with a tinge of gray. The colour of throat and chest region is paler.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

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VλflSV)lSOME INFORMATIONS ON DISTRIBUTION AND
SEASONAL MOVEMENT OF THE GANGES DOLPHINTOSHIO KASUYA* AND A. K. M. AMINUL HAQUE**
ABSTRACT

By analizing the data on the distribution of Platanista gangetica obtained in
Nepal and East Pakistan in 1969 and 1970, following conclusion was obtained.
The upper range of the distribution in the Narayani River is at Dio Ghat,
about 100 km north of the range reported before. In monsoon season, theyextend the distribution to smaller streams, and go down to larger streams in dry
season. The density is lower in the estuary. They were observed swimming
mostly single or in couple in dry season. But they often assemble to special
narrow area of waters, which is probably affected by the distribution of food.
INTRODUCTION

Though Anderson (1878) and Pilleri (1970) accomplished a intensive study on the
distribution of the Indus and Ganges dolphins, their upper limit of the distribution in
the Himalayan piedmont area, and the seasonal movements are not still clear.
Here, we report some informations on the distribution of the Ganges dolphin,
Platanista gangetica, obtained by the Cetacean Research Expedition, University ofTokyo, directed by Prof. M. Nishiwaki.
The observation in Nepal was made in Feb. 1970, and that in East Pakistan,present Bangladesh, in the period from Oct. 1969 to May 1970.
DISTRIBUTION IN NEPAL

It is reported that the Ganges dolphin distributes in India up to near the boundaryof Nepal along the Gandak (Anderson 1878). Present investigation was made at the
Narayani River and its tributary, the Rapti River. They form one of the three large
river systems in Nepal, and the lower stream of the Narayani River is called theGandak which meet with the Ganges River at Patna, India.
On the Rapti River, the observation was made from Hitaura (85°02'E, 27°26'N)
down to Jhawani in dry season on Feb. 2, 1970. The stream of this river was too
shallow to expect the dolphin, and according to the informations obtained from thepeople in Jhawani and other several villages, the dolphin, which is called Suongsu,
distributes not in the Rapti River but in the Narayani River.
Along the Narayani River, observation was made on the next 2 days with asmall country boat from Dio Ghat to Bhwasara Ghat. The former situates at the confluence of the Kaligandaki and the Burigandaki. The water depth of this river was* Ocean Research Institute, University of Tokyo, Tokyo.
* * Bangladesh Agricultural University, Mymensingh, Bangladesh.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972, 109-115.

110

KASUYA AND HAQUE

measured with a weight and a line, and the width of the stream was presumed by eye,which are shown in Fig. 1. Though we could not find the dolphin, following informations were obtained from the people who live in the valley.
1. Dio Ghat: The dolphin is seen at this spot both in dry and rainy seasons,but none in the upper streams.
2. Narayani Bazar: Dolphins are seen sometimes in summer season, usually 1
or 2 individuals, recently (winter) no sighting.
3. Pitonj Ghat: Dolphins are seen sometimes (from Nepalese people). A
dolphin was observed once between Dec., 1963 and Jan., 1964 by Mr. T. Shimada aJapanese proprietor of a farm.
4. Bhwasara Ghat: No dolphin is seen in the dry season, but have been seenin August to October (rainy season).
5. Gola Ghat: No dolphin was seen by us.
6. Gola Ghat to Tribeni Ghat: A Japanese doctor Iwashita sighted thedolphins on several occasions in March, 1969.

- - - - - l 27°50'N

64'E

84'30'E

Fig. I. Map showing the Narayani valley, Nepal.
water, and W width in m.

D indicates the depth of theAmong these informations, those obtained from Mr. Shimada and Dr. Iwashita
are most reliable. Considering all of these informations it is concluded that theGanges dolphin distributes in the Narayani River both in winter and summer seasons
but the density between Gola Ghat and Dio Ghat will be lower in the winter season
than in the summer season. Probably, most of the dolphins in the upper stream
will move to the downstream in the winter. Though the stream with 10 m or more
depth was found at Dio Ghat, most of the part of the stream between Dio Ghat andGola Ghat was shallow and rapid. This environment will not be suitable for thisspecies. But in the summer season, considering from the water mark on the rock, thewater level at Dio Ghat seems to be about 3 m higher than in the winter.
The streams upper than Dio Ghat, or the Kaligandaki and Burigandaki are
shallow and run in the rocky mountaineous area. So the migration of the dolphin is
not expected. It will be safe to say that the upper limit of distribution along theSci. Rep. Whales Res. Inst.,
No. 24, 1972.

DISTRIBUTION OF THE GANGES DOLPHINTABLE 1.

WATER AND AIR TEMPERATURE AT NARAYAN! VALLEY
AND MYMENSINGH (BRAHMAPUTRA RIVER)
Narayani valley

Water
Air

111

14.9°C (Dio Ghat, 09.00)
15.8°C (Pitonj Ghat, 10.55
7 .9°C (06.00)
2 l.3°C (13.30)

Mymensingh
19.0-20.7°C (Morning)
10.5-13.3°C (06.00)
21 -23°C (14.00)

Narayani River will be at around Dio Ghat, which situates about 250 m above thesea level and about 100 km north from the uppermost range of the distribution
confirmed by Anderson (1878).
The air and water temperature in the Narayani valley is shown in Table 1.
The air temperature is nearly same with that at Mymensingh and Assam (Pilleri1970), but the water temperature seems slightly lower than that at the Brahmaputra.
SEASONAL MOVEMENT

The seasonal movement of the Ganges dolphin was studied in East Pakistan, present
Bangladesh. The observation was made at fixed stations on the Brahmaputra andthe Meghna, or from the cruising ships in the Meghna and theJamuna. In the caseof the fixed stations, a half hour or one hour observation was repeated with the several
days intervals. All the stations on the Brahmaputra River were placed around
Mymensingh, and the distance from the uppermost station at Khagdahar to thelower station at Kalir Bazar is about 25 km along the river. All of these 8 stations are
situated at the depths or at the confluence of a small river (Kewatkhali), where thedolphins are observed more numerously than the other places.
The Brahmaputra was once a main stream of the Brahmaputra river system,
but in the present days it is only a branch of the main stream connecting the two big
streams, or the J amuna River and the Megha River. So in the winter season, its
water depth is usually less than several meters except some deep spots. In January,
the water depth near the station at Kalir Bazar was only about 1 m. The station at
Sandarghat in Dacca is also on the relatively small branch of the Meghna River.
Other observations were made at the maiP stream of the Meghna and the J amuna.
Table 2 shows the seasonal fluctuation of the density of the dolphin consideredfrom the frequency of the surfacing individuals. The density was classified into 4categories of many, several, few, and none. In case when the number of individuals
was estimated, it was also recorded. As seen in this table, the population of thedolphin in the Brahmaputra starts to decrease at the beginning of November. And
in December and January, only few individuals seem to have remained in the observed area of the Brahmaputra near Mymensingh. Same tendency was also observed at the station at Sandarghat. Other information on the population density inthe Brahmaputra was obtained from the result of" J agatber " fishing, in which one
net is set across the river and another net which is set in the upper stream is moved
slowly day by day toward the down stream, finally to catch all the fish between theSci. Rep. Whales Res. Inst.,
No. 24, 1972.

112

KASUY A AND HAQUETABLE 2. SEASONAL FLUCTUATION OF THE DENSITY OF THE GANGESDOLPHIN SIGHTED AT THE STATION OR ON THE SHIP
Month

DecadeBrahmaputra
Khagdahar
Govindapur
Shambhuganj
Kewatkhali
Sutiakhali
Phulpur
Bhabakhali
Kalir Bazar
MeghnaBhairab Bazar
Sandarghat, Dacca
Chandpur-Dacca
JamunaTistamukhghat-Goalundoghat

Nov.

Oct.

2

3

*
* *
* *0
* +
*
-te
* *
*

2

Dec.

3

+

+

0

0

*

+ o, 1-2

+

1

*
*
ttt

2
0

0

0
0
0, 1
0
0
1-2

Jan.

3

0
0
0
0
0 0, 1, 2
0, 1
0
0
0
0
0
0
0
0
0

1

2

O, 1
0
0
0
0
0

ttt

ttt
0

ttt
ttt

ttt

two nets. TheJagatber operated in January at the Brahmaputra River near Jamalpur (see the map in Kasuya 1972) showed that there was 3 dolphins in the stream of
5 km length.
In Assam the rainy season lasts from May to September and there is very few
rainfall in the remaining months (Pilleri 1970), as the result the water level of theGanges-Brahmaputra river system is considered to decrease from October to April.
So we consider that the most of the Ganges dolphin in the tributaries may have retreated to the main streams and will come back again in the rainy season. However,some individuals seem to be left in the tributaries in the dry season. They are mostly
juvenile animals of about one year old (Kasuya 1972).
In the large stream of the Meghna and the J amuna the dolphin is observed inboth rainy and dry seasons.
The geographical variation of the density of the Ganges dolphin in dry season
was observed from the cruising ship by one or two persons in 1970 in the following
area (for the name of the place, see Kasuya 1972).
J amuna River2, Jan.; 2 persons, Jagannathganj Ghat-Sirajganj Ghat, Steamer.
14, Jan.; 2 persons, Bahadurabad Ghat-Tistamukh Ghat-J agannathganj
Ghat, Launch.
19, Jan.; 2 persons, Jagannathganj Ghat-Sirajganj Ghat-Goalundo Ghat,
Launch.
20, Jan.; 2 persons, Chandpur-Narayanganj, Steamer.
27, Jan.; 1 person, Narayanganj-Chandpur-Barisal (to Sundarbans, continue
to 28th), Steamer.
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

DISTRIBUTION OF THE GANGES DOLPHIN

113

Sundarbans
28, Jan.; 1 person, (Barisal)-Tharacatti-N alchiti-Mouth of Haring a ta R.Chalna-Khulna, Steamer.
30, Jan.; 1 pc rson, Khulna-Mouth of Pusur R.-Khulna, Launch.
Meghna river
30, Apr.-3, May; 1 person, Streams from Bhairab Bazar to Sunamganj, Several
launches.
TABLE 3. GEOGRAPHICAL VARIATION OF THE DENSITY OF GANGESDOLPHIN BASED ON THE OBSERVATION ON THE SHIP
Distancefromestuary 1 >0- 30
30- 6060- 9090-120120-150
150-180
180-210130<llLocality

Number ofsightings
individuals

lower Sundarbans
up to Khulna (upper Sundarbans)
up to Chandpur (lower Meghna)
up to Dacca
up of Goal undo Ghat
up to Sirajganj Ghat
up to Tistamukh Ghat
Meghna, upper streamof Bhairab Bazar

Number ofindividuals
per 100 miles'>

Month

29
32
34
95
15
37
37
4

29
67
35
191
182
57
69
16

January

540

229

April and May

"
"
"
"

"

"
"

in nautical miles.

Table 3 shows the total number of individuals sighted, and the relative densityof the dolphin shown by the calculated number of sighted individuals per 100 nautical
miles (186 km) of observation. In case of the Meghna, calculation was made assuming the speed of launch as 8 knot (15 km/hour).
According to this result the dolphin seems to distribute densely in the lower andupper Meghna, and lower Jamuna. But the density in the estuary is slightly low.
Other than the Ganges dolphin, 6 Orcaella brevirostris, which were identified by
the dark colour and the pointed dorsal fin, were observed in 5 occasions at Mongla
and Sundarbans.
SCHOOLING BEHAVIOR

Because of the turbidity of the water, the behavior of the dolphin under thewater is not observable. In this study, dolphin or dolphins surfacing at close distanceand swimming toward nearly same direction were considered to belong to one school.
Table 4 shows frequency distribution of the number of individuals constituting aschool. This observation was made in the dry season in the same cruise mentioned in
the preceding chapter. It is shown in the table that most of the schools, 90.0 % of thetotal number of schools sighted or 80.4 % of the dolphin of this species are single individual. The schools formed by 2 individuals are found in only 8.4 % of all theschools, and the number of animals constituting these schools is 15.0 %· So, it is conSci. Rep. Whales Res. Inst.,
No. 24, 1972.

KASUYA AND HAQUE

114
TABLE 4.

SCHOOL SIZE OF THE GANGES DOLPHIN
Month

Locality%no.
Tistamukh Ghat to Golundo Ghat
Jan.
Lower Meghna and Sundarbans
Jan.
Upper MeghnaApr., May
Total no. of schools
Total no. of individuals

73 90.l
189 85.9
550 91.5
772 90.0772 80.4

No. of individuals in a school
3
4
2
no.
% no. % no. %
5
28
39
72
144

6.2
12.7
7.0
8.4
15.0

2 2.5
3 1.4
7 1.3
12 1.436 3.8

0
1
2
8

1.2
0.0
0.2
0.2
0.8

total
OJ
no.
lo
81
220
557
858
960

100.0
100.0
100.0
100.0
100.0

~

!'...-50
>.
u

c
Cll
&30

Cll
.....

IJ...

10

2

0

3

4

Distance in nautical mile
Fig. 2. Frequency distribution of the length of the course where the Ganges dolphin
was sighted with the interval less than 1/3 nautical mile. Closed circle and solidline indicate theJamuna River, and open circle and dotted line the lower Meghnaand Sundarvans .

........
~

~20
>-.

u

c

Cll
::::J

g-10

....

IJ..

0

7
8
6
4
5
3
Distance in nautical mile

2

Fig. 3. Frequency distribution of the length of the course where the Ganges dolphin
was not sighted. In case where the dolphin was sighted with the interval less than
1/3 miles, it is dealt as continuous. For other marks see Fig. 2.
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

DISTRIBUTION OF THE GANGES DOLPHIN

115

sidered that the Ganges dolphin is not a gregarious species, at least in dry season,quite different from the other oceanic dolphins.
Fig. 2 shows the frequency distribution of the length of the course of the ship
where the dolphins were observed with the intervals less than 1 /3 nautical mile
(620 m). This indicates that the dolphin assembles to some narrow placess in theriver. We think that this will be related with the distribution of the food of thedolphin, because the dolphins were often observed at the confluence of a river or down
streams of a shallow place. As seen in Fig. 3, the places where dolphin assembles areusually scattered with the distance less than 3 nautical miles (5.6 km), but sometimes with 4 miles or more distance.
The Ganges dolphin never comes to the bow of the ship, which is different fromthe usual oceanic dolphins.
ACKNOWLEDGEMENT

We acknowledge all the members of the Catacean Research Expedition, University ofTokyo, who helped us in collecting the data on distribution of the Ganges dolphin.
Mr. Hamada and Dr. Shimada of the Rapti Agricultural Experimental andModel Farm helped us in having a small trip to the Narayani River, and Dr. Iwashita
informed us of his observation on the dolphin in i"epal. These persons are greatly
acknowledged.
REFERENCES
ANDERSON, J., 1878. Anatomical and zoological researches, comprizing an account of the zoological result of the two
expeditions to Western Yunnan in 1868 and 1875 and a monograph of the two cetacean genella, Platanista and Orcella, vol. 1. B. Quaritch, London, 564 pp.
KASUYA, T., 1972. Some informations on the growth of the Ganges dolphin with a comment on the Indus
dolphin. Sci. Rep. Whales Res. Inst., 24: 87-108.
PrLLERI, G., 1970. Observations on the behavior of Platanista gangetica in the Ind us and Brahmaputra Rivers.
Investigations on Cetacea, 2: 27-60. G. Pilleri (ed.), Berne.

