THESCIENTIFIC REPORTS
OF
THE WHALES RESEARCH INSTI1'UTE
No. 23

THE WHALES RESEARCH INSTITUTETOKYO·JAPANSEPTEMBER 1971~

j Res. Inst., No. 23 l~

THESCIENTIFICREPORTSOFTHEWHALESRESEARCHINSTITUTE
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THE
SCIENTIFIC REPORTS
OF
THE WHALES RESEARCH INSTITUTE

No. 23

THE WHALES RESEARCH INSTITUTETOKYO, JAPANSEPTEMBER 1971

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

THE SCIENTIFIC REPORTS OF THE WHALESRESEARCH INSTITUTE
CONTENTS OF NUMBER 23

Page

0HSUMI, S,
Some investigations on the school structure of sperm whale . . . . . . . .
KAWAMURA, A.
Influence of chasing time to stomach contents of baleen and sperm whales .
27
KASUYA, T.
Consideration of distribution and migration of toothed whales off the Pacificcoast of Japan based upon aerial sighting record . . . . . . . . . . . . . . 37
OMURA, H.
A comparison of the size of vertebrae among some species of the baleen whales
with special reference to whale movements . . . . . . . . . . . . . . . .
61
OMURA, H., NISHIWAKI, M. and KAsUYA, T.
Further studies on two skeletons of the black right whale in the North Pacific .
71
NrsHIWAKI, M. and KAsUYA, T.
Osteological note of an Antarctic sei whale . . . . . . . . . . . . . . . .
83
HosOKAWA, H. and KAMIYA, T.
Some observations on the cetacean stomachs, with special considerations on thefeeding habits of whales . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
LuGASSY, A. A., KoROSTOFF, E. and RABINOWITZ, J. L.
Influence of incremental lines upon the compressive strength of sperm whale
dentin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
103
NrsHIWAKI, M. and OauRo, N.
111
Baird's beaked whales caught on the coast of Japan in recent 10 years
MizuE, K., NisHIWAKI, M. and TAKEMURA, A.
The underwater sound of Ganges river dolphins (Platanista gangetica) .
123
KASUYA, T. and NISHIWAKI, M.
First record of Mesoplodon densirostris from Formosa .
129
KAWAMURA, A. and KASHITA, K.
139
A rare double monster of dolphin, Stenella caeruleoalba
TsuYUKr, H. and I TOH, S.
Fatty acid components of Ganges river dolphin oil .
141

SOME INVESTIGATIONS ON THE SCHOOL STRUCTURE
OF SPERM WHALE*SEIJI OHSUMI**
ABSTRACTSocial structure of the sperm whale is studied by means of catch of all individuals which form the same school, whale marking and whale sighting.
The sperm whale is matriarchal in social organization. Types of schools
are classified into nursery school, harem school, juvenile school, bachelor school,bull school and lone bull. The fundamental is nursery school which is a maternal family and is composed of mature females, suckling and immature
males and females. Puberal males lose their association with the nurseryschool, and make a loose bachelor school. Harem is only temporary, and it isformed joining a winned bull into nursery school in the breeding season.
Social tightness of nursery school is very close, and family lives within
the same school for long years.
Number of mature females served by a bull in harem is estimated to be 14
on an average.
INTRODUCTION

As one of the biological parametres on the stock assessment of the sperm whale(Physeter catodon), there is the number of mature females served by a bull in the
reproduction. The sperm whale is gregarious and polygamous, and it is consideredthat the males which join into the reproductive activity are only a part of all adultmales. However, it has not been confirmed yet how many bulls are needed for
reproduction. Without solution of this problem, it is difficult to get the sustainable
yield which is needed for stock management of the sperm whale. The study ofsocial behavior must be introduced for this problem.
Sperm whales migrate in the wide space of seas during the period of theirwhole life span, and their habitat is cubic and wide, so that observing the structureof schools in the waters is very difficult by means of the present technics, although
there are relatively many reports on the social behavior of the sperm whale as reviewed by Caldwell, Caldwell and Rice (1966).
For the purpose to approach the solution of the problem of school structure, I
used some results of biological investigations, such as catching all whales which form aschool, whale sighting and whale marking. And I want to offer a hypothesis on theformation of sperm whale schools, and to introduce a preliminary calculation of theratio of the number of males needed to that of mature females for reproduction.

* Draft was offered for the Special Meeting of IWC, Honolulu, March, 1970 (Doc. No. SM/SP/8)
Far Seas Fish. Res. Lab. Contribution No. 61** Far Seas Fisheries Research Laboratory, Shimizu.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971. 1-25.

2

OHSUMI

MATERIALS AND METHODS

The Whales Research Institute was permitted by the Japanese Government to takeeach and every individuals forming three schools of the sperm whales for the scientificpurposes in the coastal waters of Japan and in the pelagic oceans of the Southern
Hemisphere. The outline of the schools investigated is shown in Table 1.
TABLE 1.

THREE SCHOOLS OF SPERM WHALES CAUGHT
FOR THE SCIENTIFIC PURPOSE

Items

School A

School B

School C
0600 10 Nov., '66
40°41 1 S, 71°561 E
Long oval, long axis :120m
30-34 1 : 34, 25-29 1 : 12,
Calves: 2,
Total 48
Not recognized
S-SW
Separated into twogroups, one (14 whales)
E--+N, another SSW-S
Not found

Time found
Position found
Form of school

1015 29 Sept., '65
40°35 1 N, 144°34 1 E
A rank, 50 m spread1505 9 Nov., '66
40°341 S, 73°28' E
Fan shaped, 30 m 2 spread

Composition observedat the time of finding

35-39 1 : 5, 30-34 1 : 11, 2529 1 : 5, Calves : 5,

LeaderMoving direction
Escaping direction

Total 26
Not recognizedNE
NE/N

35-39 1 : 5, 30-34 1 : 25, 2529 1 : 11, Calves: 2,
Total 40
Not recognized

Relation to otherschools
Relation to otherwhale species
WeatherWind force anddirection
Visibility
Water and airtemperature
ShiomeSea birds
FishesNo. of' catcher boats
engaged in catching
No. of whales caught

A school of 5-6 of 35-361
long sperm whales, 3
miles apart from the
School A moving NE
Not foundw
W-WSW
Not recognized clearly but
some sperm whale likespouts were observed
Unknownbern

w, 4-5NW, 6

A sei whale 3 miles
apart from School C,
eastward
c
w, 5

Good
15.4°C, 19.5°C

5 miles
12.6°C, 14.1°C

8 miles
12. 8°C, 12 .4°C

No
Some
Mackerels
4

No
No
No
5

No
Few small birds
No
7

20*

12

39

* One whale lost

In each case of taking schools, crew of a catcher boat which found an objective
school observed and noted some informations about it on the field sheets, chasing
the school until all other boats got to gather at the position where the school was
found. These catcher boats tried to take all whales of the school co-operatively.
Four catcher boats co-operated to take School A, and five and seven boats totake Schools B and C, respectively. Positions taken are shown in Appendix-Fig.I.
Twenty whales were taken from School A, which was composed of 26 whales, 12
whales from School B of 40 whales and 39 whales from School C of 48 whales. RealSci. Rep. Whales Res. Inst.,
No. 23, 1971.

3

SCHOOL STRUCTURE OF SPERM WHALE

conditions of school composition can be estimated from Schools A and C, but School
Bis too small for its composition to be estimated. However, the materials obtained
from School B are also useful to get other biological knowledges. Biological data oneach whales caught are shown in Appendix-Tables 1-3.
As the second method of studying school structure of the sperm whales, I used
the records of the scouting boats which were engaged in the whale marking on someitems of information about sperm whales forming a school. The recorded items are
the position and time of sighting, sea conditions, whale species, number of whales
which form a school and estimated size ranges of individuals of school.
TABLE 2.

SCHOOL SIZE OF THE SPERM WHALES OBSERVED
North Pacific
Antarctic
Pelagic groundSize(whales)
1
2
3
4- 5
6- 10
11- 20
21- 3031- 5051- 7576-100101-125
Total no.
Average

Bonin Is.

2
3
5
3
3

19
19.4

Off Japan

South 50°N

North 50°N

North
of A.G.

Southof A.G.

16
12
8
22
45
54
26
30
15
7

23
5
4
13
6
11
7

221
30
21
26
24
7
10
2

15
14
9
10
10
6
3
2

23
1
7

236
20.3

69
7 .1

342
3.3

69
6.3

31
1.5

I also examined the continuance of school composition of sperm whales bymeans of checking the recaptured whales which had been marked in the same schoolat the same time of whale marking investigation.
NUMBER OF WHALES FORMING .A SCHOOL

It is really very difficult to identify the range of a school in waters. When many
whales scatter around, it is quite hard to recognize which whales form which schools.
Long time of observation will be taken to identify the same school clearly, as be used
for the social behavior of terestrial mammals. However, such an observation isalmost impracticable technically and economically in the case of marine mammals.
Whales are mobile and there have not been any proofs whether the territory of eachschool exists in the whale society in open seas. Therefore, two or more schools might
be found closely to each other in some cases. On the other hand, there is a possibility
that some whales move separately from a main school (Caldwell et al., 1966). Sometimes a school separates into two or more sub-schools, when we chase the school. It
is a problem how we should recognize a school in such cases. The individuals in thesame school must move in the same manner, then in the former case, the separate
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

OHSUMI

4ones will move with main school, and the separate groups in the latter case will gather
each other soon.
Furthermore, counting of the number of whales forming a school is practicallyvery difficult. Some members of a school may be diving at the time of counting.
Unless a long time is spent for observation on the same school or for catching all
individuals at the same chance, the real number is not obtained.
100r-~~~~~~~~~~~~~~~~-i

50

10
<f.,

5

',

'o,,
'

'o/

/P. ..................

o. . ,,' ' 'o''''\.,~c: 0.5

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\

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I

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I

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I
I
I
I

0

5
School10
composition

50

100

(whales)Fig. 1. Frequency distribution of school composition (number of whales in a school)in the sperm whale.
Open circle and broken line: Japanese coastal waters,
Closed circle and solid line: northern part of the North Pacific (north of 50°N).

In the case of whale sighting by scouting boats, the sound of engine will affectthe behavior of whales abnormally, so that we have to take this problem into accountat the time of observation of whale school by vessel. Whale sighting by means ofSci. Rep. Whales Res. Inst.,
No. 23, 1971.

SCHOOL STRUCTURE OF SPERM WHALE

5aircraft as reported by Nishiwaki (1962), Gambell (1967, 1968), Bannister (1968)
and Best (1969) will be good for this purpose, for it does not so much affect the behavior of whales. However, the method requires much money and is limited in its
activity.
Table 2 shows the frequency of school occurrence by number of sperm whales ineach school, based on the reports of scouting boats. Seasons of investigation werefrom May to September in the North Pacific, and from October to March in theSouthern Hemisphere. They are during the period from mid-spring to early autumn
in the both Hemispheres. The largest school was composed of 120 sperm whales.
There were other large schools which were composed of over 50 whales, but mostof them were noted to be composed of some smaller sub-schools. Therefore, it isconceivable that the large school is a combined group of several sub-schools. Concerning with the large sperm whale school, Caldwell et al. (1966) reviewed manyrecords, and summarized as twelve to several hundreds in harem-type groups,
with the largest record of" well over 1,000" by Boyer (1946). According to Gambell(1967), the highest number was 200 animals off the coast of South Africa.
Frequency of occurrence of single whale increases as the investigation area
shifts to higher latitude. Table 2 also shows the average numbers of whales which
form a school in each area. In the sea around the Bonin Is. and off Japan, it isabout 20 whales,in the pelagic whaling ground south of 50°N it is 7 .1. In thewaters north of 50°N it decreases to 3.3 (Fig. 1). In the waters north of the Antarctic
Convergence, it is 6.3, but it becomes only 1.5 in south of the Convergence. Although
there were no schools which were composed of more than four whales south of the
Antarctic Convergence, there were some schools observed which were composed ofmore than 10 whales in the waters north of 50°N of the North Pacific. This phenomenon will be related to the fact that the oceanographic structure is more complicatedin the North Pacific than in the Antarctic, and a warm water mass extends into thearea north of 50°N (Ohsumi and Nasu, 1970).

and

SIZE DISTRIBUTION OF WHALES WHICH FORM A SCHOOL
It is practically rather difficult to measure with the eyes the body length of a whale
which swims in the waters. And the estimated length sometimes differs very muchfrom the real one. Ohsumi (1960) shows that this difference is -7,..., +4 feetcomparing the estimated body lengths of sperm whales with eyes at the time ofmarking with the real lengths of the same ones which were recaptured soon after th~
marking.
Table 3 shows a size distribution of lone sperm whales. The smallest was 32
feet long and the largest was 57 feet. The average lengths were 44.3 feet in the North
Pacific and 44.6 feet in the Antarctic. The modes were both 44-45 feet. The
estimated size distribution of lone sperm whales which were found in the waters
north of 50°N closely fits that of the male sperm whales which were caught in bothwaters of the Bering Sea and surrounding the Aleutian Is. by the Japanese expeditions in 1957, as shown in Fig. 2. Since in this area almost of sperm whales seem
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

OHSUMI

6
TABLE 3.

ESTIMATED SIZE DISTRIBUTION OF SOLITARY SPERM WHALES SIGHTED
North PacificEstimatedbodylength(feet)

Antarctic
Convergence_______,---------50°N

Bonin
Is.

32-33
34-35
36-37
38-39
40-41
42-43
44-45
46-47
48-49
50-51
52-53
54-55
56-57
Total
Average (ft)

Off
Japan

South

1
1
2
2
4

48.5

12
40.5

3
3
3
1
3

16
45.5

North

Total

North

3
10
33
28
41
21
12
15
7
3

3
5
11
35
35
45
24
14
19
7
4

175
44.5

204
44.3

2
7

14
43.9

South

Total

2
2
4
4
2
2

2
3
4
11
4
2
3

17
45.1

31
44.6

25

20

15

5

35

48
Body

45
length (feet)

50

Fig. 2. Estimated size distribution of solitary sperm whales and size distribution ofmale sperm whales caught in the northern part of the North Pacific in 1957.
Closed circle and solid line: solitary whales, Open circle and broken line: males
caught.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

7

SCHOOL STRUCTURE OF SPERM WHALE

to be male and lone, the great part of the whales caught were regarded as lone whales.
Furthermore, this means that lone sperm whales are mostly males.
Male sperm whales attain to their sexual maturity at 31 feet in body length(Clarke, 1956). According to Best (1969), 50% of testes of males at 39-46 feet ofbody length are mature, and those of most males at 45-46 feet become fully mature.
Lone sperm whales appear from 32 feet in body length at which male whales begin to
be sexually mature, increase in number from the stage of 40 feet, and attain to the
maximum at the time when most male's testes are fully mature. In other words, itwill be regarded that lone sperm whales are males with fully matured testes.
TABLE 4.

ESTIMATED SIZE DISTRIBUTION OF PAIRED SPERM WHALES SIGHTED
North PacificBody
length(feet)
20-21
30-31
32-33
34-35
36-37
38-39
40-41
42-43
44-45
46-47
48-49
50-51
52-53
54-55
Total
Average (ft)

Antarctic Convergence
Off
Japan

North
50°N

South
50°N

1
2

North·

South

Total

2

6
2
1
3
3
3

4
8
10
10
6
4
2

3
18
39.3

Total

8
44.8

46
41.9

7
6
9
11
13
6
4
7
2
3
1
72
41.6

2
6
6
8
6
2

30
41.6

2

2
40.5

2
6
8
8
6
2

32
51.5

Size distribution of paired whales is shown in Table 4. Range of estimatedbody length is within 20-55 feet, and the averages are 41.6 and 41.5 feet for the
North Pacific and the Southern Hemisphere, respectively. These are lower thanthose of the lone whales. There is a tendency that similar sized whales make paired
schools in most cases, and paired whales are all over 30 feet long. It is considered thatsexually mature males are apt to make a paired group, but they are younger thanthe lone whales on an average.
The schools which are composed of more than three whales are classified into thefollowing groups by head: 3, 4-5, 6-10, 11-20, 21-30, 31-50, 51-75, 76-100, and101-125. And the range of estimated body length is shown by each group of schoolin Fig. 3 A-H. The schools which are distributed in higher latitude have a tendency
to be composed of large sized whales.
Fig. 4 shows the change of frequency ratios of occurrence of the schools which
are composed of whales over 40 feet long together with the changes of school size.
The larger the school size becomes, the smaller the ratio of the school which compose
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

8

OHSUMI

20

A

I

30

lj

~

~

0

.c

a,
40
c

.!

....

i]1r1111rrr··rrrr111·1rrr·1

0

"'
50

or
B
20

~ 30

"'

j

.,~40

]] ]!11!1rr11rr1]j· ,0

1I lI.,,
r.

50
20

c

40

50

of the Antarctic Convergence,

Fig. 3. Range of estimated body lengthsof the sperm whales which compose ofa school.
A: three whales in a school, B: fourfive whales in a school, C: six-ten
whales in a school, D: 11-20 whales
in a school, E: 21-30 whales in a school,
F: 31-50 whales in a school, G: 51-75
whales in a school, H: 76-100 whales
in a school.
Open circle: off Japan, Cross: Bonin
Is., Closed circle: northern part of theNorth Pacific, Open triangle: north
Closed triangle: south of the Antarctic Convergence.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

SCHOOL STRUCTURE OF SPERM WHALE

9

D

G
x

20

20

ll

40

SOL..____ _ _ _ _ ,

E
20

H

20

[] ... Ill!irll] ]'· ...

40

l

50

40

F

20

1
40

50

Sci. Rep. Weales Res. Inst.,
No. 23, 1971.

IJ

IJJJl!I r1l

. )I

10

OHSUMI

100..,.._~·-·~--... """')(-\x_.-X•-·.x-·4\(30 feet

\
\

80

\

\
\

','

...... 60

'$

""'

' ...
''

including''............ .......

}40 feet'<30 feet,,) 30 feet

\

20

\
\

\

\ /

,•,
\

I
'
L......L~L........L.~L........L__:c::~:::::..6~-~~'&

1

2

3

11

4

6

5

10 20

s

s

s

21

s

31

s
30 so

51

76

101

75 100

125

s

s

s

Size of school
Fig. 4. Change in ratio of frequency occurrence of sperm whale schools classified
by range of body length according with the size of school.
+40 feet: Schools composed with individuals over 40 feet in body length, +30
feet: Schools composed with individuals over 30 feet in body length, Including+30 feet: Schools composed with individuals including less than 30 feet in bodylength, +30 feet: Schools composed with individuals less than 20 feet in bodylength.
TABLE 5.
SchoolSize(whales)
1
2
3
4-5
6-10
11-20
21-30
31-50
51-75
76-100101-125
Total
Average

FREQUENCY OCCURRENCE OF SCHOOL SIZE BY THE GROUPSSEPARATED WITH RANGE OF BODY LENGTH
Range of body length in feet
>40

>30

222
30
27
20
14
4
3

13
21
5
11
30
28
19
13

320
2.2

107
16.8

Including <30

<30

11
30
41
28
21
17
6

2
4
2

157
27 .1

10
8.2

Total
235
52
35
44
78
75
50
45
17
7
594

Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

SCHOOL STRUCTURE OF SPERM WHALE

11

with the whales over 40 feet becomes, and the ratio is about 80% with regard to theschools of 3 whales, but it becomes under 20% in the schools of 6-10 whales or over.
This means that most schools of 3 whales and less are composed of mature males, andmature males seldom make larger schools of over 6-10 whales. The average whale
number of the schools composed with over 40 feet long whales is 2.2. Fig. 4 also
shows that the number ratio of the schools which are composed of whales over 30 feetlong is the highest with regard to those of6-10 whales. The average whale numberof the schools is 16.8. The number ratio of the schools which are composed of thewhales including under 30 feet long whales increases with the increase of school size.
The mode of occurrence frequency of this kind of school lies at their size of 11-20
whales, and the average whale number of the schools is 27.1. The schools which
include whales of under 30 feet long are considered to be nursery ones as described in
the following chapter. If it is true, the average size of nursery schools will be about
27 whales.
There is another kind of school which is composed of only the whales under 30
feet long. The size of the schools is 3-50, having a mode at their size of6-10 whales.
The schools are regarded as juvenile ones.
CONTINUANCE OF SOCIAL SCHOOL COMPOSITION
The behavior of formation and separation of a school is a biologically interesting
problem. However, it is very difficult to study on this problem about marine
animals. Because, it is still almost impossible to observe the same school in thewaters for long time.
Whale marking will be one of the ways to approach this subject. Table 6
shows the results of recaptured sperm whales which were marked in the same schoolat the same time. School No. 3 had been composed of 50 whales, of which 15
whales were marked. Two females of them were recaptured from the same school
10 days after the time of the marking. Two females of School No. 5 were recaptured
from the same school 6 days after. There have been .no whales which had beenmarked in a school and were recaptured from separated schools in the same season.
There were some examples of whales which had been marked in a school andwere recaptured one year and over after from the same school. Two females ofeach of School Nos. 4 and 7 were recaptured from the same schools after 10 years
elapsed from the time of marking. Two females were also recaptured from thesame school 5 years after. According to the reports of recoverey, two females wererecaptured by the same catcher boat on the same day after 8 years elapsed. Although the positions of these two recaptured whales are little apart from each other,
they are regarded as belonging to the same school at the time of recapture.
Above examples are all considered showing the fact that sperm whales moveand migrate belonging to the same school for long years. If sperm whales easily
form a school and separate from the school, such results would not be obtained, forsperm whale stocks are very large (Ohsumi et al., 1971) and the chance that theseveral whales which had been marked in the same school meet again and belongSci. Rep. Whales Res. Inst.,
No. 23, 1971.

OHSUMI

12TABLE 6.

RESULTS OF SPERM WHALE MARKING WHICH SHOWSCONTINUANCE OF THE SCHOOL COMPOSITIONAt the time of recapture

At the time of marking

Sample Mark
No.
No.
{1889
1898
{2871
2878

3
4

r881,85,89
2882,83
3051

5

{2983
2984
{6429
6434

7
12
14

{6650
6669

15

r304
7326
7811

16

r660
7342
7348

Position

Date
3/VIII/51
12/IX/52
12/IX/52

39-46N
145-19E
43-44N
148-44E
44-00N
149-40E

43-44N
148-44E
39-09N
5/VIII/55
148-52E
41-12N
7/VIII/55
148-30E
45-55N
18/VIII/55 152-56E
12/IX/52

7/VIII/55

41-19N
148-52E

SchoolBody
No./length Marked
(ft)
No.
30
33

Position

41-56N37
146-59E
36.4
41-22N, 144-52E 35
24/X/62
41-24N, 144-51 E 35
40-05 N, 146-56 E 36
}18/IX/52
40-06N, 146-52 E 36
40115
42-55N, 148-05E 36
23/IX/60
41-17N35
60/12 24/X/62
144-53 E
38
42-0IN36
60/11 12/IX/60
146-41 E
37
42-17N, 147-46E 35
100/10 22/IV/56
41-28N, 148-00E 35
36-21 N, 144-24 E 36
}20/VIII/63
36-22N, 144-35E 37
30112
Shinshil Is. (USSR)-/VII/57
41-51N, 146-43E 40}14/VI/63
42-07N, 146-03 E 38
40/7
42-06N, 146-15E 45
20/VI/63
50/15

30
28-34
34
30
30
33
32
32
32
36
35
38
32
35

Date

Body
length(ft)
Sex

26/VIII/51

F
F
F
F
F
F
F
F
F
F
F
F
M
F
F
M
F
M

TABLE 7. A RECORD ON RECAPTURE OF SPERM WHALES WHICH WERE MARKED
IN A SAME SCHOOL (SCHOOL NO. 6, 50 WHALES WERE MARKED OF 120
WHALES IN A SCHOOL AT 43°43 1N, 148°361E ON 12 SEPTEMBER, 1952).
Body length (feet)
Mark
No.
2896
2906
2917
2931
2934
2936
2947
2954
2960

Sex

At marking

At recapture

Data recaptured

Position recaptured

M
M
M
M
F
M
F
F

37
38
28
35
27
25
34
37
40

36
37
41
35
36
41
35
35

4/V/56
6/XI/59
25/VI/53
2/VIII/58
24/X/62
20/VI/63
11/IX/55
17/IX/57
27/VIII/54

42°091 N, 147°43 1 E
41°591 N, 145°41 1 E
39°49. 51 N, 143°421 E
42°061 N, 145°381 E
4! 0 17 1 N, 144°53 1 E
52°52 1 N, 170°401 E
41°221 N, 148°381 E
4! 0 45 1 N, 146°06 1 E(42°08 1 N, 147°11 1 E)

ing to another same school is almost negligible. From this viewpoint, it will be
probable that sperm whale schools have a tight family union for long time. It isnotable that the above six examples are all related to females. Sperm whales arepolygamous, and the fundamental type of schools is a nursery one which is composedof mature females and calves as described below.
There is another example that a male and a female which had been marked
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

SCHOOL STRUCTURE OF SPERM WHALE

13

in the same school were recaptured at almost the same position (School No. 14)
on the same day of next year. These two whales are regarded as moving about inthe same school for at least 8 months. In the case, the male was reported to be
35 feet long at the time of recapture and may be at the age of puberty. The relationship between whales Nos. 6660 and 7342 of School No. 16 is an example almost
similar to that in School No. 14. These two examples will witness that some males
at the age of puberty remain in breeding school.
On the separation of bachelor from nursery school, there is a case of School
No. 6 of which 50 whales were marked (Table 7), and it was apparently nurseryschool from the size distribution. Of the marked whales 9 individuals has been
recaptured, and one bachelor (No. 2936) was recaptured in the northern part of
the North Pacific, although others were all recaptured in the coastal waters of Japan.
This means that the male separates from the nursery school after attainment ofpuberty.
CATCH OF ALL WHALES WHICH FORM A SCHOOL
We have the results of the three cases of investigations for catching all members ofa school under special licence of the Japanese Government. School A was caught
in the waters off Hokkaido in late September, 1965. Schools Band C were caught
in the southern part of the Indian Ocean in early November, 1966. These positions are the waters where nursery schools are commonly distributed.
The results of observations on the schools at the time of finding are noted asshown in Table 1. So-called "harem master" was not found in any of these threeschools, although calves and immature whales were found. Therefore, all of theseschools are considered to be nursery ones. Catching of these schools was done by
the co-operation of several catcher boats, and the number of whales caught are 20(one of which sank and lost) and the catch rate was 76.8%, 12 (30.0%) and 39(81.3%) for Schools A, B and C, respectively. Excluding the result from School
B which was difficult to be caught because of bad weather condition, the whalescaught from Schools A and C will represent a certain type of composition of nursery school of sperm whales.
I. Sex ratio: The sex ratios of males were 15.8%, 16.7%, 28.2% and 22.9%
for Schools A, B, C and their average. Then, it is clear that females are the subjectof the nursery school.
2. Sexual maturity: All males were calves, sexually immature or puberal,and the estimated body length of the whole whales including escaped ones were allunder 39 feet. Therefore, it is considered that there were no socially mature males,
which could join the nursery schools for reproductive action (Table 8).
Rate of calves and immature females were 31.2%, 20.0%, 14.3% and 20.4%
for Schools A, B, C and their average. Calves and immature whales are composedof 12 males and 11 females, so that the sex ratio of both sexes is almost the same insuch developmental stage in the nursery school. This will mean that males andfemales remain in the school at least until attainment of sexual maturity in theSci. Rep. Whales Res. Inst.,
No. 23, 1971.

14

OHSUMITABLE 8.

SIZE DISTRIBUTION OF SPERM WHALES CAUGHT

School A
Body
length(feet)
18
23
26
27
28
29
30
31
32
33
34
35
36
Total
Average

Male

FemaleSchool B
Total Male

~

I

SM PM

P

School C

FemaleTotal
Male..----------.
...-------.
I SM PM
C
I
P

Total

P

4
2

2

Grand
Total

SM PM

2

2

2

4

4

2
3

4
3
4
7
10
12
12

2

3
2
3

2
I
2

2

2

4

2

2
3
4

4
2
5
2

1
3

4
6
6
6

2

2

5

5

7
6

3
5
9
2 19
2
2
5
3 12
2
7
2
4
16
7 39
29.3 29.6 32.6 35.0 31.5 30.5 26.0 31.6 31.7 30.5 18.0 25.0 26.5 29.3 33.0 30.9 32.6 30.7

Remarks :

I
70
30.9

I : Immature, P : Puberal, C : Calf, SM : Sexually mature, PM : Physically mature.

TABLE 9.

AGE DISTRIBUTION OF SPERM WHALES CAUGHT

School A
Male
Age(yrs.)

FemaleSchool B
Total Male

~

I

SM PM

P

FemaleSchool C
Total

Male

2

4

2
3
2
I

8

I

I

SM PM

2

C

3

2
2
3

2

2

2

3

Total

~

2
2

Female

~~

0- 3

4- 7
8-11
12-15
16-19
20-23
24-27
28-31
32-35
36-39
40-43
Unknown
Total
Average

Female

~

I

P

P

2
3
2

2
2

2

Grand
Total

SM PM

I
6
4

4

4

6

10
14
15

4
9

4

2
I
1

3
6.7

5
9
2 19
2
9.0 16.6 38.5 15.4 10.0

2
5
3 12
5.0 16.4 32.0 17.3

6
4

2

2

7

0.0

5.3

5

3
3

1

2

7

8
70
14.3

2
4
16
7 39
8.0 10.5 12.0 18.5 37.o 12.6

same ratio.
3. Physical maturity: Only females were physically mature, and the ratioof physically mature females to sexually mature females are 28.5% in the combined
three Schools. The range of body length in physically mature females was 3136 feet, and the average length of them was 32.8 feet.
4. Size distribution: As shown in Table 8, the maximum body length of males
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

SCHOOL STRUCTURE OF SPERM WHALE

15caught was 31 feet, and that offemales was 36 feet. The ranges of body lengths were28-36 feet, 26-33 feet and 18-35 feet for Schools A, B and C, respectively. Two
18 feet long whales contained milk in their stomachs, so that these whales wereclearly sucklings. The average body lengths of the whole whales were 31.5 feet,
30.5 feet, 30. 7 feet and 30.9 feet for Schools A, B, C and their average.
5. Age distribution: The maximum age of males was 10 years and that offemales was over 45 years, by means of tooth reading (Table 9). Old whales were
not easily identified of their ages because of the wear of a tooth at tip. Two sucklings
were both 0 year. The average ages of whales caught were estimated to be 15.4,
17.3, 12.6 and 14.3 years for Schools A, B, C and their average, respectively.
TABLE 10.