EXPLANATION OF PLATE
Fig. 1.

Fig. 2.
Fig. 3.

Gola Ghat, the upper limit of distribution of Platanistagangetica on the Narayani River in
Nepal. The stream of this side is the Burigandaki River, the other the Kali gandaki
River, and the lower stream at the left.
Fishing boats in the Brahmaputra River, at Samoganj near Mymensingh, Jan. 1970.
The Meghna River at Bhairab Bazar, Jan. 1970.

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

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FATTY ACID COMPONENT OF VARIOUS BLUBBER OIL
OF GANGES RIVER DOLPHIN*HIDEO TSUYUKI** AND SHINGO ITOH**
ABSTRACTThe oil contained in various blubbers of Ganges river dolphin, Platanista
gangetica, has been investigated in the present work.
The fatty acid component of sample oil has been analyzed by GLC.
Thirty-seven fatty acids with chain lengths from 5 to 24 carbon atoms andzero to six double bonds were tentatively identified in Ganges river dolphin oil.
Three fatty acids of C16 saturated, C16 monoenoic and C18 monoenoic acids
constituted an average of more than 66.45 % of total acids. The fatty acidcomponent of each sample oil was found to be relatively rich in unsaturated
fatty acids (62.35-77.62%), and saturated fatty acids were contained in small
amounts (22.38-37.65°/o).

INTRODUCTION

In the previous paper (Tsuyuki and Itoh, 1971), we reported that Ganges riverdolphin oil comprized more than 24 kinds of fatty acids with 12-22 carbon atoms,
including mostly hexadecanoic, hexadecamonoenoic and octadecamonoenoic acids.
Further, Pilleri has studied the chemical properties on the lipid of the blubber of
Platanista indi and gangetica (1971).
In the present investigation, the fatty acid component of various blubber oils of
two Ganges river dolphins was studied by gas liquid chromatography using ahydrogen ionization detector.
This study is reported as a part of the examination of Platanistidae which had
been continuing to date by organized Japanese Scientists.
It was a pleasure for us to join in this study.
MATERIALS AND METHODS
The materials used in this study were two Ganges river dolphins (body length
126.0 cm, body weight 17.0 kg, immature female as sample A and 199.0 cm, 84.0 kg,
mature male as sample B).
Oils were extracted by boiling various blubbers of Ganges river dolphins withwater. The chemical properties of these oils were examined by ordinary methods(Tables 1 and 2).

* An outline of this article was presented to the Annual Meeting ofJapanese Society of Scientific Fisheries,
Tokyo, April 4, 1972.

** Department of Food Engineering, College of Agriculture & Veterinary Medicine, Nihon University.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972, 117-125.

TSUYUKI AND ITOH

118

TABLE 1.

PROPERTIES OF OILS CONTAINED IN VARIOUS BLUBBERS
OF GANGES RIVER DOLPHIN (A).

Parts of blubbers
Thoracic blubber
Umbilicus blubber
Abdominal hind blubber
Frontal back blubber
Middle back blubber
Posterior back blubber
TABLE 2.

Oilcontent
(%)

Acid
value

Iodinevalue

Sapon.
value

Unsapon.
matter
(%)

38.4
49.l
40.4
40.1
50.7
33.2

1.40
1.26
0.62
1.01
1.46
1.07

115.5
125.6
114.2
102.9
113.3
96.1

193.1
197.5
189.3
194.6
190.4
189.3

1.36
1.02
1.26
1.16
1.72
1.10

PROPERTIES OF OILS CONTAINED IN VARIOUS BLUBBERS
OF GANGES RIVER DOLPHIN (B).

Part of blubbers

Oilcontent
(%)

Acid
value

Iodinevalue

Sapon.,
value

Unsapon.
matter(%)

Thoracic blubber
Umbilicus blubber
Frontal back blubber
Middle back blubber
Tail blubber
Melon

48.3
48.9
52.5
50.l
34.2
51.8

1.10
0.90
1.04
1.41
1.05
1.00

113.9
117.4
121.9
99.3
101.2
70.9

198.1
207.0
208.2
195.3
128.0
218.3

1.70
1.65
1.46
1.03
31.80
0.92

The fatty acid methyl esters of various blubber oils were prepared with BF 3 methanol reagent according to Metcalfe et al (1966). Approximately 200 mg sampleof each blubber oil was added to I 0 ml of 0.5 N potassium hydroxide-methanol andheated on a steam bath for several minutes. Next, 10 ml of BF3 -methanol (125 g
BF3 per liter of methanol) was added to the above sample and boiled for a few minutes
under an atmosphere of nitrogen gas. Then, enough of half saturated sodium
chloride solution was added to the sample to float up the methyl esters. About
30 ml of ethyl ether was added to the sample to extract the methyl esters, and thesame extraction was repeated for 5 times. The ethyl ether solution was dehydrated
with anhydrous sodium sulfate, and evaporated under an atmosphere of nitrogen gas
on a water bath. The methyl esters obtained were refined by thin layer chromatography on silica gel (petroleum ether: ethyl ether: glacial acetic acid, 90: 10: I).
The fatty acid component of each blubber oil was determined quantitatively by
GLC of methyl esters in a Shimadzu Gas Chromatograph Model GC-lC apparatus
equipped with a flame ionization detector. The columns were 1.80 m x 3 mmdiameter stainless-steel tubing packed with 25 % DEGS on 60/80 mesh Chromosorb
W, and also 2.68 m X 3 mm diameter glass coil packed with 5 % PEG on 60 /80 mesh
Chromosorb W. The carrier gas was nitrogen at a flow rate of 70 ml per minute forstainless-steel column and 35 ml per minute for glass coil column. The stainlesssteel column was operated isothermally at 205°C, and the glass coil column was
programmed from 70°C-150°C at 4°C per minute and 150°C-190°C at 8°C per
minute. The injector block was at 275°C for stainless-steel column and glass coilcolumn was injected by on-column.
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

GANGES DOLPHIN OIL

119

The fatty acid components were identified by comparing their retention times tothose of purified standards and estimated by comparing the semilog plots of retention
times vs carbon numbers of the blubber oil methyl esters with those of known mixtures of methyl esters run on the same columns under the same conditions, according
to Nelson and Freeman (1960). Also, the identification of fatty acids of odd-carbon
chain lengths was checked by hydrogenation over platinum black as a catalyst.
The fatty acid component of sample oil was expressed as percentage of area tototal area of all methyl esters, according to Ettre and Kabot (1963).
RESULTS AND DISCUSSION

The fatty acid component of various blubber oils of two Ganges river dolphins arelisted in Tables 3 and 4. A detailed analysis of the fatty acid component of various
blubber oils revealed the presence of fatty acids 5-24 carbon atoms with zero to six
double bonds.
With a few exception, the fatty acid distribution in each blubber oil is nearly
seemed to be the same pattern. The three main fatty acids which represented anaverage of more than 64.18 %(A)-68.72 %(B) of total fatty acids in each blubber oil of
Ganges river dolphins are as follows; hexadecanoic acid, hexadecamonoenoic acidand octadecamonoenoic acid.
In the case of Ganges river dolphin A, oils in abdominal hind and middle backblubbers were found the presence of 37 kinds of fatty acids, but it was not find to bepresence of eicosatrienoic acid in thoracic, frontal back and posterior back blubber
oils, and docosatetraenoic acid in umbilicus blubber oil. The total ofhexadecanoic,
hexadecamonoenoic and octadecamonoenoic acids had an average of more than
64.18% of total fatty acids in all blubber oils of Ganges river dolphin A. Also,
various blubber oils of Ganges river dolphin A had the large portion of total unsaturated acids (63.93-77.62%) which contained almost twice the amount of total saturated acids (22.38-36.07 %). Finally, the fatty acid distribution of each blubber oilfrom Ganges river dolphin A was found relatively the same trend.
In the case of Ganges river dolphin B, the fatty acid component of blubber oils
contained mainly hexadecanoic, hexadecamonoenoic and octadecamonoenoic acids
which represented an average of more than 68. 72 % of total fatty acids. An amountof total saturated acids (25.46-37 .65 %) was almostly half of total unsaturated acids(62.35-74.54%). The oils of thoracic and umbilicus blubbers were found the presence of36 kinds of fatty acids, and were not identified docosatetraenoic acid. Frontal back blubber oil was found the presence of 37 kinds of fatty acids. Middle backblubber oil contained 33 kinds of fatty acids and did not contain eicosapentaenoic,
docosatetraenoic, docosapentaenoic and tetracosamonoenoic acids. Moreover,middle back blubber oil had very small amount of tetradecanoic acid (0.40%) compared with other blubber oils (average 6.61 %) and conversely the higher amount ofoctadecamonoenoic acid (35.28%) more than that of other blubber oils (average
25.41 %). Tail blubber oil contained 32 kinds of fatty acids with absence of eicosadienoic, eicosatrienoic, eicosapentaenoic, docosatetraenoic and tetracosamonoenoic
Sci. R.ep. Whales Res. Inst.,
No. 24, 1972.

TSUYUKI AND ITOH

120
TABLE 3.
Blubbers

FATTY ACID COMPONENT OF OILS CONTAINED IN VARIOUS
BLUBBERS OF GANGES RIVER DOLPHIN (A).
Abdominalhindblubber(%)

Frontalback
blubber(%)

Middleback
blubber(%)

Posteriorback
blubber
(%)

0.13
0.05
0.03
0.81
tr
tr
0.20
tr
tr
tr
6.62
1.33
1.61
0.82
0.32
11.59
23.89
2.32
2.64
1.15
2.14
29.09
3.95
1.54
0.28
0.76
0.88
0.49
1.36
0.32
0.35
1.32
0.29
1.48
1.85
0.39

0.34
0.21
0.07
0.87
0.22
tr
0.57
0.13
0.06
tr
4.13
1.85
1.64
0.69
0.38
13.61
23.72
0.92
1.48
1.14
1.01
29.12
4.36
1.43
0.35
0.71
1.07
0.96
0.67
1.05
0.74
0.68
0.41
0.48
1.91
2.38
0.64

0.16
tr
tr
0.46
tr
tr
0.48
0.10
tr
tr
4.50
3.12
1.08
0.75
0.44
12.72
21.87
2.65
2.26
1.82
3.61
28.17
3.96
0.82
0.20
0.31
0.23
0.44

2.83
3.94
0.78

0.23
0.11
0.07
0.79
0.12
tr
1.06
0.07
0.03
0.19
7.56
1.30
0.79
0.58
0.60
20.34
16.78
0.84
1.55
0.62
2.43
24.83
2.33
1.65
0.32
0.82
1.13
0.95
1.04
2.53
0.45
0.20
0.48
0.43
3.11
3.21
0.46

22.38
77.62

36.07
63.93

25.25
74.75

25.04
74.96

25.84
74.16

Thoracic
blubber

Umbilicus
blubberFatty acid

(%)

(%)

iso-5-0
n-5-0
6-0
8-0
10-0
12-br*
12-0
12-1
13-0
14-br*
14-0
14-1
14-2
15-0
16-br*
16-0
16-1
16-2
16-3
17-0
18-0
18-1
18-2
18-3
19-0
20-0
20-1
20-2
20-3
20-4
20-5
21-0
22-1
22-4
22-5
22-6
24-1

0.22
0.06
tr
0.75
0.13
tr
1.02
0.04
tr
0.21
5.48
2.94
1.07
0.44
0.31
12.76
23.22
1.46
1.47
0.91
1.55
27.71
3.84
1.52
0.25
0.76
0.71
0.95

tr
tr
tr
0.25
tr
tr
0.37
tr
tr
0.17
5.39
1.72
0.24
0.26
0.43
12.66
22.29
2.30
1.43
0.89
0.95
30.68
3.47
0.82
0.19
0.36
0.49
0.60
0.52
3.25
1.10
0.46
1.16

Saturated
Unsaturated

25.27
74.73

1.38
0.54
0.42
0.69
0.60
2.75
2.91
0.93

1.90
0.66
0.39
1.30
0.27
2.17
2.54
0.62

* Branched fatty acids.

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

GANGES DOLPHIN OIL
TABLE 4.

121

FATTY ACID COMPONENT OF OILS CONTAINED IN VARIOUS
BLUBBERS OF GANGES RIVER DOLPHIN (B).