DEVELOPMENTAL AND REPRODUCTIVE COMPOSITION
IN THREE SPERM WHALE SCHOOLS
School A

Males Females
CalvesImmature
PuberalPregnant
LactatingResting
Total
Remarks:

School B*

Males Females

5
I

~al}
3

16

*

Males Females

2
2
2

l

7
2
26

jC)

7

2

5
10

*

2

2

5

3

School C

I

I.]

9

28

9

61»

28

1I

* : Number of whales which were not caught, a): One of which was simultaneously
lactating, b): One of which was simultaneously ovulating, c): Lost after catch.

6. Sexual conditions: The mature females of School A were composed of one
puberal, five pregnant (one of which was simultaniously lactating), and five lactating
ones, so that there were no resting females. The number of lactating females, six,
almost corresponds with the number of calves, five, which were not caught (Table
10). School B had two pregnant, one lactating and five resting females, but I
wonder whether these values represent the actual composition of this school or not,for the catch rate was too low. There were one puberal, three pregnant, 14 lactating and six resting females in School C. It will be a questionable point of School
C that calves were only two, although we found 14 lactating females. The ratio of
each sexual conditions is similar to the figures in November in the Southern Hemisphere as reported by Best (1968).
FORMATION OF SPERM WHALE SCHOOL

I want to offer my hypothesis on the formation of sperm whale school on the basisof the informations mentioned above, previous biological knowledges on sperm
whales and ecological knowledges on the formation of school of other kinds ofmammals.
I consider that the fundamental form of sperm whale school is " nurseryschool ". This type of school is composed of mature females and calves which arenursed by mature females. Immature males and females are also nursed by mature
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

16

OHSUMI

females until the time of sexual maturity. The average size of school is estimatedto be 27 .1 whales, and the half of them will be mature females. A nursery school is
supposed to move as a tightly united school as a family for long time. In conclusion,
the behavioral foundation of sperm whales will be regarded as a maternal familygroup.
TABLE 11. REAL AND CALCULATED STRUCTURES OF THE
SPERM WHALE SCHOOLS A AND C COMBINED.

Suckling calves
Immature
PuberalPregnant
LactatingResting

Real

Calculated

7 (19)
20

15 ( 16)
28-37
2-3
8
16
32
8

4

8
19
6

}

33

}

We have not got a real information yet on the question whether all of immature
whales remain in their nursery school after weaning or some of them leave the school.
I tried to approach this subject using the data obtained from Schools A and C. The
number of whales caught or estimated by developmental stage are shown in Table
11. Mature females excluding those at puberty are 33 in total of Schools A and C.
The reproduction cycle of sperm whales was reported to be four years (Ohsumi,
1965; Best, 1968), so that the number of calves which are born from this school will
be about eight (33/4) per year. Gestation period of the sperm whale is about 15-16
months, but in September in the North Pacific (when School A was caught; Ohsumi,1965) and in November in the Southern Hemisphere (when School C was caught;
Best, 1968), there will be no foetuses which were fertilized in both the year and theprevious year, therefore, the calculated pregnant whales must be eight. This is thesame as the actual figure. We have no confirmed value on the natural mortality
rate of the sperm whale during calf and immature stages, but if the survival rateduring these stages is set up as 0.9-0.85 (which is higher than that in adult stage when
the natural mortality coefficient is 0.06-0.07; Ohsumi, 1966; Best, 1970), thenumber of survival calves and immature whales at each age would be calculated.
As lactation period is 24-25 months (Ohsumi, 1965; Best, 1968), the number ofsucklings are calculated to be 15. This figure is smaller than the actual lactating
females, but more than the actual sucklings. Furthermore, it is almost the sameas the number of calculated lactating females, 16. I think the number of calvessighted is fewer than the real number of calves in the school, for counting or recording
calves in the waters may be difficult and incomplete, although there remains a doubtthat the estimated survival rate may be higher than the true one. However, we
would not need to care much about the doubt, because there were 19 lactating
females which had functional mammary glands and therefore which were supposed
to nurse calves, as Best (1968) studied.
Age at sexual maturity of the sperm whale is considered to be nine years(Ohsumi, 1965), so that the calculated number of immature whales is 28-37 in total
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

SCHOOL STRUCTURE OF SPERM WHALE

17

excluding sucklings, if survival rate at immature stage is 0.90-0.85. The actual
figure of immature whales was 20. If this figure reflects the real phase of schools, apart of immature whales must leave the nursery school after weaning. There aresome whale sighting materials as shown in the previous section that smaller whales
under 30 feet long make a small school (8.2 whales form this type of school in average). This kind of school may afford proof of the present examination, and will becalled as " juvenile school ".

Fig. 5. Types and their relationship of social organization in the sperm whale.
M: mature, I: immature, C: suckling, P: puberal.

After attainment to puberty, all males gradually leave the nursery school.
Sexual segregation of male sperm whales was studied by Ohsumi (1966), and there
were no males older than 10 years of age in the investigated three Schools, althoughsome males at puberty were found. Males at puberty or bachelors which haveleft nursery school are considered to form a " bachelor school ". Size of this kind of
school is uncertain, but a part of schools which were composed of whales over 30 feetin body length in Table 5 may be regarded as bachelor schools.
Socially mature males or bulls form a small " bull school " or live alone. Mostof bulls are considered to live solitary.
Bulls struggle with each other for joinning a nursery school in the breeding
season, and winning bull and the nursery school make so-called a " harem ". Tooth
scars which are found on the head and back of large males may be the result of
struggle at that time.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

18

OHSUMII think a harem is a temporary formation only in the breeding season, and theharem bull leaves the nursery school by the end of breeding season. School A wascaught in September, and the main breeding season ends by that months in the
North Pacific (the main season is in April; Ohsumi, 1965). Therefore, it is conceivable that there would be no bull in School A. In Schools B and C bulls werealso not found. The main breeding season begines in late November in the Southern
Hemisphere (Best, 1968), and the schools were investigated in early November, sothat grouping for reproductive activity may not be made on these schools.
NUMBER OF MATURE FEMALES SERVED BY BULL
The main purpose of the present report is to obtain the rate of number of males
needed for reproduction of sperm whales. However, result was not directly obtained with the present materials.
The average size of a nursery school was estimated to be 27.1 whales, and thehalf of the whales which form a nursery school is mature females. If it is reasonable,
the mature females of an average nursery school would be 14. If one bull is enoughjoin the typical nursery school in the breeding season as a harem master, the ratio of
the number of sexually mature females to a bull will be 14: 1 in average. The age
at social maturity has not certainly obtained yet, but it is estimated to be about 25
years (Ohsumi, 1966; Best, 1970). If the natural mortality coefficient of adultstage is 0.06 for the males as same as females, the ratio of stock sizes at initial population level of mature females and socially mature males is calculated into 1: 0.34.
Then, the rate of needed bull stock size for reproduction per socially mature malestock size is also calculated into 1: 4.8.
DISCUSSION

In the present report I classified the sperm whale school into the following types:(1) Nursery school(2) Harem school(3) Juvenile school(4) Bachelor school(5) Bull school(6) Lone bull
Bennett (1940)'s grouping of sperm whale schools is basically valid still today asreviewed by Caldwell et al. (1966). And Rice (in Caldwell et al., 1966)'s detailed
discription of the sperm whale schools is similar with the present report. The
fundamental school is a nursery one, and harem school is considered to be formed
only in the mating season.
There are many types of social organizations among mammals. The socialorganization in the sperm whale is resemble to that in the red deer herd. According
to Etkin (1964), the red deer herd is matriarchal in organization, and the young all
associate with their mother for the first three years. Sexually mature males lose
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

SCHOOL STRUCTURE OF SPERM WHALE

19

their association with the herd, whereas the females remain with the maternal herd.
The mature males live in loosely organized herds separated from the females. In therut season the male herds break up and the individuals scatter widely. They invade
the female territories, round up the hinds, and keep them in harems. Leaderships
are exercised by the older females. In contrast to the females herd, no hierarchy orleadership is evident in the male herds.
In the case of nursery school of the sperm whale, older females are considered tohave leadership of the school, but it must be need to observe the behavior of the sameschool for long time for the solution of this existense ofleadership in the sperm whale
school.
It is interesting but unknown how the bulls join into the nursery school andform " harem ". In the case of the red deer, males display aggressively to othermales which try to approach and as necessary, fight to exclude other males from their
harem areas (Etkin, 1964). On this connection, it will be one of the proofoffighting
among sperm whale bulls that the sperm whale bulls have much scars which arecaused with teeth on the head and back, although females and young males have notsuch scars. If these scars are caused with the fighting among bulls before forming
harem, the tooth scars on the male will be one of the features of social maturity of themales.
Social maturity of the sperm whale males is difficult to be estimated. Ohsumi(1966) estimated by means of sexual segregation of the sperm whale that the age of
25 years or body length of 45 feet was suggested to be the age at full maturity whenmales commenced breeding activity. According to Best (1970), the males reach fullsexual maturity at a body length of44-45 feet and an age of25-27 years by means ofhitological examination of tesetes, and he (1969) also consideres that harem masterstatus is achieved at this stage.
There are some doubts on the assumption that the solitary old males join into
the nursery schools and serve for the mature females in breeding. Caldwell et al.
(1966) note that some whalers believe that solitary males are more or less "outcast ", and most of breeding are done by the younger adult males. Therefore, it isimportant to investigate the harem master directly. On this connection, Best
(1969) shows the size distributions of mature males accompanying female sperm
whales. This result does not support the above assumption.
Best (1969) discusses on a very interesting problem from analogy with theSouthern elephant seal that the disproportional exploitation of large males will
result that the number of bulls per schools would increase so that the smaller animals
each controlled fewer females than the larger breeding bulls. It is considerable thatthe number of females served by a bull in the case of the sperm whale will changewith the exploitation of the adult males. Then, we must investigate thouroughly on
this important problem, for it is one of the biological parametres on the stock assessment of the sperm whale.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

20

OHSUMIACKNOWLEDGEMENTS
My sincere thanks are due to Dr. Hideo Omura, Director of the Whales ResearchInstitute, for his leading of the project on special permits of taking all individuals in aschool, and kindly offer me the data on this project.
My grateful thanks are also extended to Fisheries Agency of Japanese Government who granted the special permit and to staff of whaling companies, Taiyo
Gyogyo Ltd., Nippon Suisan Ltd. and Kyokuyo Ltd. for their cooperation and help
on the data collection of whale marking, whale sighting and school catch.
I am much indebted to Dr. Fumio Mitani, Head of Bottom Fishes and Marine
Mammal Department of the Far Seas Fisheries Research Laboratory, who kindly
read my draft and gave many suggestions.
REFERENCESBANNISTER, J. L., 1968. An aerial survey for sperm whales off the coast of Western Australia, 1963-1965.
Aust.]. Mar. Freshw. Res., 19: 31-51.
BENNETT, F. D., 1840. Narrative of a whaling voyage around the globe from the year 1833 to 1836. London, Richard
Bentley, 2 vol. (cited from Caldwell et al., 1966).
BEST, P. B., 1968. The sperm whale (Physeter catodon) off the west coast of South Africa. 2. Reproductionin the female. Invest!. Rep. Div. Sea. Fish. S. Afr., 66: 1-32.
BEST, P. B., 1969. The sperm whale (Physeter catodon) off the west coast of South Africa. 3. Reproduction in
the male. Invest!. Rep. Div. Sea Fish. S. Afr., 72: 1-20.
BEsT, P. B., 1970. The sperm whale (Physeter catodon) off the west coast of South Africa. 5. Age, growth andmortality. Invest!. Rep. Div. Sea Fish. S. Afr., 79: 1-27.
CALDWELL, D. K., CALDWELL M. C. and D. W. RmE, 1966. Behavior of the sperm whale, Physeter catodon, L.
Whales, Dolphins and Porpoises (ed. K. S. Norris), 677-717.
CLARKE, R., 1956. Sperm whales of the Azores. Discovery Rep., 28: 237-298.
ETKIN, W., 1964. Social behavior from.fish to man. Phoenix Books, Univ. Chicago Press, pp. 205.
GAMBELL, R., 1967. Seasonal movements of sperm whales. Symp. Zoo!. Soc. London, 19: 237-254.
GAMBELL, R., 1968. Aerial observations of sperm whale behavior based on observations, notes and coments by
K.J. Pinkerton. Norsk Hvalfangst-Tid., 57(6): 126-138.
N1sHIWAKI, M., 1962. Aerial photographs show sperm whale's interesting habits. Norsk Hva(fangst-Tid.,
51 ( 10): 395-398.
OHSUMI, S., 1960. Examination on age and growth of the fin whale by means of whale marking. Geiken
Tsushin 105: 1-14 (in Japanese).
0HSUMI, S., 1965. Reproduction of the sperm whale in the northwest Pacific. Sci. Rep. Whales Res. Inst., 19:
1-35.
0HSUMI, S., 1966. Sexual segregation of the sperm whale in the North Pacific. Sci. Rep. Whales Res. Inst., 20:
1-16.
0HSUMI, S. and K. NAsu, 1970. Range of habitat of the female sperm whale with reference to the oceanographic structure. Document for the Fourth Sperm Whale Meeting, IWC, Honolulu, Sp/7: pp. 18.
0HSUMI, S., Y. SmMADZU and Dm, T., 1971. The Seventh memorandum on results of Japanese stock assessment of whales in the North Pacific. Twenry First Rep. I. W.C. 76-89.
TARASEVICH, M. N., 1967. On the structure of cetacean groupings. I. Structure of the groupings of Physetercatodon males. Zoo!. :(,hur., 46 (1): 124-131.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

21

SCHOOL STRUCTURE OF SPERM WHALE
144°34'E

144°38' E

••
-=·

•

..•.

School

•

c

•
•

••

•

•

@•

••

@•

41°3s'N

•

•

•
••

40•40'5

.•

·=·

·=·

• • •
•

• • •
•

Sch.ool A•

41°30'N

40° 45'5

••

•

••

•

• •••

40•5o's.

71°45' E

11°55'E

11•5o'E.

School••40°34'5'"40°32'5

.

•
•

•
•

• •

•

B

.
.

®

• ••
I

73°15 1 E

73°20' E

73°25' E

Appendix-fig. 1. Positions found and caught of the sperm whales in the special
investigations of school catch.
Double circle: position found, Closed circle: position caught.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

22

OHSUMIAPPENDIX TABLE 1.
Mammary
gland,....------------..
Samp. No.

Sex

Body
length(m)

ThickAgeness Conditiona>(years) (cm)

A
A 2
A 3
A 4
A 5
A 6
A 7
A 8
A 9
AlO

F
F
F
F
M
F
F
F
F
M

10.3
8.6
9.9
8.8
8.5
10.3
9.3
9.8
9.7
9.3

34
10
13
7
3
18
11
18
13
8

All
A12
A13
A14
Al5
A16
Al7
Al8
Al9

F
F
F
M
F
F
F
F
F

10.3
10.4
10.4
8.6
9.1
8.9
9.1
9.3
11.1

22
36
18
4
8
10
10
8
41

Remarks:

Breadthof uterine
cornu (cm)

BIOLOGICAL DATA ON THE

Foetus

~

Left

Right

Gonadb>Length ~Left Right
(cm)

~

Sex

19.0
7.0
9.0
8.5

L
I
R
I

24
9
38
12

29
9
51
12

None
None
M
108
None

20.0
10.0
21.0
15.0

L
I
L
L

18
9
15
23

18
10
17
23

None
None
None
None

17.0
8.5
14.0

L
R
L

18
21
30

16
17
34

9
13
12
36
57

9
12
11
18
45

6.0
6.0
7.0
7.0
11.0

I
I
L

None
51
80

F
F
None
None
None
F
M

76
106

0-6,
0-0,
0-0,
0-0,
0.55,
0-3,
0-0,
0-2,
0-1,
0.45,

v.c>

0-2
0-0
1-2
0-0
lost
0-2
0-0
0-2
0-1
lost

n
N
n
N
N
N
N
n
n
N

0-3, 0-3
1-3, 0-4
0-1, 1-1
0.30, 0.25
0-0, 0-0
0-0, 0-1
0-0, 0-0
1-0, 0-0
1-6, 0-5

n
a
n
N
N
N
N
N
A

a) L : Lactating, R : Resting, I : Immature.
b) Number of corpora lutea and corpora albicantia in ovary for females and weight oftestis (kg) for males.
c) Ossification of column of dorsal vertebrae : N: Clearly not ankylosed, n: Not ankylosed.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

SCHOOL STRUCTURE OF SPERM WHALE

23

SPERM WHALES CAUGHT FROM SCHOOL A
Number of teeth
Thickness
contents
ofblubber Spe- Quan- Fresh- Body
(cm)
cies
tity
ness colour
8.0
9.0
10.5
8.0
7.0
11.5
10.0
10.5
10.0
8.5
10.0
9.5
10.0
8.0
9.0
9.0
8.5
7.5
10.0

Sq
Sq
Sq
Sq
Sq
Sq

Sq

Sq
Sq

0
r
0
r
r
r

r
r
0
0

B
A
B
B
B

c
c

r

f
f

Left

A

c
B

c

f

D
CD
D
A

+

+

+
+

+
+
+

±
±

+

~

Upper
Time
caught

Right
22
28
20
25
26
22
27
24
26
21

L 13
Ll5
Rl2
RIO+
Rl4
Rl3
Rll+
Rl5
Ll6
LIO+

12: 10
13: 05
12: 20
12: 50
15: 30
12: 20
12: 55
12: 00
12: 20
13: 10BrokenBroken
23
23
24
25
23
23
22
22
23
22
22
22
21
21

Ll2
Rl3+
Ll3+
Rl3
Rl5
Rl4+
Rl4
Lll
Rl4

10: 35
12: 00
12: 30
14: 35
14: 25
13: 10
12: 45
12: 25
12: 10

22
27
20
25
25
22
27
22
26
21

Remarks

MotherMotherLarge sca(ontop of head
Motherc++a : Ankylosed, A : Fully ankylosed.
+ : Erupted, - : Not erupted, ± : Erupting.
All whales had nematoda in stomach, and all whales had no external parasites.
0

d)
e)

Lower Upper

+
f
f
f
f
f

ff

r

~

+

0
Sq

Lower

,..-----".__________

f

r
0
0
0
r

Eruptionct>of teeth

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

~-='"""'._~~

vt.\:l ~"'° ::0

.~~
"'

~

~

::0

,..~

F
F
F
F
F
F
F
M
F
M
F
F

c 2
c 3
c 4
c 5
c 6
c 7
c 8

C I

Sample
No.

F
F
F
F
F
F
F
F

Sex

Remarks:

B 1
B 2
B 3
B 4
B 5
B 6
B 7
B 8
B 9
B JO
B JI
Bl2

Sample
No.
Sex

21
R
6
I
26
R
12
R
R
20+
4
I
23
R
JO
35+(1-3) L
JO
12
R
14
R
F

300
None

None

None
None
303
F
None
None
None
None

9.5
9.1
8.9
10. l
9.3
9.9
8.5
9.8

36
6
33

11

17
15
16
23+

R
R
L
R
R
R
R
L

0-4,
0-0,
1-3,
0-2,
0-6,
0-0,
0-8,
0.8,
0-5,
0.8,
1-3,
0-1,

0-1
0-0
0-3
0-1
0-4
0-0
0-0
0.8
0-4
0.8
0-1
0-1+

8.5
8.0
J0.5
9.0
10.0
8.0
8.5
10.5
8.5
9.0
7.0
8.5
Sq

Sq
Sq
Sq
Sq
Sq
Sq
Sq
Sq
Sq

Species

r
r
r
r
0
rr
0

r

rrr
rr
rr
rr
n
A
N
A
N
N
n
A
n
N
N

Ossification of
Quantity vertebrae

Stomach contents,....----17: 40
18: 40
17: 00
18: 35
17: 25
17: 30
17: 05
18: 10
16: 35
19: 05
18: 30
17: 15Timecaught

339
None
None
None
None
Unknown
None
UnknownM

0-5, 1-0
0-3, 0-2
0-2, 0-1
0-8, 0-3
0-3, 0-2
1-2, 0-4
0-0, 0-0
1-2, 0-6

Gonad

6.0
4.5
6.0
7.5
7.0
7.5
7.0
7.5

Thicknessofblubber
(cm)

Sq
Sq
Sq

Sq

Sq
Sq

Species

r

r
rrr
0
r
0
r
r

N
N
N
A
N
n
N
a

Ossification of
Quantity vertebrae,.--"~

Stomach contents

09: 2508: 1008: 30
09: 55
09 :40
10: 15
10 :00
09 :40Time
caughtRemarks

Remarks

Cyamus on dorsal
head

Cyamus on belly

BIOLOGICAL DATA ON THE SPERM WHALES CAUTHT FROM SCHOOL C

FoetusBody~
Mammary
Lengthlength Age(m) (years)
gland
Sex (cm)

APPENDIX TABLE 3.

Symbols are the same as Appendix Table I.

9.9
7.8
9.8
9.7
9.7
8.0
JO. I
9.6
9.5
9.2
9.5
9.2

Gonad

Thicknessofblubber(cm)

BIOLOGICAL DATA ON THE SPERM WHALES CAUGHT FROM SCHOOL B

Foetus~Body
length Age
Mammary
Length(m) (years)
gland
Sex (cm)

APPENDIX TABLE 2.

::r:
~
.....

c::

Ul

0

"">!>-

:-"·

~
"'
~-

~

"'

.~~
"'
~

·""~
.....

""~

~

~~

F
M
F
F
F
M
F
F
M
F
M

F
M
F
F
F
F
F

C22
C23
C24
C25
C26
C27
C28
C29
C30
C31
C32

C33
C34
C35
C36
C37
C38
C39

Remarks :

F
F

F
F
F

F
M
M
M
M
M
M
F

Cl!
Cl2
Cl3
Cl4
C!5
C!6
Cl7
Cl8
Cl9
C20
C21

ClO

c 9

9

17+

8.0

9.4
8.3

14
14
13
19+
45+
R
I
I
R
R

L

L

L
L
L
I
L
I

L

F

F

None
None
None
None

313

None

None

None
None

None
None
None

None

None
None
None
None
None
None

285

Symbols are the same as Appendix Table I.

9.8
9.0
9.8
9.8

8.8

32

JO. I

7

3

12

20+

0

10.2
7.0

10.0
5.5
10.8

9

13
18
28+

8. I

13+

9.1
9.6

9.4

L

38+

5

L
L
L
L

9

9.0
9.3
8.9
9.7
10.4
8.2
10.2

13
14
20
17

5

3
4

4+(2-4)

0

12

7 .1

8.9
5.4
8.0
7.0
7.0

0-4, 0-2

0-0, lostLost

0-2, 0-2
0.8, 0.6
1-1, 0-1
0-0, 0-0

0-5, 0-4
0.3, 0.4
0-3, 0-1
0-4, 0-1
0-4, 0-2
0.2, 0.2
0-4, 0-3
0-1, 0-0
0.3, 0.3
0-3, 0-1
0.4, 0.7

1-0, 0-0
0. I, 0.1
0.3, 0.3
0.2, 0.3
0.3, 0.3
0.3, 0.3
0.3, 0.2
0-1, 0-0
0-2, 0-2
0-2, 0-1
0-4, 0-0
0-0, 0-0
0-3, 0-2

8.0
8.0
7.0
7.5
9.0
7.5
8.0

7.5

10.0

7.5
7.5
7.5
7.5
8.0
5.0
9.5
10.0
6.0

8.0
5.5
6.5
7.0
7.5
7.0
8.0
8.5
8.0
8.0
8.5
7.5
8.0

Sq
Sq
Sq
Sq

Sq
Sq

Sq
Sq

Sq

Milk

Sq
Sq
Sq

Sq
Sq

Sq

Sq

Milk

rr

n

A
A
r

N

n

N

n

N

n

N

n

N
A

r

r

0

r

r

rr

r

0

r

0

N

0
0

n

n

n

a

A

n

N
N
N
N

n

n

N
N
N
N
N

r

rr

r

r

r

0
0
0
0

r

0

r

0
0

0

08 :0508: 45
14: 10
14: 30
14: 20
14: 05
14: 20

09: 40
12: 10
10: 20
10: 3508: 30
09: 15
10: 4508: 20
II: 4008: 3508 : 30

I I: 20
12: 50I I : 15
12: 10
12: 25
12: 10
12: 10
11: 00
09: 0508: 1508: 25
09: 05
09: 35lower tooth

Conchoderma on

Conchoderma on
tip of lower jaw

U1

""

I

~

f,a

'"C

rn

"l

0

~

d

0

~

rn

t""

60

rn
0

INFLUENCE OF CHASING TIME TO STOMACH CONTENTS
OF BALEEN AND SPERM WHALESAKITO KAWAMURA
ABSTRACTThe duration of chasing time by catcher boats which might influence on
the fulness of stomach contents of whales was examined on fin, sei, andsperm whales caught in the northern North Pacific during the summer of1969. Of 895 whales observed only 28 whales (3.6%) vomited out theirstomach contents while chasing, and sperm whale vomited most frequently(16.8%) whereas sei and fin whales were 1.1 % and 0.78% respectively. The
diet of the whales concerned was consisted of boarfish, squid, copepods andeuphausiids. It was often observed that the whales likely to vomit out morelarger sized foodstuff such as boarfish than smaller one. The amount of
stomach contents vomited was negligibly few, and has no significant influences on the amount of stomach contents which have been obtained fromcarcasses. Most whales (81 %) were caught within 40 minutes of chasing,and the number of whales which would vomit out their stomach contents
does not always increase in proportion to the prolongation in the duration ofchasing time. It was estimated also that the fully repleted stomach of thebaleen whales would be almost emptied by digestion within 15 hours or so.

INTRODUCTION

The quantity and its fulness of the stomach contents of baleen whales have long been
observed, and a considerable amounts of those knowledges were accumulated in the
pelagic and coastal whaling operations (e.g. Collett, 1911-12; Klumov, 1961;
Nemoto, 1957, 1966, 1970: Brown, 1968; Gambell, 1968; Kawamura, 1970a).
These observations can be considered as one of the very important items in the biological observations of whales to offer basic data for realizing a feeding behavior ofwhales along with the swarm forming mechanisms of prey organisms such as an
estimation of swarm density (Kawamura, l 970b; Omori et al., 1971 ). In addition,
they will give a fundamental material for a nutritional budget between predator
and prey animals as Marr (1962) tried to evaluate an approximate estimation ofquantitative relationships between Euphausia superba, one of a principal food sourcesof the Antarctic baleen whales, and the feeding of baleen whales.
In the post-war years, on the other hand, the proportional increase of vacantstomachs among the whales caught was reported as Mackintosh (1965) denoted(e.g. Nishiwaki and Oye, 1951; Peters, 1955). Nemoto (1957) pointed out thatthe actual fulness of first stomach of the North Pacific fin whale in percentage
figures has been reduced distinctly in accordance with the prolongation of chasingtime of catcher boats, and later, he suggested a possible causative reason on thisSci. Rep. Whales Res. Inst.,
No. 23, 1971. 27-36.

28

KAWAMURA

subject (Nemoto, 1959), i.e. an awful improvements of fishing effort especially in
the greately increased power of modern whalers enabled them to chase the whale
more actively rather than stalk so as to the whales can not swim so powerfuly
anymore. Hence a possible causative factors which may induce the decrease in
the fulness of stomach contents on the whole would be due to a vomit of foodstuff
during those long and restless chasing by the whalers though it seems partly due todigestion. The decrease in the quantity of stomach contents in relation to chasing time can be considered to be caused by both vomit and digestion, although
there still remains some physiological problems whether such a muscle fatigue is
responsible for the vomiting behavior of whales.
In this point of view, the present observations were chiefly focussed on theabove mentioned subject to know how much and often the whales actually vomit
out their stomach contents by chasing in the recent whaling operations. If the actual
amount of stomach contents vomited was negligibly small, it would be needless totake these loss of food into considerations when we measure the whole amountof stomach contents of carcasses. I made a brief analysis on the materials to givesome criterion concerning to those " vomit " problems.
MATERIALS

The material used in the present study was compiled by the personnel who belonged
to .six whale catchers which participated in the North Pacific whaling operations
during the summer of 1969. Sending a form to whaling companies, I asked themto fill the following observation items, i.e. date, position at which whale caught,
time (L.T.) of first sight, beginning time of chasing, time of harpooned, occurrenceof vomit, amount and kind of food organisms vomited, chasing speed, and whale
species concerned. Season, localities and whale species were not designated beforehand because any of these were not thought likely to give inherent effects on the
results.
The whale catchers participated in the observations in the whaling ground were
six in all as described below, and I will extend my great appreciations to the whaling
companies and all personnel on boad.
Taiyo Gyogyo K.K. Toshi Mam No. 17 and Toshi Maru No. 18
Nihon Suisan K.K. Konan Mam No. 25 and Konan Mam No. 26
Kyokuyo Hogei K.K. * Kyo Mam No. 12 and Kyo Mam No. 15
RESULTSAn outline ef observations
The general features of the investigation are summarized in Table I. In theseason of 1969 three Japanese whaling fleets operated in the mid-latitudes of thenorthern North Pacific, approximately between 40°N and 50°N. It was 0420 hour

* Present name:

K. K. Kyokuyo.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

CHASING TIME AND STOMACH CONTENTS

29

TABLE I. NUMBER OF WHALES OBSERVED BY SIX CATCHER BOATS WHICH
PARTICIPATED IN THE NORTH PACIFIC WHALING OPERATIONS IN 1969.
FleetsCather boats
participated
Duration of operation(day/month)
Sei whale{Vomited
None
Unknown{Vomited
Fin whale
None
Unknown{Vomited
Sperm whale
None
Note:

Kyokuyo Maru No. 3,.-------....

Tonan Maru

Nisshin Maru,.------'..._______,.------'-------

Kyo
Maru
No. 12
18/V25/VI

KyoMaru
No. 15
6/V18/VIII

Ko nanMaru
No. 25
19/V24/VII

Konan
Maru
No. 26
24/V8/VII

22

74

55
15
25
8

4

16
20
81

Toshi
Maru
No. 17
16/V4/VIII

Toshi
Maru
No. 18
17/V4/VIII

Total

102
13

175

5
174
6

6
427
209

16
7

24
28

85
43
21
104

23

Sperm whale was not observed except Kyo Maru No. 15 and Toshi Maru No. 18.

that the whale was sighted at the most earliest in the morning, and 2105 hour forthe latest time of catch. The observations were performed throughout the whole
whaling seasons, May to August, and the material can be considered to represent a
general results of whaling of this season. The total numbers of fin, sei, and sperm
whales concerned to this study were 129, 742, and 125 whales respectively. They
were chased at various ship speed but usually it was 17-18 knots in the first ofchasing then slowed down to 8-12 knots when the whales were harpooned. The
whaling sonar was often used while under chasing. As it is noticed in the resultsof two Konan Maru and Toshi Maru No. 17, there were considerable number of
unknown whales. This fact suggests that there was some difficulties in practicalobservations of whale's vomit from heavily heaving ships. The actual number ofwhales which leaked out their stomach contents to some extent while under chasing
was only 28 whales (or 3.6%) among 895 whales through three whale species
concerned. Kyo Mam No. 15, however, observed one fifth (20.0%) of vomited
sperm whales. The sperm whale on the whole seems more likely to vomit out thestomach contents (16.8% on an average) than fin (0.78%), or sei (1.1 %) whales.
It was suggested from those facts that the whales unlikely to vomit their foodstuff
so frequently by chasing of whale catchers as to have been thought previously.

Kind offood organisms
Table 2 shows the degree of fulness of the first stomach by the kind of foodorganisms along with the time of whale caught, which concerns to only whales
vomited during chasing. Of 28 whales vomited only 3 whales were caught in
the early morning when the degree of fulness of the first stomach is relatively high in
general (Nemoto, 1957, 1959; Kawamura, 1970a). It is suggested on the wholethat both baleen and sperm whales likely to vomit out their stomach contents mucheasier when their stomachs are not so fully repleted. However, as it is noticed in
the table, the acutual fulness of stomachs in percentage figures as being found later
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

30

KAWAMURA
TABLE 2.

TIME OF WHALES CAUGHT AND THE DEGREE OF THE FULNESSOF STOMACH BY THE KIND OF FOOD ORGANISMS
Fin whale

Sei whale

Sperm whale~~

Boar fish
Cope pod a
Squid
Euphausiids
Squid
Time ofTime ofTime ofTime ofTime ofNo. ofwhale
whale
Stomachwhale
Stomachwhale
Stomach whale
Stomachwhalecaughtfulness
fulnesscaughtfulnesscaughtcaughtfulness
observedcaught
1420
1445
1605
1820

Note:

rrr
rr
rr
R

1210

R

0807

Fulness of stomach in percentage figures
R: 75-100 %, rrr: 50-75 %, rr: 25-50 %,

r

1110

rr

0610
0855
1010
1120
1250
1300
1440
1600
1630

3
3
2
4
1
4
2

r: less than 25 %by flensing carcasses varied from "r" (less than 25%) to "R" (completely full).
There observed no clear trends that well repleted whales do not vomit out thestomach contents much easier but rather moderately repleted whales. It seems
difficult to draw any conclusive tendency from these observations, but it can besaid that there are no clear relationships between vomiting behavior and the degreeof the fulness of whales stomach.
The kind of food organisms found in sei and fin whales was consisted of boarfish(Pseudopentaceros richardsoni), Calanus cristatus, Calanus plumchrus, Euphausia pacijica,
Thysanoessa inermis, and squids. Among these food organisms boarfish and squids

are quite large in body size as the diet of baleen whales usually found. As the size ofboarfish which was found in the whales stomach was varied 22-32 cm in folk length,
its population seems to be consisted of sexualy immature individuals which form adense swarms in the very surface water during the night (Sengoku, 1970). The sei
whale vomited boarfish most frequently than much smaller organisms, i.e. copepods
or euphausiids. However, the very few instances of vomiting those copepods andeuphausiids might be the results partly due to some difficulties to detect the vomit
which is accompanied by so small organisms at the rough high sea only by visualobservations.
Relationship between chasing time and vomit

Table 3 shows the frequency distribution of the number whales of in relation to
the duration of chasing time in 10 minutes intervals. The duration of chasing wasrepresented by the time between beginning of chasing and whale harpooned. There
were no sperm whale being reported as unknown possibly because the observations forsperm whales on this matter would be much easier than the baleen whales due tolarger size of main foodstuff in sperm whales. In the frequency distribution of eachwhale species by the duration of chasing, 10 percent or more of whales were caught
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

31

CHASING TIME AND STOMACH CONTENTSTABLE 3. OCCURRENCE OF WHALES CONCERNING TO VOMITING BEHAVIORIN RELATION TO THE DURATION OF CHASING BY CATCHR BOATS.
Durationof chasing(min.)

Sei whale
VomitedNone

Unknown

9>

3

68
103
74
53
33
26
20
J4
9
4
6
3
J5
428

60
63
33
19
J4
9
5
2

10

20
30
40
50
60
70
80
90
JOO
JJO
JJO<
Total

6

Sperm whale,,.---------'....________

Fin whale
VomitedNone

Unknown

Vomited

None

10
9
14
13
9
9
6
3

4
12
6

5
4
6

20
30
23
JO
7
3
3

3

2

J
6
83

42

10

2
2

2
3

2
3
210

21

2
104

within 20 minutes to 30 minutes. These percentage figures decreased steadily inproportion to the prolongation of chasing time. There were only 2.9 percent of
whales which were caught after two hours or more of chasing. Sei and sperm whales
as they are shown in the table, it is clear that the whales do not always likely tovomit their stomach contents by the longer chasing time, but they vomit rather
more frequently by very short duration of chasing time within 20 minutes. Thistendency seems to run parallel with the variation in the numbers of whole whale
catch (see also Fig. 3).
TABLE 4.

AMOUNT OF STOMACH CONTENTS VOMITED.

Whale species

Kind of foodAmount of food vomited

Sei whale
Fin whale
Sperm whale

Boarfish
Squid
Squid

3-J5 individuals
ea. 10 individuals
ea. J individual

The actual amount of stomach contents which was vomited out into the sea
by the whale under chase was negligibly small (Table 4). Even the most heavily
vomited cases, the amount was about 15 individuals of boarfish in a sei whale, and10 squids in a fin whale. From those amount of food organisms vomited, it may
be considered that the whales usually do not vomit out any amount of their stomach
contents so as to make under-estimate the whole amount of stomach contents whichis measured on carcasses later when they are £lensed on the deck. Consequently,
the duration of chasing time does not seem so responsible for vomiting be havior
as to result a significant decrease in the degree of the fulness of first stomach.

Possible cause induces a decrease in the fulness of stomach contents
It is well known fact that the more the whales stomach repleted well the more
fresher stomach contents are expected (Nemoto, 1957). The baleen whales likely to
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

32

KAWAMURA

50- 75 o•
0

...

00
H

+

75- J00

A••

oo:::.ooSunrise - 0900

••

•

+

nl=J •••• •25- 50 •+

... .

••
•:. •••
25> ••• TT
++

••+-

•

A

75-JOO

..c:
0
<O

E

50- 75

0

t)

0
en
en

<D

c

25- 50

OQ

o"

OOo

00

•• .... •••~F• •:£}•• .....
++

25>

lL

•

I

J2.5

I

0

75.0

JOO

0

00

...•• ...
+•

0

..o
00

50- 7500••

25- 50

\·~·
A

•o9o9

•o9o9

25> ~«ii

00

00

0900- J500

•

...

••+

+

75.0

+

••
•
+

•
I

I

vacantStomach(%) 45.5 46.J 52.7 45.8 57.J 25.0 50.0 57.2
00

JOO

•

I

75-100

I

0

•

•

00

i\•.=
:;= -:=.· ·~·· +"'00000 0000

::;

•

•

I

VacantStomach(%) 53.5 45.4 47.6 53.3 83.3~•••• ••

100

I

100

0

••
I

25.0 50.0

1500 - Sunset
0

0

....

•

.. .....,,... . ...•• •• .. •
••

A

A

+

I

VacantStomach 40.6 47.2 58.4 22.J 36.3 59.0 62.5
(%)
JO

20

30

40

50

60

70

0

JOO
80

90

0

JOO

0

JOO

I

I

I

JOO

J JO

120

Duration of Chasing (min.)•Calanus

OFish+ Euphausiid L'>Squid

Fig. 1. Relationship between the duration of chasing and the fulness of stomach by
the kind of food organisms in sei whale.

become so dull when they took much foods as to be caught easily by a slight chasing.
According to Ingebrigtsen (1929), the North Atlantic sei whales with vacant stomach
are so shy, and could not be harpooned easily from a reasonable shooting range.
Figs. 1 and 2 demonstrate the relationship between the duration of chasing time
and the quantitative degree in the fulness of first stomach. The figures are shown
separately in three different time bands which roughly correspond to the generalfeatures of daily change of feeding percentages in the North Pacific baleen whales(Nemoto, 1957). The number ofsei and fin whales well repleted with food decreased
along with the duration of chasing growing longer over 40 minutes regardless thekind of food organisms. The whales with fully repleted stomach were found up to
30 to 40 minutes of chasing time in the morning but they decreased gradually down
to less than 10 minutes chasing in the evening. The whales with moderately repleted stomach, on the other hand, were found up to 70 to 80 minutes of chasingtime in the morning, then it remarkably prolonged to more than 120 minutes ofSci. Rep. Whales Res. Inst.,

No. 23, 1971.

33

CHASING TIME AND STOMACH CONTENTS
75-100++50- 75

+t

+

+

+

++-

Sunrise-0900+•

25- 50

•

•

25>

+

•

.6

+.6

.6

+

•
I

I

Vaoant16.6 37.4 25.0 33.3 33.3
stomach(%)
75· IQQ r

1-

50- 75

•

•

~
.<::
0

"'E
.s
(f)

(f)
(f)

<D

c

100

0
0900-1500

25- 50

•+ +E

++

+

25>

++ +tt •••

••

•

0

0

I

•
•
+

•+

I

+
I

I

Vacant30.0 55.5 33.3 50.0 66.0
stomach(%) 50.0 50.0

I

I

100

0

50.0

100

~

LI..

75· IQQ r++

I SOO-Sunset•

SQ- 75 r
25- 50

-+

25>

••

+

6

+

•+
I

I

Vacantstomach(%)

050.0 66.6
10

20

100
30

I

I

33.3

0

40
60
70
80
90
50
Duration of chasing ( min)•Calanus

OFish+ Euphausiid

100
100

I iO

120

6SquidFig. 2. Relationship between the duration of chasing and the fulness of stomach by
the kind of food organisms in fin whale.

chasing during midday until it was shortened again in the evening. There observed
to present two different kinds of variation patterns in relation to the daily changeof the duration of chasing time and the degree of the fulness of stomach. Oneof possible explanations for those two different patterns would be found in theproceed of digestion, that is, most whales with moderately repleted stomach in
midday might have had been fully repleted in the morning, and such whales would
shift to those moderately repleted stomach by digestion toward midday (Fig. 3).
The duration of chasing time which corresponds to the degree of the fulness of
stomach seems to be shortened from morning toward evening. There observed
more or less inversed relationship between the duration of chasing time and thedegree of the fulness of first stomach through three different time bands, i.e. themore the stomach fully repleted, the more shorter time of chasing is expected. This
fact makes us confirm the former observations (Ingebrigtsen, 1929; Nemoto, 1957).
So often occurrence of well repleted whales in the morning along with relatively
longer duration of chasing time and its hourly change lead to a consideration that
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

34

KAWAMURA
0

-§

(J)

"'E "'~
0

B .!::

(J)

0

i
i

'- Rp',r~"'-/ .............. \.......

... . . t.........

....................... I......

6_.... .........

""'--------.... . . . . . . . . . . . . . . .

................. _·--.. .. - - . . : ,

----

'hq
. --.. ..__ ___ ~-------------1-~-"'c "'"'"' 5"':.;(J)____ _..:; :;r-------- ------

<D

l..L

6::,

~-~

<D

""O

_L

I

+-+---decrease - -Duration of chasing-

increase- - - · - 0900-1500 -+- !SOO-Sunset
Fulness of stomach: R 75-100, rrr 50-75, rr 25-50, r 25>---<>--- Sunrise-0900

Fig. 3. Schematic curves showing regressive tendency of the fulness of stomach
contents along with the duration of chasing in three different time bands. Curves
with circles and cross by four different degrees of the fulness of stomach show ashift of those degrees toward lesser direction with the lapse of time from sunrise
to sunset.

the most whales take a bulk of foodstuff once a day in the morning.
The copepod and euphausiid foods were found in the whales which werecaught after more or less longer duration of chasing than those fed on squid orboarfish. This may be the result partly due to vomit, i.e. the large sized food organisms likely to be vomited much easier than the smaller one.
It is also supposed from the figures that an approximate time required for thedigestion of foods may be estimated. The whales which carry a well repleted
stomach were found most frequently in the morning, and consequently they were
found being widely scattered up to the duration of 30 to 40 minutes chasing before
0900 hour. However, these whales were greatly decreased in the late afternoon,
and they were only found in 10 to 20 minutes chasing after 1500 hour. This must
be a result of decrease in the absolute number of whales which are well repleted withfood. If it is assumed that the whales with fully repleted stomach could be expected
to be caught by the same difficulties throughout the day, the time being required tocatch them would give an index for estimating the speed of digestion. The number of whales with fully repleted stomach reduce down to about 70 percent in thefirst half of day and then to 50 percent in the afternoon; the relative abundance ofwhale with fully repleted stomach is considered to have decreased down to about
half in a day time. In another words, 25 to 30 percent of their stomach contents
would be digested within 5 hours or thereabouts, and these whales should beshifted to the stomach conditions of " r " to "rrr " of degrees. The fully repleted
stomach with foods would be emptied in this way by the proceed of digestion in thefollowing 14-15 hours.
DISCUSSION
The aim of this study was to know whether the duration of chasing time by catcher
boats has any influences on the decrease in the fulness of first stomach of whales inSci. Rep. Whales Res. Inst.,
No. 23, 1971.

CHASING TIME AND STOMACH CONTENTS

35

relation to vomiting behavior induced by the chasing as has been suggested previously (Nemoto, 1957, 1959). The sei, fin, and sperm whales were vomited theirstomach contents more or les by the restless chasing of catcher boats. The numberof those vomited whales to total catch, and their amount of stomach contents were
negligibly few. Relatively larger sized food organisms such as boarfish are considered to be vomited more easier than the foods consisted of copepods or euphausiids.
Vomiting of stomach contents was not always occurred along with the longer duration of chasing. Most whales vomited were moderately repleted with foods rather
than those fully repleted. So it is supposed that there are no obvious and causal
relation between vomiting behavior and degree of the stomach fulness. Accordingly, it is supposed that the decrease in the degree of the fulness of stomach
contents which have been found in recent whaling operations does not seem to be
explained fully only by those vomiting behavior of whales which might be induced
by some improvements in fishing ability of modern whalers. The amounts ofstomach contents which has been measured (Nemoto, 1959; Klumov, 1961; Kawamura, 1970a) can be considered reasonable as they are, and there seems little possibility to give a significant under-estimation on to those measurements.
There are one possibility left behind that whales may vomit the stomach
contents in the subsurface waters during long restless chasing by catcher boats,since it must be fairly difficult to detect any vomited foodstuff from the boats.
The behavior of vomiting a bulk of foodstuff in the subsurface waters, however, presumably causes heavy muscular activity for those whales, and they would not vomit
any foodstuff in the subsurface waters since the whales under diving likely to minimize the oxygen consumption as little as possible (Scholander, 1940; Slijper, 1962).
It was observed that the whales concerned were caught or at least in visible
during 0420-2105 hours throughout the operations, and accordingly 16-17 hours
are the upper most extreme of the duration elapsed as far as Figs. 1 and 2 concerned. From the regressive trends in the number of whales fully repleted withfoods as time goes by, it was estimated that 25-30 percent of stomach contents
seems to be digested in 5 hours or so, and the fully repleted stomach would be almost
emptied in the following 15 hours or thereabouts. It is known in the blue whitedolphin (Stenella caeruleoalba) and Gill's bottle nosed dolphin (Tursiops gilli) whichwere kept alive in aquarium that their stomachs likely to be emptied within 10 hours
or more (Tobayama, personal communication). He also observed that a small
instrument swallowed by mistake was excreted after 17 hours. The digesting speed
proposed above for baleen whales as found in this study does not seem unreasonable estimations by taking account of the fact that high feeding rates in percentage
figures are usually found twice a day with intervals of 10 to 15 hours.
REFERENCESBROWN, S. G., 1968. Feeding ofsei whales at South Georgia. Norsk Hvalfangst-Tid., 57(6): 118-125.
COLLETT, R., 1911-12. Norges Pattedyr. Kristiania. (cited from Hinton, M.A. C., 1925: Reports on
papers left by the late Major G. E. H. Barrett-Hamilton relating to the whales of South Georgia. The
Crown Agents for the Colonies, London.
Sci. RejJ. Whales Res. Inst.,

No. 23, 1971.

36

KAWAMURAGAMBELL, R., 1968. Seasonal cycles and reproduction in sei whales of the southern hemisphere. Discovery
Rep., 35: 31-134.
INGEBRIGTSEN, A., 1929. Whales caught in the North Atlantic and other seas. Rapp. Cons. Explor. Mer.,
56(2): 1-26.
KAWAMURA, A., 1970a. Food of sei whale taken by Japanese whaling expeditions in the Antarctic season
1967/68. Sci. Rep. Whales Res. Inst., 22: 127-152.
KAWAMURA, A., 1970b. [On the abundance of Antarctic copepods collected during the cruise of R. V.
Hakuho Maru (KH 68-4) with special reference to feeding habit of sei whales.] Papers presented at themeeting of the Oceanogr. Soc. Jap., Tokyo, April, 1970. (in Japanese).
KLUMOV, S. K., 1961. Plankton and the feeding of the whalebone whales (Mystacoceti). Trudy Inst.
Okeanol, 11: 142-156.
MACKINTOSH, N. A., 1965. The Stock of Whales. Fishing News, London, 232 pp.
MARR, J. W. S., 1962. The natural history and geography of the Antarctic krill (Euphausia superba Dana).
Discovery Rep., 32: 33-464.
NEMOTO, T., 1957. Foods of baleen whales in the Northern Pacific. Sci. Rep. Whales Res. Inst., 12: 33-89.
NEMOTO, T., 1959. Food of baleen whales with reference to whale movements. Sci. Rep. Whales Res. Inst.,
14: 149-290.
NEMOTO, T., 1966. Feeding of baleen whales and krill, and the value of krill as a marine resource in the
Antarctic. Symposium on Antarctic Oceanography. 240-253.
NEMOTO, T., 1970. Feeding pattern of baleen whales in the ocean. Marine Food Chains (ed. J. H. Steele).
Oliver & Boyd, Edinburgh, 241-252.
NrsHIWAKI, M. and T. 0YE, 1951. Biological investigation on blue whales (Balaenoptera musculus) and fin
whales (Balaenoptera physalus) caught by the Japanese Antarctic whaling fleets. Sci. Rep. Whales Res.
Inst., 5: 91-167.
0MORI, M., KAWAMURA, A. and Y. A1zAWA, 1971. Sergestes similis Hansen, its distribution and importance asfood of fin and sei whales in the North Pacific Ocean. (in press).
PETERS, H., 1955. Uber das Vorkommen des Walkrebschens Euphausia superba Dana und seine Bedeutung
for die Ernahrung der stidlichen Bartenwale. Arch. FischWiss., 6: 288-304.
ScHOLANDER, P. F., 1940. Experimental investigations on the respiratory function in diving mammals andbirds. Hvalradets Skr., 22: 1-131.
SENGOKU, S., 1970. A profile of unfamiliar fish: Boarfish. Enyo, 3: 1-4. (in Japanese).
SLIJPER, E.J., 1962. Whales. Hutchinson & Co., London. 475 pp.

Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

CONSIDERATION OF DISTRIBUTION AND MIGRATIONOF TOOTHED WHALES OFF THE PACIFIC
COAST OF JAPAN BASED UPON AERIALSIGHTING RECORDTOSHIO KASUYA*ABSTRACTThe seasonal and annual fluctuation of the sperm whale, Baird's beaked
whale, killer whale, the globicephalids, and the dolphins and porpoises in thepast 11 years are discussed. The sperm whale is abudant in the northern areas,in summer and autumn seasons. Its density fluctuates with a period of 4
years. The Baird's beaked whale is found only in the northern areas in theseason from spring to autumn. The killer whales is relatively abundant in thenorthern areas.
The globicephalids and the delphinids from the warmer waters migrate
into the northern areas in summer season.
INTRODUCTION

In this report the distribution, seasonal movement and annual fluctuation of several
toothed whales off the Pacific coast of Japan was discussed basing on the sighting
records from airplane. About the larger cetacea caught by commercial whaling,much informations on the distribution and abundance are available from the whaling
result, however it is necessary to compare them with the data free from the bias
caused by whaling operation or whaling regulation. About the most of the delphinid species the identification of the species was not acomplished, and, in thisreport, only the seasonal fluctuation of the density or seasonal movement is studied.
But this can afford rough information on the seasonal fluctuation of the populationof the delphinid species, and can be a first step of the population study of them as oneof the members of the marine ecosystem.
MATERIALS AND METHOD OF ANALYSIS

The materials used in this study are the aerial sighting record made in the 11 years
from April 1959 to March 1970. It was conducted by The Suisan Kaku Co., Ltd.
(Fisheries Aviation Co., Ltd.), which has been mostly operating the survey offishing ground or other oceanographic observation in the adjacent waters of Japan.
The aerial sighting of the cetacea was conducted, during the flight for these oceanographic survey, as one of the routine works by Messrs. S. Takashima, Y. Ogawa or
S. Tana. The types of used aircrafts were Cessna 175 from 1959 to 1965, and* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971. 37-60.

38

KASUYAIc:>x. " " . "if:·1·:1·: ~.: ··X ........
~XI

Fig. 1. Section of areas used in this report.
range covered by the flight.

Dotted area indicates the approximate

TABLE 1. SIGHTING EFFORT SHOWN BY NAUTICAL MILES OF THE
DISTANCE FLOWN, FROM APRIL 1959 TO MARCH 1970.
Month
Area
II
III
IV

v
VI
VII
VIII
IX

x
XI
XII
Total

Dec.

Total

0
0 1,802
350
0
0
0
106
55
0
0
0
552
0
212 2,928 13,984 7,085
756
63
0
0
0
0
85
455
629
913 1,287 1,365 1,315
50
0
0
0
830
471
350
19 217 1,513 2,705 3,970 3,686 5,013 6,933 8,533 1,199
132
115
155
123
74
202
55
0
0
36
160
71
2,585 1,265 1,019 1,165 6,254 6,076 4,344 2,894 3,671 5,123 11,766 6,474
326
808
399
486 1,523 1,169
1,623 572 601
662 1,55800371 2,543 2, 179 1, 186
1,269 802 1, 146 721 1,633
488 2,560
845
924 2,061
0
0 1,441 1,415
0 3, 197
0
0 1,3050001,237 916
56
0 3,499
0
372
39
0
145
0
0
384
130
808
585 985
0
0
0
0
140
951
0
0
0
269
669 1,483
00
4809,302 6,083 7,370 2,907 19,220 9,675 10,661 16,344 26,682 24,008 27,767 11,790

2,313
25,5806,929
34,6091, 123
52,636
9,727
14,89811, 188
6,209
3,037
3,560
171,809

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Cessna 182 from 1965 to 1970. The cruising speed was 100 knot and the height was
500 m, but in case of precise observation it was lowered to 50 m. The flight was
operated only on the day with good visibility and the wind less than 7 m/sec. The
flown area covered the waters within 90 to 130 miles from the coast (Fig. 1). It is
told that efficient observation was made within the range of 15 nautical miles oneach sides of the airplane.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

AERIAL SIGHTING OF TOOTHED WHALE

39

In this report, the Japanese coastal waters is divided into 12 areas, and theseasonal and annual fluctuation of the densitly of the whales or schools are discussed in each areas. The density index of the whales are expressed by the numberof the whales sighted per 1,000 miles flown, and that of schools by the number ofschools encountered per 1,000 miles flown. The speceies of the cetacea are classified,after the flight records, into following 5 categories or sperm whale, Baird's beaked
whale, killer whale, Globicephalids whales, and dophins and porpoises.
SPERM WHALE

Distribution
In the Pacific coast of Japan 759 sperm whales, Physeter catodon, in 188 schools
were sighted during the 11 years. The number of the schools sighted in each 1°
squares is shown in Fig. 2. As seen in this figure, the schools sighted distribute from

5 2
7 3
5

t--~--l-o_J_1~~~-+-~~~~t-~~~----t~-13QON
4135°E
Fig. 2. Number of schools of the Baird's beaked whale and the sperm whale sighted
in the 11 years. The number is shown in each 1° squares.

off Ryukyu Islands in the southern waters to the coastal waters of Hokkaido I. in thenorth. But most of the schools were found at the waters east of l 40°E, and the sightings in the south west waters are only 9 occasions which occurred in the coastal
area of Ryukyu Islands.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

40

KASUYATABLE 2.
1 degree squares
CoastalIntermediate
Off shore
Total

NUMBER OF SCHOOLS SIGHTED IN RELATION TO THE
DISTANCE FROM THE COAST, AREAS I-VI.
Pk. catodon

B. bairdi

no.
27
117
34
173

no.
18
64
9
91

%
15.3
65.6
19.1
100.0

0. orca
no.
4
17
5
26

%
19.8
70.3
9.9
100.0

%
15.4
65.4
19.2
100.0

Globicephalids

Delphinids

no.
87
260
56
403

no.
263
327
43
633

%
21.6
64.5
13.9
100.0

%
41.5
51. 7
6.8
100.0

In the waters off the west coast of Kyushu I. (area X), inspite of sighting effort,
there was no sighting. It will indicate that only few sperm whale migrates into thisshallow waters.
Table 2 shows the number of schools sighted in relation to the distance from thecoast in the areas I-VI. In this table " coastal square" indicates the one degreesquares which contain the coast in it, the " intermediate " does those which arebordered by the former square, and the "off shore" does those which don't border on
the first or those which do only at the corner. As seen in this table, the number ofschools sighted in coastal squares is only 15.7% of the total, and that in off shore
squares is 19.3%. This ratio is nearly same with that of killer whale, indicatingthat the sperm whale distributes in off shore waters compared with the Baird's beaked
whale, the Globicephalids, and the dolphins and porpoises. Same phenomenon isseen also in Fig. 3, the density of this species is rather low in the coastal areas IV, VI
and VII, and higher in the off shore areas of I, II, III and V.

6
4
2

(•)

(•)

16

20

II

0:=::::===:~!::!:::!!::::!::::~;=::!~::!::!::::!::::!::::!::::!:::!:::1
l/l

6

Ill

0

IV

Ill

0

..c.
u

l/l

'014
z.12
·u; 10
c
~ 8

VI

v

0
>.

50

~40

5; 30
Cl 20

6
4
2

10

Oi-=..-......................_.._.~'-+-~~~~~--,

20

2

10
0D~J~F~M~A~M~J~J~A~S.:::::..O~N~D~J~F~M~A~M......._J~J~A~S~O~N'-!D

ol--'"-...._.._--'---"~'-'-.i....:.::'-+-"--'--'-._._-'--"--'--'-"--1

Oi...::.....a-L..L..lL...._.._.._.~L-.L-1....L...~-'-'-.........._.._............

DJFMAMJJASONOJFMAMJJASOND
Month

Month

Fig. 3. Monthly fluctuation of the density of the sperm whale (right) and of theschools (left) in areas I-VII.
Sci. Rep, Whales Res. Inst.,

No. 23, 1971.

AERIAL SIGHTING OF TOOTHED WHALE

41

2

3
2

x

Vlll

IX

Xl

Ill

0

06

4~

3~

.!:

z-5

'~ 4

0

1

I

~3

2~

2

;\,

~

t

Q ' I
DJFMAMJJASONDJFMAMJJASOND
Month

~

1
Q

Fig. 4. Monthly fluctuation of the density of the sperm whale (closed circle andsolid line) and of the schools (open circle and dotted line) in areas VIII-XII.

~;.
I

I\

I

l \; '+
''
' '
'' ''

''
'
'
'''
' '''I
I I\
~ \ ~

:
:: \ :¥ o. \
e>-0,0-0

~

+

+

0\ +

~

Q

o'.o•

.o

o=--~-5'--~-1~0~~1~5-=--~2~0~-=--2~5~__,Size of school
Fig. 5. Frequency distribution of the number of individuals in a school (school size).
Closed circle and solid line indicate the sperm whale, open circle and dottedchain the Baird's beaked whale, and cross mark and dotted line the killer whale.
TABLE 3.

MONTHLY FLUCTUATION OF THE DENSITY OF SPERM WHALE
Jan.

Areas I-II
no. of schools
no. of whales
density of schools
density of whales
Areas III-VI
no. of schools
no. of whales
density of schools
density of whales
Areas VII-XII
no. of schools
no. of whales
density of schools
density of whales

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

Feb.

Mar.

Apr.

May

June

July

0
0
0
0

0
0
0
0

I

2
(15.9)(31.7)

0
0
0
0

8
34
0.83
3.54

15
37
1.63
4.02

0
0
0
0

0
0
0
0

2
13
1.41
9.17

4
15
0.48
I. 79

4
3
22
7
1.14 0.90
0.49 4.92

0
0
0
0

1
17
0.64
0.84

0
0
0
0

2
5
0.63
1.58

Aug.

Sept.

Oct.

Nov.

2
30
23
2
144
156
0.68 1.46 4.03
0.68 9.12 21.0

I
I

1.81
1.81

11
60
1.45
7.89

21
54
2.07
5.33

17
47
1.23
3.47

17
65
0. 78
3.00

19
60
2.41
7.61

4
0
0
13
0 0.690 2.24

I

0
0
0
0

I

I

1
1.30
1.30

Dec.