Blubbers

thoracic
blubber

Umbilicus
blubber

Abdominalhindblubber(%)

Frontalback
blubber(%)

Middleback
blubber(%)

Posteriorback
blubber
(%)

tr
tr
tr
0.47
tr
tr
0.23
tr
tr
tr
0.40
0.81
0.34
0.15
0.83
18.20
26.84
1.22
1.76
1.49
2.89
35.28
2.37
0.95
0.37
0.24
0.55
0.67
0.30
0.56

0.26
0.19
0.08
1.32
0.41
tr
0.81
0.23
0.10
0.27
7.15
3.24
1.16
0.43
1.13
22.47
23.94
1.06
2.09
0.83
1.29
24.83
1.56
0.53
0.20
0.71
0.30

0.55
0.27
0.10
1.93
0.36
tr
0.97
0.18
0.09
0.12
7.08
3.76
1.17
0.41
0.75
17.09
38.97
0.40
1.86
0.38
1.02
21.31
0.45
0.39
0.14

0.19
1.28

tr
0.52

1.61

0.83
1.04

25.46
74.55

37.65
62.35

Fatty acids

(%)

(%)

iso-5-0
n-5-0
6-0
8-0
10-0
12-br*
12-0
12-1
13-0
14-br*
14-0
14-1
14-2
15-0
16-br*
16-0
16-1
16-2
16-3
17-0
18-0
18-1
18-2
18-3
19-0
20-0
20-1
20-2
20-3
20-4
20-5
21-0
22-1
22-4
22-5
22-6
24-1

0.15
tr
tr
0.53
tr
tr
0.29
tr
tr
tr
5.84
0.92
0.19
tr
0.66
16.20
22.05
0.99
2.43
1.01
1.17
27.32
2.89
1.69
0.35
0.84
1.34
1.30
0.62
1.54
1.13
0.37
0.85

0.35
0.27
tr
0.99
tr
tr
0.38
tr
tr
0.19
6.33
2.92
0.35
0.31
0.37
14.13
17.24
0.40
1.92
0.94
3.82
29.30
1.68
1.12
0.23
0.51
0.77
1.17
0.48
2.23
1.04
0.55
1.29

3.13
3.44
0.76

3.61
3.90
1.21

0.17
0.10
tr
0.94
0.21
tr
0.32
0.16
tr
0.22
6.65
2.09
1.10
0.53
0.40
15.48
25.99
0.90
2.52
1.28
3.04
24.31
2.02
0.64
0.14
0.32
0.78
0.69
0.24
1.47
0.98
0.27
0.73
0.38
1.56
2.45
0.92

Saturated
Unsaturated

27.41
72.59

29.37
70.63

30.07
69.93

* Branched fatty acids.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

0.25

1.02

31.26
68.74

122

TSUYUKI AND ITOH

acids. Although the fatty acid component deviated from other blubber oils, there
were a few exception. For example, the ratio of total unsaturated acids (62.35 %) tototal saturated acids (37.65 %) was found to be the lower amount than that of otherblubber oils, also there was a few presence of fatty acids with 20 or more carbon
atoms. Finally, with the exception of melon oil, the fatty acid distribution pattern ofthoracic, umbilicus, frontal back, middle back and tail blubber oils from Ganges
river dolphin B was relatively followed the same trend as those from Ganges riverdolphin A.
In the fatty acid component, melon oil was radically different with other blubber
oils, and the levels of individual and groups of fatty acids were unique to this sample.
The fatty acid component of melon oil was only 26 kinds of fatty acids. In melon
oil, the most notable deviation was the high level of hexadecamonoenoic acid(38.97 %), and other main fatty acids were 21.31 % of octadecamonoenoic acid and17 .09 % of hexadecanoic acid. On the other hand, the short chain acids (less than 17
carbon atoms) were present at high levels (76.44 %) while the concentrations (23.56 %)of fatty acids with more than 18 carbon atoms were considerably lower than that ofother blubber oils. It was probably seemed because melon was not a blubber andwas an adipose tissue on an upper jaw.
As concerned with the chemical properties, most of deviation in tail blubber oil
of Ganges river dolphin B can be attributed to the high level of unsaponifiable matter(shown in Table 2) and characterized by the low level ofsaponification value. It wasseemed that tail blubber oil had notably some unsaponifiable matters.
In comparison with oils of Ganges river dolphins in fresh water and oils of otherdolphins in sea water (Table 5), they have no definite analogy on the fatty acid component. The major acids of Many toothed pilot whale and Common dolphin oils
are hexadecanoic and octadecamonoenoic acids and have a low amount of hexadecamonoenoic acid which is contained as one of the main fatty acids of Ganges riverdolphin oil. Moreover, Finless porpoise oil has the high amount of hexadecamonoenoic and octadecamonoenoic acids, but it has a few presence of hexadecanoic acid
which is one of the main fatty acids of Ganges river dolphin oil. Viewing in comparison of saturated and unsaturated fatty acids, it is found that all dolphin oils haveapproximately the same distribution of ratio of total saturated and unsaturated fatty
acids. The long chain acids with 20 or more carbon atoms which represented
12.50 %(A) or 9.30 %(B) of the total acids in Ganges river dolphin oil, are only theminor presence or are not present at all in Finless porpoise oil and Many toothed pilot
whale oil. 3 kinds of short chain acids with 6 less carbon atoms are contained in
Ganges river dolphin oil, however, it is not reported in Many toothed pilot whale,
Finless porpoise and Common dolphin oils. It is seemed to be caused by that theanalytical method was different in each experiment. The docosahexaenoic acid(10.4%) of highly unsaturated acid which is contained in Common dolphin oil, areonly 2.81 %(A) or 1.24%(B) of total acids in Ganges river dolphin oil.
Finally, it was seemed that Ganges river dolphin, Finless porpoise, Many
toothed pilot whale and Common dolphin oils had not a completely analogicaldistribution pattern of fatty acid component in this study.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

II,,
GANGES DOLPHIN OIL
TABLE 5.
Dolphins

A COMPARISON OF FATTY ACID COMPONENT OF
DOLPHINS OIL.
Ganges riverdolphins

Fatty acids

A'I

B•>

iso-5-0
n-5-0
6-0
8-0
10-0
12-br
12-0
12-1
13-0
14-br
14-0
14-1
14-2
15-0
16-br
16-0
16-1
16-2
16-3
17-0
18-0
18-1
18-2
18-3
19-0
20-0
20-1
10-2
20-3
20-4
20-5
21-0
22-1
22-4
22-5
22-6
24-1

0.18%
0.07
0.03
0.66
0.08
tr
0.62
0.06
0.02
0.10
5.61
2.04
1.07
0.59
0.41
13.95
21.96
I.13
1.81
1.09
1.95
28.27
3.65
1.30
0.27
0.62
0.75
0.73
0.37
I.91
0.64
0.42
0.89
0.35
2.37
2.81
0.64

0.19%
0.11
0.02
0.85
0.12
tr
0.41
0.08
0.02
0.14
5.27
2.00
0.63
0.28
0.68
17.30
23.21
0.91
2.14
1.ll
2.44
28.21
2.10
0.99
0.26
0.52
0.75
0.77
0.33
1.36
0.63
0.28
0.93
0.08
1.83
I.24
0.58

Saturated
Unsaturated

26.64
73.36

29.99
70.01

1

> Average of all blubbers.

•l Average of blubbers without melon.
3 > Tsuyuki and Itoh (1969a).
•> Tsuyuki and Itoh (1969b).
5 >Japan Oil Chemists' Society (1971).

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

123

Many toothedpilot whale3 >Finless
porpoise•>

Commondolphin 5 >

-%

-%

-%

0.1
0.3

0.1
0.2
0.3
0.9
0.7
0.2
0.4
8.4
4.1
0.7

1.3
2.0
0.3
7.3
13.8
4.9
0.5

2.0

1.1

11.4
5.3
6.9
0.9

7.2
2.6
1.9
1.2

21.2
6.0

0.8
28.1
3.7
0.8
1.4
1.7
0.6
1.5

0.9
20.4
2.1
2.0
1.6
1.8
1.4

2.7
27.5
1.3
0.6

2.3

1.7
4.6

0.7
5.8

2.5
7.9
4.1

25.l
70.8

3.9
5.3

2.3
10.4

23.1
76.9

26.6
68.4

124

TSUYUKI AND !TOH

SUMMARY

1. The properties of oils contained in various blubbers of two Ganges riverdolphins (A and B), Platanista gangetica, were studied.
2. The fatty acid component of Ganges river dolphin oil was analyzed by GLC
on DEGS and PEG columns.
3. The fatty acid component is as follow:
total saturated fatty acids 26.64% (average of A), 29.99% (average ofB);

iso-C 5
n-C 5
c6

Cs
C10

C 12 br
C12

c13

C 14 br
C14
C1s

C 16 br

c16

C11
C1s

C19
C20

A (ave.)B (ave.)0.18%,
0.07%,
0.03 °/o,
0.66%,
0.08%,

0.19%,
O.llo/o,
0.02%,
0.85%,
0.12%,

tr.

tr.

0.62%,
0.02%,
0.10%,
5.61 %,
0.59%,
0.41 %,
13.95%,
1.09%,
1.95%,
0.27%,
0.62%,

0.41 %,
0.02%,
0.14%,
5.27%,
0.28%,
0.68%,
17.30%,
l.ll %,
2.44%,
0.26%,
0.52%,

total unsaturated fatty acids 73.36 %(A), 70.01 %(B);C 12 monoenoic
C14 monoenoic
C 14 dienoic
c16 monoenoic
C 16 dienoic
c16 trienoic
C 18 monoenoic
C18 dienoic
C 18 trienoic
C 20 monoenoic
C 20 dienoic
C 20 trienoic
C 20 tetraenoic

A (av.)
0.06%,
2.04%,
1.07%,
21.95%,
1.13%,
1.81 %,
28.27%,
3.65%,
1.30%,
0.75%,
0.73%,
0.37%,
1.91 %,

B (av.)
0.08%,
2.00%,
0.63%,
23.21 %,
0.91 %,
2.14%,
28.21 %,
2.10%,
0.99%,
0.75%,
0.77%,
0.33%,
1.36%,
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

GANGES DOLPHIN OIL

C 20 pentaenoic
C 22 monoenoic
C 22 tetraenoic
C 22 pentaenoic
C 22 hexaenoic
C 24 monoenoic

0.64%,
0.89%,
0.35%,
2.37%,
2.81%,
0.61 °/o,

125

0.63%,
0.93%,
0.08%,
1.83%,
1.24%,
0.58%.

4. The fatty acid component of various blubber oils was appeared relatively at
the same distribution pattern.
REFERENCESETTRE, L. S. and F. J. KABOT, 1963. Relative response of fatty acid methyl e$ters on the flame ionization
detector. ]. Chromatog., 11 : 114-116.
JAPAN OIL CHEMISTS' SocIETY, 1971. Yushikagaku-Binran, Maruzen, Tokyo, 11 pp.
METCALFE, L. D., A. A. SCHMITZ and J. R. PELKA, 1966. Rapid preparation of fatty acid esters from lipids
for gas chromatographic analysis. Anal. Chem., 38: 154-155.
NELSON, G.J. and N. K. FREEMAN, 1960. Phospholipide and phospholipide-fatty acid component of humanserum lipoprotein fraction. J. Biol. Chem., 235: 578-583.
PILLER!, G., 1971. Preliminary analysis of the lipids present in the blubber of Platanista indi and gangetica.
Investigation on cetacea, Volume III, Berne, Switzerland, 50-52.
TsuYUKI, H. and S. IToH, 1969a. Fatty acid composition ofFinless porpoise oil. Sci. Rep. Whales Res. Inst.,
21 : 131-135.
TsuYUKI, H. and S. lToH, 1969b. Fatty acid composition of Many toothed pilot whale oil. Sci. Rep. Whales
Res. Inst., 21: 137 :141.
TsuYUKI, H. and S. IToH, 1971. Fatty acid components ol Ganges river dolphin oil. Sci. Rep. Whales Res.
Inst., 23: 141-147.

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

THE GROWTH OF TWO SPECIES OF THE HARBOURSEAL IN THE ADJACENT WATERS OF HOKKAIDOYASUHIKO NAITO* AND MASAHARU NISHIWAKI*
ABSTRACT

We studied the growth of P. v. largha, pagophilic seal, and P. kurilensis,
pagophobic seal, in the southern Sea of Okhotsk and in the waters around
Hokkaido from 1968 to 1971.
P. v. largha: Adult type coat and white coat were observed in the fetus
stage. Parturition occurred from mid March and the end of March. Moultingof the white coat and weaning occurred 2-3 weeks after birth. The thicknessof blubber was 4.5-5.l cm in pups on the ice floe and decreased to 2.6 cm
after the ice melted. The fully grown body length was 170 and 161 cm inmales and females respectively.
P. kurilensis: Parturition occurred in the later half of May, and birthlength was 98.2 cm. Weaning occurred 4 weeks after birth. The thickness of
blubber was thinner than that of P. v. largha. The fully grown body length
was 186 and 169 cm in males and females respectively.
INTRODUCTION

It is today noted that there are 5 subspecies of the harbour seal (Phoca vitulina) in thenorthern hemisphere; P. v. vitulina in the eastern Atlantic, P. v. concolar in the western
Atlantic, P. v. mellonae in the Seal Lake, Canada, P. v. richardi in the eastern Pacific,
P. v. largha in the western North Pacific.
In the western North Pacific, more than 10 specific or subspecific names werereported for the harbour seal, but they were reduced to only one P. v. largha by
Scheffer (1958). However, recently by morphological and ecological studies, Belkin(1964) reported new species of Phoca named P. insularis, which is the same seal
reported previously as P. ochotensis kurilensis by Inukai (1942a). Concerning thespecific name of the new seal, McLaren (1966) used P. kurilensis instead of P. insularis,
recognizing the priority of the name kurilensis. Therefore, there exist two species of
Phoca, P. v. largha and P. kurilensis, in the western North Pacific.
In Hokkaido, it is noted that both of the above mentioned two species arecaught annually by commercial sealing or by fishing net (Naito, 1971). Biologicalstudies of these seals in the waters around Hokkaido and in the southern Sea of
Okhotsk were made fragmentarily by Inukai (1942 a, b), Wilke (1954), Nishiwaki
and Nagasaki (1960), Belkin (1964) and Belkin et al. (1969). Nevertheless, there arestill many general biological problems not yet solved.
It is noted that P. v. largha is a pagophilic seal and P. kurilensis is a pagophobic
seal (Belkin, 1964; Belkin et al., 1969). The present study was focussed to reveal* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,

No. 24, 1972, 127-144.

NAITO AND NISHIWAKI

128

unknown aspects of the growth of the seals, some of which may be related to such
ecological difference between two species.
In the present study, we follow McLaren (1966), and use the name P. kurilensis.
146°E

lllil.11---l-----l4
SoN

SEA OF OKHOTSK

46°N

PACIFIC OCEAN

Fig. 1. Sampling areas for P. v. largha and P. kurilensis in the southern Sea of Okhotsk
and the Pacific coast ofNemuro Peninsula.