2
2
0.18 0.26
0.35 0.51

42

KASUYA

Seasonal movement
In the areas VII to XII, though the sighting record is scarce and the seasonal
fluctuation of the density is not clear, it can be said that both densities of schools
and whales are slightly higher in winter season and lower in summer (Fig. 4 andTable 3). But the winter density is not so high and nearly same with that of thecorresponding season in the north eastern warters.
The seasonal fluctuation of the density of this species in the areas I-VI is shownin Fig. 3 and Table 3. In these areas the density is highest in summer season andlowest probably in February and March. The pattern of the seasonal fluctuationof the density is similar with the monthly catch shown by Omura (1950). The
high density in June in area II is due to only one sighting, and the sighting data inarea V is also very scarce, so they will not correctly indicate the real seasonal fluctuation. If these points are took into consideration, it is possible to say that in areas I
and II the density fluctuation has only one peak in October. On the other hand,in areas III-VI, it has two peakes in August and December. The former may correspond to the north bound whales going up to areas I and II, and the latter may
do the south bound whales probably comming from areas I and II or more north.
The second peak seems to continue till January. The whales sighted in areas IV
and VI in April to June may containe the male whales on the way to the north.
School size
The frequency distribution of the school size, or the number of individuals in aschool, of the sperm whale is shown in Fig. 4, which is based on 188 schools sighted inareas I-XII. The number of individuals in a school is usually lower estimate of thereal number, because some member may be diving. The largest number of thewhales in a school is 25, and the mininum is 1. There is a discrepancy of the frequency between the schools with 5 or more members and those with 4 or less. Mostof the schools, 77.2% of total number of the schools, are smaller schools and composed of 4 or less individuals, and the number of whales composing these schools is
41.7% of the total number of the whales sighted. The larger schools may be mostly
so-called harem schools. As seen in Table 4 the percentage of the small schools,
with 4 or less individuals, decreases from July to October and again increases from
November to December.
Fig. 6 shows the monthly fluctuation of the mean school size in the areas I-VI.
It indicates that the mean school size is high in August and September, and decreases
after the summer. This is related with the increase of the percentage of small
schools which will be the non-harem schools arriving from the north.
The mean school size in areas VII-XII is 4.3, and no significant difference
between the northern areas was found.
Annual fluctuation
Fig. 7 shows the annual fluctuation of the density of this species migrating inareas I to VI. This annual density was calculated combining the above six areas
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

AERIAL SIGHTING OF TOOTHED WHALE

43

0

8
<I>

.!::! 6

0

VI

+

+

0

_g L.

0

u

VI

0

~2

+

<I>
~

+

+

0
D J F M A M J J A s 0 N D J
MonthFig. 6. Monthly fluctuation of the mean school size of the sperm whale. Double
circle and solid line indicate the mean school size calculated combining the areas
I-VI, cross mark areas I and 11, open circle areas III and IV, closed circle areas
V and VI.

12
10

Ill

Ul

~

0

..cB
3:

4.C
u

0

ltl

-

-Ill

R

/I
I\

05
>.....
+

I

+
I\

I
I

I
\

I

I

''
'

'64
Year

'66

I
I

\
\

2 0

''

0
'60

I

\j

"iii

\

.P

\

'\

2~
Cl

0

"'

I

o,

,,

'

f

I
\

I

\

I

>-

\
\
\
\

I

p..
f

/ + \

Cl

I
I

I

+

\

30

\

I
I

I\

I

I

+

+

0

'iii
~4

I

+

I

0

'62

'68

Fig. 7. Annual fluctuation of the density of the sperm whale (closed circle andsolid line) and of the school (open circle and dotted line). Areas I-VI and seasons
June to October are combined. For the cross mark read the left scale and see
the text.
TABLE 4.

MONTHLY FLUCTUATION OF THE RATIO OF SMALL SCHOOLSOF SPERM WHALE. "SMALL SCHOOL" INDICATES THE
SCHOOL WITH 4 OR LESS INDIVIDUALS.

Area I-VI
no. of total school% of small school
Area VII-XII
no. of total school% of small school
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

Jan.

Feb.

Mar. Apr.

2
100

0

0

3
100

4
50.0

0

May June

July Aug.

Sept.

Oct.

Nov.

2
50.0

4
75.0

9
77.8

15
93.3

13
84.6

44
77.3

47
63.8

18
19
83.4 84.3

1
0

0

0

0

4
75.0

1
100

0

1
100

Dec.

1
100

44

KASUYAand the season from June to October which is considered to be the flourishing migratory season. The annual density fluctuates with the interval of 4 years. Though
Omura (1950, Fig 70) did not mention, same periodical fluctuation is seen in thecatch of prewar period, but in this case the cycle is 4 or 3 years.
I consider that this fluctuation is resulted by the condensation of the whale in the
coastal waters, due to some oceanographic condition. The cross marks in Fig. 7
indicate the distance, measured along 145°E meridian and shown by degree of
latitude, between the isothermal lines of 24°C and l8°C surface water temperature
in September (Japan Meteorological Agency, 1962-1970). They show the reverse
correlation with the annual fluctuation, but further study will be necessary to have aconclusion on this relation.
Another stable trend of the increase of the annual density is observed in Fig. 7,
but no explanation was obtained in the present data.
BAIRD'S BEAKED WHALE

Distribution
The distribution of this species, Berardius bairdi, off the Pacific coast of Ja pan isalready studied by Omura (1955), and Nishiwaki and Oguro (1971). According tothese reports the position of the catch in the Pacific coast is mostly restricted in theeast of 139°E or east of the Sagami bay in the north east part of the area VIII, andsouthern most catch is approximately at 34°N.
In the present data, 414 whales in 91 schools were sighted in areas I-VI, and

I

7
6
J!!
5
0

IV

I

e

e

I

I

0-

lll24

<I>

"'iii20.c
3:: 16

~3
'Q2
>-1

II

ol.

llI

_g 4

IV

Ill

'Q12

]::' 8'iii 4

~o

c
~4
3
2
1
Oi:::a..........~'--'-..L...J.--'-''--'-~_._._._................_.._._.._..~
0

!t

1

I

VII
DJFMAMJJASONDJFMAMJJASOND
Month

~
Cl

0

~~~~~~_.._.,.~~~~~~..,

16

v

12

8
4
Q.-.,.._.__..,,._,__,'-'-..___._._.__,____,_,._.__.._.__.__..__._...,

0VII
DJFMAMJJASONDJFMAMJJASOND
Month

Fig. 8. Monthly fluctuation of the density of the Baird's beaked whale (right) andits schools (left) in areas I-VII.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

45

AERIAL SIGHTING OF TOOTHED WHALE
TABLE 5. RELATIVE ABUNDANCE OF EACH SPECIES OF WHALES.
ABUNDANCE IS SHOWN BY THE RATIO TO THE SPERM WHALE.
III-VI

VII-XII

no. schools no. whales

no. schools no. whales

I-II
Areas

no. schools no. whales

Sperm whale (no.)
Baird's beaked w.
Killer whale
Globicephalids
Dolphins & porpoises

57
0.32
0.053
1.2
2.7

305
0.31
0.059
3.2
110

116
0.63
0.20
2.9
4.1

390
0.82
0.35
17
250

15
0
0.067
2.1
8.2

64
0
0.16
9.9
280

none in area VII and in the Sagami Bay. This will be due to the few flight in thewarmer season in this warters.
As seen in Table 2, the percentage of schools sighted in the coastal squares ishigher than that of the sperm and the killer whale. This will indicate that this species
comes closer to the coast.
The number of whales sighted is about 30% of that of sperm whale in areas
I-II, and 80% in areas III-VI (Table 5).

Seasonal movement
In the summer season the density of this species is higher in areas III and VI,
and rather low in the northern three areas I, II and IV.
The monthly fluctuation of the density of this species shows vague bimodal
distribution in areas II, III, IV and VI. The first mode arrives at area VI in May,at areas III and IV in July, and at area II in August. The second mode is not soclear as the first, but observed in September and October. The first peak is considered to show the north bound whales, some part of which will go further northbeyond the area I, and the second the south bound. Probably the south boundmigration will be started at a same season in all the areas, so the second peak will not
be conspicuous.
Though some individuals are still found in November and December in thearea VI, no individual is found in J anualy to April in all the coastal waters of Japan.
In these months they seem to leave the coast of Japan.
School size
The frequency distribution of school size is shown in Fig. 5. The largest
school observed was composed of 30 individuals and the smallest with one.
TABLE 6.

SOME CHARACTERISTIC FIGURES OF THE
SCHOOL SIZE IN AREAS I-XII

Species

Sperm whale

Baird's beaked w.

Killer whale

Globicephalids

Range of school size
School size at mode
Mean school size
School size at the modeof no. of whales

1-25

1-30

I, 5

19.1
16-25

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

4.0

4.5

1-30
1-3
6.0

2-4, 20

2-3, 8-10

4, (?)I

1-500

KASUYA

46

TABLE 7. MONTHLY FLUCTUATION OF THE RATIO OF SMALL SCHOOLS
WITH 3 OR LESS INDIVIDUALS IN BAIRD'S BEAKED WHALE
MonthAreas I-II
no. of schools% of small schools
Area III-VI
no. of schools% of small schools

May

June

July

Aug.

Sept.

Oct.

Nov.

0

0

0

2
50.0

8
50.0

7
42.8

0

2
100

5
80.0

28
50.0

12
66.7

15
53.3

4
50.0

6
66.7

Dec.

100

8
(I)

N

"iii ~

0
0

£ L.
Ill

c

111
2
(I)

~

0

M

J

J

A

S

0

N

D

Month
Fig. 9. Monthly fluctuation of the mean school size of the Baird's beaked whale.
Cross mark and dotted line indicate the value calcurated combining areas I andII, open circle and dotted chain areas III and IV, and closed circle and solidline areas V and VI.

When the number of the individuals constituting each school size is considered,its distribution have two modes, one at the school size with two individuals and theother at that with 8 or 10 individuals.
As in the case of sperm whale the frequency distribution can be devided into
two parts, or the part of the smaller schools and that of the larger. The former
schools are composed of 3 or less individuals, and hold 56.0% of the total numberof schools and do 22.7% of the total number of the individuals. These informations
on the school are shown in Table 6, which shows that the Baird's beaked whale in theadjacent waters ofJapan forms relatively larger schools than the sperm whale.
The monthly fluctuation of the percentage of the smaller schools is shown in
Table 7, which shows no significant fluctuation. Fig. 9 shows the monthly fluctuation of the mean schools size of this species. It shows slight increase of the meanschool size in summer season, but no significant difference between the areas.

Annual fluctuation
Fig. 10 shows the annual fluctuation of the density in the areas I-VI and in theSci. Rep. Whales Res. Inst.,
No. 23, 1971.

AERIAL SIGHTING OF TOOTHED WHALE

47

12
10

Vl

~

~8
~

3..!!?
0
0

.c.

0

I

'•"

u

2 Vl
..-

I

/' \
..... O---o'2 o',, ..o--

I

0

\
\

1~

I

Vl

c

o .........-:-::-'-~._,.,,.___.__._-1--,-l~..___,,._--L...Joc3'60'62
Fig. 10. Annual fluctuation of the density of the Baird's beaked whale (closed circle
and solid line) and its schools (open circle and dotted line). Areas I to VI andseasons June to October are combined.

period from June to October, calculated same with the sperm whale. It is interesting to see that the annual fluctuation of the density of this species, especially when
the density of whales is compared, shows the reverse correlation with that of the
sperm whale. These fluctuation may be, at least in some part, related with someoceanographical conditions.
KILLER WHALE
During the 11 years, only 161 individuals in 27 schools were sighted in the Pacificcoast of Japan. As shown in Fig. 17, this species, Orcinus orca, distributes in all thearea of the Pacific coast of Japan, but most of the sightings were made in the areas
I-VI in the months from April to November. Because the killer whale is smaller
than the sperm whale or Baird's beaked whale, the ratio of the overlooked schools
or individuals may be higher than that in the larger two species. But it seems to be
TABLE 8.

MONTHLY FLUCTUATION OF THE DENSITY AND MEAN SCHOOLSIZE OF THE KILLER WHALE IN AREAS I-VI

Month

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

Total

No. of schools
No. of whales
Density of schools
Density of whales
Mean school size

8
92
5.25
60.4
1.2

0
0
0
0

5
18
0.52
1.86
3.6

2
5
0.21
0.53
2.5

1

4
22
0.15
0.85
5.5

3
8
0.14
0.38
2.7

3
5
0.13
0.23
I. 7

26
151
0.25
1.50
5.8

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

0.10
0.10
1.0

48

KASUYA

true that the density of this species is far smaller than that of them (Table 5 ).
The monthly fluctuation of the density of this species is shown in Table 8, but
the data is too scarce to get some informations on its migration.
As shown in Fig. 5, Tables 6 and 8, the number of whales in a school ranges
from 1 to 30. And the mean school size is 6.0 in areas I-XII, which is larger than thecorresponding value of the sperm whale or Baird's beaked whale.
GLOBICEPHALID WHALESDistribution
The toothed whales other than dolphins and porpoises and the three larger
species dealt with in the former chapter are recorded as " smaller whales ". Considering the photographs and information from the crues of the airclaft, the " smallerwhales" is thought to indicate mostly the Globicephala, Pseudorca and Grampus. And
in this report it is dealt as the globicephalid whales. Though Mr. Takashima saysthat he has not seen Ziphius from the air, it is probable that some smaller ziphioid
whales may have included in this category, but the number will be negligible.
As seen in Fig. 11 and Table 2, the globicephalids distributes rather off shore

Globicephalids

2

12 11

~.-----+---1 40°N
27 23

10 55 1722 51 112 71 21

2~ 19 2 2v----1--1---1

2

35°N

l'iJ-1od1

f----+------+------t------+---13Q 0 N
3

145°E
Fig. 11.

Number of the globicephalid schools sighted in each 1° squares.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

AERIAL SIGHTING OF TOOTHED WHALE

49

waters, and found in all the waters off the Pacific coast of Japan.
The relative abundance is so high that the number of whales sighted is about
3 to 17 times of that of sperm whales (Table 5 ).

Seasonal movement
The seasonal fluctuation of the density is shown in Figs. 12 and 13. In the south
west waters, generally speaking, the density of the globicephalids is low, but slightly
increases in autumn to spring. This is the reverse of the condition found in thenorth east waters. Same fluctuation is observed also in the Dolphins and porpoises.

t ... NI.:.

12
Ill

0

10L'.' .. .dl

I

111

IV

I

I

e

e

I

I

I

I

300

6

_g 0
~27

-

VJ

;21

'iii

~15

0

9

100

3

OFA-...__.___,_.._._.._.__._._.....,1-"-_._.....i....;"-'-..............._.'-"--lL.

0D~J~F~M~A~M~J~J~A~S~O~N~D=-""J~F~M~A~M":-':-J~J~A~S~O~N~D

75
25......,_~_..,.L....L....L...L~'""""'~~,...._L,....L.._.__.__,_,'-'--'

Month
Fig. 12. Monthly fluctuation of the density of the globicephalid whales (right) andtheir schools (left) in areas I-VII.

Vl
Cl>

100

~

;::

x

IX

VIIJ

2

01---~_i_.!._._........_,_....L..J~~.._,__,_,__._,__,_,_~~t,-,Y~-':-":=~~
(15)

0 200

Xl

XII

:::-

'iii

a; 100

20

Cl

0

0

'

'

•

'

"

.~
Vl

0 c

DJFMAMJJASONDJFMAMJJASOND ~MonthFig. 13. Monthly fluctuation of the density of the globicephalid whales (closed
circle and solid line) and their school (open circle and dotted line) in areas VIIIXII.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

KASUYA

50

This will mean that the globicephalid whales migrate to the southern warters in thewinter season. It is reported that, in the winter season, Pseudorca, Grampus andGlobicephala migrate in the coastal waters adjacent to the north and west coast of
Kyushu, area X, (Fisheries Agency of Japan, 1968, Table 16).
In the north east waters the density of the globicephalids is high in the off
shore areas, or the areas III and V, and it is lower in the areas I and II. The density
in the areas I-VI increases in summer season, but there is slight delay of the arrivalin the northern areas. They arrive at area VI in March, area IV in May, andarea II in July. The same tendency is observed also in the off shore areas I, III and
V. · In the areas III-VII the density decreases in Octorber and December, as theresult the duration of high density is longer in the southern areas. This will show
the expansion and retreat of range of the distribution.
However, in the areas I and II, the density shows bimodal fluctuation andthere is a rapid increase of the density in October and November. It is supposedthat this second mode may be composed of some species of the globicephalids,
probably Globicephala, coming down from the northern warters, and spend thewinter season in the northern areas without migrating to far south. According to
the sighting records from the ship (Kasuya, unpublished), the range of distribution of
Globicephala sp. extends from off the coast of Kyushu (areas IX and X) to the waters
around 43°N, l 77°E via the southern coast of Hokkaido. A part of this northern
population might come to the areas I and II in the early winter.

School size
Fig. 14 shows the frequency distribution of the school size of all the globicephalids schools. The number of individuals in a school is a rough estimate, especiallyin case of large school. The school size ranges from I to 500. Its distribution isbimodal, with a mode at 1 and the other at 5. This is a quite unique character
observed in the globicephalids schools. But this feature does not seem to be special
case seen in the present aerial sighting records. Table 9 shows some characteristic

5

l'
~3
c

~

CIJ

5-2
CIJ
....

u. 1

0

5

15 25
School size

9

45

65

Fig. 14. Frequency distribution of the number of individuals in a schools (schoolsize) of the globicephalid whales sighted in a reas I-XII. The horizontal scale
is not in equal interval.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

AERIAL SIGHTING OF TOOTHED WHALE
TABLE 9.

51

SCHOOLS OF SOME GLOBICEPHALID WHALESOBSERVED ON THE SHIP

SpeciesGlobicephala sp.

Pseudorca

GrampusRange of school size
School size at mode
Mean school size
No. of sample

1-100
1, 10
19.6
30

2-200

3-25

55.0
6

l 1.3

6

50
~L.0
"iii

Fig. 15. Monthly fluctuation of the mean school size of the globicephalid whales.
For marks see Fig. 9.

Ill

Ill

5g.c

<I>
rcl

.c

~100

u

Ill

............ o_ .. 0----0\......
0

4._

\

\

>.

~ 50

0

~'

c

<I>

Cl

0

'60

'62

'6L.

Year

'66

z.

'\

'68

2'iii

c

::...

<I>

'

Cl

0

Fig. 16. Annual fluctuation of the density of globicephalid whales (closed circle
and slid line) and their schools (open circle and dotted line). Areas I to VI, andseasons June to October are combined.

figures of school size of three globicephalid species in the north Pacific. These
datum were cited from Nemoto et al (1966), Nishiwaki (1967), Kawamura andKureha (1970) and Kasuya et al (unpublished) which are all obtained from thesighting on the research vessels. Several characters of the school, especially those of
Globicephala sp. coincides with the bimodal distribution obtained from the aerialSci. Rep. Whales Res. Inst.,
No. 23, 1971.

52

KASUYAsightings (Table 6).
Fig. 15 shows the monthly fluctuation of the mean school size in areas I-VI.
It shows slight increase in the Autumn, but no significant difference between theareas. The mean school size in areas VII-XII of all seasons is 20.5. So it can beconcluded that there is no significant difference of the mean school size between theareas in the north and the south.

Annual fluctuation
Fig. 16 shows the annual fluctuation of the density of the globicephalid species
in areas I-VI. It was calcurated by the same method used in the case of the sperm
whale. The density does not show periodical fluctuation as in the case of the sperm
and Baird's beaked whales.
DOLPHINS AND PORPOISESDistribution
In case of the dolphins and porpoises, only the date, locality, size of the school
were recorded, and no specification was recorded except few cases. The size of school
was grouped into three categories of the " large ", " middle " and " small ". The
large school is composed of estimatedly more than 300 individuals, the middle from50 to 300, and the small less than 50 individuals.
The total number of the sighted large, middle and small schools are 121, 315
and 321 respectively. They are shown in Fig. 17 according to the locality and theschool size.
As seen in Table 2, the ratio of the number of schools sighted in the coastal
waters is about two times higher than the case of other species. This indicates that.the dolphins and porpoises are rather coastal species.

Seasonal movement
In areas II, IV and VI monthly fluctuation of the density is bimodal withspring and autumn peaks. Among these three areas, the spring mode arrives
earlier and finishes later in the southern area than the northern one. The autumn
mode is conspicuous and arrives earlier in the area II, but appears late and inconspicuous in area VI.
In the area VI, the spring mode attains the peak in May or June, and is characterized by the high ratio of middle and small schools, however, autumn mode ispeculiar in the decrease of them. The density of the large school is relatively
stable all the year round. As the result, the percentage of the large school is highest
in August.
In area IV, though the density in January to April is not available, thespring mode attaines the peak in June and July about one month later than area VI.
In area II the spring mode is restricted only in June and July.
The autumn mode in area II begins in September, area IV in October, andarea VI probably in November. The lowest density between the two peaks in area
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

53

AERIAL SIGHTING OF TOOTHED WHALE

O.orca02

11/';4 13
8 1
2 9
2

1

217 3311 2 6 3 2

3t----t-1 3

8 5

15 17

1

13

17

7

1

2 2
4
2
2a 1

34 17
3 5 1
27 1
7 1

35°N

2

Dolphins and Porpoises

•

1. 1

135°E

145°E

Fig. 17. Number of the schools of the killer whale, and that of dolphins and porpoises
sighted in each 1° squares. For the dolphins and porpoises number of large
school (upper right), middle school (middle), and small school (lower left) are
shown separately.

II is observed in August, in area IV in September, and in area VI probably in
October.
In area VII, present data suggests a peak in November and December, but the
spring mode was not indicated because of the scarecity of the flight. In othersouthern areas, area VIII-XII, monthly fluctuation of the density has one mode in
the months from January to March or April.
The above features of the density fluctuation suggest 'that the spring mode inareas II, IV and VI may be composed of the delphinid species from warmer waters.
They, in the summer, will extend the range of distribution up to the area II. Then,in the August they start the retreat to the south, passing the area VII and northeast part of area VIII in November and December, and may arrive in the west partof areas VIII and in area IX in January and February.
The distribution of the subtropical or tropical delphind species in area VI isindicated by the catch of Stenella attenuata at Onahama (36°56'N, 139°55'E) insummer season (S. Uchida, personal communication). The migration of thisspecies is also seen in the fishing result at Sagami Bay (north east part of area VIII)
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

54

KASUYA

Fig. 18. Monthly fluctuation of the ratio of the number of schools of each sizes
in the dolphins and porpoises. Black square indicates the density of the small
school, square with larger spots the density of the middle school, and square withsmaller spots the density of the large school.
TABLE 10.

NUMBER OF PHOCAENOIDES SPP. BROUGHT TO
KAMAI SHI FISHING HARBOR**

Month

Jan.

Feb.

Mar.

Apr.

May

1969*
1970
Total

76
85
161

458
239
697

89
351
440

31
109
140

0

* calculated from the weight data m 1970.

** approx. 39°16'N 141°54'E.

TABLE 11. RATIO OF EACH SCHOOL SIZE OF THE DELPHINIDS IN
ACCORDANCE WITH DISTANCE FROM THE COAST, AREAS I-VI

School size
Large
MiddleSmall
Total

CoastalIntermediate

Off shore~---------no.
°lo,-----''-----....

,-------'"------._

no.

%

no.

%

38
122
103
263

57
143
127
327

17.4
43.8
38.8
100.0

10
20
13
43

23.2
46.5
30.3
100.0

14.4
46.5
39.1
100.0

in late October to early November before the arrival of St. caeruleoalba in November
and December (Tobayama, 1969). These two species of Stenella had been caught at
the Suruga Bay, in the north east part of area VIII and west of the Sagami Bay,in the season from May to July (Nishiwaki and Yagi, 1954; Nishiwaki 1965).
In the areas IX, and the west par of area VIII, Tursiops and Stenella caeruleoalba
are known in all the year round. The concentration of Legenorhynchus is seen mwinter season at the north east part of area X.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

AERIAL SIGHTING OF TOOTHED WHALE

10

55

VII

8
6

Fig. 19. Monthly fluctuation of the density of the schools of the dolphins and porpoises in areas I-VII. White small squares on the horizontal scale indicate nosighting in spite of the flight. Other marks are same with Fig. 18.

Phocaenoides and Lissodelphis are considered to be the species in the colder
waters. In areas III, IV and VI, these species are sighted only in the season from
September to June. The presence of Phocaenoides in winter and its decrease in April
to May is also seen in the selling record in Kamaishi fish market (Table 10). In
March and April Lagenorhynchus, which is considered to live in temperate warter's,
migrates in area VI, in July Tursiops and Lagenorhynchus in area IV, and in September
Phocaenoides appears again in this area. But some Phocaenoides seems to stay in thecolder waters adjacent to Hokkaido coast north of 42°N. (Nemoto et al 1966;
Nishiwaki 1967; Kasuya unpublished).
These informations also suggest the alternations of the delphinids fauna inareas II, IV and VI in June and September.
School size
Fig. 18 shows the monthly fluctuation of the ratio of the schools of three sizes.
In areas VIII-XII, the ratio oflarge, middle and small schools, in the whole year, is11.5, 23.0 and 65.5% respectively, and the percentage of the small school is slightly
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

56

KASUYAhigher than that in the northern areas.
In the northern areas the school size changes by the distance from the coastand by the season. Table 11 shows the ratio of the sizes of the schools in accordancewith the distance from the coast (for explanation see Table 2). The large school
seems to frequent in the off shore waters and the small school in the coastal.
In areas II and IV, the large school is found only in the months from August
to October. These large schools seems to be formed on the way to south boundmigration by some species in the warmer or colder waters. But there may arise aquestion whether the low density of schools in this season is due to the annexation ofseveral small or middle schools. To check this problem, the weighted density
index is calculated for areas II, IV and VI (Table 12), summing the weighted
density index of each school size. The weight of 1, 6 and 30 were used tentatively
for small, middle and large schools, assuming the mean school sizes 25, 150 and 750
respectively. But there is still observed the same spring and autumn modes, thiswill suggests that these two modes are due to the real fluctuation of the number ofindividuals in that waters.
TABLE 12. WEIGHTED DENSITY INDEX OF THE SCHOOLSOF DOLPHINS AND PORPOISES
Area

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Oct.

Nov.

0
36.4

0
1.0

0

0
6.6

61.3
18.4

41.2
11.4

21.4

47.3
51.4

41.6
17.0

98.0

83.0

5.9
42.8
105.6

48.7

0
21.0

36.1

48.0

52.2

30.3

8

x

II

IV
VI

IX

~-

57.2

Dec.
20.0
21. 7

VIII

6
1114

0
0

-52
Ill

-oo
>-

~
~6

XII

Cl

4
2
0
Fig. 20. Monthly fluctuation of the density of schools of the dolphins and porpoises
in areas VIII-XII. Marks are same with Fig. 19.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

AERIAL SIGHTING OF TOOTHED WHALE

57

l/l

0
0

-510
l/l

o-- ... o,

z. 5
.iii
c(J)

\

,o.-._o"
\

I
\

I

\

o'

p

I

I

0

Fig. 21. Annual fluctuation of density of schools of the dolphins and porposises,
areas from I to VI are combined. Closed circle and solid line indicate the seasonfrom April to July, and open circle and dotted line from September to December.

Using mean school sizes assumed in the above, the relative abundance of thenumber of individuals of dolphins and porpoises are calcurated in Table 9.

Annual fluctuation
Fig. 21 shows the annual fluctuation of density of the schools in areas I-VI.
For the calculation of the density of the spring fauna, number of schools and theflight distance in the period from April to July are used, and for the autumn thosefrom September to December. Though there will be remaining members of theautumn school in J anruay to March, it was ignored because of the absence of reliable
density index.
The annual fluctuation of the autumn school is smaller and the density is morestable, however, that of spring school seems to show a long term fluctuation with thecycle of I 0 years.
The correlation of the densities of both spring and autumn schools is not observed.
SUMMARY

I. The relative abundance of the species varies according to the season and locality.
The ratio of the numbers of the sperm whale, the Baird's beaked whale, the killer
whale, the globicephalids, and dolphins and porpoises sighted in the areas I-VI inpast 11 years is I: 0.60: 0.22: 11: 180 respectively, and that of number of schools is
I: 0.51: 0.15: 2.3: 3.6 respectively.
2. The affinity of the cetacea for the coast differes by species, and it decreases in thefollowing order; the dolphins and porpoises, the globicephalids, the Baird's beaked
whale, the killer whale, and the sperm whale.
3. Though the mean school size changes by species, locality and season, generally
speaking, it increases in the order of the sperm whale, the Baird's beaked whale, theSci. Rep. Whales Res. Inst.,
No. 23, 1971.

58

KASUYA

killer whale, the globicephalids, and the dolphins and porpoises. The large meanschool size of the latter species is resulted in both the increase of maximum size of theschool and the decrease of the frequency of small sized schools.
4. The density of the sperm whale is higher in the northern areas than in the southwest areas. Most of the schools, probably with females, migrates up to off the coastof Hokkaido in summer and return to the south in autumn and winter. The densityof this species in the northern areas fluctuates with the cycle of 4 years.
5. The Baird's beaked whale, off the Pacific coast of Japan, distributes mainly inthe waters east of 139°E. It arrives, in the spring, off the Boso Peninsula, migratingin summer to the north beyond Hokkaido, and comes back to the south in winter.
The wintering place will not be in the Japanese coastal waters. The annual fluctuation of the density shows the reverse correlation with that of the sperm whale.
6. The killer whale was sighted mostly in the northern waters.
7. The density of the globicephalids is higher in northern waters. In the summer,
the range of high density extend to the north and retreats in winter. But it is suggested the existence of some population migrating, in autumn, from the north to thewaters off the coast of Hokkaido and probably stay there in the winter.
8. From the density fluctuation of the dolphins and porpoises, it is suggested thatspecies from the warmer waters seems to go up to the waters off the coast of Hokkaido
in spring and summer season, on the other hand, those from the colder waters comedown as far as area VI in autumn and winter season. The fluctuation of annual
density indices of the both groups are independent and the former may show afluctuation with the cycle of about 10 years.
ACKNOWLEDGEMENTS
Greatest thanks are due to Mr. S. Takashima of Suisan Koku Co., Ltd. who kindly
offered me the privilege to analyse the flight records and to reffer the aerial photographs of the cetacea. Thanks are also due to The Asahi Shinbun for offering
the photograph of Neophocaena in Tokyo Bay.
Prof. M. Nishiwaki of the Ocean Res. Inst., Dr. S. Ohsumi of the Far Seas
Fish. Res. Lab., Mr. S. Uchida of the Terushima Land, and Dr. H. Omura, Directorof The Whales Res. Inst. kindly gave me many suggestions and informations. For
analyzing the flight records, I was helped by Miss. K. Nagayama and Miss. M.
Kamata. These persons are acknowledged.
REFERENCESBANNISTER, J. L., 1968. An aerial survey for sperm whales off the coast of western Australia 1963-1965.
Aust.]. Mar. Freshwater Res., 19(1): 31-51.
BEST, P. B., 1969. The sperm whale (Physeter catodon) off the west coast of South Africa 4. distribution andMovements. Div. Sea Fish. Investigational rep., 78: 1-12.
CALDWELL, D. K., M. C. CALDWELL and D. W. RICE, 1966. Behavior of the sperm whale, Physeter catodon L.
Whales, dolphins and porpoises: 678-717. K. S. Norris (ed). Berkley and Los Angeles, Univ. of Calif.
press.

Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

AERIAL SIGHTING OF TOOTHED WHALE

59

GAMBELL, R., 1968. Aerial observation of sperm whale behaviour. Norsk Hvaifangst-Tid., 6: 126-138.
JAPAN FISHERIES AGENCY (ed), 1968. Report on the damage of the fisheries caused by the small toothed whales in thewestern waters of Japan (in Japanese). pp. 1-96. Japan Fish. Agency, Tokyo.
JAPAN METEOROLOGICAL AGENCY (ed), 1962-1970. Marine climatological table of the north Pacific ocean, 19591964. Japan Meteorological Agency, Tokyo.
NEMOTo, T., S. 0HSUMI, T. lcHIHARA and K. NASu, 1966. Ovservation and marking of whales off the coast of
Sanriku and Hokkaido conducted with Tansei-maru (in.Japanese). Geiken Tsushin., 173: 113-122.
NISHIWAKI, M., 1965. A rare species of dolphin (Stenella attenuata) from Arari, Japan. Sci. Rep. Whales Res.
Inst., 19: 53-64, Pls. I-VI.
N1smwAKI, M., 1967. Distribution and migration of marine mammals in the north Pacific area. Bull.
Ocean Res. Inst. Univ. Tokyo, 1: 1-64.
N1smwAKI, M., 1967. Observation and marking of whales conducted with Tansei-maru, 1966 (in Japanese).
Geiken Tsushin, 187: 23-26.
NISHIWAKI, M. and N. 0GURO, 1971. Baird's beaked whale caught on the coast of Japan in recent 10 years.
Sci. Rep. Whales Res. Inst., 23: 111-122.
NISHIWAKI, M. and T. YAGI, 1954. On the age-determination method of the toothed whale by the study of
tooth. Proc. Japan Academy, 30(5): 399-404.
KAWAMURA, A. and K. KuREHA, 1970. Sighting record of whales and sea-birds. Preliminary Rep. Hakuho
Maru Cruise KH-68-4: 141-170. Y. Horibe (ed). Ocean Res. Inst. Univ. Tokyo, Tokyo.
OMURA, H., 1950. Whales in the adjacent waters of Japan. Sci. Rep. Whales Res. Inst., 4: 27-113.
ToBAYAMA, T., 1969. Study of the school size and its fluctuation of Stenella caeruleoalba, based on the fishing
result in Sagami Bay (in Japanese). Geiken Tsushin, 217: 109-119.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

60

KASUYA

EXPLANATION OF PLATESAll the photographs, except Plate IV Fig. 3, are offered by courtesy of Suisan Koku Co.,
Ltd., Kojimachi, Tokyo, and the copyright be-longs to it.
PLATE I
Fig. I.

A school of 21 sperm whales. 2 calves are seen by the mothers in the right sub-school.
41°35'N, 144°50'E, 28 Sept. 1967.
Fig. 2. A school of 5 sperm whales, probably all males. 40°40'N, 142°30'E, 24 Dec. 1960.
Fig. 3. A school of 10 Pseudorca crassidens. 33°40'N, 129°40'E, 27 Jan. 1968.
PLATE II
Fig. I. A school of 12 Baird's beaked whales. 37°20'N, 142°40'E, 1 Aug. 1958.
Fig. 2. A school of 2 Baird's beaked whales. Off Cape Shioyazaki (37°00'N, 141°00'E), 16
May 1958.
Fig. 3. A small school of Lagenorhynchus obliquidens. 32°40'E, 128°20'E, 28 Jan. 1968.
PLATE III
Fig. I.
Fig. 2.

A school of Globicephala macrorhyncha. 37°20'N, 142°40'E, 14 June 1966.
A school of Globicephala macrorhyncha. 42°00'N, 143°40'E, 12 Sept. 1961.

Fig. I.
Fig. 2.
Fig. 3.

A large school of Delphinus delphis. 41°50'N, 141°50'E, 19 Sept. 1968.
A school of 17 Tursiops gilli. 35°05'N, 139°20'E, 31 Aug. 1970.
A school of 6 Neophocaena phocaenoides. 35°25'N, 139°50'E (by courtesy of Asahi Shinbun,
Tokyo).

PLATE IV

PLATE V
Fig. I.
Fig. 2.

A middle school of Lissodelphis borealis. 35°50'N, 141°20'E, 18 May 1958.
A large school of Lissodelphis borealis. 36°20'N, 141°50'E, 6 Apr. 1960.
PLATE VI

Fig. I. Stenella caeruleoalba attacking mackerel school. 35°14'N, 139°2l'N, 6 Feb. 1970.
Fig. 2. A school of 7 Grampus griseus. 37°20'N, 142°05'E, 15 July 1963.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

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KASU、八A COMPARISON OF THE SIZE OF VERTEBRAE AMONGSOME SPECIES OF THE BALEEN WHALES WITH
SPECIAL REFERENCE TO WHALE MOVEMENTSHIDEO OMURAABSTRACTIn the baleen whales the caudal region occupies about 30% of the total
combined length of the skull and vertebrae, notwithstanding the different
size of the skull and regardless of the number of vertebrae. Long distantmigrating 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.

INTRODUCTION
In the past the osteological studies of whales were carried out mainly from the taxonomic viewpoint and most of the authors deal with skull in detail, but they placed lesser
weight on the vertebrae except their number. Consequently only a few papers
report detailed measurements of each vertebra, but now they cover seven species ofbaleen whales i.e. Greenland right, black right, gray, pygmy blue, sei, Bryde's, andminke whales. In this paper these measurements are treated for the comparison ofvertebrae among these species, in a hope that such study may give a basis for the
ecological study of baleen whales e. g. feeding, swimming or migration. As to thethree remaining important species, ordinary blue, fin, and humpback whales, nomaterial is still available for inclusion in this study.
MATERIAL
In order to compare the size of vertebrae among different species it is desirable touse fully grown up or physically matured specimens, because it is well establishedthat the proportions of the whale body are changeable during the course of growthin almost all species, but this is not possible at present. The materials used in thisstudy are shown in Table 1. As seen in this table the Greenland right and graywhale specimens are very small and young. Nishiwaki and Kasuya (l 970a, l 970b)
presume on their ages about 1.36 years for the Greenland right whale and between
one and two years for the gray whale. In addition to this for the size of the vertebral
body they present only the length of the centra and no figure of their height andbreadth is given. Accordingly these two species are treated separately from others
in detailed calculation of the size of vertebrae.
Among the other species only the black right and pygmy blue whale specimens
are physically matured, since all of the vertebral epiphyses are fused completely to
Sci. Rep. Whales Res. Inst.,
No. 23, 1971. 61-69.

62

OMURA
TABLE I.

LIST OF MATERIALS USED IN THIS STUDYSpeciesCommon name

Sex

Body
length(m)Balaena mysticetus

Greenland rightwhaleBlack right whale
Gray whaleM

6.4

Very young

M
F

17. I
9.0

Physically mature
Very young

Pygmy blue whale

M

18.6

Physically mature

Nishiwaki andKasuya !970a
Omura et al., 1969
Nishiwaki andKasuya, 1970b
Omura et al., 1970

Sei whale
Bryde's whale
Minke whale

F
F
M

12.9
13.5
7.5

Physically immature
Physically immature
Physically immature

Omura, 1959
Omura, 1959
Omura, 1957

Eubalaena glacialis
Eschrichtius robustus*

Balaenoptera musculus
brevicauda
B. borealis
B. edeni
B. acutorostrata

Maturity

Author* After Kasuya and Rice, 1970.
their centra. Specimens of the sei, Bryde's, and minke whales are all physicallyimmature, though in the latter two specimens sexual maturity was already attained,
and for the sei whale the specimen is thought at or approaching puberty.
In the light of the different stages of growth the conclusion derived from these
specimens are consequently premature.
LENGTH OF SKULL AND VERTEBRAE
Table 2 shows the lengths of the skull and vertebrae, in actual length in mm as well
TABLE 2.
Species

SKULL AND VERTEBRAL LENGTH IN SEVEN SPECIES OF BALEEN WHALES
Skull

G. right

1,980

B. right

5, 100

Gray

2,000

P. blue

4,860

Sei

3,062

Bryde's

3,480

Minke

1,520

G. right
B. right
Gray
P. blue
Sei
Bryde's
Minke

33.79
33.80
23.60
30.54
24.87
27.42
22.25

CervicalLumbarCaudalTotal(Actual figure in mm)
174
820
1,013
(10)
(7)
(12)
274
2,479
2,576
(JO)
(7)
(14)
1,911
338
1,489
(7)
(14)
( 12)
618
2,750
2,949
(14)
(7)
( 15)
425
2,942
2, 116
(7)
(13)
(14)
441
2, 125
3,272
(7)
( 13)
( 13)
241
1,951
1, JOO
(12)
(7)
(11)

Dorsal

1,873
(24)
4,658
(25)
2,736
(23)
4,737
(27)
3,768
(22)
3,374
(21)
2,019
(18)

5,860
(53)
15,087
(56)
8,474
(56)
15,914(63)
12,313(56)
12,692
(54)
6,831
(48)

31.96
30.87
32.29
29. 77
30.60
26.58
29.56

100.00(% figure)
2.97
1.82
3.99
3.88
3.45
3.48
3.53

13.99
16.43
17.57
18.53
17 .1916.74
16.10
Figures in parentheses show number of vertebrae.

17.29
17.08
22.55
17.28
23.89
25.78
28.56

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

63

VERTEBRAE OF BALEEN WHALES

as their proportional length, for seven species of the baleen whales. For the vertebrae the length of each centrum are added, dividing into four regions i. e. cervical,
dorsal, lumbar, and caudal. The total length of the vertebrae in this table does not
denote, therefore, the total length of the back bone in situ, because spaces between
vertebrae are neglected.
Fig. 1 shows the proportional length of the skull and each region of vertebrae
against the combined length of the skull and vertebrae, comparing each species.
As seen in this figure the skull length is greatest proportionally in the Greenland
right and black right whales and it occupies 34% or one third of the total length inboth species. In the other species only the pygmy blue whale exceeds 30% and thesmallest figure is 22% of the minke whale. Thus in the proportional length of theskull there is a big difference by species. For the Greenland and black right whales
the huge size of the skull can be explained by the different type offeeding (skimming)