MATERIALS AND METHODSIn the southern Sea of Okhotsk and the north east coast of Hokkaido, field surveys
were made between 1968 and 1971. In the present study, the area surveyed was
divided into the following 4 areas according to the sealing area (Fig. 1): I) the mouthofTerpeniya Bay of Sakhalin, II) the Kitami-Yamato bank, Lake Saroma, and Point
Notaro, III) the area between Shiretoko Peninsula and Nemuro Peninsula, IV) the
Pacific coast ofNemuro Peninsula. Studies of P. v. largha were made mainly in areas
I, II, III, and studies of P. kurilensis were made in area IV. In area I, studies were
performed on a sealing boat from the end of April to the beginning of May in 1971.
In area II, studies were made from December in 1968 to March in 1969 at Lake
Saroma and Point Notaro, and also made on a sealing boat in Kitami-Yamato bankfrom mid April to the beginning of May in 1969 and 1970. In area III, studies were
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH OF THE HARBOUR SEALS IN HOKKAIDO

129

made from December in 1968 to March in 1969. In area IV, studies were made in
May and June in 1969, 1970 and 1971, and in October in 1969. In this area, fieldobservations of P. kurilensis were also made at Moyururi Island and other places in 1969
and 1971. P. kurilensis was chiefly caught in area IV in May and June. However,some of this species appeared in area III and were caught by fishing net occasionally(Salmon set net). P. v. largha seemed not to appear in area IV in May and June
except for pups or very young seals, but some appeared in area IV and were caught
by the fishing net in Autumn.
Through these studies, body length was measured from the tip of the snout tothe end of the tail in a straight line along the body axis in cm. Concerning the seals
collected on board, measurements were mostly made before rigor mortis occurred.
Some were measured in the condition of rigor mortis, and yet they were not so muchcurved that we could not measure in a straight line along the body axis. In small
embryos (under 100 mm) the length was measured along the curved body axis fromthe tip ofthesnouttotheendofthetailinmmbyusingtheuniversal projector, and thelength of middle sized embryos (100-400 mm) was measured by using the divider.
Large embryos (over 400 mm) were measured same as postnatal seals. Reproductive organs were preserved in 10 % formalin. In some cases, they were preserved in
10 % formalin after preservation in a freezer.
For age determination, canine teeth were taken from the skulls or lower jaws
after connective tissues rotted in the laboratory, and then they were cut longitudinallyby grinder and their surface was polished by wetstone. After they were glued to thetransparent plastic plate, the half of the remaining tooth was ground again to become
about 0.1 mm in thickness. The growth layers were observed by the binocular
microscope in reflected and transmitted light. In the present study, age determination was made following the method of McLaren (1958), Mansfield and Fisher (1960),
and Bigg (1969). In the seal under 7-8 years of age, both cementum and dentine
growth layers were examined, but only cementum growth layers were examined after
7-8 years of age. Ages were calculated from number of growth layers, assuming thatevery collected P. v. largha was born at the end of March and P. kurilensis was born in
mid May respectively.
PRENATAL GROWTH AND PURTURITION
The prenatal growth of P. v. largha and P. kurilensis is almost unknown. Tikhomirov (1971) reported the length of near-term fetuses of P. v. largha from the Bering
Sea. There are no record of fetus of P. kurilensis. However, Scheffer and Slipp(1944) and Bigg (1969) reported the prenatal growth of P. v. richardi from Washington
State and the southern Vancouver Island.
Concerning the parturition Tikhomirov (1971) in the Bering Sea, Wilke (1954)
in the southern Sea of Okhotsk, Belkin (1964) and Belkin et al. (1969) in the southern
Kurile Islands reported on P. v. largha, and Inukai (1942a), Belkin (1964) and Belkin
et al. (1969) stated on P. kurliensis from the southern Kurile Islands. In the present
study, mating season, growth of fetus in body length, parturition season and birth
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

NAITO AND NISHIWAKI

130

length were investigated.

Phoca vitulina largha
In area II from the 12th to the 16th of April in 1969, we collected 9 paired
females which were on ice floes with males and pups together. Couples of ovaries
were collected from 5 out of 9 paired females. The condition of these ovaries wascompared with that of single females which were alone on ice floes and were captured
from the 17th of April to the 2nd of May. As seen in Table 1, paired females were
TABLE 1.

CONDITION OF OVARIES IN THE SINGLE FEMALE AND
THE PAIRED FEMALE OF P. V. LARGHA.
SinglePeriod of catch
Number of specimens
Specimens with large follicles and no newly
formed corpus luteum in ovaries
Specimens with follicle changing to corpus
luteum in ovaries
Specimens with newly formed corpus
luteum in ovaries
Mean diameter of maximum-sized follicle(length+width/2; mm)

Pair

23

April 12th-l 7th
5

62

April l 7th-May 2nd

0

23

2

5.0

12.7

classified into three groups according to the condition of ovaries. 1) two paired
females had large follicles and no corpus luteum in their ovaries, which indicated that
fertilization had not occurred yet. 2) one paired female had the large follicle which
was partly changing to the tan-color corpus luteum, and partly contained theopaque gelatin like structure. This follicle indicated that the ovary was just after
the fertilization. 3) two paired females had the newly formed corpus luteum in theirovaries, and this indicated that fertilization had already occurred. The mean diameter of maximum sized follicles of 5 paired females was 12.5 mm. On the other
hand, in the single females only newly formed corpus luteum was found in the ovaries,
and this indicated that fertilization was over. The mean diameter of maximum
sized follicles was 5.0 mm and was less than half of that of paired females. Fromthese facts, it is indicated that the paired females were in the mating season, and in
the single females mating season was over. In the present study, it was difficult toknow exactly when the beginning of the mating season occurred, however, it may besupposed that mating occurred from early April to mid April.
Concerning the growth offetus, we examined 20 fetuses of P. v. largha collectedfrom survey area II and III. Figure 2 shows that body length offetuses increased inaccordance with time. In this study, the time of implantation is unclear, so thegestation period is also unclear. The fetuses collected in mid October, about 5
months before parturition season, were 175-268 mm in body length and the final
stage fetuses collected in later half of March, just before birth, was 780-925 mm.
The growth rate seemed to be same in both sexes.
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

GROWTH OF THE HARBOUR SEALS IN HOKKAIDO

131

Pups having an umbilical cord may indicate that they were born within thepast few days, and from such pups parturition season and birth length would be
estimated. In this study we could not collect pups with an umbilical cord, but 4
final stage fetuses were caught which were estimated that they would be born within a
few days. These fetuses appeared from the 16th to the 27th of March and did notappear after the 27th of March. Therefore, it seemed that parturition occurred fromthe mid to the end of March. According to other studies, Wilke (1954) reported
from the same area as our area II that parturition may occur in the early half of

~

.

./ .
•

R

/o o

800

/

E

~600>.r:.

~

-:(·

1000

/~

f-

/"
.

0.

_,~400>-

0/.0

200 -

.. A
I

5

l------i

1-----i
I

I

0

N

D

F

M

A

M

A

Month

Fig. 2. Prenatal growth of P. v. largha and P. kurilensis in standard length. e, 0,males and females of P. v. largha ; (!), new born pups with white coat ; .A, .6.,
males and females of P. kurilensis ; X, new born pups with umbilical cord ; - ,time of parturition of P. v. largha ; - - -, time of parturition of P. kurilensis.

March, the earliest record of parturition was in late January and the latest was on the
15th of April. Belkin (1964) suggested that pups were born on ice floes from the endof March to mid April in the southern Kurile Islands. However, Belkin et al. (1969)suggested that new born pups were observed from early March to the end of Marchin the same area.
In the present study, birth length was estimated from following considerations.
1) the largest fetus and the smallest new born pup may indicate the birth length. 2)
growth curve and parturition season also indicate the birth length. According to1), birth length was assumed to be 933 mm, since the largest fetus was 925 mm
and the smallest new born pup was 940 mm. According to 2), birth length wasestimated to be about 850 mm. Since the new born pup was not captured justafter birth, the result of the first was relatively large. Therefore, we employed thesecond result.
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

NAITO AND NISHIWAKI132

Phoca kurilensis
Concerning the mating season, 4 couples out of 67 population were observed tocopulate at hauling ground area of Moyururi Island from the 9th to 13th of June in1969. While copulations were rarely observed in 75 population from 22nd to 27th ofJune in 1971 at the same hauling ground area. From these data, it is concluded thatmating occurs in June, but is difficult to estimate the mating period exactly.
There was no report previously on the prenatal growth of this seal. In the present study, the length of 4 fetuses collected in October from Nemuro Peninsula was
95 mm in males, and 85, 84 and 39 mm in females (Fig. 2). In these fetuses nopigmentation was observed (Plate I).
To estimate the parturition season and the birth length, the appearance ofpups with umbilical cords was investigated. Figure 3 shows that parturition of thisseal may occur from the middle to the end of May in the Pacific coast of Nemuro
Peninsula and the mean body length at birth is 98.2 ± 3 .2 cm. The birth length of thisspecies is much larger than that of P. v. largha indicated in the present study and thatof P. v. richardi shown by Bigg (1969). Inukai (1942b) and Belkin (1964) and Belkin
et al. (1969) suggested that parturition of this seal occurs in mid May and copulation
occurs in July in the southern Kurile Islands.
~ 6

110

:::J

a.

~ 4

2

"'

.Q

E
~ 2

0

100 ~

:::J

'°

90 J

(20)

12

14

16

18

20

22

24

26

28

MAY

30

2

80

JUNE

Fig. 3. Frequency of new born pups with umbilical cord, at two days intervals,
and birth length(total 20 pups). Vertical line, range; box, standard error;
horizontal line in box, mean.

POSTNATAL GROWTH

I.

Moulting of white coat and weaning

It is generally believed that only P. v. largha of all 5 subspecies bears the creamy
white coat in its early pup stage for several weeks after birth, and also weaning seems
to occur subsequently with moulting of this coat. However, the moulting and weaning season are still unknown. As for P. v. largha, Wilke (1954) suggested the time ofmoulting in the southern Sea of Okhotsk, but the weaning seasons are not obvious.
Concerning weaning of P. kurilensis, Belkin (1964) and Bilkin et al. (1969) suggested
from his finding in the southern Sea of Okhotsk.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH OF THE HARBOUR SEALS IN HOKKAIDO

133

Phoca vitulina largha
In the fetuses collected in October, clear pigmentation was observed (Plate I).
Scheffer and Slipp (1944) traced three progressive changes in type of pelage in P. v.
richardi: 1) an early, sparse fetal coat, perhaps the forerunner of the third coat, 2) along, silky white lanugo coat, and 3) a short varigated coat. The first fetus on whichappeared fetus pelage according to Scheffer's 1), was caught in early November.
From early December, about 3.5 months before parturition season, the fetus began toshow the white lanugo coat, which corresponded with Scheffer's 2) change (Plate I).
There are no records of pups which have the fetus coat corresponding to Scheffer's 3)change. The near-term fetus of P. v. largha do not shed the white lanugo coat, but
continue to bear after birth. Stutz (1966) reported the changes oflanugo coat in thefetus of P. v. richardi. Firm and dirty white or pale yellowish-grey hair corresponding to Scheffer's 2) change, which resist tugging, appeared characteristic offetus at about half term. As the fetus neared parturition, this hair become looser
enough to be scraped from the skin, and almost near-term fetus lost their lanugo coat.
This near-term fetus seemed to exhibit the same pelage as Scheffer's I) change.
From the catch record of pups captured in area I from the 27th of April to the
4th of May in 1971, and in area II from the 13th of April to the 12th of May in 1969,
the time of moulting of the white coat and the time of weaning were considered(Table 2). In order to know the moulting season of the white coat, three pups stages
were considered from the condition of white coat: 1) stage of complete white coat, 2)stage of a partial white coat, 3) stage of moulting the white coat.
In area II, as shown in Table 2, pups were considered in the moulting season of
their white coat in mid April, and it seemed that the moulting season was over at theTABLE 2.

FREQUENCY OF PUPS OF P. V. LARGHA IN THE THREE MOULTING
STAGES. PARENTHESIS SHOWS PERCENTAGE.

Area II
1969 Apr. 12
Apr. 13
Apr. 14
Apr. 15
Apr. 16
Apr. 23
May 2
Area I
1971 Apr. 27
Apr. 28
Apr. 29
Apr. 30
May 1
May 2
May 3
May 4
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

Number of pups
in white-coat
stage

Number of pups
in second stageof moulting(45.4)(27.3)

Number of pups
in final stageof moultingl) l) Il

(27.3)~ } (0)~ }(20)~ }(80)

0
0
0
0
0
0
0
0

1
0
0
0
0
0
0
0

6
5
6
2
4
3
7

NAITO AND NISHIWAKI134

end of April. In area I, there were no catch records of pups bearing completely
white coat from the 27th of April to the 4th of May in 1971. Almost all pups captured in this area had shed their white coat. Therefore, we can suggest that themoulting season was already over at the end of April and the beginning of May inarea I in this year. According to Wilke (1954), pups of this subspecies landed byhunters at Abashiri in late April were in the moulting stage, and three stages classified
above have been reported. As it is possible to think that Wilke also treated thepups from the same area as area II, the time difference in the moulting season may berelated to the ice conditions in each year.
100 I - - - - - - ,areall-1969. 1970

50

>~

0

(1) (2) (3) (3) (7) (3) (0) (5) (2) (2) (O) (1)12
3
3 15 8072
30
3(0) (0)

0

0

:J

gwo

areall-1969. 1970~50(1) (2) (4) (3) (1) (0) (O) (0) (0) (0) (0) (0) (O) (O)01486200
00300

12

13

14

15

16

17

18 19 20 21

22

23 24

25

(0) (0) (0) (O) (0) (0)00003026

27 28 29 30

APRIL

1

2

3

4

MAY

Fig. 4. Frequency of appearance oflactating females (above) and pups cared by its
mother (below) in P. v. largha. Number in the parenthesis shows the number of
lactating females out of total number of sexual mature females, and the number ofpups cared by its mother out of total number of pups.

TABLE 3.

FREQUENCY OF PUPS OF P. v. largha WITH MOTHER IN RELATION
TO THREE MOULTING STAGES.

No. of pups with motherTotal No of pups
Percentage (%)

complete whitecoat stage

partly moulted
stage

completely
moulted stage

9
10
90

7
14.3

0
10
0

Since the parturition season in area II was considered from mid March to theend of March in 1969, it is considered that moulting of the white coat occurred
two or three weeks after birth in this year. This period from birth to moulting is thesame as that of King's suggestion (1964).
Time of weaning was estimated by the appearance of pups that were caught with
their mothers and the appearance of the lactating females in area II (Fig. 4). In
this study, a lactating female was determined when milk secretion was found in the
mammary glands. This figure shows that pups with their mothers appeared by mid
April, and may indicate that frequency of appearance of lactating females is decreasingfrom mid April to the end of April in 1969 and 1970. Therefore, it could be suggested
that weaning occurs in mid April in area II. We also studied weaning in relation
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH OF THE HARBOUR SEALS IN HOKKAIDO

135

to moulting of the white coat. As shown in Table 3, weaning occurs simultaneouslywith moulting of the white coat. Since the parturition season in area II was considered to be from mid March to the end of March in 1969, as described above, it isconsidered that weaning occurred after two or three weeks from birth.