than the other species (swallowing or both types combined, Nemoto 1959), but it isthought rather difficult in the other species at least at present to explain the slightdifference among them in connection with feeding.
G. RIGHT----~~~.=1111=1111=1111=1111+-J------{

c-!

!f

I

\

B. RIGHT .____ _ ___...,~"'""·~"-"fll'·lll=llllliilllllllllllll'!---1'1------{..;~~~faJll.;111111111111111111(\

GRAY

\\ \\

~;11111111111111111111111(

SEI

I

I

I
1

I

I

"

1-

-------l

/I ,1

MINKE

'

si ---1,~~.~
L.£. .L~.~l l l \ li l\l\ =\ \l=\ \ =1 \ cw.\ \ "I-()I

BRYDE'\\·~1111111111111111j

P. BLUE,':'~i1111111111111111111111111I
SKULL CD

L

Ca

L_VERTEBRAE--J

Fig. I.

Proportional length of skull and vertebrae in seven species of baleen whales.

The pygmy blue whale has comparatively large skull than other species except
those of Balaenidae, but before going into detail the material for the ordinary blue
whale as well as those of the fin and humpback whales are needed.
On the other hand the proportional length of the caudal region of the vertebrae
is almost similar in these species, notwithstanding rather big difference in their
number (Table 2). The greatest number of the caudal vertebrae is 27 of the pygmy
blue whale and the smallest is 18 of the minke, but the proportional length of thisregion is quite similar, showing 30% in both species. The smallest percentage figure
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

64

OMURA

of this region is 27% of the Bryde's whale, which does not follow long distant migration and living locally. The highest figure is 32% of the Greenland right and graywhales, but both specimens are very young as stated before and there is a possibilityof decreasing with growth. In any case it can be concluded that the caudal region
occupies about 30% of the combined length of the skull and vertebrae in most of
the baleen whales and this length may be required for swimming.
It is also seen from Fig. 1 that the difference in the length of the skull is balancedby the length of the dorsal and lumbar regions of the vertebrae, especially by thelatter. The largest number of the lumbar vertebrae is 14 of the pygmy blue whale,
but the proportional length of this region of the specimen is 17%, which is the lowest
among the balaenopterid whales and lesser than the gray. The proportional lengthof the dorsal region is roughly proportional to the number of the dorsal vertebrae.
The proportional length of cervical region is smallest in the black right whale,
but no remarkable difference in length of this region is noted among the species.
SIZE OF VERTEBRAE

In order to compare the size of each vertebra among the species of the baleen whales
I made calculation of the mean length of the centrum using the following formula:Mean length= Vaxbxc
where a, b and c are the breadth, height and lengthof the centrum respectively.
The mean length thus calculated can be used as an index of the volume of thecentrum. The results of the calculation are shown in Appendix Table 1 for theblack right, pygmy blue, sei, Bryde's, and minke whales. The original measurements used in this calculation are given by the authors listed in Table 1.
Then I have calculated the percentage figures of the mean length of eachvertebra, using the first lumbar vertebra as a standard. The results are shown inAppendix Table 2. In the table figures for the Greenland right and gray whales
are also shown for reference, but in these two species only the length of the centrum
was used due to lack of material and hence these figures do not denote the volume of
the centra.
Fig. 2 shows the proportional size of each vertebra against the first lumbar infive species of the baleen whales based upon the values shown in Appendix Table 2.
As seen in Fig. 2 there is no remarkable difference in the proportional size of vertebra
in the cervical and dorsal regions, but quite large difference are present in the posterior portion of the lumbar region and in the anterior portion of the caudal region.
The highest value in these regions are those of the minke whale, which follows long
distant migration. In this species the lesser number of vertebrae are covered by thewell developed vertebrae in these regions.
In comparing the sei and Bryde's whales it is notable that the caudal vertebrae in the anterior portion are much developed in the former than in the latter, due
to possibly the difference in extent of the migration between the two species. The sei
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

65

VERTE.BRAE OF BALEEN WHALES
-

%
140
130
120
110
I00-',• -~ BLACK RIGHT·~ PYGMY BLUE--·-· SEI~~· BRYDE'S[

0-~MINKE~~ ~'',,,__ ',',,,
~~-

70

60

50
40
30
20-

\; -

'

10 - L.______J '--------~CERVICALDORSALLUMBARCAUDAL

Fig, 2. Comparison of size of vertebra against first lumbar in five species of baleen
whales.

whale is migratory, even though extent of its movement is thought lesser than that of
the blue and fin whales. In the Antarctic it distribute mostly in the northern partof the whaling ground and in the North Pacific its movement is confined up to the
Aleutian chain and very seldomly enters into the Bering Sea, whereas the fin whale
penetrates through the Bering Strait into the Arctic basin. But still it has muchwider range of migration than the Bryde's whale, which is only a local population.
In the offshore waters ofJapan the distribution of the Bryde's whale is confined fromthe Bonin Islands in the south to the east coast ofSanriku in the north and it is seldom
to travel beyond 40 degree North Latitude. The highest value of the sei whale is
at 7th caudal (128%) and that of the Bryde's whale is at 3rd caudal (124%).
The relation between the black right and pygmy blue whales is also of someinterest. In general the curves for the two species show similar tendency, but in%x - x - x GREENLAND RIGHT WHALE
140~GRAY WHALE
130
120
110
100
90
/'
80
,x
/
70
I.
60
50
/
40
30 L__ _ _ _ _ _ ___J
L _ __ _ _ _ _ _ ,'------"
20

/~--

v::··

)<.._)(,,,,>(

'

\

\,

\

~

\

;;

CERVICALDORSALLUMBAR' x, ......

~'\
\x

'x'><

CAUDAL

Fig. 3. Percentage length of each vertebra against first lumbar in the Greenlandand gray whales.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

66

OMURA

the black right whale the vertebrae are more developed than the pygmy blue whalein the lumbar region and up to 13th caudal. Both whales are slow swimmer andvery little is known of the migration of the pygmy blue whale. It is highly possible,
however, that the range of migration is much wider in the black right whale thanin the other which is thought to be only a local population.
In conclusion above it can be safely said that in the species which follow long
distant migration and in the fast swimmers the vertebrae in the posterior portionof the lumbar and in the anterior portion of the caudal are much developed than theother.
Fig. 3 shows the proportional length of each vertebra of the Greenland rightand gray whales. Both curves are similar in general and each corresponding value
is smaller in the gray whale than in the Greenland right whale, except those in thecaudal region, up to 6th caudal. The Greenland right whale is inhabiting in the
Arctic Ocean, whereas the gray whale migrate very long distance between the coastof Mexico and Arctic Ocean, passing through the Bering Strait. It seems rather
queer the general agreement of these curves, but since the both specimens are very
young and they are presumed below two years, as stated before, and since thesecurves denote only the lengths of the centra, no definite conclusion may be derived
from this figure in relation to movement of whales. Or an explanation may bethat that no remarkable difference in the size of vertebrae is present among different
species of whales when they are young and the difference in size noted before aredeveloped during the course of growth of the whale body.
REFERENCES
KAsuYA, T. and D. W. RICE, 1970. Notes on baleen plates and on arrangement of parasitic barnacles ofgray whale. Sci. Rep. Whales Res. Inst., 22: 39-43.
NEMOTO, T., 1959. Food of baleen whales with reference to whale movements. Sci. Rep. Whales Res. Inst.,
14: 149-290.
NrsHIWAKI, M. and T. KASUYA, 1970a. Recent record of gray whale in the adjacent waters of Japan and aconsideration on its migration. Sci. Rep. Whales Res. Inst., 22: 29-37.
N1sHIWAKI, M. and T. KASUYA, 1970b. A Greenland right whale caught at Osaka Bay. Sci. Rep. Whales
Res. Inst., 22: 45-62.
OMURA, H., 1957. Osteological study of the little piked whale from the coast of.Japan. Sci. Rep. Whales Res.
Inst., 12: 1-21.
OMURA, H., 1959. Bryde's whales from the coast of.Japan. Sci. Rep. Whales Res. Inst., 14: 1-33.
OMURA, H., S. 0HSUMI, T. NEMOTO, K. NAsu and T. KAsUYA, 1969. Black right whales in the North Pacific.
Sci. Rep. Whales Res. Inst., 21: 1-78.
OMURA, H., T. lcHIHARA and T. KASUYA, 1970. Osteology of pygmy blue whale with additional information
on external and other characteristics. Sci. Rep. Whales Res. Inst., 22: 1-27.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

67

VERTEBRAE OF BALEEN WHALESAPPENDIX TABLE I.

MEAN LENGTH OF VERTEBRAE OF FIVE SPECIESOF BALEEN WHALES

Mean length = .Vaxbxc
where a: breadth; b: height; c: length; of each vertebra in mm.
Vertebral
No.

Black right

c 1
2
3
4
5
6
7
D 1
2
3
4
5
6

7
8
9
JO

11
12
13
14
15
L I

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

2
3
4-

5
6
7
8

294

205
214
231
253
241
243
250
257
265
272
276
279
281
283
292
300
313
321
328
329
333
341
348
350

352
345
349
343
350
348
349
345

Pygmy blue

Sei

Bryde's

Minke

233
202
173
175
187
178
196
202
211
220
232
244
247
249
254
260
263
265
266
271
273
275
281
285
292
287
295
300
304
301
303
304
309
312
315
316
316
319
316
317
316
321
323
319

165
133
122
118
121
126
129
134
146
157
167
173
177
180
181
184
188
192
194
193
195

160
129
116
126
127
133
141
147
157
167
177
179
180
185
188
192
198
200
201
206

87
85
70
71
72
76
78
83
89
95
104
106
106
111
114
118
118
119

197
199
201
206
207
211
214
215
215
219
225
235
230

211
214
217
222
225
228
231
232
235
241
246
251
254

123
127
131
131
135
138
140
141
146
152
157
164

239
244
248
251
251
252
253
251

259
260
261
258
256
251
248
241

167
166
170
169
170
168
159
150
Continued ...

Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

68

OMURA
APPENDIX TABLE !. Continued.

Vertebral
No.

Black right

Pygmy blue

Sei

Bryde's

350
341
336
319
312
270
239
215
189
164
154
138
123
109
93
77
60

314
309
302
295
284
271
251
219
177
163
141
133
118
105
85
72
59
42
31

241
235
221
204
172
142
121
113
97
84
70
55
45
31

233
225
204
167
129
Ill
105
95
83
67
55
44
34

Ca9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27

Minke
138
111
86
73
66
57
47
39
29
23

APPENDIX TABLE 2.

PERCENTAGE LENGTH OF EACH VERTEBRA AGAINSTFIRST LUMBAR
Mean length, shown in Appendix Table 1, are used for comparison, except
last two columns in which species only vertebral lengths are available.

Vertebral
No.
c I
2
3
4
5
6
7
D

2
3
4
5
6
7
8
9
10
II

12
13

B. right

P. blue

Sei

Bryde's

Minke

lr@

82.92
71.89
61.57
62.28
66.55
63.35
69.75
71.89
75.08
78.29
82.56
86.83
87.90
88.61.
90.39
92.53
93.59
94.31
94.66
96.44

83.76
65.51
61.93
59.90
61.42
63.96
65.48
68.02
74.11
79.70
84.77
87.82
89.85
91.37
91.88
93.40
95.43
97.46
98.48
97.97

75.83
61.14
54.98
59.72
60.19
63.03
66.82
69.67
74.41
79.15
83.89
84.83
85.31
87.68
89.10
91.00
93.84
94. 79
95.26
97.63

70.73
69.11
56.91
57.72
58.54
61.79
63.41
67.48
72.36
77.24
84.55
86.18
86.18
90.24
92.68
95.93
95.93
96.75

70.21
73.29
79.11
86.64
82.53
83.22
85.62
88.01
90. 75
93.15
94.52
95.55
96.23

(G. right)(Gray)
42.86
45.71
30.00
30
25.00
28.57
32.86
38.20
36.43
42.70
39.29
49.44
46.43
58.43
53.57
67.42
60.00
65.00
73.03
77 .53
68.57
83.15
79.29
87.64
85.71
94.38
90.00
94.38
92.14
95.51
93.57
97 .75
95.00
93.57
Continued ...

1157

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

69

VERTEBRAE OF BALEEN WHALESAPPENDIX TABLE 2.
Vertebral
No.

14
15
L
2

3
4
5
6
7
8
9

10

B. right

P. blue

Sei

96.92

97 .1597.86
100.00101.42103.91102.14104.98106.76108.19107. 12107.83108. 19109.961I1.0398.98

100.00102.74107 .19109.93I 12. 33112.67Il4.04116. 78
119.18Il9.86

1I

12
13
14
Ca I

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

JI2.JO

120.55IJ8.15
119.52117 .47119.86119.18119.52118.15119.86116. 78
Il5. 07109.25106.85
92.47
81.85
73.63
€4.73
56.16
52.74
47.26
42.12
37.33
31.85
26.37
20.55

Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

112.46112.46
I 13.52
I 12.46112.81
I 12.46114.23Il4. 95
113.52I I I. 74
109.96107.47104.98101.0796.44
89.32
77 .9462.99
58.01
50. 18
47.33
41.99
37.37
30.25
25.62
21.00
14.95
11.03

100.00101.02102.03104.57105.08107. I I
108.63109. 14109. 14I I I. I 7

114.21
119.29116. 75
121.32123.86125.89127.41
127.41
127.92
128.43127.41
122.34119.29112. 18103.55
87.31
72.08
61 .42
57 .36
49.24
42.64
35.53
27.92
22.84
15.74

Continued.

Bryde'sMinke(G. right)(Gray)

101.43100.00
JOI. 42102.84105.21106.64108.06109.48109.95111.37114.22ll6.59118.96120.38100.00103.25106.50106.50109. 76112.20113.82114.63118. 70
123.58127 .64133.33100.00102.25104.49111.24112.36117.98120.22121. 35
122.47125.84100.00102.14105.00110.71110.00116.43Il2.86
I15. 71118.57123.57125.00125.00122.75123.22123.70122.27121. 33
118.96117.54114.22110.43106.64
96.68
79.15
61.14
52.61
49. 7645.02
39.34
31. 75
26.07
20.85
16.11

135.77134.96138.21137.40138.21136.59129.27
121 .95
Il2. 20
90.24
69.92
59.35
53.66
46.34
38.21
31. 71
23.58
18.70

128.09128.09129.21129.21129.21130.34130.34126.97
123.60117.98II0.11102.25
89.89
74.16
67.42
60.67
57.30
53.93
49.44
44.94
39.33
31.46
26.97
23.60

133.57130.00131.43133.57132.86131.43122.14119.29114.29ll2.86106.43
95.00
79.29
66.43
57 .14
54.29
50.71
47.14
44.29
36.43
30.71
25.00
unknown

FURTHER STUDIES ON TWO SKELETONS OF THE
BLACK RIGHT WHALE IN THE NORTH PACIFICHIDEO OMURA, MASAHARU NISHIWAKI* AND TOSHIO KASUYA*ABSTRACTTwo skeletons of the black right whale were studied, supplementing ourprevious report. In the skull, studied together with four specimens reported
before, the proportional length of the rostrum increases and the rostrum becomes more curved downwards with age, whereas the skull breadth decreases its
proportion slightly. The numbers of vertebrae of these specimens were erroneously reported in the previous paper, but now they are corrected. In
one specimen the lst dorsal vertebra united to the mass of cervicals. Sexual
difference in the form and size of the pelvic bone is suggested.

In our previous paper (Omura et al. 1969) are also included the two black rightwhales taken in 1968 in the Okhotsk Sea. They are a male and a female of 15.20
and 12.60 m in length respectively (Whale nos. 68A and 68B). The skeletons ofthese whales had been burried for about two years in the sand of the beach at Mombetsu in Hokkaido, where the whales were processed. In July 1970 we dug out thebones from the sand and sent them to Taiji \iVhale Museum in Wakayama prefecture, after cleaning. In December of the same year we made observations and aseries of measurements of the skeletons, and results of which are reported in thepresent paper. The specimen 68A is now being kept at the museum and the 68B
specimen was sent to Landessammlungen for Naturkunde in Karlsruhe, \Vest
Germany, where it is planned to mount the skeleton for display.
The skull of the specimen 68A was broken into three major portions, i.e. the beak,and right and left cranial portions, and many small flagments, being hit at the timeof taking by a harpoon. But the major broken parts are in such a good condition
that the skull could be restored, and thus enabling us to make some of the series ofthe measurements. The skull of the specimen 68B is complete.
SKULL
The results of the skull measurements are shown in Appendix Table 1, together
with the calculated percentages of each measurement against their skull length aswell as those of skull breadth.
\Ve have now the skull measurements for six specimens of the black right whale in
the North Pacific as listed in Table 1, and some selected measurements of these
specimens are compared in Fig. 1. As seen in Fig. 1 the smallest and the largest* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971. 71-81.

72

OMURA, NISHIWAKI AND KASUYAPERCENT OF
SKULL LENGTH.-----.-----,~~~~~~~~-;;::~~---;:~(T.";;\l(56A)(568) (688)(SBA)(SIA) (SIB)

100

80

70

50 ---- ----- ----------------------- ---------- -- -----------

40---------

30--~~ --- ___ tL__~__:=-_-~-:--~---=:__::::__=_ :__: : _:-_:-: ___: :-: _-~-_:-::_~---=-=--=--~--+--~-=--=1----- ----

20

20

3

4

5

SKULL LENGTH IN METER
Fig. 1. Proportional growth of bones in the skull of the black right whale in the
North Pacific. Numerals in the figure indicate measurement number in Appendix
Table 1, but see also text.

skulls are those of the specimens 56A and 61B, being their lengths 3,022 and 5,240 mm
respectively. The other four specimens are not distributed evenly between theselengths, but rather biassed towards the extremities. It is suggested from Fig. 1,
however, some trends of the changes of the proportional lengths of various parts ofthe skull with the growth or age of the whale. These changes can be grouped into
two categories.
Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

BLACK RIGHT WHALE
TABLE I.
Specimenno.

LIST OF THE SKULL SPECIMENS OF THE BLACK RIGHT WHALE
IN THE NORTH PACIFIC USED FOR COMPARISON

Body
lengthSex

Skulllength

cm
56A
56B
61A
61 B
68A
68B

73

I, 165
1,240
I, 710
1,700
1,520
1,260

Maturity

AuthorSexually immature

Omura, 1958

Physically mature

Omura et al. 1969

Sexually immature

Present pa per

mm
F
M
M
M
M
F

3,022
3,230
5, JOO
5,240
4,620
3,270

1.

Proportional length increases with the age.
In this category are included: length of maxillaries at superior border, straight(no. 2); length of premaxillaries, straight (no. 4); anterior end of nasals to end of
rostrum, on curve (no. 7); length from tip of premaxillaries to posterior end ofpterygoid (no. 8); and length from tip ofpremaxillaries to posterior end of palatines,
medial (no. 9).
2. Proportional length decreases or practically no change with the age.
In this category are included: breadth of skull, orbits (no. 14); breadth ofskull at orbital processes of maxillaries (no. 16); breadth of skull at squamosals(no. 17); greatest breadth of occipital bone (no. 19); height of supraoccipitalbone, from foramen magnum (no. 20); breadth of rostrum at middle (no. 18);
length of nasals (no. 11); breadth of two nasals distally (no. 12); greatest breadth
offoramen magnum (no. 23); and length of mandible, straight (no. 25).
The measurements which belong to the first category are those concerned withthe length of the beak or longitudinal growth of the facial region of the skull, and themeasurements in the second category are mainly those concerned with the width ortransverse growth of the skull. The proportional growth with age of the maxillaries and premaxillaries are very conspicuous, whereas the width of the skull at
various parts stay fairly constant or show rather decrease. The proportional increase of the curved length from the anterior end of nasals to end of rostrum isquite striking. This may be attributable to the fact that the proportional size ofthe nasals decreases slightly with age, but it is also possible that the beak itself
becomes more curved downwards. The proportions of the greatest breadth of theoccipital bone and the height of the supraoccipital bone decrease slightly with age.
In the breadth of the foramen magnum is shown also similar trend.
Practically no change is observed in the percentage length of mandible in relation toage.
VERTEBRA

The numbers of vertebrae were erroneously reported in the previous paper (Omura
et al. 1969) in Table 30 as having 57 and 55 vertebrae respectively. These numbers
were counted at the time of dismembering of the whale carcasses when some meatand other soft parts still attached on the surface of bones. These numbers are now
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

74

OMURA,NI
SHIWAKIANDKASUYA

cor
r
e
c
t
e
da
sf
o
l
l
o
ws:
68A. C 7,D 14,L 1
0,Ca2
7,Total58.
68B. C 7,D 14
,L 1
0,Ca2
6
,Total5
7
.
Int
h
es
pe
c
ime
n68Acpiphysesareonlyf
us
e
dt
ot
h
ec
e
n
t
rai
nt
h
ecaudalregi
onfrom1
3
thcaudalonwar
dse
xc
e
p
tt
hel
a
s
tt
h
r
e
ewhic
har
eno
tu
n
i
t
e
d
. Fromah
is
t
o
lo
g
i
c
a
l
examinati
onoft
h
et
e
s
t
e
st
h
i
swhal
ewasa
s
s
i
g
n
e
dasimma
t
u
r
e(
Omur
aela
l.1
969)
,
buti
ti
spo
s
s
i
b
let
ha
tt
h
ewhalewasa
tt
hes
t
a
geofapproachingpube
rty,judged
0
・
omt
hewe
i
ght
soft
e
s
t
e
s
. I
nt
hes
p巴cim
en68Bnoneoft
h
ee
piphy
s
e
suni
t
edt
ot
he
i
r
c
cn
t
r
a
.
Themo
s
ti
nt
er
e
st
i
n
gf
e
a
t
u
r
eoft
h
e
s
ever
t
ebr
aei
st
h
a
toft
h
ecer
vi
c
a
l
soft
h
especimen
68A. Inthiss
pecimen t
he centrum oft
he 自rst dor~al ver
t
e
b
r
a ha
scomple
t
e
l
y
f
us
ed t
ot
h
eu
n
i
t
ed mas
sofc
er
vi
cal
s
, makinganappearanc
ea
si
ft
h
i
si
st
hel
a
s
t
c
e1
vi
c
a
landi
nt
h
iss
peciment
h
e
r
epre
s
en
te
i
g
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tc
e
r
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i
c
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l
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ss
howni
nF
i
g
.2. But
i
tha
st
r
a
ns
v
er
s
eproce
s
s
e
sofno
td
i
f
f
e
r
i
n
gfromot
hers
pe
c
ime
n
s
,andi
ti
sp
o
s
si
b
l
e

ー一一ー−−一−一一一
ー
一
ー
一
一
一
一
ー「

日g
.2
. C
c
1v
i
c
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so
ft
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kt
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twhal
ei
nt
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e:
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引：
s
p
e
ci
m
e
n68t
¥
. I
nt
hi
ss
p
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ci
me
nt
h
:
<1
s
td
o
r
s
alv
e
r
t
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r
ah
a
5f
u
s
e
d1
0
t
h
ema
s
詩o
fc
c
1v
i
c
al
s
.
L
i
・
we
r
:s
p
e
c
i
me
n68B.
しぐf
t
:l
a
t
e
r
a
lv
i
e
、
、
＼ R
i
g
h
t
:f
r
o
n
t
a
l,
・
,
c
w
.
S
c
i.Re
/
J.Whal
e
sRe
s.l
n
s
t.
λぐ
.
o23.1971.

75

BLACK RIGHT WHALE

that the first ribs articulate at these processes. In the specimen 68B, only sevencervicals united into a mass of bones as usual.
Measurements of each vertebra are shown in Appendix Table 2 for the both specimens.
RIBS AND STERNUM

In the specimen 68A fourteen pairs ofribs are present. But in the 68B there present
one small rib in addition to fourteen pairs. This rib is small and slender, and its
length is only about a half of the preceeding one and rudimental. On the transverse
processes of the 22nd vertebra there are no trace of facet for articulation of rib. Thus
we assigned the number of dorsal vertebrae as fourteen and that of lumbar ten as
stated before, but if we count fifteen dorsals then the number of lumbars becomesnine. In any case the total number of vertebrae is the same. The straight lengthsof ribs are shown in Table 2.
TABLE 2.

STRAIGHT LENGTH OF RIBS OF THE SPECIMENS 68A AND 68B (in mm)
68A

Rib no.
2
3
4
5
6
7
8
9
10
11
12
13
14
15

68B

Right

Left

Right

Left

1, 375
1,715
1,805
1,910
2.010
2, 1052,095
2,050
1,920+*
1,900
1, 785
1,665
1,525
930

1,335
1, 7401,810
2.000
2,070+*
1,950+*
2,090
2,010
1,940+*
1,860+*
1,805
1,690
1,510
975

790
1,195
1,480
1,615
1,690
1,755
1,830
1,755
1,675
1,645
1,555
1,505
1,320
1,135

680+*
1,095
1,465
1,600
1,675
1, 740
1,795
1,730
1,655
1,565
1,5.50
1,495
1,325
1,160
500

* Partly broken.
The sternum of the specimen 68B was missed at the time of treating the carcass,and that of68A is 510 mm long and 381 mm width with no special feature.
PELVIC BONE AND FEMUR
Pelvic bones of these two specimens are of some interest, suggesting a sexual differencein the form and size (Fig. 3). The bones of the male specimen 68A are quite similar
to those of the specimens 61A and 61B, both male, as reported by Omura et al.
(1969). The length and the breadth at tuberculum laterale of the right and leftbones are 447, 83 and 440, 76 mm respectively. On the other hand in the female
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

7
6

OM
URA,
Nl
S
HlWAKlANDKAS
UYA

s
pe
c
imen68Btheformi
sd
i
百e
r
e
n
tandt
hel
engthismuchs
hor
t
e
ri
nr
e
l
a
t
i
o
nt
oi
t
s
br
eadth. Thec
o
r
r
e
s
p
ondingf
i
g
u
1e
soft
h
er
ightandleftbonesare207,67and201,
55m mr
e
sp
e
c
t
i
ve
l
y. Furthertheanglebetween t
h
ecran
ia
l andcaudalp
r
o
c
e
s
s
e
s
i
sg
r
e
a
t
e
ri
n68Athani
n68B. Hosokawa(
1951)roundamar
k
eds
e
x
u
a
ld
i町erencei
nt
heformofpel
vi
si
nt
h
ef
i
nandb
l
u
ef
o
e
t
u
s
e
s
. Jonsgarcl(l970)hasa
l
s
or
e
p
o
r
t
s
t
h
a
tt
hep
e
l
v
i
cbonemaybeusd
u
lf
o
rs
e
xdet
ermination,andperhap
sal
s
of
o
rage
determinationoftheminkewhaleintheNorthAt
lanti
c
.

F
i
g
.3
. P
e
l
v
icb
o
n
e
s(
i
n
ne
r
)a
n
dl
e
mur(
o
u
t
e
1
)o
ft
h
eb
l
a
c
kr
i
g
h
tw
h
a
l
ei
nt
h
eNor
t
h
Pa
c
i日ι
．
Le
f
t
:s
p
e
c
i
m
e
n6
8A (
m
a
l
e
)
. R
i
g
h
t
:s
p
e
ci
me
n6
8B(
f
emal
e
)
.
Thefemurtoosomewhatd
iffer
entbetween thetwospecimens. Thelengthsandbreadthsoft
h
er
i
g
h
tandl
e
f
tbone
sort
h
e68Aare106,123and 1
07,1
29m mr
e
s‑
p
e
c
t
i
v
c
l
y
,buti
nt
he68
Bt
h
ebonesaremuchlongerandmorep
o
i
n
t
e
d
. Thecor‑respondingf
i
g
u
r
e
si
nt
hi
ss
p
e
cimenare1
15,77and 1
23,75mm. Inbothspecimensthefemurisveryl
ightandhasasponge
‑
l
i
kes
t
r
u
c
t
u
r
eandnotd
i
f
f
e
r
sf
r
om t
h
a
tof
t
h
es
p
e
c
imens61Aand61Bi
nt
h
isr
e
s
p
e
c
t
.
HYOIDBONE
Hyoidbonesofthebo
thtwospeeimensareofnospec
i
a
lf
e
a
t
u
r
e,exceptt
h
a
ti
nt
he
combined boneofb
a
s
i
h
y
a
land t
h
y
r
o
h
y
a
l
soft
h
espec
imen68B. Inthisbonet
h
e
b
a
s
i
h
y
a
l hasnot bee
nfus
ed completelywith le
丘thyrohyalandt
hes
utureisveryloose. Omura(
1
958)r
e
port
sal
s
oi
nt
h
es
pe
cimen56Bt
h
es
u
t
u
r
e
sar
es
t
i
l
l,
・
i
s
i
b
le
thoughthesebonesareuni
tedcompletely. Measurementsofhyoidbone
sareshowninTable3.
TABL[
.3
. ルf
E
r
¥S
UR
I
て
蜘f
ENTSOFHYOIOBONESOFTHI:・SPECIMENS
6
8
AAND6
8
B(
i
nmm)
》'
f
e
a
s
ur
e
m
e
n
t
s
6
8
A
68B
S
t
r
a
i
g
h
tl
e
n
g
t
h
7
十4
578
He
i
g
h
ta
tm
i
d
d
l
e
1
6
5
98
L
e
n
g
tho
fs
r
yl
o
hy
a
lR.
379
2
56
L
.

389

263

S
c
i
.Rψ
.I
V
/
wl
e
sRe
s
.I
n
s
t.
,
λo.23
,1
97
1
.

＇

77

BLACK RIGHT WHALE

SCAPULA, HUMERUS, RADIUS, AND ULNA
The bones are of no special feature and measurements of these bones are shown in
Table 4.
TABLE 4.

MEASUREMENTS OF SCAPULA, HUMERUS, RADIUS, AND ULNA
OF THE SPECIMENS 68A AND 68B (in mm)
68A

ScapulaBreadthHeightHumerus
LengthBreadth at middle
RadiusLengthBreadth at middle
Ulna
Length at middle
Breadth at middle

68B

Right

Left

Right

Left

I, 152

948

1,129
933

942
764

936
747

628
264

629
261

523
238

520
229

674
243

678
234

571
172

580
161

536
124

524
119

459
98

465
98

CARPALS AND PHALANGESEach five carpals were saved from right and left flippers of the both specimens.
The phalangeal formulae for the specimens 68A and 68B are 13 , II 5, III 6, IV 4 , V 4
and I 2 , Il 5 , III 5 , IV 4 , V 4 respectively.
CHEVRON BONE
Thirteen chevron bones were preserved from the specimen 68A. Among these
the lst, 12th, and 13th are not united of the right and left laminae. For the 68B
specimen are present twelve chevrons and in which lst, 2nd, llth, and 12th are notunited.
ACKNOWLEDGEMENTS
Our sincere thanks are due to the staff of the Taiji \!\!hale Museum, Mr. A. Kawamura of the \!\Thales Research Institute, Mr. T. Miyodori and personnel of the
Taiyo Gyogyo K. K. who assisted our works. They all helped us greatly in preparation of the specimens as well as in measurements.
REFERENCES
HosoKAWA, H., 1951. On the pelvic cartilages of the Balaepoptera-foetuses, with remarks on the specificaland sexual difference. Sci. Rep. Whales Res. Inst., 5: 5-15.
,JoNsGARD, A., 1970. Progress r~port on whale research covering the period April 1969 to April 1970, submitted to the International Whaling Commission.
OMURA, H., 1958. North Pacific right whale. Sci. Rep. Whales Res. Inst., 13: 1-52.
OMURA, H., S. 0HSUMI, T. NEMOTO, K. NAsu and T. KAsUYA, 1969. Black right whales in the North Pacific.
Sci. Rep. Whales Res. Inst., 21: 1-78.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

27.

28.

. "'

""~

~~

~-=.,....

" "'...l.>J ~;,..
c--, "'
~

26.

~

'?-

~

~

L

Length of skull, straight ................................ .
Length of max. at superior border, straight ......................................... .
Length of max., following curve of sup. external border ....................... .
Length of premax., straight .............................................................. .
Length of premax., along dorsal convexity ......................................... .
Length of rostrum, straight .............................................................. .
Anterior end of nasals to end of rostrum, on curve ............................. .
Length from tip of premax. to posterior end of pterygoid .................... .
Length from tip of premax. to post. end of palatines, median .............. .
Length from tip of premax. to ant. end of palatines, median ................. .
Length of nasals, median ................................................................. .
Breadth of 2 nasals distally .............................................................. .
Breadth of 2 nasals proximally ........................................................... .
Breadth of skull, orbits .................................................................... .
Breadth of skull at ant. and dist. ends of orbital process of frontal ........ .
Breadth of skull at orbital processes of maxillaries ................................ .
Breadth of skull at squamosals ........................................................... .
Breadth of rostrum at middle, straight ............................................... .
Greatest breadth of occipital bone ..................................................... .
Height of supraoccipital bone, from foramen magnum .......................... .
Transverse breadth of occipital condyles ............................................ .
Height of occipital condyle .............................................................. R

L
Length of mandible, on curve ........................................................... R
L
Depth of mandible at coronoid ...
............................................. R
L
Depth of mandible at condyle ....
..... R
L

151.8
137.0
164.4

87.6
79.0
94.8

4,045
3,650
4,380

30.1
24.1
7.6
6.2
6.2
2.8
3.1
96.5
95.8
103.4
101.2
1,392
I, 112
353
288
285
129
145
4,460
4,425
4,675
468
463
502
490

10.0
10.9
10.6

JO. I

52.2
41. 7
13.2
10.8
10.7
4.8
5.4
167.4
166.0
179.2
175.4
17.6
17.4
18.8
18.4

57.7

2,665

4, 775

100.0

8.5
6.7
6.0

391
308
276

14.7
11.6
10.4

159.8
139.2
145.0

100.0
80.3
83.7

4,620
3,710
3,865

% of
breadth% oflength

in mm

WA

3,270
2,425
2,520
2,567
2,675
2,516
2,410
3,080
3,020
2,610
295
197
287
2,038
2, 121
1,904
2,022
391
1,061
836
370
304
305
109
161
3,180
3, 185
3,395
3,370
381
373
378
387

in mm

11.8

4.9
97.3
97.4
103.8
103.1
11. 7
11.4
11.6

3.3

9.3
9.3

11. 3

62.3
64.9
58.2
61.8
12.0
32.5
25.6

8.8

100.0
74.2
77 .1
78.5
81.8
76.9
73.7
94. 2
92.4
79.8
9.0
6.0

% of
lengthWBSKULL MEASUREMENTS OF THE BLACK RIGHT WHAIE IN THE NORTH PACIFIC

23. Greatest breadth of foramen magnum ............................................... .
24. Greatest height of foramen magnum ................................................. .
25. Length of mandible, straight. .............................................................. R

21.
22.

12.
13.
14.
15.
16.
17.
18.
19.
20.

11.

10.

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

Measurements

APPENDIX TABLE I.

161. 7119.9
124.6
127 .0
132.3
124.4
119.2
152.3
149.4
129.1
14.6
9.7
14.2
100.8
104.9
94.2
100.0
19.3
52.5
41.3
18.3
15.0
15.1
5.4
8.0
157.3
157.5
167.9
166.7
18.8
18.4
18.7
19.1

% of
breadth

~

~

[/).

>-

~

ti

~

~
......

~

::i::

[/).

~
z
......

c:::

0

co

.._,

BLACK RIGHT WHALE

79

APPENDIX TABLE 2. MEASUREMENTS OF VERTEBRAE OF THE BLACKRIGHT WHALE IN THE NORTH PACIFIC (in mm)
I.

Specimen 68A

Serial Vertebral
no.
no.
1
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
3I
32
33
34
35
36
37
38
39
40
4I
42
43
44

Cl
2
3
4
5
6
7
DI
2
3
4
5
6
7
8
9
10

II
12
13
14
L I
2
3
4
5
6
7
8
9
10
Ca I
2
3
4
5
6
7
8
9
10

II
I2
13

Greatest
breadthGreatestheightCentrum
BreadthHeight

LL
J

685
694
692
664
623
617
625
624
668
692
694*
746
818
947
1,039
1,104
1,114
I ,II9I, I2II, I28I, I22
I,III
1,041
I ,08I
983
933
867
786
689
606
570
51I
478
436
398
366
347

J

Length

Note

1240

518
529
564
593
604
598
604
616
623
622
620
626
626
647
665
681
-**
70I
732
720
739
714
7I8
699
702
671
669
-**
630
608
580
568

307
296
281
275
276
277
280
287
304
322
313
345
335
340
337
339
338
338
342
346
344
35I
360
359
367
364
354
350
354
346
352
346

250
251
240
237
236
235
236
239
240
244
244
248
248
255
274
285
288
294
309
305
304
312
323
312
343
347
354
35I
356
361
364
355

67
88
101
117
125
133
141
155
169
181
170
185
193
203
206
210
2I5
2I7
225
229
236
239
240
24I
242
245
240
241
238
234
232
232

545
518
482
45I
405

35I
346
342
340
325

354
352
345
337
328

22I
2I6
205
198
185

Fused to cervicals* Estimated** Spinous process broken** Spinous process broken

Incomplete foramen on t.
processT. processes perforated.

T. process ends
Continued ...

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

80

OMURA, NISHIWAKI AND KASUYAAPPENDIX TABLE 2. Continued.

I.

Specimen 68A

Serial Vertebralno.
no.

Centrum

Greatest
breadthGreatestheightBreadthHeightLength

45

14

332

365

301

304

171

46
47
48
49
50
51
52
53
54
55
56
57
58

15
16
17

299

315

282
257
216
194
172
162
138
122
102
85
65
45
30

275
247
205
185
172
157
139
123
103
83
63
47
30

147
132
123
115
108
103
93
82
71
63
55
47
24

18

19
20
21
22
23
24
25
26
27

Note
Epiphyses fused to centra
from 13 th caudal, except
last 3
Neural canal disappear

2. Specimen 68B
Centrum
Serial Vertebral
no.
no.
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

Greatest
breadthGreatestheight

) 600

) 451

273
484
620
466
445
495
484
482
478
490
496
538
568
631
714
750
727
718
703
758

464
460
459
471
494
514
520
517
519
516
510
507
489
489
486
503
526
544
564
565

BreadthHeightLength

Note

Cl
2
3

4
5
6
7
DI
2
3
4
5
6
7
8
9
10
II
12
13
14
L I
2
3
4
5

) 213

273
269
285
271
249
250
249
256
258
267
274
290
309
313
317
299
295
293
292
295

223
224
220
218
214
210
210
210
214
216
216
214
217
215
216
225
239
251
264
272

41
78
72
99
113
122
129
140
149
161
165
168
172
177
180
182
189
188
199
202
Continued ...
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

BLACK RIGHT WHALE
APPENDIX TABLE 2.
2.

81

Continued.

Specimen 68B

Serial Vertebral
no.
no.
27
6
28
7
29
8
30
9
31
10
32
Ca I
33
2
34
3
35
4
36
5
37
6
38
7
39
8
40
9
41
10
42
II
43
12
44
13
45
14
46
15
47
16
48
17
49
18
50
19
51
20
52
21
53
22
54
23
55
24
56
25
57
26

Greatest
breadth
750
725
718
716
693
674
643
617
585
560
520
496
461
418
387
360
337

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

Greatestheight
552
577
562
570
567
567
555
561
553
557
535
534
517
503
475
452
418
382
326

Centrum
Breadth
298
293
293
304
305
309
312
314
314
315
319
321
324
339
327
338
324
312
300
259
231
194
173
161
152
131
115
102
84
61
39

Height
263
266
258
282
282
295
291
299
306
314
328
334
334
333
335
332
318
305
272
246
223
191
171
157
143
127
107
89
70
53
38

Length
279
205
211
226
227
235
235
237
235
236
237
236
233
229
222
219
203
196
181
151
128
117
109
105
95
87
75
65
56
57
31

Note

Foramen on left t. process
Both t. processes perforated

T. processes end

Neural canal disappear

OSTEOLOGICAL NOTE OF AN ANTARCTIC SEI WHALE
MASAHARU NISHIWAKI* AND TOSHIO KASUYA*ABSTRACTThis is a report of measurements on the skeleton of a male se1 whale
caught in the Antarctic.
The skeleton of a sei whale (Balaenoptera borealis) was collected in the Antarctic
Ocean for the purpose of exhibits at the Taiji Whale Museum.
Taiji is the place where ancient Japanese whaling commenced. It is famedthat Taiji whalers first established their revolutionary method of taking whales, inwhich whales are entangled in a net to prevent them from escape and killed withhand harpoons. Until now, Taiji Town, V\rakayama Pref., has yielded many gunners
and crew of factory ships and catcher boats.
\Vhen The \Vhale Museum was constructed by the demand of town people,
various specimens were collected as varid and many as possible in the districts far andnear.
Catch data of this whale is as follows:
Date of catch
position of catchwater temperature at the time
air temperature at the time
body lengthsex
number of corpus luteum and albicans
fetus: body lengthsex
name of the catcher boat
name of the senderFeb. 18, 1967
58°-53'S, 83°-09'E
l.8°C
2.0°c
15.3 mfemaleR.0,3 L.1,3
268cm
male
the Kyo-maru No. 10.
Mr. K. Sakamoto

The skeleton had arrived Yokohama from the Antarctic whaling ground in
April 1967 and has been buried in the sandy ground of Tokai University campus,
Orido in Shimizu City, Shizuoka Pref. It was excavated on Sept. 9, 1968 and it
takes 15 days to be cleaned and measured.
This report is merely a record of measurements on the skeleton of the sei whale,
not a comparative study, and we did not find peculiar characters in the skeleton, so
no discussion were done.
Measurements of the skull are shown in Table I and the dorsal, lateral andventral views are shown in Plate I. As it is seen in the Plate I, the tip of rostrum
was broken at the time of excavation, but most of the fragments were secured.

* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971. 83-89.

84

NISHIWAKI AND KASUYA

Some errors were made after it was measured and photographs were taken. vVhen
the exhibition was arranged, waiting for its repairement, the broken pieces had been
kept aside. But one of the laborer took it for rubbish and threw it into the reclaiming hole. Though we looked for, it could not be found again. Now the skull isappeared in original shape repaired with a unit of another tip from the Antarctic.
Measurements of vertebra are shown in Table 2, as well as in Plate II. The
vertebral formula is
C 7 +D 13+L 14+Ca 22=56
All epiphyses of the vertebrae are ankylosed to the centrum, but still, gaps areseen in the Dorsal and Lumbar vertebrae. Compared with the spinal processes ofB. edeni, those in this species are less slanted to the backward.
In the 2nd to 6th cervical vertebrae the upper and lower lateral processes areunited at the tip to form a loop, but in the lst and 7th they are separated.
There are 13 pairs of ribs and the lst rib has bilateral head, this character iscommon with B. borealis as seen in Fig. 6 of Plate II. Measurements of ribs areshown in Table 3.
There are fourteen lumbar vertebrae.
There are twenty one caudal vertebrae as shown in Fig. 4 and Fig. 5 of Plate
II. It is certain that one more vertebra might have existed at the extreme rear,
but seems to have been lost at collection. In the lst caudal vertebra, the facet
where chevron bone attached to is clear and was easy to be distinguished as seenin Fig. 7 of Plate II. Ten pairs of chevron bones are present, none of which haslaminae separating to both side. Their measurements are shown in Table 4.
The hyoid bones are slender in shape and the basihyal and the thyrohyals are
combined. Measurements of this bone is shown together with Fig. 1. There areno special feature on the specific consideration.
The sternum has short processes and is roughly star-like in shape as shown in
Fig. 2. This bone is 28 cm in length and about 45 cm in breadth. Right posterior arm was broken off.
Pelvic bones were missed at collection.
The scapula is shown in Fig. 3 with measured data. The acromion and thecolacoid are well developed. Fortunately, both sides of humerus, radius andulna were collected and are present, the phalangial bones were cleaned up at
The vVhales Research Institute and transported to Taiji, but they were lost during
the preparation of exhibition. Measurements of the above three are shown in
Table 5.
\,Ye express sincere gratitude to Director Hideo Omura of The Whales ReseachInstitute and to Prof. M. Iwashita and the stuff members of the Faculty of Marine
Science and Technology of the Tokai University for help in burying and cleaning
the skeleton at their campus. Our gratitude are also to the director, Mr. T. Higashi,
and the stuff members of the Taiji Whale Museum for cooperation throughout
the study.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

SE!W HALESKELETON

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86

NISHIWAKI AND KASUYATABLE I.

SKULL MEASUREMENTS OF THE ANTARCTIC SEI WHALE

Measurements
Length of skull, straight
Length of beakLength of premaxillary, straight
Length of maxillary along upper surface
Tip of premaxillary to posterior end of maxillary
Tip of premaxillary to vertex
Tip of premaxillary to tip of nasals (mesial)
Tip of premaxillary to anterior end of palatines (mesial)
Tip of premaxillary to posterior end of palatines (mesial)
Tip of premaxillary to posterior end of pterygoid
Tip of premaxillary to anterior end of maxillary
Length of supraoccipital from foramen magnum
Greatest breadth of skull, squamosal
Breadth of skull, frontal
Breadth of skull, maxillary
Breadth of beak at base
Breadth of beak at middle
Breadth across premaxillaries, greatest
Breadth across premaxillaries, at base of beakBreadth across premaxillaries, at middle of beakBreadth across maxillaries at posterior ends
Breadth of pterygoids
Breadth of palatines
Breadth between tympanic bullae, outer
Length of nasals mesially
Length of nasals, laterally
Breadth of nasals at anterior ends
Breadth of nasals at posterior ends
Breadth of orbit (frontal wing)
Breadth of occipital between aquamosal sutures
Breadth across occipital condyle
Height of occipital codyle
Breadth of foramen magnum
Height of foramen magnum
Breadth across mastoid process, tip to tip
Breadth across mastoid process, greatest
Length of mandible, straight
Length of mandible, along outer curve
Height of mandible at coronoid
Height of mandible at processus articularis
Height of mandible at middle

Actuallength (mm)% ofskull length% ofskull breadth

3790
2630
R. 2980
L. 2960
R. 2860
L. 2860
R. 3010
L. 3010
2987
2635
2700
3260
3470
R.
80
L.
90
800
1640
1550
1420
990
620
370
280
260
320
280
480
550
260
R. 310L. 290170
87
R. 260L. 2601190
300
R. 210L. 210
110
145
1280
1460
R. 3460
L. 3470
R. 3610
L. 3630
R. 400L. 390R. 275
L. 294
R. 270L. 270

100.0
69.4
78.6
78. l
75.5
75.5
79.4
79.4
78.8
69.5
71. 2
86.0
91.6
2.1
2.4
21.1
43.3
40.9
37.5
26. l
16.4
9.8
7.4
6.9
8.4
7.4
12.7
14.5
6.9
8.2
7.7
4.5
2.3
6.9
6.9
31.4
7.9
5.5
5.5
2.9
3.8
33.8
38.5
91.3
91.6
95.3
95.8
10.6
10.3
7.3
7.8

231.1
160.4
181. 7
180.5
174.4
174.4
183.5
183.5
182.1
160.7
164.6
198.8
211.6
4.9
5.5
48.8
100.0
94.5
86.6
60.4
37.8
22.6
17 .1
15.9
19.5
17 .1
29.3
33.5
15.9
18.9
17.7
10.4
5.3
15.9
15.9
72.6
18.3
12.8
12.8
6.7
8.8
78.1
89.0
211.0
211.6
220.1
221.3
24.4
23.7
16.8
17.9
16.5
16.5

7 .1

7 .1

Sci. Rep. Whales Res. Inst.,.No. 23, 1971.

87

SEI WHALE SKELETONTABLE 2.

MEASUREMENTS OF VERTEBRAE OF THE ANTARCTIC SEI WHALE (cm)Centrum

SerialNo.
1

Vertebral
No.

Greatest
breadthGreatestheightBreadthHeightLength

c

54.0
79.0
73.0
78.0
75.0
71.0
71.0

34.0
35.0
31.0
36.0
38.0
43.0
45.0
46.0
49.0
56.0
61.0
64.0
67.0
76.0
73.0
75.0
76.0
78.0
79.0
82.0
84.0
85.0
88.0
87.0
89.0
90.0
91.0
91.0
90.0
90.0
90.0
90.0
90.0
87.0
85.0
81.0
75.0
69.0
62.0
53.0
44.0
40.0
37.0*
34.0
31.0
27.0
22.0

30.0
31.0
26.0
25.0
24.0
24.0
25.0
26.0
27.0
27.0
28.0
27.0
26.0
26.0
26.0
26.0
26.0
26.0
27.0
27.0
27.0
27.0
28.0
28.0
28.0
28.0
29.0
29.0
29.0
29.0
30.0
30.0
31.0
31.0
31.0
32.0
32.0
32.0
32.0
32.0
32.0
32.0
31.0
28.0
26.0
24.0
20.0

21.0
18.0
19.0
20.0
20.0
20.0
20.0
20.0
20.0

11.0
8.0
6.0
6.0
6.5
7.0
8.0
9.0
11.0
14.3
16.0
17 .0
18.3
19.7
20.6
21. 3
21. 7
22.2
22.4
23.2
23.7
24.2
24.5
25.3
25.7
26.3
26.9
27.3
27.9
28.6
29.5
30.0
30.2
30.6
30.4
30.6
30.7
30.8
30.7
29.9
29.8
29.2
28.0
26.7
25.0
19.5
14.4

2

2
3

3

4

4
5

5

6
7
8
9

6

7
D

72.0
2

10

3

11

4
5
6

12
13
14
15
16
17
18
19
20
21

7
8
9

10
11

12
13
L 1

22

2

23
24
25
26
27
28
29
30
31
32

3

33

34
35
36
37
38
39
40
41
42
43

4

5

6

7
8
9

10
11

12
13
14
Ca 1

73.0
73.0
80.0
86.0
94.0
99.0
104.0
106.0
107.0
108.0
109.0
103.0
108.0
107.0
102.0
108.0
106.0
108.0
105.0
103.0
101.0
100.0
99.0
94.0
89.0
82.0
78.0

2

72.0

3

69.0
63.0
59.0
50.0
48.0
40.0
36.0
30.0
28.0
25.0
21.0

4
5
6

7
8
9

44

10

45
46
47

11

12
13

20.0

20.0
19.0
19.0
19.0
19.0
20.0
20.0
20.0
20.0
20.0
21.0
22.0
22.0
22.0
22.0
23.0
24.0
24.0
24.0
24.0
25.0
25.0
26.0
26.0
27.0
27.0
28.0
27.0
28.0
29.0
28.0
28.0
28.0
27.0
26.0
22.0
19.0

Continued ...

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

NISHIWAKI AND KASUYA88

TABLE 2.

Continued.
Centrum

SerialNo.

Vertebral
No.

Greatest
breadthGreatestheightBreadthHeightLength

48
49
50
51
52
53
54
55
56

14
15
16
17
18
19
20
21
22

19.0
17.0
14.0
11.0
9.0
7.0
5.0
4.5
lost

18.0
15.0
14.0
11.0
9.0
7.0
4.0
3.0

17.0
15.0
13.0
10.0
9.0
7.0
5.0
4.5

15.0
13.0
12.0
10.0
8.0
6.0
4.0
3.0

11.9
10.9
10.0
8.8
7.0
6.1
5.3
4.0

*:

has some deficit

TABLE 3.

STRAIGHT LENGTH OF RIBS OF THE ANTARCTIC SEI WHALE (cm)
Rib No.
2
3
4
5
6
7
8
9
10
II

12
13

TABLE 4.

right

left

89
148
181
197
176+
208
204
198
181
170
158
148
139

88
151
201
209
209
205
200
190
181
170
146
146
135

MEASUREMENTS OF CHEVRON BONES OF THE ANTARCTIC SEI WHALE (mm)No.

LengthHeightBreadth, (greatest)

2
3
4
5
6
7
8
9
10

110
120
150
140
150
140
130
130
120
120

240
300
300
310
180
230
230
190
160
120

170
160
210
210
180
190
180
160
140
130
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

89

SEI WHALE SKELETONTABLE 5. MEASUREMENTS OF HUMERUS, RADIUS ANDULNA OF THE ANTARCTIC SEI WHALE (mm)Humerus
Right
Left
Radius
Right
Left
Ulna
Right
Left

Length at center

Breadth at middle

410
410

160
160

680
670

85
85

720
740

70
70

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

Dorsal view of the skull of the Antarctic sei whale.
Lateral view of the skull of the Antarctic sei whale.
Ventral view of the skull of the Antarctic sei whale.
Dorsal view of the mandibles of the Antarctic sei whale.

Fig. I.
Fig. 2.
Fig. 3.
Fig. 4.
Fig. 5.
Fig. 6.
Fig. 7.

Lateral view of the cervical vertebrae of the Antarctic sei whale.
Lateral view of the thoracic vertebrae of the Antarctic sei whale.
Lateral view of the lumbar vertebrae of the Antarctic sei whale.
Lateral view of the caudal vertebrae (lst 12th) of the Antarctic sei whale.
Lateral view of the caudal vertebrae (13th 21 th) of the Antarctic sei whale.
Caudal view of the lst right side rib of the Antarctic sei whale.
Ventral view of the vertebrae of the Antarctic sei whale from 13th lumbar to 2nd caudal,
showing attachment facets for chevrons.

PLATE II

Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

I'
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PLATE II~ I S HI\\"A KI A~D

KASUYASOME OBSERVATIONS ON THE CETACEAN STOMACHS,
WITH SPECIAL CONSIDERATIONS ON THE
FEEDING HABITS OF WHALESHIROSHI HOSOKAWA* AND TOSHIRO KAMIYA**ABSTRACT

Macro- and microscopical observations on the sei, fin, blue and sperm
whale stomachs are described and discussed on the base of comparative-anatomical and functional viewpoint. The compartmentalization of the cetacean
stomach is a unique character in the animal kingdom and it must be attributed
to the aquatic life of the group. An attempt has been made to establish therelationship between the anatomical features of the cetacean stomach andits physiological function.
INTRODUCTION
In the latter half of the seventeenth century Tyson (1680) described the complicatedstomach of the common porpoise. About one hundred years later Hunter (1787) remarked that the cetacean stomach revealed generally a highly characteristic feature ofthis group of animals, divided into several compartments. He noticed, furthermore,that it resembled very closely those of cattles and sheep, and he supposed the whales
probably belonged to the ruminants, or had at least an intimate phylogenetical
relationship with the ungulata. Thereafter, many anatomists directed their attention to the cetacean stomach and numerous reports were published, dealing directly
or incidentally with this special feature of cetacean anatomy. Though it was soon
ascertained that the cetacean stomach was, in spite of its resemblance to the ruminantone, quite different from the latter, its extraordinarily complicated structure remained for a long time without a clear comparative-anatomical explanations, not tospeak of its physiological interpretation. The specifical differences in form of
stomachs among all different kinds of whales were so extreme that it was very
difficult to abstract the standard figure of them. We will quote here, for example,
various numbers of stomach-chambers recorded by many authors for Mystacoceti. In
most cases, the research materials of these authors were adult or fetal minke whale(Balaenoptera acutorostrata ), though some of them studied the blue whale (B. musculus)
or fin whale (B. physalus). Schulte alone used a fetus of the sei whale (B. borealis).
Hunter (1787) 5,

Cuvier (1805) 4,

Meckel (1829) 3,* The late Professor of the Department of Anatomy, Faculty of Medicine, University of Tokyo, he deceasedon the way to this work in 1967.

** Department of Anatomy, Faculty of Medicine, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971. 91-101.

92

HOSOKAWA AND KAMIYA

Eschricht (1849) 3, Murie (1865) 4, Carte & Macalister (1868) 5,
Perrin (1870) 4, Weber (1888) 3*, Pilliet (1891) 4,
Turner (1892) 5, Schulte (1916) 4*, Slijper (1962) 3*.
*without counting the duodenal ampulla.
At the end of the nineteenth century, however, ·weber (1888) and Jungklaus(1898) published very splendid works on this problem and the macroscopic anatomyof the cetacean stomach was brought to a general conclusion. Thus, Weber classified the stomach of toothed whales, based on the development of its first compartment covered with the oesophageal mucous membrane, into the following 5 types:
3) Phocaena-type,1) Ziphiidaes-type,2) Hypothetic intermediate-type,4) Globicephalus-type and 5) Lagenorhynchus-type, and he explained thatthese types had developed one by one in the order of their number from the mostprimitive Ziphiidaes type. On the other hand, according to J ungklaus, who
endeavoured to use generally the comparative-anatomical characteristics of thecetacean stomach, not only of the toothed whales but also of the baleen whales, themost remarkable peculiarity of the cetacean stomach distinguishing itself from thesame of other mammals did not lie in its mere complexity caused by the compartmentalization but consisted in the fact that the glandular stomach itself was separated
into two divisions, one of those being provided with the peptic or fundus glands
and the other with the pyloric glands. The latter divisions were, moreover, apt
to be divided into two or more secondary compartments. On the difference between
the Odontoceti and Mystacoceti stomachs he stated that in the latter the constrictions
between each divisions or compartments were not so sharp as in the former. Jungklaus's conclusion of the characteristic feature for cetacean stomach is quite rightfrom the comparative-anatomical standpoint, as was confirmed afterwards by
Beddard (1900). From the physiological standpoint, however, we suppose that thecomplexity of the cetacean stomach, which is caused not only by the compartmentalization of the glandular portions but also by the oesophageal dilatation etc. has agreat significance. Against this background information we will, in the present
paper, try to present a detailed histological picture of the cetacean stomach.

MATERIALS

Baleen whale:
14.0 m male, 14.6 m female, 15.7 m female,
16.2 m female.
Fin whale (Balaenoptera physalus): 21. 3 m female.
Blue whale (Balaenoptera musculus): 23.8 m male.
Sei whale (Balaenoptera borealis):

Toothed whale:
Sperm whale (Physeter catodon): several adults, of which one 11.0 m longfemale and one 15.6 m long male were studied with special attention.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

CETACEANST
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94

HOSOKAWA AND KAMIYA

pancreas. The other two, namely the second and the third, are real gastric compartments providing with digestive glands. Between these two, however, there isanother small division developed especially in the fetal stage. In the female sei
whale of 15. 7 m length the largest compartment is the third one, measuring 110 cm
and 85 cm respectively in the transverse and longitudinal diameters in relation to
the axis of the digestive canal, followed by the fourth (85 x 75 cm) and the second(80 x 80 cm) in that order, and the first compartment is still smaller. Communication between the first and the second chambers is through a not so strong constriction. Where the second chamber leads into the third through the small connecting
division, there exist two semilunar valves separating the two compartments. The
third compartment opens into the fourth through the narrow passage constricted
sharply by the pyloric sphincter (Fig. 1).
Macroscopical features of the mucous membrane: (Plate I)
The mucous membrane of the oesophagus is lined by the thick, graywhite andcornified epithelium folded with numerous longitudinal, fine furrows. The sameepithelium clothes the inner surface of the first compartment too, and there aremany reticular folds of several millimeter in width, which are ramified and anastomosed to each other. These reticular folds disappear, when the wall of the stomach is
stretched, so that they are formed by the undulation of the whole wall. It is clear,
therefore, that this compartment is able to contract and dilate to a considerable
extent by the aid of the mural muscle strata. Where the first compartment leads
into the second one, the mucous membrane changes its character abruptly, there is adistinct lineal boundary between the oesophageal epithelium of the former and thegastric lining of the latter (Plate I-1 ). This is covered by the soft, mucous epithelium of dark gray colour with some tone of yellow. Its surface is smooth for 2-3 cmfrom the line separating the oesophageal epthelium and the gastric lining referred
to above, followed by thick reticular folds, about 1 cm in width, resembling theconvolution of the human cerebrum. These folds do not disappear even when thestomach is stretched; that is to say that they are formed in the mucous membrane
itself merely for the purpose to increase the inner surface of the stomach. The
second compartment has, therefore, no anatomical feature to contract or dilate
itself extensively. In the lower half of the second compartment the reticular folds
are reduced as the compartment approaches the third one, in which the surface ofthe mucous membrane is quite smooth and without any furrows or folds. It iscoloured yellowish gray, with some tone of pink. The duodenal ampulla is clothed
also with smooth, soft membrane, coloured brownish red and it continues with thatof the small intestine, without any constriction or valve. For the female sei whale(15.7 m long) the first compartment has the thickest wall measuring 2.5 (-3.0) cm,
containing very well-developed muscular strata. The wall of the remaining three
are somewhat thinner and measure about 1.2 (1.0-1.5) cm. The wall of the small
intestine is 0.8-1.0 cm thick. For the male blue whale of 23.8 m length the wallsof the first, second, third and fourth compartments were 4.0 cm, 2.0 cm, 1.5-2.0 cm(mucosa: 0.5, muscularis: 0.9, serosa: 0.1) and 1.3 cm (mucosa: 0.3, muscularis:
0.7, serosa: 0.3) respectively.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

CETACEAN STOMACH AND FEEDING HABITS

95

Histological structure: (Plate II)
Oesophagus is lined by an extensively stratified flat epithelium of about 1 mm
in thickness. The most superficial layer of the epithelium (25-30 µ) is completely
cornified and the cells have no trace of nucleis in contrast to the case in humans.
The next layer of about 25 µ has cells containing rudimentary nuclei. These twolayers are followed by a third layer, 4-5 cells in thickness the cytoplasm of the cells
staining deep red with eosin and the nuclei are shriveled, indicating probably thecommencement of the cornification of cells. The next layer is composed of several
strata oflarge cells, occupying the greater part of the epithelium. While the cells of
the upper portion of this layer are situated with their axis almost parallel to thesurface of the epithelium, those of lower part make a right angle with the same especially in the areas between the papillae. While the nuclei of the former are
smaller and stain deeply, those of the latter are larger and stain lightly. The deepest
layer is bounding to the propria, and composed of crowded cells of small size. The
connective tissue, propria, of about 3-4 mm in thickness, contains many vessels
and fat-cells and forms high papillae, which are very well-developed, and the thickness reaches as high as 95% of the total thickness of the epithelium (in the case ofhumans oesophagus it is only 50%). The density of the papillae is also larger in the
cetacean oesophagus than in the human case.
The smooth muscle fibres of the lamina muscularis mucosae are arranged not soorderly as in other mammals, but are scattered irregularly. This unsystematicarrangement of the muscularis mucosae is noticed not only in the oesophagus but
also in every compartment of the stomach and throughout the intestine, thereby
losing the significance of the the name of " lamina ". The submucosa, formed byloose connective tissue, has nothing special to be described. The muscularis presents an inner, circular and an outer, longitudinal layer of muscle bundles. In theupper portion of the oesophagus it consists exclusively of striated fibres, but in the
middle and lower parts the muscularis is composed wholly of smooth fibres. Between the inner and outer layers there are scattered nerve fibres and ganglia, analogous
to Auerbach's plexus, which we come across in the intestines. The outer surface ofthe muscularis is covered with a thick membrane of connective tissue reinforced byelastic networks (adventitia).
The histology the first compartment of stomach is not very different from thatof the oesophagus, in spite of the slight difference in the relative thickness of thecorresponding layers or strata. It is quite obvious that this compartment isnothing but a dilated sack of the lowest part of the oesophagus.
The second compartment. The simple cylindrical epithelium lines the entire
inner surface of this compartment, including the gastric pits. It is composed oflight cells having distinct boundaries between each other. Nuclei of these cells
are small-sized, deeply stained and are situated at the base of the cells. At the floorof the gastric pits open numerous gastric glands occupying the propria and we candiscriminate two kinds of glands, the cardiac and the fundus glands.
The cardiac glands. Contrary to the earlier belief that the cetacean stomach is
destitute of the cardiac glands, we found cardiac glands to exist in the stomach of aSci. Rep. Whales Res. Inst.,
No. 23, 1971.

96

HOSOKAWA AND KAMIYA

blue whale, occupying the narrow zone adjacent to the border-line at the junction
between its first and the second compartments. They are quite like the pyloric
glands of the third compartment in their structure, both being of the tubulo-alveolar
nature and composed of light cells of one kind.
The fundus glands. This type of gastric glands, branched tubular in nature,are extended in the greater part of the mucous membrane of the second compartment, situated within the propria and are 2-3 mm in thickness (in humans it is at
most about 1.0 mm). The zymogenic cells of this gland, 6-7 µ in diameter, arecharacteristic with the fairly coarse granules they contain, which stain with basic
dyes in the same way as the chromatin of the nucleus. The second kind of cells
found in this gland, the parietal cells, are much more developed than in the humanstomach. They differ from the chief cells in being considerably larger (10-20 µin diameter) and in their spherical or pyriform shape, containing sometimes two or
more nuclei. Frequently, especially in the lower part of the gland, they do notreach the lumen of the tube, being connected with it by a narrow pedicle. The moststriking characteristics of these cells are their strong affinity for acid dyes. Numeral
ratio between the zymogenic and the parietal cells is about 3: 1 and this index shows,compared with that of 5-6: 1 in the human case, that the cetacean stomach has
plenty of parietal cells, which are said to secrete hydrochloric acid. This peculiarityof the cetacean fundus glands must have some important meaning for the gastricfunction of this animal. Mucous neck cells are situated near the openings of theglands into the gastric pits and can be discriminated easily by their light cellularbody and somewhat shriveled nucleus, lying aside at the bottom of the cells.
The propria consists mainly of reticulated tissue, containing many free cells or
aggregated lymphatic cells.
The muscularis mucosae, which separates the propria from the underlying
submucosa, does not form a well-defined layer and is divided into the following fourgroups of muscle bundles; 1) muscle-fibres scattered in the propria, some of which
extend along the fundus glands up to the superficial layer underlying the epithelium,2) fibre-bundles running in the same direction as the reticulated folds of the mucous
membrane, 3) and 4) two muscle bundles in the deeper layer, which run independently of the direction of the reticulated folds, crossing each other at almost
right angles.
In the loose connective tissue of the submucosa run arteries provided with very
thick walls, just like the case in the cattle.
As muscularis was stripped of in our materials it was not possible to examine ithistologically.
The third compartment. The simple cylindrical epithelium clothes the inner surface, where numerous gastric pits are developed. Glands of this compartment that
extend into the propria are the pyloric glands. They are of the branched tubuloalveolar nature, and the glandular epithelium here presents great differences from thatof the fundus glands as these are composed of only one kind of cells. Althoughthese cells differ slightly from the zymogenic cells of the fund us glands, they resemble
the latter in all essential particulars so much so that we may take them for the same.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

CETACEAN STOMACH AND FEEDING HABITS

97

The propria of this compartment does not differ from that of the second chamber. The muscularis mucosae also resembles that of the second one, but the firstgroup of muscle-bundles is more developed in this compartment and the second
group is lacking, while the third and fourth groups are only weakly developed.
In the submucosa there are scattered fat-cells, vessels, nerve-cells and fibres.
The muscularis is stripped off.
The fourth compartment (duodenal ampulla). The histology of the fourthcompartment in the oral half is not very different from that of the third compartment and in the anal half in their structure leads into the small intestine.

Stomach of the sperm whale
As refered to in the introduction, the constrictions between adjacent gastriccompartments in the sperm whale are marked more sharply than in the baleen
whales, and we can easily discern four compartments. The first and second compartments are very large, each measuring 140 x 140 cm for an adult male of 15.6 m
length, and the third and fourth are somewhat smaller, measuring 130 X 60 cm and
130 X 100 cm respectively.
The inner surface of the first compartment is covered with the same, yellowish
white epithelium as is the case with that of the oesophagus. There are, however,no well-developed folds, the inner surface here being provided only with the irregular
reticular fine furrows, especially in the region between the opening of the oesophagus
and the passage into the second compartment. The oesophageal epithelium of thefirst compartment stands out distinctly from the soft, mucous membrane of thesecond one. The surface features of the latter resemble that of the sei whale, having
been provided with the reticular folds, which diminish in the areas near the first
and third compartments. The third and fourth compartments are clothed by asimilar smooth membrane as in the sei whale, though in the fourth come into sight
semilunar folds as it approaches the opening into the small intestine.
Thickness of walls of different compartments. The thickness of the wall of thefirst compartment is 2.5-3.0 cm (mucosa 0.7, muscularis 1.7, serosa 0.4) of thesecond compartment 2.5-3.0 cm (mucosa 0.8, muscularis 1.4, serosa 0. 7), and eachof the third and fourth compartments 1.0-1.5 cm. It was not possible to do histological studies of the stomach of this whale, as it is very difficult to get seasonably
fresh materials to be used for microscopical work.
DISCUSSION

1.

Cetacean stomach seen from the comparative-anatomical viewpoint:

To understand the physiological meaning of the complicated feature of thecetacean stomach, we may first briefly review the comparative anatomy of thestomach in the animal kingdom. Fishes have stomachs of various shapes. Amphibians and reptiles have also gastric sacks and the birds posses in addition to thecrop, dilated sack of the oesophagus, glandular and muscular stomachs. As to themammals though the monotremata and a small group ofrodentia are said to have noSci. Rep. Whales Res. Inst.,

No. 23, 1971.

98

HOSOKA WA AND KAMIYA

glandular stomach, almost all others have glandular stomach, where three distinct
regions or areas can be identified, namely the cardiac glandular, the gastric or
fundus glandular and pyloric glandular. Besides, there very often are also theoesophageal, non-glandular region or expansions. According to the combinationsof these regions among mammals, there are many types of stomachs, and Ellenberger(1926) classified them into the following groups:
1) Simple stomach composed merely of glandular regionsa) simple form lacking in cardiac sacksi) shaped like a simple sack, e.g. phoca;ii) provided with swelling of fundus, e.g. carnivora, insectivora,
many rodentia, chiroptera, apes and man;b) complex form provided with one or more cardiac blind sacks, e.g.
sirenian, large kangaroos and pig;2) Complicated stomach composed not only of glandular regions but also of
oesophageal region or expansions (always possess the cardiac area).
a) simple form ... the glandualr and oesophageal regions make altogether a simple stomacheal sack.
i) provided with not so large fundus, e.g. horse and tapir.
ii) provided with conspicuously large fundus, e.g. mouse and rat.
b) complex form ... the oesophageal ampulla makes one or more forestomachs independently of the glandular, real stomach, e.g. cetacean
and ruminantia.
From this classification it is clear that the complexity of the mammalian stomachs is caused mainly by two reasons by the expansion of the fundus or cardiac
blind sacks, and by the oesophageal forestomach that can be divided again into two
or more compartments. In view of these facts, the cetacean stomach, of which thecomplexity lies in the subdivisions of the glandular stomach itself, is an exceptionalcase in the animal kingdom. Though Ellenberger in his classification grouped thecetacean stomach with the ruminantia, we see now that there is a distinct difference
between these two. In the latter, though it is composed also of four compartments,
the first three, rumen, reticulum and omasum, are clothed with the oesophageal
epithelium and only the last one, abomasum, represents the real digestive part ofthe stomach. Thus in the ruminantia the stomach may be regarded as being primarily divided into two regions, the last of which only is the digestive region, and thefirst, non-digestive, being again sharply divided up into three compartments. In
the cetacea, on the other hand, the stomach, although divided primarily into twoparts like that of the ruminantia, shows a further subdivision of the digestive region
which may be exceedingly complicated in the Ziphiidae, while the non-digestive
region is not divided at all.

2. On the function of the cetacean stomach, with considerations on its interrelation to the foodcatching modus ef whales:
Anatomical features of various organs in the animal body are generally formed
and elaborated by two components, the external or the environmental and theSci. Rep. Whales Res. Inst.,
No. 23, 1971.

CETACEAN STOMACH AND FEEDING HABITS

99

internal or the hereditary. While the latter moment defines the hereditary features,the former modifies often the anatomical structures so as to be adapted to the environments of the animal. And such organs, under the influence of the environment, canget strongly modified in their shape, size and structure. We consider the stomach tofurnish an example of this latter kind, as this organ is apt to be modified according to
the alimentary life of its possessor.
From this view-point the complicated stomach of the cetaceans seems to be
intimately related to its alimentation, especially with its mode of food-catching in theaquatic environment. ·Weber (1885) mentioned already that the complexity of thestomach of the cetaceans was caused by the impossibility of their chewing in the aquatic
medium, which seemed to be quite acceptable to us. He, however, did not explain
the reason for the cetacean inability to masticate food. We would therefore, like to
put forward our view-point here to explain this.
Judging from the anatomy of the cetacean oral cavity, it is evident that thewhales do not masticate their food. To say nothing of the baleen of Mystacoceti, thenumerous teeth of Odontoceti are also far from being suited for mastication, for they
are conical homodont teeth, not to adapted for chewing, although aparently wellsuited for biting foods. The case of sperm whale and ,Ziphius also is not muchdifferent from that of Mystacoceti, as the former has only ten and several teeth in themandible and that with wide diastema in between the teeth, and the latter possess
only one or two pairs of teeth in the rostral end of the mandible. The mandibular
articulation and masticatory muscles of whales, together with the poor developmentof their lips also lend support to the above view, which is further augmented by thepoor development of the salivary glands indicating that the cetacean mouth is not
anatomically and physiologically meant for mastication. Thus deprived of thefunction of mastication, the cetacean mouth is devoted, we believe, exclusively toprehension of food.
Of the two major functions of mouth in higher animals, namely prehension andsalivary digestion, the cetacean mouth seems to be primarily concered with theformer function. This can be explained by the aquatic environment and foodhabit of these animals, as they require a large quantity of food, and like the ruminantia, they cannot be expected to waste their time between catching and swallowingof food. This feature needs a large stomach with compartments given to different
functions like storing, grinding and digestion. Thus the complex stomach of whales
with its four compartments is very well adapted for their aquatic life.
SUMMARY

Some of the notable findings on the anatomy of the cetacean stomach are summarized
as follows:
1. The cetacean stomach is composed of four serially arranged compartments,of which the first one is a oesophageal sack, the second one has numerous fundus
glands, the third one possesses many pyloric glands and the last one represents awell-developed duodenal ampulla.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

100

HOSOKAWA AND KAMIYA

2. Between the second and the third compartments there is, moreover, asmall communicating division, which is prominent especially in the fetal stages.
3. The first compartment is dined with an extensively stratified fiat epithelium, of which the superficial layer is completely cornified and the cells have no
trace of nucleus, just like in the oesophagus.
4. The wall of the first compartment is the thickest of the four, and contains
very well-developed muscular strata. This compartment has undoubtedly a considerable contractibility.