Phoca kurilensis
lnukai (1942b) reported that new born P. kurilensis in the southern Kurile Islands had the white coat, yet Belkin (1964) and Belkin et al. (1969) opposing lnukai,
said that pups of the same seal do not have the white coat. In this study, 20 pups
with umbilical cords were observed and the same result as Belkin was obtained.
In some cases, however, pups with lanugo coats were observed. One pup captured in the 20th of May 1969 had a grey long lanugo coat except for the head andflippers (Plate I), and also a pup captured the 25th of May in 1970 had such a coat alittle on its back. These facts may indicate that near-term fetuses have lanugo coats.
Although we have no record of a lanugo coat fetus, we obtained the informationfrom a fisherman that near-term fetuses which have such a coat were removed fromtheir mother seals caught in mid March by fishing net. This may suggest that pups
normally shed their coat in the uterus before birth. The same occurrance wasfound in P. v. richardi in the Alaska Peninsula by Stutz (1966) and Burns (1970).
The pups born in early parturition season in late May, retain all or most of theirlanugo coat for a short period after birth. Fisher (1952) has reported the yellowish
coat pup of P. v. richardi born in the peak of parturition on June 8, 1946 from the
Skeena River. In the present study, pups with lanugo coats were born not in early
but in mid parturition season.
The weaning season of this seal was estimated from the following three investigations: 1) existence of milk in the stomach of pup, 2) appearance of lactating
females, 3) appearance of pups together with their mothers in the hauling groundarea (Table 4 and 5). Table 4 seems to show that pups of which the stomachs had
contained some amount of milk, appeared in May and the beginning of June, anddisappeared at the end of June. Table 5 may show that lactating females appeared
TABLE 4.
Date
May 16
May20
May21
May22
May24
May31
Jun. 1
Jun. 2
Jun. 21Jun. 27
Jun. 28

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

FREQUENCY OF SUCKLING PUPS OF P. KURILENSIS.
Number of pupsof which stomach
contains milk

Number of pupsof which stomach
contains no milk

2

0
0
0
0
0
1
0
0

0
3
3
0
1
0

3

Total
8

0
1
9
3
4
1

136

NAITO AND NISHIWAKITABLE 5.
Date
May 13
May 16
May 18
May22
May25
May29
May30
Jun. 7
Jun. 16
Jun. 27FREQUENCY OF LACTATING FEMALES OF P. KURILENSIS.
Number oflactatingfemalesNumber ofnonlactating
females

1
2

0
0
0
0
0
0
0
0
0

I

2

1
0

Total
1
2

1
2

till mid of June.
The appearance of suckling pups in the hauling ground area was observed at
Moyururi Island. From the 9th to the 13th ofJune in 1969, all 4 pups were observedin suckling and being cared for by their mothers. From the 22nd to the 26th ofJune in 1971, 4 pups out of 7 rarely suckled, but they were observed to swim with
their mothers, and the other remaining three pups were observed in groups without
their mothers. From these three investigations, we conclude that weaning of thisseal begins to occur at the end of June. Belkin et al. (1969) suggested that the pups
caught at mid May and the Bth of August in 1963 had milk (100-450 g) in theirstomachs and their suckling continue till August, however, his result may be toolong compared with this result.

II.

Thickness of blubber in early stage of pups

Bigg (1969) and Tikhomirov (1971) suggested that the body weight of pups become
double their birth weight during the suckling period. This remarkable increase in
their body weight is mostly due to the increase in thickness of blubber. In this study,
comparison of the blubber thickness between ice breeding P. v. largha and land breeding P. kurilensis was made. The thickness of blubber was measured at the middle
point between the mammae and the umbilicus where the blubber seems to be thethickest.

Phoca vitulina largha
Measurement of blubber thickness was made on pups caught in area I, II and
III (Fig. 5). In area I, 21 pups were caught on ice floes from the 27th of April to the
2nd of May in 1971. Most pups captured here had already lost their white coats except one which still partly had its white coat, and it was estimated that weaning had
already occurred but not so long time before. Their mean blubber thickness was
5.1 cm, and seemed to be still in maximum condition. In area II, 9 pups werecaught on ice floes from the 12th of April to the 2nd of May in 1969. Seven of these9 pups were on the point of weaning and moulting the white coat, but 2 pups had
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH OF THE HARBOUR SEALS IN HOKKAIDO

137

already shed their coats. The mean blubber thickness was 4.5 cm and estimated to
be in the thickest condition. Seven pups were caught in area III from the 22nd of
May to the 27th of June in 1970 and 1971. The mean blubber thickness was
2.6 cm. All pups were caught not on the ice floe, but in water by fishing net.
6

:8" 2
arerll"en:a - - - - - - J
1--------fa.rerm0.
' ·--'---c'=----'--.,.,,___.__,.,___.__,..,____,__..___._____,.,.,,.____._---1
(9)

;l]

30

~ 6
:c
..... 410 APRIL 2030

10 MAY20

30-+--i-Y-

_J_

1

(14)

(8)

(16)

0

15

MAY

!-------~

31

15
JUNE

30
JULY

15

30

Fig. 5. Change of blubber thickness in pups of P. v. largha (above) and P. kurilensis(below). Vertical line, range; box, standard error; horizontal line in box, meanand sampling period ; foot horizontal line, time of parturition ; foot brocken line,
time of weaning.

As seen in figure 5, pups on the ice floe (area I and II) had the pretty thicker
blubber than pups in swimming life stage (area III). However, it is not clear as towhat is reason why blubber thickness seen in pups of area III is much thinner than inpups of area I and II. The following reasons should be considered: Pups consume
their blubber by swimming in the cold water (-1 to 0°C) after weaning. Concerning
the difference of blubber thickness of pups found between area I and II, we could
not discuss for the sake of short data. Tikhomirov (1971) reported that the meanvalue of 8-12 day-old pups caught on the 15-20th of April was 26.3 kg and of 1.2-2
month-old pups caught at the end of May and June was 23.9 kg. In addition, therapid growth in body length during the first month from birth were reported (Tikhomirov, 1971). These facts suggest that decrease in weight is due to decrease inblubber thickness.

Phoca kurilensis
Sixty-five pups were caught on the Pacific coast ofNemuro Peninsula from the16th of May to the 6th of July in 1969, 1970 and 1971. Figure 5 shows the blubber thickness of 48 pups out of 65 pups that were measured. As shown in figure 5,
the mean blubber thickness of pups with umbilical cord caught in later half of
May was 2.1 cm, and it was increased rapidly until 3.4 cm in early half of June.
The maximum condition of the blubber thickness may occur in the end ofJune simultaneously with the beginning of weaning. The difference of maximum
Sci. Rep. Whales Res. Inst.,

No. 42, 1972.

138

NAITO AND NISHIWAKI

thickness of blubber between two species is related to the difference in breeding
environment. As described above, pups of P. kurilensis are born on narrow rocky
shores and they begin to swim with their mothers just after birth differing from pupsof P. v. largha which do not swim before weaning. Therefore, pups of P. kurilensis
may regularly consume their blubber by swimming, and therefore remarkable accumulation may not occur.

ill.

Growth of ovaries and testes

As the index of sexual maturity, weight of ovaries and testes, and existence of the
newly formed corpus luteum in ovaries and sperm in testes and epididymis were examined in relation to age. Data collected from area I, II, III during April andMay, were examined not in each but altogether. The testes were weighed together
with the epididymis. Concerning P. kurilensis, it was difficult to describe the sexual
maturity owing to scanty of data.
20

0

8

15

0

0

.,

0

~-o--o,---;;---0-00

00o /o 8

o

;o o

o

o

/;

~ii

o

B

10

15

20

25

30

Age (years)

Fig. 6.

Growth in the weight of the ovaries of P. v. largha.

Total number is 102.

In growth of weight of ovaries and testes, 102 specimens from females and 61
specimens from males were used in figure 6 and figure 7 respectively. As shown inthese figures, decrease in weight was observed in both ovaries and testes during thefirst year. Actually, however, these decreases of weight seemed to have occurred
within short period after birth. The same occurrence was reported by Tikhomirov(1971). After that, sharp increase in weight was shown in both ovaries and testes
from 1-2 years of age to 4-5 years of age. Then, weight of these organs increase
gradually until 10 years of age.
Existence of the newly formed corpus luteum was examined in 26 females out of
102 females described above. As seen in Table 6, females from 2-7 years of age
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH OF THE HARBOUR SEALS IN HOKKAIDO

139

were used, and the corpus luteum was observed in 20% of females at 3 years of age.
All of 6 females at 4 years of age had the corpus luteum in their ovaries. Similary,
existence of sperm in testes and epididymises was examined in 15 males from 1-8
years of age. Table 6 shows that 20 % males of 3 years of age and 50 % males of 4
years of age were matured, and all of males matured from 5 years of age.

200

g

150

0

0

00

.r:.
01

"'

:;:: 100

0

50

0

0

Fig. 7.

1015
Age (years)

20

Growth in the weight of the testes of P. v. largha.

TABLE 6.

Total number is 61.

AGES AT SEXUAL MATURITY IN BOTH SEXES OF
P. V. LARGHA.
Females

Age
1
2
3
4
5
6
7
8

25

Number of
specimens
6
5
6
2
4
3

Males

Number of
mature females

Number of
specimens

0
6
2
4
3

5
4

Number of
mature males
00l2

From these data, it is difficult to estimate the age of sexual maturity in both
sexes exactly, but it is approximately considered that females and males of this species
reach sexual maturity from 3 years of age and mostly mature at 5-6 years of age.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

140

NAITO AND NISHIWAKI

IV. Growth of body length
Postnatal growth was well shown by Tikhomirov (1971) in P. v. largha from the Bering
Sea and Bigg (1969) in P. v. richardi from the southern coast of Vancouver Island andAlaska. In addition, Belkin (1964) and Belkin et al. (1969) reported about P.
kurilensis, in the Kurile Islands.

Phoca vitulina largha
In this chapter, data collected from areas I, II, III were summed up to describe
the postnatal growth of body length. The number of specimens used here was 150
in males and 176 in females. The growth curves are shown in figure 8, which weredrown by eye, but as for the growth curve of females, the following growth formula
was approximately applied by using Walford's graphic methods:
0<t<2
It= 132(1-e-o.ss<t+o.so>),
lt=161(1-e- 0· 26 <t+ 4 .o>)(t ' ages·' 1t• length) •
t >=2
180

160

"E
-" 140
:5

"'

c

"'

...J

120

.--t
••o • -s .-=io ·~ •u• :e °·• • •o-o~

t .
0

:

0

0

0

~Ko~•"'
8

;'11
t'f'
•o •

0

(1)

8

0

0

0
0

•

·,

(2b

~

!h

:~~

180

160

(2) 140

0

0

{:8 ~
0

100

80

•:2'

""

·"
0

:

0

10

15

20

25

Age (years)

Fig. 8. Postnatal growth in body length of P. v. largha, males (1) and females (2).
Total number is 150 in males and 176 in females. Vertical line, range- box,
standard error ; horizontal line in box, mean.

Concerning the final growth length, mean body length was obtained from theseals over 15 years of age, since the formula did not fit accurately with plots fromabout 15 years of age. In this figure, the mean length at 0 years age was 97 cm inmales and 96 cm in females, which were calculated from the length of pups collected
about one month after birth during April and May. Since birth length was presumed to be about 85 cm in former chapter, it was assumed that pups grow more than
10 cm during the first month after birth. The mean length at 1 years of age was
119 cm in males and 117 cm in females, and pups grow 34 cm for males and about
32 cm for females during the first year. About 35 %of the body length growth during
the first year seemed to be attained in the first month after birth. The growth rate in
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH OF THE HARBOUR SEALS IN HOKKAIDO

141

the first year observed in the present study is the same as Bigg (1969) showed in
P. v. richardi, but little lower than P. v. largha shown by Tikhomirov (1971).
From birth to 5 years of age, both sexes grow at about similar rate. The
growth continue until 14-15 years of age in males and 10-11 years of age in females.
Finally attained body length of the seals over 15 years of age was 169.9±4.0 cm formales and 159.0±3.1 cm for females, and the finally attained body length offemales
was 94.1 % of males.
According to Tikhomirov (1971 ), P. v. largha continues growing until 9 years ofage in males and 8 years of age in females, and physically matured body length was
168 cm in males and 162 cm in females. Sexual mature body length of females is
96.4% of males. Bigg (1969) suggested that P. v. richardi continued growing until
9-10 years of age in males and 5 years of age in females. He also reported that fullygrown body length was 161.1 cm and 147.7 cm in males and females respectively,
and sexual mature body length of females is 92.3 % of males.
Concerning the longevity, the oldest seal was 26 years of age in males and 32
years of age in females, and it seemed that females live longer than males. In another study, it was found 29 years of age and 35 years of age in male and female respectively for P. v. largha (Tikhomirov, 1971).
200

..

;{

180

'Eu

-

h

1·:
"/
0

140

Cl

c

"'

-' 120

100

80

..

.r-:

160

:

(1)
0

(2)

0

:

~·o

j
0
0

0

10

15

20

25

Age (years)

Fig. 9. Postnatal growth in body length of P. kurilensis, males (1) and females (2).
Total number is 49 in males and 57 in females.

Phoca kurilensis
Most of these data were collected from area IV, and a few from the southernpart of area III. The number of specimens used here was 49 males and 57 females,
which were collected from area IV. The extent of growth is shown in figure 9, which
was drawn by eye. In this figure, the mean length at 0 years of age was 109. 7 cm in
Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

142

NAITO AND NISHIWAKI

males and 108. 7 cm in females, which was based on the pups collected about a monthafter birth during May and June. Since the birth length of this species was 98.2 cm
as shown former chapter, new born pups grow about 10-11 cm in length during
the first month. Concerning specimens over 2 years of age, we are short of data to
describe precisely the growth aspect, but we can discuss the general tendency. Males
and females grow at about the same rate until 5-6 years of age, and from this age
onward dimorphism in body length seems to become clear. By 9-10 years of age,males attain nearly the final growth length, and females attain such length by 7-8
years of age. The maximum body length observed was 191 cm in males and 175 cm
in females. Final growth length is assumed to be about 186 cm in males and 169 cm
in females, and the final growth length of females was 90.9 % of males. This ratio
was smaller than that of P. v. largha, and P. v. richardi according to calculation basedon Bigg (1969). Belkin et al (1969) suggested that the mean length of sexual mature
males was 174 cm and 160 cm in females, and the maximum was 181 cm and 180 cm
in males and females respectively. They (1969) also recognized the clear dimorphism
in body length in immature seals, describing the mean length of 3 males and 7 females
as 139.6 cm and 126.4 cm respectively.
Concerning longevity, it is difficult to discuss with these scanty data.
DISCUSSION
In the present study, we obtained some new facts on prenatal and postnatal growth in
P. v. largha and P. kurilensis.
It was appeared that mating season and parturition season of P. kurilensis
occurred 2 months later than that of P. v. largha, and the birth length of P. kurilensis
is larger than that of P. v. largha. After the parturition, pups of pagophilic P. v.
largha bears white coat for 2-3 weeks and live on ice floes without swimming. Weaning occurs simultaneously with moulting of white coat 2-3 weeks after birth. Concerning the weaning, it is exactly unknown whether weaning occurs suddenly or
gradually. If weaning occurred suddenly, pups would suddenly have the completely
independent life and would not have the swimming life with their mothers,
furthermore they would not learn the feeding from their mothers. Table 3 mayshow that departure from the mother occurs quickly as moulting begins to occur.
So that, pups may be left alone on ice floes and have the completely independent life.
It is also unknown whether pups have swimming life soon after weaning or some timeafter weaning. If they remained on ice floes, they would be carried by ice floes andtheir distribution would spread. On the other hand, pups of pagophobic P. kurilensis
do not have the white coat when they were born. They have the swimming life
with their mothers soon after birth, and their suckling is chiefly performed in thewater. Weaning occurs about 4 weeks after birth. This period is longer than thatof P. v. largha. It is also exactly unknown whether weaning occurs suddenly or
gradually. However, observation that pups were found with their mothers without
showing the suckling behavior may indicate that weaning occurs gradually in thisspecies, and pups may learn the feeding from their mothers.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

GROWTH OF THE HARBOUR SEALS IN HOKKAIDO

143

Concerning the early stage oflife, we also studied the thickness of blubber. In
P. v. largha, pups on ice floes have the thicker blubber and pups in the water have thethinner blubber. This result seems to indicate that change in blubber thickness isdue to change in nutritional condition of pups during suckling and weaning period.
the other hand, pups of P. kurilensis had the thinner blubber as compared with
P. v. largha. The difference in blubber thickness between two species seems to berelated with the difference in nutritional condition of life in early stage describedabove.
Concerning the growth of body length, sexual dimorphism in body length wasobserved clearly in P. kurilensis as Belkin et al. (1969) reported.
ACKNOWLEDGEMENTGreatest thanks go to Drs. T. Kajihara, K. Numachi, and T. Kasuya for their valuable advice and discussions. In the field work, greatest thanks go to Mr. K. Shibuta
and Mr. Y. Suzuki, Engaru Fur. Co., who permitted us to be on board for collecting
specimens. Greatest thanks also go to Mr. N. Kanazawa, Kanazawa Fur Co., whohelped us in collecting specimens from a number of hunters. Special thanks go to
the Abashiri Light House Office and Nemuro Light House Office of Japanese Maritime Safety Agency for assistance in field observation. Special thanks also go to Mr.
I. Yoshida, Yoshida Fisheries Co. and Mr. T. Kasahara, Kasahara Fisheries Co.,
who permitted us to use some facilities.
REFERENCES
BELKIN, A. N., 1964. A new kind of seal from the Kurile Islands. Doklady Akad. Nauk SSSR., 158(2): 12171220.
BELKIN, A. N., G. M. KosYGIN, and K. I. PANIN., 1969. Marine mammals. Academy of Sciences of U.S.S.R.,
Ministry of Fisheries of U.S.S.R., Moscow., 157-175.
Bma, M.A., 1969. The harbour seal in British Columbia. Bull. Fish. Res. Bd. Canada, 172 : 1-33.
BuRNs,J.J., 1970. Remarks on the distribution and natural history ofpagophilic Pinnipeds in the Bering and
Chukchi Seas. J. Mamm. 51(3): 445-454.
FISHER, H. D., 1952. The status of the harbour seal in British Columbia, with particular reference to the
Skeena River. Bull. Fish. Res. Bd. Canada, 93: 1-58.
INUKAI, T., 1942a. Hair seals in our northern waters (I). Shokubutsu Dobutsu, 10(10): 927-932. (in Japanese).
INUKAI, T., 1942b. Hair seals in our northern waters (II). Shokubutsu Dobutsu, 10(11): 1025-1030. (inJapanese).
KING, J.E., 1964. Seals ef the world. British Museum, London, 154 pp.
MANSFIELD, A. W., and H. D. FISHER, 1960. Age determination in the harbour seal, Phoca vitulina. Nature,186: 192-193.
McLAREN, I. A., 1958. The biology of the ringed seal (Phoca hispida Schreber) in the eastern Canadian Arctic.
Bull. Fish. Res. Bd. Canada, 118: 1-97.
McLAREN, I. A., 1966. Taxonomy ofharbor seals of the western North Pacific and evolution of certain otherhair seals. J. Mamm., 47(3): 466-473.
NAITO, Y., 1971. A report on Japanese sealing. Geiken Tsushin, 238: 49-52. (in Japanese).
NISHIWAKI, M., and F. Nagasaki, 1960. Seals of the Japanese coastal waters. Extrait de Mammalia, (243):459-467.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

144

NAITO AND NISHIWAKISCHEFFER, V. B., andJ. W. SLIPP, 1944. The harbor seal in Washington State. Am. Midland:Nat., 32(2):373-416.
SCHEFFER, V. B., 1958. Seal sea lions and walruses. Stanford University Press, Stanford, 179 pp.
STUTZ, S.S., 1966. Foetal and postpartum white coat pelage in Phoca vitulina. J. Fish. Res. Bd. Canada, 23(4):607-609.
TrKHOMIROV, E. A., 1971. Body growth and development of reproductive organs of the North Pacific Phocids.
Pinnipeds ef the North Pacific. (Israel program for scientific translations). Keter Press, Jerusalem, 213241.
WILKE, F., 1954. Seals of northern Hokkaido. J. Mamm., 35(2): 218-224.

EXPLANATION OF PLATE I
Fig. 1.
Fig. 2.
Fig. 3.
Fig. 4.

A female embryo of P. v. largha, 20 cm in length, about 5 months before birth (collected
on 14th of October).
A male embryo of P. kurilensis, 9.5 cm in length, about 7 months before birth (collected
on 14th of October).
A male white coat embryo of P. v. largha, 58.5 cm in length, about 2 months before
birth (collected on 19th of January).
A new born male pup of P. kurilensis with umbilical cord which beared grey lanugo
coat, 89 cm in length (collected on 20th of May).

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

．
−
−

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＂
＇

．
一
−
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DiV／
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DIVING DEPTH OF NORTHERN FUR SEALSIN THE FEEDING TIMETADAYOSHI ICHIHARA* AND KAZUMOTO YOSHIDA*
Northern fur seals (Callorhinus ursinus) are sometimes taken by fishing gears in the
open waters. Scheffer (1946) reports seven cases of fur seals taken accidentallyby the floating drift net along the Oregon coast of the eastern Pacific and he estimates that fur seals can dive 24 feet (7 meters) to 240 feet (73 meters) below thesea surface. Kenyon ( 1952) states that fur seals off Sitka, Alaska, have no evidence
which they descend much deeper than 30 fathoms (55 meters). He estimates thediving depth of fur seals from the depth of fishing lines on which fur seals sometimes get hooked. In these two reports, there is no description on the time when
fur seals were taken by nets or lines.
Generally, fur seals at sea show the inactive behaviors in the day time, except
for the migrating period from the breeding islands to wintering areas or from thelatter to the former. In the wintering area off the Pacific coast of the northern
Ja pan, sleeping fur seals often are observed in the day time. Japanese research
vessels for fur seals have observed and recorded the behavior of seals before these
seals are taken at sea. Provided that swimming or moving to some directions
indicates the active behavior and sleeping or resting at a location does the inactive
behavior of seals, we can examine from the observation records when fur seals move
about at sea. The activity index (M) of seals at sea, therefore, will be expressedby the following formula.

100
90

£> 80

:;:;
u

"'

~

cQ)

u

70
60

m
0.. 50
40
30
4

5

6

7

8

9

10 11 12 13 14 15 16 17 18 19 20
Hour in the day

Fig. I. Activity offur seals at sea in each hour of the day, in the Pacific coast of thenorthern Japan from March through June.

* Far Seas Fisheries Research Laboratory, Fisheries Agency.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972, 145-148.

146

ICHIHARA AND YOSHIDA

M=a / a+i X 100
Where, a is the number of active seals and i is the number of inactive seals
at the time of observation. Fig. 1 is given when the value of M is arranged byeach hour in a day on the basis of observation records from March through June,
when is the latter half of the wintering season of fur seals. Number of seals observed comprised 1483 males and 1677 females from 1958 to 1967. In both sexes,
while seals are the most inactive at 1000 in the morning, they are active before
0600 in the morning and after 1800 in the afternoon. Hence, 5 of 10 seals are in
the state of sleeping or resting at 1000. This pattern of activity is maintained inspite of the progress of month. Although females are relatively more active thanmales, it is clear that fur seals are the nocturnal animal. According to several
records, fur seals unexpectedly observed at night always were quick in action.
Such a nocturnal behavior relates directly to feeding activity of fur seals. Mostof seal stomaches collected in the day time has no food or food under digestion.
According to the report of the Japanese pelagic research in 1958 off the coast of
the northern Japan, about 90% of seals taken at 0500 has food in their stomachs.
With the progress of hour in the day time, the occurrence of empty stomach increases and reaches 80% of the total samples collected at 1800 in the afternoon.

---------~...,•• 1"11""••*"'4UW:sa •au 11·--· t

·'

M
0

50

Fig. 2. Images of diving fur seals recorded by the echo-sounder of 28 KHz, in theJapan Sea.

After examining the digestive stages of food in the stomach by each hour, thisreport suggests that fur seals generally take food before sunrise. When the feeding
activity of fur seals reaches the maximum is not known because the hunting of seals
at night is difficult. Probably the searching activity for food at night determines
the nocturnal behavior of fur seals.
In the pelagic research in the Ja pan Sea, we fortunately took the records ofSci. Rep. Whales Res. Inst.,
No. 24, 1972.

DIVING DEPTH OF NORTHERN FUR SEALS

147

diving fur seals with eco-sounder of 28 KHz. At 1900 on May 3 in 1970, theresearch vessel Tokai University II, 702.61 ton, stopped to sail as it became dark
at the location of 39-47 N, 132-47 E in the western Japan Sea. It was foggy inthe evening and the visibility was about 150 meters. In the afternoon of that day,no seal was observed along the sailing course of the vessel. Induced by the lightfrom the deck, however, 5 seals began to swim about the vessel and sometimes passed
beneath the bottom of vessel. The sonar which operated continuously throughthe voyage to examine the vertical distribution of marine organisms, took the swimming images of fur seals on the recording paper. As the vessel was equipped withthe sonar at the bottom of the bridge, from the bridge we could confirm seals coming
to surface to respire. The other mammals than fur seals were not observed in thewaters near the research vessel. The click of dolphins recorded through 28 KHz
echo-sounder by Shibata and Nishimura (1969) was not observed in our recording
paper. Fig. 2 shows the diving images of seals within the beam of 28 KHz sound.
Such clear images were recorded from 1937 through 2245 at night and afterwards
1 or 2 seals repeated to enter the beam of sonar.

0
M

.•·
~, ....

50

Fig. 3.

Experimental image of a killed fur seal recorded by the echo- sounder of

28KHz.

In order to confirm the image of animal observed on the record of sonar, we
Sci. Rep. Whales Rep. Inst.,
No. 24, 1972.

148

ICHIHARA AND YOSHIDA

tried a test by using a killed fur seal. On May 19, we took a female seal of age
5 in the Pacific coast of the northern Japan. The body weight and the body lengthof the animal was 34 Kg and 128 cm respectively. Two small boats were prepared
for the test in both sides of the research vessel. The weighted seal tied up witha long rope was pulled rapidly in the water along the center of beam of sound.
When the seal passed through the bottom of the research vessel, an image wasrecorded as shown in Fig. 3. We can find the similarlity in images between Fig.
2 and Fig. 3, although the recorded depths are different between them.
In Fig. 2, fur seals swim in the depth of 100 meters and over from 40 meters
under the drifting vessel. The record of sonar shows that deeply diving seals do
not move horizontally but move rapidly to the deeper waters. As fur seals pursued
after schools of squids which were induced by the light of vessel, it is reasonable
to suppose that these records indicate the diving depth in the feeding periodof fur seals. The species of squids was not determined. The water temperature
was 10.1°C in 0 meter, 9. 7°C in 10 meters, 8.6°C in 25 meters, 5.3°C in 50 metersand 2.8°C in 100 meters deep at the position of recording, and no remarkable
thermocline was observed within 100 meters in depth. These fur seals were notbull at the naked eye observation on their sizes in the sea surface. This record
indicates that fur seals descend the depth over 100 meters in the feeding and thatthey can dive deeper than in the previous records.
REFERENCES
JAPANESE FISHERIES AGENCY, 1959. Report of Japanese fur seal research in 1958. Tokai Regional Fisheries
Research Laboratory, Special publication, 6: 32 p.
KENYON, K. W., 1952. Diving depths of the steller sea lion and Alaska fur seal. J. Mamm., 33 (2): 245-6.
SCHEFFER, V. B., 1946. How deep will a fur seal dive? Murrelet, 27 (2): 25.
SHIBATA, K. and M. NrsHIMURA, 1969. Analysis offish-finder records-VIII, Classification and interpretationof echo trace on the tuna fishing ground. Bull. of the Faculty of Fisheries, Nagasaki University, 28: 43-67.

Sci. Rep. Whales Res. Inst.,
No. 24, 1972.

THE SCIENTIFIC REPORTS OF THE WHALES RESEARCHINSTITUTE, T9KYO, JAPANNUMBER 1, JUNE 1948
Akiya, S. and Tejima, S. Studies on digestive enzym,:: in whale. 3-7
Akiya, S. Ishikawa, Y., Tejima, S. and Tanazawa, T. Studies on tryptase from a whale (Balaenoptera borealisL.). 8-10
Akiya, S., Tejima, S. and Ishikawa, Y. Studies on tJ:ie utilization of whale meat by the use of pancreatic
tryptase of whales. 11-14
Akiya, S. and Kobo, F. The test culture of some microorganisms with whale meat peptone. 15-16
Nakai, T. Chemical studies on the freshness of wha,le meat. I. Evaluation of freshness and changes inquantity of several kinds of nitrogen in whale meat following deterioration of freshness. 17-26
Nakai, T. Chemical studies on the freshness of whale meat. II. On comparison between whale meat andbeef on deterioration of freshness and autolysis. 27-30
Tawara, T. On the simultaneous extraction of vitamin A-D and vitamin B2 complex from the liver of afin whale (Nagasu-Kujira, Balaenoptera physalus L.). 31-37
Tawara, T. Studies on whale blood. I. On the separation of histidine from whale blood. 38-40
Nakai,J. and Shida, T. Sinus-hairs of the sei whale (Balaenoptera borealis). 41-47

NUMBER 2, DECEMBER 1948
Ogawa, T. and Arifuku, S. On the acoustic system in the cetacean brains. 1-20
Yamada, M. Auditory organ of the whalebone whales. (Preliminary report). 21-30
Nakai, T. Chemical studies on the freshness of whale meat. III. Effect of hydrogen-ion concentration on
decrease in freshness and titration curve of whale meat·with HCl and Na 2 C0 3 • 31-34
Ishikawa, S., Omote, Y. and Soma, Y. Analytical distillation of vitamin A in the whale liver oil. 35-41
Ishikawa, S., Omote, Y. and Kanno, H. Molecular distillation of sperm whale blubber oil. 42-45
Kaneko, A. Molecular distillation of fin whale liver oil. 46-50
Akiya, S. and Takahashi, K. Determination oftryptophane in whale meat. 51-54
Ishikawa, Y. and Tejima; S. Protein digestive power of sperm whale pancreatic enzyme. 55-60
Tsukamoto, S. Experiment on digestion of whale meat by koji-mould. 61-66

NUMBER 3, FEBRUARY 1950
Ogawa, T. and Shida, T. On the sensory tubercles of lips and of oral cavity in the sei and the fin whales.
1-16Ohe, T. Distribution of the red marrow in bones of the fin whale. 17-22
Hosokawa, H. On the cetacean larynx, with special remarks on the laryngeal sack of the sei whale andthe aryteno-epiglottideal tube of the sperm whale. 23-62
Akiba, T., Tsuchiya, T., Umehara, M. and Natsume, Y. Bacteriological studies on freshness of whale
meat. (Report No. 1). 63-70
Ishikawa, Y. Protein digestive power of sperm whale pancreatic enzyme. II. 71-78
Mori, T. and Saiki, M. Properties of fats and oils contained in various parts of a sperm whale body.
79-84
Tawara, T. and Fukazawa, R. Studies on kitol. I. Preparation ofkitol from whale liver oil. 85-88
Tawara, T. and Fukazawa, R. Studies on kitol. II. Influence ofkitol fraction on the determination of theInternational Unit of Vitamin A. 89-91
Tawara, T. and Fukazawa, R. Studies on kitol. III. The effect of sunlight, air and heat on the vitamin
A and kitol fractions. 92-95

ii
Tawara, T. On the respiratory pigments of whale (Studies on whale blood II.). 96-101
Yoshida, M. Research on methionine in whale. 102-105
Mizue, K. Factory ship whaling around Bonin Islands in 1948. 106-118
Mizue, K. and Jimbo, H. Statistic study of foetuses of whales. 119-131
Nishiwaki, M. and Hayashi, K. Biological survey of fin and blue whales taken in the Antarctic season
1947-48 by the Japanese fleet. 132-190

NUMBER 4, AUGUST 1950
Omura, H. On the body weight of sperm and sei whales located in the adjacent waters of Japan. 1-13
Omura, H. Diatom infection on blue and fin whales in the Antarctic whaling area V (the Ross Sea area).
14-26
Omura, H. Whales in the adjacent waters of Japan. 27-113
Nishiwaki, M. Determination of the age of Antarctic blue and fin whales by the colour changes in crystalline
lens. 115-161
Nishiwaki, M. Age characteristics in baleen plates. 162-183
Nishiwaki, M. On the body weight of whales. 184-209

NUMBER 5, JUNE 1951
Akiba, T., Umehara, M. and Natsume, Y. Bacteriological studies on freshness of whale meat. (Report
No. II.). 1-4
Hosokawa, H. On the pelvic cartilages of the Balaenoptera-foetuses, with remarks on the specifical andsexual difference. 5-15
Ohe, T. Iconography on the abdominal cavity and viscera of the Balaenoptera, with special remarks upon
the peritoneal coverings. 17-39
Akiya, S. and Hoshino, 0. Isolation ofhistidine from whale blood using 3, 4-dichlorobenzene sulfonic acid.
41-47
Tawara, T. and Fukazawa, R. Studies on kitol. IV. Purification of kitol by chromatographie. 49-51
Ishikawa, S., Omote, Y. and Okuda, H. Substances related to vitamin A in the whale liver oil. 53-59
Ishikawa, S., Omote, Y., Kijima, M. and Okuda, H. Thermal decomposition ofkitol. 61-69
Mizue, K. Grey whales in the east sea area of Korea. 71-79
Mizue, K. Food of whales (In the adjacent waters of Japan). 81-90
Nishiwaki, M. and Ohe, T. Biological investigation on blue whales (Balaenoptera musculus) and fin whales(Balaenoptera physalus) caught by the Japanese Antarctic whaling fleets. 91-167

NUMBER 6, DECEMBER 1951
Hosokawa, H. On the extrinsic eye muscles of the whale, with special remarks upon the innervation andfunction of the musculus retractor bulbi. 1-33
Murata, T. Histological studies on the respiratory portions of the lungs of cetacea. 35-47
Kojima, T. On the brain of the sperm whale (Physeter catodon L.). 49-72
Mizue, K. and Murata, T. Biological investigation on the whales caught by the Japanese Antarctic whaling
fleets season 1949-50. 73-131
Nishiwaki, M. On the periodic mark on the baleen plates as the sign of annual growth. 133-152
Nishiwaki, M. and Hibiya, T. On the sexual maturity of the sperm whales (Physeter catodon) found in theadjacent waters of Japan (I). 153-165
Nakai, T. Chemical studies on freshness of whale meat. IV. Some informations of Archomobacter ubiquitum
isolated from whale carcass. 167-176
Nakai, T. and Ono, H. The effects of electric shock and fatigue on post-mortem changes in muscle. 177185

iii
Omote, Y. Complete recovery of vitamin A from molecular distillation residue of whale-liver oil. 187191
Omote, Y. Chemical structure ofkitol (I). Double bonds and hydroxyl groups. 193-198
Hirata. M. Experimental investigation on flatterned head harpoon. An attempt for restraining ricochet.
199-207"NUMBER 7, JULY 1952
Ogawa, T. ,On the cardiac nerves of some cetacea, with special reference to those ofBerardius bairdii Stejneger.
1-22
Akiya, S., Hoshino, 0. and Motohashi,' N. On an attempt to preserve whale meat freshness with 5-nitrofurfuriden aminoguanidine from decay. 23-30
Akiya, S. and Sawamura, R. Colorimetric determination of 5-nitro-2-furfuridene aminoguanidine. 31-36
Tomiyama, S. and Takao, M. Studies on utilization of higher fatty alcohol from sperm whale oil. 3746
Omote, Y. A rapid method for the separate determination of vitamin A and kitol in the whale-liver oil.
47-50
Arai, Y. and Sakai, S. Whale meat in nutrition. 51-67
Yamaguchi, K. and Fujino, K. On the serological constitution of striped dolphin (f'rodelphinus caeruleo-albus(Meyen)) (I). 69-77
Nishimoto, S., Tozawa, M. and Kawakami, T. Food ofsei whales (Balaenoptera borealis) caught in the Bonin
Island waters. 79-85
Nishiwaki, M. On the age-determination of Mystacoceti, chiefly blue and fin whales. 87-119
Nishiwaki, M. and Hibiya, T. On the sexual maturity of the sperm whales (Physeter catodon) found in theadjacent waters of Japan (II). 121-124
Ohno, M. and Fujino, K. Biological investigation on the whales caught by the Japanese Antarctic whaling
fleets, season 1950/51. 125-188

NUMBER 8, JUNE 1953
Yamada, M. Contribution to the anatomy of the organ of hearing of whales. 1-79
Omura, H. Biological study on humpback whales in the Antarctic whaling areas IV and V. 81-102
Fujino, K. On the serological constitutions of the sei-, fin-, blue- and humpback-whales (I). 103-125
Ogawa, T. On the presence and disappearance of the hind limb in the cetacean embryos. 127-132
Nishiwaki, M. and Yagi, T. On the age and the growth of teeth in a dolphin (Prodelphinus caeruleo-albus).
(I). 133-146
Kakuwa, Z., Kawakami, T. and Iguchi, K. Biological investigation on the whales caught by the Japanese
Antarctic whaling fleets in the 1951-52 season. 147'-213
Nishiwaki, M. Hermaphroditism in a dolphin (Prodelphinus caeruleo-albus). 215-218

NUMBER 9, JUNE 1954
Akiya, S., Hoshino, 0. and Motohashi, N. Attempt to preserve freshness of whale meat with germicides.
II. 1-10
Ogawa, T. On the musculature of the sinus venosus and its continuation with the so-called conducting
system of the whale's heart. 11-35
Yamada, M. Some remarks on the pygmy sperm whale, Kogia. 37-58
Yamada, M. An account of a rare porpoise, Feresa Gray from Japan. 59-88
Omura, H. and Fujino, K. Sei whales in the adjacent waters ofJapan. II. Further studies on the external
characters. 89-103
Fujino, K. On the serological constitution of the sperm- and baird's beaked-whales (I) Bldod groups of theiv
sperm- and baird's beaked-whales. 105-120
Fujino, K. On the body proportions of the fin whales (Balaenoptera physalus (L) caught in the northern
Pacific Ocean (I) (Preliminary report). 121-163
Nishiwaki, M., Hibiya, T. and Kimura, S. On the sexual maturity of the sei whale of the Bonin waters.
165-177
Uda, M. Studies of the relation between the whaling grounds and the hydrographical conditions (I). 179187

NUMBER 10, JUNE 1955
Hosokawa, H. Cross-section of a 12 mm dolphin embryo. 1-68
Nemoto, T. White scars on whales (I) Lamprey marks. 69-77
Omura, H. and Nemoto, T. Sei whales in the adjacent waters ofJapan. III. Relation between movement
and water temperature of the sea. 79-87
Omura, H., Fujino, K. and Kimura, S. Beaked whaleBerardius bairdi of] apan, with notes of,Z:iphius cavirostris.
89-132
Fujino, K. On the body weight of the sei whales located in the adjacent waters of Japan (II). 133-141
Nishiwaki, M. On the sexual maturity of the Antarctic male sperm whale (Physeter catodon L.). 143-149
Ohta1 K. et al. Composition of fin whale milk. 151-167

NUMBER 11, JUNE 1956
Omura, H. and Sakiura, H. Studies on the little piked whale from. the coast of Japan. 1-37
Nishiwaki, M., Hibiya; T. and Kimura, S. On the sexual maturity of the sperm whale (Physeter catodon)
found in the No~th Pacific. 39-46
Fujino, K. On the body proportions of the sperm whales (Physeter catodon). 47-83
Fujino, K. On the serological constitution of the fin whales II. Further studies on blood groups. 8598
Nemoto, T. On the diatoms of the skin film of whales in the northern Pacific. 99-132
Hoshina, T. and Sugiura, Y. On a skin disease· and a nematode parasite of a dolphin, Tursiops truncatus(Montagu, 1821). 133-138
Iwai, E. Descriptions on unidentified species of dibranchiate cephalopods. I. An oegopsiden squid belonging to the genus Architeuihis. 139-151 .
Iwai, E. Descriptions on unidentified species· of dibranchiate cephalopods. II. A cranchiidae squid- of thegenus Taonius. 153-161
Uda, M. and Nasu, K. Studies of the whaling grounds in the northern sea-region of the Pacific Ocean inrelation to the meteorological and oceanographic conditions. (Part I). 163-179
Kimura, S. and Nemoto, T. Note on a minke whale kept alive in aquarium. 181-189
Ishikawa, Y. A characteristic property of whale -Oils concerning the absorption of gases. I. On the absorption of carbon dioxide by whale oils. 191-213

NUMBER 12, JUNE 1957
Omura, H. Osteological study of the little piked whale from the coast ofJapan. 1-21
Nishiwaki, M. Age characteristics of ear plugs of whales. 23-32
Nemoto, T. Foods of baleen whales in the northern Pacific. 33-89
Nasu, K. Oceanographic conditions of the whaling grounds in the waters adjacent to Aleutian Islands andthe Bering Sea in summer of 1955. 91-101
Kimura, S. The twinning in southern fin whales. 103-125
Ichihara, T. An application of linear discriminant function to external measurements of fin whale. 127189

v

Nishiwaki, M. Very small embryo ofcetacea. 191-192.
Nishiwaki, M. One-eyed monster of fin whale. 193-195
Ogawa, T. and Kamiya, T. A case of the cachalot with protruded rudimentary hind limbs. 197-208
Uda, M. and Dairokuno, A. Studies of the relation between the whaling grounds and the hydrographic
conditions. (II) A study of the relation between the whaling grounds off Kinkazan and the boundary.of water masses. 209-224·Abe, T. Notes on fishes from the stomachs of whales taken in the Antarctic. I. Xenocyttus nemotoi, a new
genus and new species of zeomorph fish of the subfamily Oreosonimae (Goode and Bean, 1895). 225233
Tsuyuki, H. On the oils contained in various blubbers of northern elephant seal, Mirounga angustirostris.
235-240NUMBER 13, SEPTEMBER 1958
Omura, H. North Pacific right whale. 1-52
Nishiwaki, M. and Kamiya, T. A beaked whale Mesopladon stranded at Oiso beach, Japan. 53-83
Nishiwaki, M. and Handa, C. Killer whales caught in the coastal waters off Japan for recent 10 years.
85-96
Ohsumi, S. (Kimura), Nishiwaki, M. and Hibiya, T. Growth of fine whale in the northern Pacific. 97-133
Nishiwaki, M., Hibiya, T. and Ohsumi, S. (Kimura). Age study of sperm whale based on reading of toothlaminations. 135-153
Nishiwaki, M., Ichihara, T. and Ohsumi, S. (Kimura). Age studies of fine whale based on ear plug. 155169
Fujino, K. On the serological constitution of fin whale. III. Human B blood group substances in erythrocytes and some notes on anti-fin Ju specific antibodies. 171-184
Nemoto, T. Cocconeis diatoms infected on whales in the Antarctic. 185-191
Nemoto, T. and Nasu, K. Thysanoessa macrura as a food of baleen whales in the Antarctic. 193-199
Ichihara, T. Gray whale observed in the Bering Sea. 201-205
Ohsumi, S. (Kimura). A descendant of Moby Dick or a white sperm whale. 207-209
Nasu, K. Deformed lower jaw of sperm whale. 211-212
Omura, H. Note on embryo of Baird's beaked whale. 213-214
Uda, M. and Suzuki, N. Studies of the relation between the whaling grounds and the hydrographic conditions. III. 215-229
Seki, Y. Observations on the spinal cord of the right whale. 132-251
Kamiya, T. How to count the renculi of the cetacean kidneys, with special regard to the kidney of theright whale. 253-267
Hosokawa, H. and Sekino, T. Comparison of the size of cells and some histological formations between
whales and man. 269-301
Ogawa, T., Tsunoda, T. and Osawa, M. Amino acid composition of whale meat. 303-307
Ishikawa, Y. A characteristic property of whale oils concerning the absorption of gases. II. On theabsorption of nitrogen by whale oils. 309-321
Tsuyuki, H. Component fatty acids of northern elephant seal oil. 323-332

NUMBER 14, SEPTEMBER 1959
Omura, H. Bryde's whales from the coast ofJapan. 1-33
Nishiwaki, M. and Kamiya, T. Mesoplodon stejnegeri from the coast ofJapan. 35-48!'lishiwaki, M. Humpback whales in Ryukyuan waters. 49-87
Cushing, John E., Fujino, K. and Takahashi, K. Glycerol-freezing technique as an aid in blood typing
ofwhales. 89-100
Fujino, K. and Cushing, John E. Blood typing of dried whale erythrocytes with 1 311 labelled antibody.
101-106

vi
Ichihara, T. Formation mechanism of ear plug in baleen whales in relation to glove-finger. 107-135
Nasu, K. Surface water condition in the Antarctic whaling Pacific area in 1956-57. 137-143
Ohsumi, S. (Kimura). A deformed fin whale foetus. 145-147
Nemoto, T. Food of baleen whales with reference to whale movements. 149-290
Yamada, M. and Yoshizaki, F. Osseous labyrinth of cetacea. 291-304
Nakai, T. Distribution of amino acid in proteins from various parts of whale body. 305-326

NUMBER 15, NOVEMBER 1960
Nishiwaki, M. Ryukyuan humpback whaling in 1960. 1-16
Ohsumi, S. Relative growth of the fin whale, Balaenoptera physalus (Linn.). 17-84
Fujino, K. Immunogenetic and marking approaches to identifying subpopulations of the North Pacificwhales. 85-142
Nasu, K. Oceanographic investigation in the Chukchi Sea during the summer of 1958. 143-158
Tokita, K. and ECG Research Group. Electrocardiographical studies on bottlenosed dolphin (Tursiops
truncatus). 159-165

NUMBER 16, MARCH 1962
Omura, H. Bryde's whales occurs on the coast of Brazil. 1-5
Omura, H. Further information on Bryde's whales from the coast ofJapan. 7-18
Nishiwaki, M. Ryukyuan whaling in 1961. 19-28
Nemoto, T. A secondary sexual character of fin whales. 29-34
Omura, H., Nishiwaki, M., Ichihara, T. and Kasuya, T. Osteological note ofa sperm whale. 35-45
lchihara, T. Prenatal dead foetus of baleen whales. 47-60
Nishiwaki, M. Mesoplodon bowdoini stranded at Akita beach, Sea ofJapan. 61-77
Nishiwaki, M. Observation on two mandibles of Mesoplodon. 79-82
Sinclair, John. An early dolphin embryo (Stenella caeruleoalbus) in serial sectibns. 83-87
Nemoto, T. Food of baleen whales collected in recent Japanese Antarctic whaling expeditions, 89-103
Uda, M. Subarctic oceanography in relation to whaling and salmon fisheries. 105-119

NUMBER 17, FEBRUARY 1963
Nishiwaki, M., Ohsumi, S. and Maeda, T. Change of form in the sperm whale accompanied with growth.
1-14
Ohsumi, S., Kasuya, T. and Nishiwaki, M. The accumulation rate of dentinal growth layers in the maxil·
lary tooth of the sperm whale. 35-35
Ichihara, T. Photometric method for counting laminae in ear plug of baleen whale. 37-48
Yoshikawa, T. and Suzuki, T. The lamination of the masseter of the humpback whale. 49-52
Fujino, K. Intra-uterine selection due to maternal-foetal in compatibility of blood type in the whales. 53-65
Cushing, J.E., Fujino, K. and Calaprice, N. The Ju blood typing system of the sperm whales and specificsoluble substances. 67-77
Nemoto, T. New records of sperm whales with protruded rudimentary hind limbs. 79-81
Nemoto, T. and Nasu, K. Stones and other aliens in the stomachs of sperm whales in the Bering Sea. 83-91
Nishiwaki, M. Taxonomical consideration on genera of Delphinidae. 93-103
Nasu, K. Oceanography and whaling ground in the subarctic region of the Pacific Ocean. 105-155
Nemoto, T. Some aspect of the distribution of Calanus ·cristatus and C. plumchrus in the Bering and its neighbouring waters, with reference to the feeding of baleen whales. 157-170
Tsuyuki, H. and Naruse, U. Studies on the oil of black right whale in the northern Pacific Ocean. 171-190
Yagi, T., Nishiwaki, M. and Nakajima, M. A preliminary study on method of time marking with lead-salt
and tetracycline on the teeth of northern fur seal. 191-195

vii

NUMBER 18, MARCH 1964
Fujino, K. Fin whale subpopulations in the Antarctic whaling areas II, III and IV. 1-28
Ichihara, T. Prenatal development of ear plug in baleen whales. 29-48
Ohsumi, S. Examination on age determination of the fin whale. 49-88
Nemoto, T. School of baleen whales in the feeding areas. 89-110
Okutani, T. and Nemoto, T. Squids as the food of sperm whales in the Bering Sea and Alaskan Gulf. 111-122
Ohsumi, S. Comparison of maturity and accumulation rate of corpora albicantia between the left and rightovaries in cetacea. 123-148
Omura, H. A systematic study of the hyoid bones in the baleen whales. 149-170
Nishiwaki, M. Revision of the article "Taxonomical consideration on genera of Delphinidae" in No. 17.
171-172
Tsuyuki, H. and Naruse, U. Studies on the lipids in brain of black right whale in the northern Pacific Ocean.
173-180

NUMBER 19, APRIL 1965
Ohsumi, S. Reproduction of the sperm whale in the north-west Pacific. 1-35
Kasuya, T. and Ichihara, T. Some informations on minke whales from the Antarctic. 37-43
Nemoto, T. and Kasuya T. Foods of baleen whales in the Gulf of Alaska in the North Pacific. 45-51
Nishiwaki, M., Nakajima, M., and Kamiya, T. A rare species of dolphin (Stenella attenuata) from Arari,Japan. 53-64
Nishiwaki M., Kasuya, T., Tobayama, T., Kamiya, T., and Nakajima, M. Feresa attenuatawere caught andkept at Ito, Japan. 65-90
Nakajima, M. and Nishiwaki, M. The first occurrence of a porpoise (Electra electra) in Ja pan; 91-104
Hosokawa, H. and Kamiya, T. Sections dfthe dolphin's head (Stenella caeruleoalba). 105-133
Ohsumi, S. A dolphin (Stenella caeruleoalba) with protruded rudimentary hind limbs. 135-136

NUMBER 20, APRIL 1966
Ohsumi, S. Sexual segregation of the sperm whale in the North Pacific. 1-16
Ichihara, T. Criterion for determining age of fin whale with reference to ear plug and baleen plate. 17-82
Kasuya, T. Karyotype of a sei whale. 83-88
Kasuya, T. and Ohsumi, S. A secondary sexual character of the sperm whale. 89-94
Nishiwaki, M. and Norris, K. S. A new genus, Peponocephala, for the odontoceti cetacean species electra electra.
95-100
Nishiwaki, M., Nakajima, M. and Tobayama, T. Preliminary experiments for dolphin marking. 101.;.107
Nemoto, T. Thysanoessil. euphausiids, comparative morphology, allomorphosis and ecology. 109-155
Nasu, K. Fishery oceanographic study on the baleen whaling grounds. 157-210
Ichihara, T. and Nishiwaki, M. External measurements and weight ofa southern elephant seal. ·2ll-212
Tsuyuki, H. and Itoh, S. Studies on the oils contained in blubber of a southern elephant seal. 213-221

NUMBER 21, MAY 1969
Omura, H., Ohsumi, S., Nemoto, T., Nasu, K. and Kasuya, T. Black right whales in the North Pacific. 1-78
Nishiwaki, M. and Hasegawa, Y. The discovery of the right whale skull in the Kisagata shell bed. 79-84
Ohsumi, S. Occurrence and rupture ofvarginal band in the fin, sei, and blue whales. 85-94
Hosokawa, H., Igarashi; S., Kamiya, T. and Hirosawa, K. Morphological characteristics and myelinizationof acoustic system in the dolphins (Stenella caeruleoalba). 95-123
Mo!, T. and van Bree, P.J.H. A short contribution to the history of whaling in Japan during the 17th
century. 125-139
Tsuyuki, H. and Itoh, S. Fatty acid composition offinless porpoise oil. 131-135
Tsuyuki, H. and Itoh, S. Fatty acid composition of many toothed pilot whale oil. 137.:..141

viii.

NUMBER 22, JUNE 1970
Omura, H., Ichihara, T. and Kasuya, T. Osteology of pygmy blue whale with additional information on
external and other characteristics. 1-27
Nishiwaki, M. and Kasuya, T. Recent record of gray whale in the adjacent waters of Japan and a consideration on its migration. 29-37
Kasuya, T. and Rice, D. W. Note on baleen plates and on arrangement of parasitic barnacles of graywhale. 39-43
Nishiwaki, M. and Kasuya, T. A Greenland right whale caught in the Osaka Bay. 45-62
Nasu, K. and Masaki, Y. Some biological parameters for stock assessment of the Antarctic sei whale. 63-74
Ohsumi, S., Masaki, Y. and Kawamura, A. Stock of the Antarctic minke whale. 75-125
Kawamura, A. Food ofsei whale taken by Japanese whaling expeditions in the Antarctic season 1967/68.
127-152
Nemoto, T. and Yoo, K. I. An amphipod, Parathemisto gaudichaudii as a food of the Antarctic sei whale,
153-158
Tobayama, T., Uchida, S. and Nishiwaki, M. Twin foetuses from a blue white dolphin. 159-162
Machida, S. A sword-fish sword found from a North Pacific sei whale. 163-164
Tsuyuki, H. and Itoh, S. Fatty acid components of black right whale oil by gas chromatography. 165-170

NUMBER 23, SEPTEMBER 1971
Ohsumi, S. Some investigations on the school structure of sperm whale. 1-25
Kawamura, A. Influence of chasing time to stomach contents of baleen and sperm whales. 27-36
Kasuya, T. Consideration of distribution and migration of toothed whales off the Pacific coast of Japan
based upon aerial sighting record. 37-60
Omura, H. A comparison of the size of vertebrae among some species of the baleen whales with specialreference to whale movements. 61-69
Omura, H., Nishiwaki, M. and Kasuya, T. Further studies on two skeletons of the black right whale in
the North Pacific. 71-81
Nishiwaki, M. and Kasuya, T. Osteological note of an Antarctic sei whale. 83-89
Hosokawa, H. and Kamiya, T. Some observations on the cetacean stomachs, with special considerations
on the feeding habits of whales. 91-101
Lugassy, A. A., Korostoff, E. and Rabinowits, J. L. Influence of incremental lines upon the compressive
strength of sperm whale dentin. 103-110
Nishiwaki, M. and Oguro, N. Baird's beaked whales caught on the coast of Japan in recent 10 years.
111-122
Mizue, K., Nishiwaki, M. and Takemura, A. The underwater sound of Ganges river dolphins (Platanista
gange- tica). 123-128
Kasuya, T. and Nishiwaki, M. First record of Mesoplodon densirostris from Formosa. 129-137
Kawamura, A. and Kashita, K. A rare double monster of dolphin, Stenella caeruleoalba. 139-140
Tsuyuki, H. and Itoh, S.. Fatty acid components of Ganges river dolphin oil. 141-147

NUMBER 24, NOVEMBER 1972
Omura, H. An osteological study of the Cuvier's beaked whale, Ziphius carvirostris, in the northwest Pacific. 1-34.
Nishiwaki, M. and Oguro, N. Catch of the Cuvier's beaked whale off Japan in recent years. 35-41.
Nishiwaki, M. Kasuya, T. Kureha, K. and Oguro, N. Further comments of Mesoplodon ginkgodens. 4356.
Kasuya, T. Growth and reproduction of Stenella caeruleoalba based on the age determination by meansof dentinal growth layers. 57-79.

ix

Kasuya, T. and Oguro, N. A new tagging method of dolphins. 81-85.
Kasuya, T. Some informations on the growth of the Ganges dolphin with a comment on the lndus
dolphin. 87-108.
Kasuya, T and Aninul Haque, A. K. M. Some informations on the distribution of the Ganges dolphin.
109-115.
Tsuyuki, H. and Itoh, S. Fatty acid component of various blubber oils of Ganges dolphin. 117-125.
Naito, Y. and Nishiwaki, M. The growth of two kinds of harbour seals in the waters arround Hokkaido. 127-144.
Ichihara, T. and Yoshida, K. Diving depth of northern fur seals in feeding hours. 145-000.

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工NDEX
ofviii 7t
CONTENTS
5t

carvirostriscavirostris

whale

whalesix 4t

AninulAminul

七he distribu
七ion

dis七ributionand seasonal
movement

6↓

oils

oil

7
.
]
,

kinds of harbour seals
in the wa七ers arround

species of harbour seal
in the adjacen
七 wa七ers of

9，」

feedinghour百 . 145‑000. the feeding 七ime. 145‑148.