5. Despite the general belief that the cetacean stomach is destitute of cardiac
glands, we found them in an adult blue whale stomach in the narrow region adjacentto the boundary between the first and the second compartments.
6. The fundus glands of the second compartment have extraordinarily numerous parietal cells. They may have some intimate relation with the gastric functionof whales.
7. The smooth muscle fibres of the lamina muscularis mucosae of all the four
compartments are scattered irregularly, and as such do not deserve to be called" lamina ".
ACKNOWLEDGEMENT
The authors are deeply indebted to Mr. K. Kureha of the Ocean ResearchInstitute, University of Tokyo for collaboration in collecting the baleen whale
materials.
REFERENCESBEDDARD, F. E., 1900. A book of whales. John Murray, New York. 320 pp.
ELLENBERGER, W. und H. BAuM., 1926. Handbuch der Vergleichenden anatomie der Haustiere. III Eingeweidelehre, 334-464, Springer, Berlin.
HUNTER, J., 1787. Observation on the structure and oeconomy of whales. Philosoph. Transact. Roy. Soc.
Lond., 16: 306-351.
JuNGKLAUS, F., 1898. Der Magen der Cetacean. Jen . ..(:'.F. Naturwiss., 32: 1-94.
SCHULTE, H. V. W., 1916. Anatomy of a foetus of Balaenoptera borealis. Mem. American Mus. Nat. Hist. New
series, 1 (VI): 389-502.
SLIJPER, E. J., 1962. Whales. 253-293, Hutchinson, London.
TYSON, E., 1680. Phocaena, on the anatomy ofporporse, dissected at Gresham colledge etc. Lond. (cited in
Jungklus, F., 1898)
WEBER, M., 1885. Anatomisches iiber Cetacean. Gegenbaur' Mikrosk. ]ahrb., 13: 616-663.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

101

CETACEAN STOMACH AND FEEDING HABITSEXPLANATION OF PLATES
Plate I.
Mucous membrane of the stomach of a fin whale, 21.3 m long female.
Fig. I.
Fig. 2.
Fig. 3.

( X 3 natural size)

Boundary between the first (left) and the second compartments.
Boundary between the second (left) and the third compartments.
Boundary between the third (left) and the fourth compartments.

Plate II.
Histological section of the stomach of a fin whale, 21.3 m long female.
numerals showing the first to the fourth compartments. (x 4 natural size)
Fig. I.
Fig. 2.
Fig. 3.

Boundary between the first and the second compartments.
Boundary between the second and the third compartments.
Boundary between the third and the fourth compartments.
S: sphincter muscle

Sci. Rep. Whales Res. Inst.,
No. 23, 1.971.

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PLATEIINFLUENCE OF INCREMENTAL LINES UPON THE COMPRESSIVE STRENGTH OF SPERM WHALE DENTIN
ARMAND A. LUGASSY*, EDWARD KOROSTOFF** ANDJOSEPH L. RABINOWITZ***
ABSTRACT

Compressive properties of sperm whale dentin were measured as afunction of orientation of incremental lines. With respect to the generalincremental lines' direction, three specimen orientations were selected:
longitudinal, oblique (45°) radial and transverse radial. The machined
cylindrical specimens were compressed in a mechanical testing machine. A
load cell provided with the force values developed on the samples and a displacement transducer yielded the corresponding deformation values. The resulting stress-strain curves provided with values of proportional limits, ultimate
compressive strengths and elastic moduli for each of the specimen orientation
investigated. It was found that while the ultimate compressive strength
values did not differ statistically with specimen orientation, proportional limits
and elastic moduli showed some significant differences. Based on a possiblefunctional adaptation, a theory has been formulated which correlates the results
obtained with the growth patterns found in sperm whale dentin.

INTRODUCTION

Calcified tissues in vertebrates display a combination of structure and properties
which reflect an adaption for their function in the living systems. Bones are designed
to provide the adequate framework for sustentation of the body weight and muscularaction. Teeth of ruminants display flat occlusal surfaces allowing grinding of grassand seeds whereas carnivorous animals have teeth which tear flesh and fracture bones.
Some dentitions may only be used to shear and retain as in the case of some fish,
aquatic reptiles and other sea going mammals.
Sperm whales' teeth are characterized by their conical shape, their continuous
growth patterns and their funnel-shaped attachment to the jaw, They are not known
to be used for chewing, however they can be utilized for snapping and retaining preyin the mouth. This investigation concerns itself with the influence that incrementalline orientation in dentin have upon its resistance under compressive stresses. In lightof the present findings, it is suggested that growth patterns and compressive stresses
interact in the growing organ to explain the differences in the measured properties.

* School of Dentistry, Northwestern University, Chicago, Illinois (Present address.:

School of Dentistry,
University of the Pacific, San Francisco, California 94115).
** School of Metallurgical and Materials Science, and School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania*** Veterans Administration Hospital, and University of Pennsylvania, Philadelphia, Pennsylvania
Sci. Rep. Whales Res. Inst.,

No. 23, 1971. 103-110.

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COMPRESSIVE PROPERTIES OF SPERM WHALE DENTIN

105

Specimen Orientation_,,,,,..,,--Longitudinallfl.L'-'171Ter--Oblique (45°) Radiall//)l.d-HJH'--Transverse Radial

Incremental
Lines

(A)

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Fig. 2. Sperm whale tooth: (A) Specimen source and (B) Specimen orientation
with respect to the incremental line direction.

hardened steel slab of a given thickness. The finished specimens were of the following dimension: diameter=0.085 in., length=0.158 in. Before the actual
tests, the specimens were placed in labelled jars filled with Krebs-Ringer phosphatebuffer solution and stored in a refrigerator at a temperature of about 3 °C.
The dentinal tubules' main direction in the various specimens studied are
SPECIMEN ORIENTATION

A
B

A
B

Oblique (45°) Radial
A
B

Transverse Radial
A= Dentinal Tubules - B = lntertubular Dentin
Fig. 3.

Dentinal tubule alignment in three types of specimen orientation.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

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COMPRESSIVE PROPERTIES OF SPERM WHALE DENTIN

107

machine amplifier and fed to the y axis of an x-y recorder. The deformation values
were measured by a displacement transducer and its output fed to the x axis of thex-y recorder (Fig. 5). Both loads and corresponding deformation values were
simultaneously plotted on the recorder and later converted into engineering stressand strain values by using the formulae: P/A0 and L1L/L0 respectively, where
P=load, A 0 =original cross sectional area, L1L=change in length and L 0 =original
specimen length. Because of the comparative character of the study, data analysis,
according to a true stress-true strain relationship, was not felt to be relevant andtherefore was not performed.
Before the tests, the refrigerated dentin specimens were allowed to warm up
and come to equilibrium with the ambient temperature. Once again their dimensions were checked. The deformation to failure was conducted at a constant crossTABLE 1.

COMPOSITION OF SPERM WHALE DENTIN

Oven Dried (105°C)

Ashing (1100°C. for 24 hours)% of wet weight

Water% of dry weight

Organic Matter

Inorganic Matter% of dry weight

14.72

28.55

71.45

head speed. This portion of the experiment was carried out with the specimen
immersed in Krebs-Ringer phosphate buffer solution to avoid the possibility of
specimen moisture loss during the test. The water and inorganic content of thespecimens were obtained by desiccation and ashing respectively, as shown in Table 1.
RESULTSThe results listed in Table 1 represent the composition of sperm whale dentin. The
water content is representive of the hydration water as well as the water found in thedentinal tubules. It is however recognized that some chemically absorbed water
still remained in the material and was not displaced at the selected drying temperature (Eastoe, 1967). A more detailed analysis showed that the inorganic matter was
mostly composed of calcium and phosphorus, whereas the organic phase was foundto be proteinic in nature.
In Table 2 the results for the elastic modulus, proportional limit and ultimate
strength of various specimen orientations are given along with the strain rate at
which each group of experiments was carried out.
TABLE 2.

MECHANICAL PROPERTIES OF SPERM WHALE DENTIN
SPECIMENS UNDER COMPRESSION

Specimen Orientation :Longitudinal

Oblique (45°) Radial

Transverse Radial

Ultimate Strength (psi)
Proportional Limit (psi)Elastic Modulus (psi)
Strain Rate (sec- 1)

29300*± 4400**
4400±1500(7.8±1.3)x 105(64.6± l .O)x io-•

28000±4500
3700±700(4.3±1.4)xl05(55.9±6.6)x 10-•26000±1500
3700±600(2.9±1.5)x 10 5
(64.6±8. I)x 10- 5* Mean** Standard Deviation

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

LUGASSY, KOROSTOFF AND RABINOWITZ

108

Failure30,000<Tit........ IU.

Cl)a.. 20,000

Cl)
Cl)

w

et::

LEGENDICl)

10,000E= Elastic Modulus

a: = Proportional Limit
P.I.

and

oUlt. = Ultimate Strength

5

10

15

20

STRAIN (%)
Fig. 6. Typical stress-strain curve with salient features and representative values
obtained with various specimen orientations.

A general view of the stress-strain curve is given in figure 6. Its salient featuresand stress values result from graphing several curves obtained by testing various
specimens in the different orientations. The linear portion of the curve is representative of the elastic modulus, the proportional limit was measured at the onset of aplastic strain of about 3 X 10-1 , and the ultimate strength, which here is also thestress at failure, was obtained at maximum plastic strain.
DISCUSSION

It was felt that the determination of the chemical compos1t10n of sperm whale
dentin (Table 1) would be of help in explaining, in part, some of its properties andprovide a base of comparison with other calcified tissues which have been more
extensively studied. Although some resemblance was found with bovine corticalbone (Lugassy, 1968), major similarities between the properties exhibited by these
two materials were not readily apparent. This left the possibility of other factors
such as structural arrangements of the various phases in the material to be of significant influence upon the properties observed. This suggestion will be further
developed in the discussion.
In Table 2 a trend towards increasing values seems to exist when comparing
the results obtained for the elastic moduli, proportional limits and ultimate strengthsof the transverse radial, oblique (45°) radial and longitudinal specimens, respectively.
However, when statistically analyzed the above data showed that except for thefollowing: elastic modulus values of the longitudinal and transverse radial, longitudinal and oblique (45°) radial specimens, and proportional limit values of thelongitudinal and transverse radial, and oblique (45°) radial and transverse radial
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

COMPRESSIVE PROPERTIES OF SPERM WHALE DENTIN

109

specimens, there was no difference at the 5% significance level between the average
stress values of the various group compared. No apparent reason could be found,including the effect of lower strain rate values obtained with the oblique (45°)
radial specimens or the possible misalignment of the incremental lines in the samples
for the lack of significant difference existing between the elastic modulus of theoblique (45°) radial and transverse radial specimens, and the proportional limit of
the longitudinal and oblique (45°) radial specimens. Further study on theseparticular points is contemplated in the near future.
Microstuctural organization has been found to significantly influence the typeof mechanical response observed with calcified tissue (Ascenzi et al., 1966; Evanset al., 1966; Lugassy, 1968). It has also been recognized that during formation,
the types of mechanical stimuli exerted on developing bone will condition its resulting
structure.
In the case of sperm whale den tin, it is felt that the vertical forces applied on theteeth during their growth have some influence over the dentin formed. These
forces transmitted to the pulp would be resolved as shear stresses at the level of theodontoblastic layers. In the present case, it is suggested that the shear stress lines
are, in effect, conditioning the formation and orientation of the incremental lines
through their angulation with respect to the main axis of the tooth. To some extent,
they could constitute the mechanical stimuli. With respect to the rate of deposition, nature and composition of dentin in the incremental lines, it would appear
that they are related to the mode oflife and feeding cycles of these mammals (Ohsumi
et al., 1963).
The difference between the mechanical response of the longitudinal andtransverse radial specimens could be explained as follows: When deformed at rightangle with respect to the growth patterns, the weaker areas where calcification has
been poor or incomplete would influence the overall response of the sample tested.
However, in the case of a longitudinal specimen, because of their regularity anduniformity, the incremental lines seem to act as a nest of reinforcing lines tending toincrease the resistance of the structure to the effects of vertical stress application.
Mechanically this response would be best related to the straight line portion of thestress-strain curve found under the proportional limit in figure 6.
When sperm whale dentin is subjected to large deformations, corresponding to
the stress-strain curve section above the proportional limit in figure 6, it is felt thatthe structural changes in the material produced by slippage and flow are of such magnitude that the influence of the incremental lines become of insignificant effect asrevealed by the relatively similar ultimate strength values of the various specimengroups tested. The above mechanism points to the viscoelastic character of the
response of sperm whale dentin (Lugassy, 1968; Lugassy et al., 1969), and its strain
rate dependency. These reasons explain the strain rate values given in Table 2.
Low strain rate fractures of other calcified tissues, such as those occurring inbovine cortical bone, have been characterized by shear surfaces oriented at a 45°
angle with respect to the axis of stress application. In sperm whale dentin comparable fracture surfaces have been observed and appear to have not been influenced
Sci. Rep. Whales Res. Inst.,.No. 23, 1971.

110

LUGASSY, KOROSTOFF AND RABINOWITZ

by the orientation of the incremental lines or the relatively large strains occurring at
failure.
CONCLUSION
The influence of incremental lines upon the mechanical properties of sperm whale
dentin has been studied and representative values given. It was found that except
for a difference between the elastic moduli of the longitudinal and transverse radial,
and longitudinal and oblique (45°) radial specimens, and the proportional limit of
the longitudinal and transverse radial, and oblique (45°) radial and transverse
radial specimens, there was no statistical difference at the 5% significance level forthe other properties studied including: ultimate strengths, proportional limits andelastic moduli of these and other groups of specimens. Although it is recognizedthat other factors may strongly influence the structural anisotropy of calcified tissues,
it is felt that in the case studied, for small deformations, the presence of incremental
lines offer the means of optimal resistance of sperm whale teeth to stresses applied onthem vertically and also explains their growth patterns and the mechanical properties
measured. Within these limits, sperm whale teeth seem to have been structurally
adapted for their functions in their selective environment.
REFERENCES
AscENzr, A., E. BoNUCCI and A. CHECcuccr, 1966. The tensile properties of single osteons studied using a
microwave extensimeter. In: Evans, F. G. ed., Studies on the Anatomy and Function of Bone and ]oints,
121-141. Springer-Verlag, New York.
EAsTOE, J.E., 1967. Chemical organization of the organic matrix of dentin. In: Miles, A. E.W. ed.,
Structural and Chemical Organization qf Teeth, vo. II, 279-315. Academic Press, New York.
EVANS, F. G. and S. BANG, 1966. Physical and histological differences between human fibular and femoral
compact bone. In: Evans, F. G. ed., Studies on the Anatomy and Function of Bone and Joints, 142-1.55.
Springer-Verlag, New York.
LuGASSY, A. A., 1968. Mechanical and Viscoelastic Properties of Cow Bone and Sperm Whale Dentin
Studied Under Compression, Ph.D. Thesis. University of Pennsylvania, Philadelphia.
LuGASSY, A. A. and E. KoROSTOFF, 1969. Viscoelastic behavior of bovine femoral cortical bone and sperm
whaledentin. In: Korostoff, ed., Research in Dental and Medical A1aterials, 1-17. Plenum Press, NewYork.
0HSUMI, S., T. KASuYA and M. NrsHIWAKI, 1963. Dentinal growth layer of sperm whale. Sci. Rep. Whales
Res. Inst., 17: 15-35.

Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

BAIRD'S BEAKED WHALES CAUGHT ON THE
COAST OF JAPAN IN RECENT 10 YEARSMASAHARU NISHIWAKI* AND NOBUO OGURO*ABSTRACT

It seems there has been no sign of decrease on the stock of Baird's beaked
whale on the coast of Japan in recent years. This may be the result of reduction in number of catcher boats. The length distribution of the whales caught
recently shows a good balance. That is, nearly 80% of the whales were
sexually matured. A migrating population of this species appears at Boso
Peninsula in May, reaches Hokkaido some time between July and August andcomes back again to Kinkazan off shore in the fall and then leaves Japan.
They are likely to prefer waters deeper than 1,000 m. On the Sanriku coast,
the whales eat deepwater fish, but on the coast of Hokkaido, they eat nearlyexclusively squid.
It can be presumed that the whales caught in the Abashiri area in May
through June should be Hyperoodon ampullatus.
INTRODUCTION

There are few countries in which the whaling industry catches Baird's beaked
whales as a harvest and utilize fresh or dried meat for human consumption, andoil extracted from blubber, bones and viscera are used as well as sperm whaleoil.
Biological study has been done on Baird's beaked whales caught in the periodof 1948-1952 by Omura et al. (1955). Present study was done on the whalescaught in the period of 1960-1969. However, data were fewer in the early half
period and considerable number in the latter half. Because of this unbalance,
our consideration was done mainly on the data in the latter five years 1965-1969.
CATCH RECORDS AND ITS ANALYSIS

About 25 years ago, the smaller species whaling industry in Japan made muchprofit from harvests of minke, pilot and beaked whales. And number of catcherboats gradually increased ; in the mean time, number of catch per boat becomeless and less. So the whalers competed each other by extra equipment which
often was a 50 tons boat with 50 mm caliber guns. The result was a folly, theyneed extra catch to pay for such expences. It was not enough for them to catchonly those previously permitted species from certain amount of populations migrating to the coast of Japan. They began to poach banned whales such as the sperm* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971. 111-122.

112

NISHIWAKI AND OGUROTABLE I.

Years

NUMBER OF CATCHER-BOATS AND NUMBER OF BAIRD'S
BEAKED WHALES CAUGHT IN JAPANESE WATERS
IN 1948-1969
Number of
Number of
Number of whales
catcher-boats
per catcherswhales caught

1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
TABLE 2.

Years

1965

1966

1967

1968

1969

Total

Sex
ratio

Sex
Male
FemaleTotal
Male
FemaleTotal
Male
FemaleTotal
Male
FemaleTotal
Male
FemaleTotal
Male
FemaleTotal
Male
Female

76
95
197
242
382
270
230
258
297
186
229
186
147
133
145
160
189
172
171
107
117
134

80
68
65
58
54
47
54
46
35
32
25
23
20
19
18
16
16
15
8
7

2.5
3.6
5.9
4.7
4.3
5.5
5.5
4.0
6.5
5.8
5.9
5.8
7.3
8.4
10.5
10.8
10.7
7 .1
14.6
19.1

NUMBER OF BAIRD'S BEAKED WHALES CAUGHT IN JAPANESEWATERS IN 1965-1969.
Areas

41
27
68
62
23
85
35
23
58
36
44
80
44
47
91
218
164
382
57.0
42.9

II

III

IV

Total

Sex ratio

37
23
60
33
21
54
17
10
27
15
12
27
22
10
32
124
76
200
62.0
38.0

11
8
19
6
11
17
6
8
14
5
4
9
2
2
4
30
33
63
47.6
52.4

13
12
25
5
10
15
6
2
8
1
0

102
70
172
106
65
171
64
43
107
57
60
117
71
63
134
400
301
701
57.1
42.9

59.3
40.7

3
4
7
28
28
56
50.0
50.0

62.0
38.0
59.8
40.2
48.7
51.3
53.0
47.0
57.1
42.9

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

113

BAIRD'S BEAKED WHALES IN JAPANand the sei whales by those well equipped boats. The fact became a serious problem for the Fisheries Agency of the Government. To stop that devastating catch,
the Agency recomended whalers to change their whaling objectives from the smallerwhales to the larger ones. As a measure, they gave a certain quota equally to agroup of ten 50 tons boats and a single 500 tons boat. In those days larger species
whaling promised considerable interest, many whalers converted to the larger species
whaling. The small boat, therefore, reduced in number and the catch per small
boat was recovered accordingly.
As shown in Tables 1 and 2, the number of Baird's beaked whales caught was
30-40 thirty to forty years ago, and as many as 250-300 about twenty years ago,the peak of which was 382 in 1952. Then, unpleasant tendencies began to appear
in the CPUE (catch per unit effort) by the influence of thoughtless catch. Number

200
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1966

1969

Fig. 1. Number of Baird's beaked whales caught and number of catcher-boats inJapanese waters according to the years.

of total catch also began to decrease. However, some recovery appeared in recent
10 years as 130-170. Analyzing these recent statistics, it may safe to say that thestock is somehow stabilized than ever. In Fig. I, although the number of total
catch in each year is vary, there is no tendency of decrease. And the number ofcatch per boat (CPUE) is still increasing as a result of the reduction.
There are two land stations in Area I, four in Area II and one in Areas III
and IV respectively.
Distribution of positions of catch is shown in Fig. 2. To analyze conditionsof the stock, the coastal waters was divided into some area as Omura et al. formerly
did (1955). On the other hand, there is no catch in the coast of the Sea of Japan.
It may because of that the smaller species whaling boat owners have given up thearea.
In Area I whaling operation was done by the whalers from the stations in
Boso Peninsula (Bosyu ). Operation period of that area is appeared to be longest
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

114

NISHIWAKI AND OGURO

I

145°£

OKHOTSK

AelEA

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N

HOKKAIDO

i , ~--- -,----r-- ••
,'

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140°£
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Fig. 2.

I

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Positions of Baird's beaked whales caught in Japanese waters in 1965-1969.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

115

BAIRD'S BEAKED WHALES IN JAPANof all others, which is from May to Dec. Area II was of the whalers from the stations
in Oshika Peninsula, Miyagi Pref. Although no catch is seen at Nemuro stationin Area III by Omura et al, there are some catch records in recent years on the coastof Nemuro in the present map. The waters of Hokkaido is divided into two, thePacific coast as Area III and the Okhotsk coast as Area IV, by the line between
Kunashiri and Etolov Island. As shown in Table 3 and Fig. 3, catch appearedin Area I and II in May first. Male is superior in total number as about 57%.
TABLE 3.

MONTHLY CATCH OF BAIRD'S BEAKED WHALES IN JAPANESEWATERS BY THE AREA, IN 1965-1969.
Areas

Months

Sex

I

II

May

Male
FemaleTotal
Male
FemaleTotal
Male
FemaleTotal
Male
FemaleTotal
Male
FemaleTotal
Male
FemaleTotal
Male
FemaleTotal
Male
FemaleTotal
Male
Female
Total

3
2
5
32
20
52
46
55
101
65
49
114
34
20
54
23
11
34
12
7
19
3
0
3
218
164
382

0
2
2
4
0
4
5
0
5
37
13
50
33
30
63
20
11
31
21
13
34
5
6
11
124
76
200

June

July

AugustSeptember

OctoberNovember

December

Total

III

IV

Total
3
4

0
1
0

3
2
5
16
22
38
9
7
16
2
2
4

2
0
2
8
7
15
14
14
28
4
5
9

30
33
63

28
28
56

7
36
21
57
51
56
107
107
64
171
91
79
170
66
43
109
39
27
66
8
6
14
400
301
701

Females seem to migrate to those areas eaner than males do, number of males
incleases after July.
Distance between the positions of catch and the land stations is shown in
Table 4 : 50 % of catch are within 1-30 miles. This may partly because of thatwhaling boats are so small that they have to be towing whales to a station withina day. Even the most distant catches Area about 120 miles from a land stationand the distant catches are scarce. The distance of most abundant catches are
1-30 miles in Area IV, 91-120 miles in Area III, 61-90 miles in Area II and 1-30
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

NISHIWAKI AND OGURO

116

25

AREA N

200

25

50

150

E

25

0)

::0

co

0

(f)

co"'
.c

z

3:

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/;; '\/i \. /\ \

c
3
er

'\

0100
L

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E

::0

z

100 !:!;

::;

::r

AREA

'"

°'
75 2

I

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/I v~0\ \I·,,.~~~""
\\
I

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50

'1/I/
/,I

ALL

I

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I
I

Fig. 3.

50

I

\~,

.,

25

~

~

~, ,

'1

May

CD

July

Sept.

Nov.

July

Sept.

Nov.

Number of Baird's beaked whales caught by the area and months in 1965-1969.

TABLE 4.

DISTANCE BETWEEN LAND STATIONS AND THE POSITIONS OF BAIRD'S
BEAKED WHALES CAUGHT IN JAPANESE WATERS IN 1965-1969.
Areas
Distance inPercentage
IV
Total
III
II
I
miles
42
352
50.2%
5
10
295
1-30
22.0
2
154
5
62
81
31-60
15.5
109
107
2
61-90
8.4
59
44
15
91-120
0.9
6
6
120<
3.0
12
21
5
4
unknown
701
56
63
200
382
Total
Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

BAIRD'S BEAKED WHALES IN JAPAN

117

miles in Area I. If the distance of abandant catch and the water depth of thepositions are put into a map together as in Fig. 2, positions of catch are abandantin the waters deeper than 1,000 m. On the Abashiri and Boso coasts where the
1,000 m depth contour line is close to the shore, positions of catch are appeared
to be near to the shore. Whereas on the Kushiro and Kinkazan coasts where
the contour line is far from the shore, the positions of catch are at distance.

40~_a-----MALE----FEMALE·'=
EOJ 30
:::J

<tl

0

(/)
Q)

cti

.<::

20

~

0
©
.0

10

E
:::J

z

Fig. 4. Size distribution of Baird's beaked whales caught in Japanese waters in
1965-1969.

18
16

/

--------------------------?!----.... 14
Q)

2
c

12

.<::

c;, 10
c

~

»

8

CJ

0

ro 6
4
2
Jan.

Jun.

Dec.

Date

Fig. 5.

Recorded foetuses of Baird's beaked whals by the date in 1965-1969.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

118

NISHIWAKI AND OGURO

DISTRIBUTION OF BODY LENGTH

Distribution of body length of the whales caught is shown in Fig. 4. The smallest
length of both sexes are appeared to be equal as 24 feet and the largest lengthof those are 39 feet in male and 42 feet in female. Many individuals are seen within
the range of 33-34 feet. Roughly, larger lengths are of females. According toOmura et al., the Baird's beaked whale attains sexual maturity at the length within
32-33 feet by males and 33-34 feet by females. Considered on this condition, it
can be said that 80 % of males and 70 % of females among all the whales caught
are matured.
RECORD OF FOETUSES

Records of foetuses found in the present study are shown in Fig. 5. Six in theseason from June to Oct.: in Area I, two in June, two in Aug., one in Sept. andin Area IV, one in Oct. As the records are so scarce, that they are shown in the
additional points on the growth curve drawn by Omura et al (1955).
FOOD

701 stomachs were examined; 55% of all, namely 383 stomachs contained foodremains and 30% are empty ones. 15% are the stomachs without description
because abdomens of whales are cut open immediately after catch to prevent them
TABLE 5.

STOMACH CONTENTS OF BAIRD'S BEAKED WHALESCAUGHT IN JAPANESE WATERS IN 1965-1969.

kinds of stomach contents

number of whales

percentage

deep-sea fishsquidmackerelsardineflat fish
pollack
sauryunidentified

156
111
15
5

40.7
28.9

3.9
1.3

1

93

24.2

from decomposition, so, the contents are washed away. There were various kinds
of food remained in the stomachs as shown in Fig. 5. Most are deep-water fishand squid. There are 24% of unidentified species of food because they have alreadybeen digested.
Distribution of food by area is shown in Fig. 6. Squid is found mostly in
Areas IV and III, squid and deep water fish are in Area II and deep-water fish isin the waters south of Area III. Occurrence of squid and deep-water fish is shownin Table 6 by month. Squid is frequent in Area IV from Aug. to Nov., also in
Area III from Aug. to Nov. Naturally, in Areas III and IV, fishing season of squidSci. Rep. Whales Res. Inst.,
No. 23, 1971.

BAIRD'S BEAKED WHALES IN JAPAN

119

begins in July. The whales which had squid in their stomach and caught inArea II, are supposed to have been migrating from north. In Area II, there arerecords of mackerel and sardine as well as squid and deep-water fish. Whales

140°E

45°N

•

SEA OF
0JAPAN

AREA IIl

a
.·.::

oo

0
0

0

40°N

40°N

/)

«>(-::,
{);"

.(
·0

xO

o oo• xoxo

AREA II0x~xf. o exCO
! •••
0 0

.e

•

PACIFIC

OCEAN•

Deep-sea fishes

35°N

0 Squidx Mackerel
D Sardine

AREA
140°E

I

6

Saury

0

Poollack

D Flat fish
145°E

Fig. 6. Position of Baird's beaked whales caught with stomach contents in Japanesewaters in 1965-1969.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

NISHIWAKI AND OGURO

120

seem to eat common species of the areas without intentional choice. Species ofdeep-water fish and its fishing season could not be investigated, however, it seems
that it is likely to be abundant at Boso off shore. Records of deep-water fish appear in Area I first and to Areas II and III as time passing by. Whales of thepresent population seem to migrate north in spring living on deep-water fish andthen coming back south doing on squid.
TABLE 6. NUMBER OF STOMACHS OF BAIRD'S BEAKED WHALES CAUGHT
IN JAPANESE WATERS WITH CONTENTS OF SQUID OR DEEP-SEA FISH,
BY THE AREA AND THE MONTH, IN 1965-1969.
Areas

Food
May
June
July
AugustSeptember
OctoberNovember
December

I

II

III

IV

~

~

~

~

squid

deep-sea
fish

squid

deep-sea
fish

10
9

3
3

squid

deep-sea
fish

squid

2
4

2
12

deep-sea
fish

5
14

25
41

25
3
18
7

2

2

3

25
13
4

24

8

SUMMARY

1. Whaling of the Baird's beaked whale in recent years indicates an agreeable
number of catch from the stock as about 150 whales annually, which is a certain
decrease from the number of 250-300 about-twenty years ago. On the other hand,
number of whales caught per catcher-boat has increased because of reduction of
the boats in number.
2. Length distribution of whales caught shows a good balance: nearly 80%of the whales attained at sexual maturity and the male is superior in number. So
that it may safe to say that the stock is well protected.
3. The largest body length investigated was 39 feet of male and was 42
feet of female in the present study.
4. The positions of whales caught are mainly in the waters deeper than
1,000 m. It seems that the whales do not migrate to the shallow waters. In
the whaling season, the whales are found at Boso first and migrate to Kushiro
through Kinkazan in the season from July to Oct., then they come back to Kinkazan
from Aug. to Oct.
5. The whaling commences in Abashiri sometime in May or June, this issimultaneous with that of Boso. Considering the fact, Abashiri population is
supposed to be different from that of Boso. Abashiri population is considered to
be as Hyperoodon ampullatus. Further study is required.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

BAIRD'S BEAKED WHALES IN JAPAN121

ACKNOWLEDGEMENTOur gratitude are due to the members of the Whaling Inspection Group of theFisheries Agency for presenting the data used in this report.
Thanks are also due to the stuff members of the Biology of Fisheries Resources
Division of the Ocean Research Institute, the University of Tokyo and Mr. S.
Machida of the Whales Research Institute for their helpful advices.
REFERENCES
MATSUURA, Y., 1942. On the Northern Porpoise Whale, Berardius bairdii STEJNEGER in the adjacentwaters of" BOSYU" Z,ool. Mag., 54(12): 466-473.
MAEDA, K. and Y. TERAOKA, 1953. Whaling. Isanashobo, Tokyo, 450 pp. (in Japanese)
NISHIIMURA, S. 1970. Recent records of Baird's beaked whale in the Japan Sea. Puhl. Seto Mar. Biol. Lab.
18(1): 61-68.
NrsmWAKI, M., 1965. Whales and Pinnipeds. Univ. of Tokyo Press, Tokyo, 439 pp. (in Japanese)
OGAWA, T., 1936. Studien liber die Zahnwale in Japan. (in German)
OMURA, H., K. FUJINO and S. KrMuRA, 1955. Beaked Whale Berardius bairdi of Japan, with notes on Z,iphiuscavirostris. Sci. Rep. Whales Res. Inst., 10: 89-132.
OMURA, H., K. MAEDA and I. MIYAZAKI, 1953. Whaling in the adjacent waters of Japan. Norsk Hvalfangst-Tidende. 4: 199-212.
PJKE, G. C., 1953. Two Records of Berardius bairdi from the Coast of British Columbia. J. Mamm. Vol. 34,
No. I.
Statistics and Survey Division, Ministry of Agriculture and Forestry, Japanese Government. Agriculture,
Forestry and Fishery Statistics Data 1956,-1961,-1966. Association of Agriculture-Forestry Statistics.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

NISHIWAKI AND OGURO

122

EXPLANATION OF PLATES
Bird's-eye view of Baird's beaked whales swimming in the waters off Sanriku coast taken
by Mr. S. Takashima of the Suisan Koku Co. (Fishery Aviation Co.): Copyright ofthese photographs is reserved by the company.
PLATE I
Date
Position

July 26, 1956
35°-SO'N
141°-20'E

PLATE II
upper figure

Date
Positionlower figure

Date
Position

July 22, 1970
38°-45'N143°-20'E
Sept. 12, 1961
39°-50'N
143°-50'E

The others were taken at the same area by and presented in The Scientific Reports of the Whales Research Institute, No. 23 (1971) by T. Kasuya.

Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

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THE UNDERWATER SOUND OF GANGES RIVER
DOLPHINS (PLATANISTA GANGETICA)
KAZUHIRO MIZUE,* MASAHARU NISHIWAKI**ANDAKIRA TAKEMURA*
ABSTRACT

Various types of underwater sound emitted by the Ganges river dolphin
were studied. Clicks were 87% of all, seems to be a method of echo-location.
Bursts were 5 %, far more frequently than that of sea dolphins, must be a meansof communication. Twitterings or chirps appeared on the sonargram in a
stratified zone, are a pattern of burst. The sounds like mewing of cat andcreaking boat, were both appeared in a stratified zone. Among those appeared
in a stratified zone, some were proved to be quick repetition of clicks, others
did not appear in a click pattern however play back speed was reduced.
INTRODUCTION

From the view points of various field, Ganges river dolphin (Platanista gangetica) was
studied by Japanese scientists in Pakistan from October 1969 through March 1970.
The basecamp of the expedition was set at Mymensingh, East Pakistan throughout
the period. During the period, 20 individuals were caught by the local fishermen.
Among them, 4 living individuals were transported to Tokyo by air on February
4. This is an analysis on the underwater sound emitted by them.
On the other fresh water dolphins, the Amazon river dolphin (Inia geoffrensis)
and the buffeo negro (Sotaliafluviatilis), reports were presented by Shevill (1962),
Caldwell and Evans (1962). According to the reports, the above two species ofdolphins did not emit whistles but only clicks. However, Shevill wrote about hissusticion that Sotalia might emit whistles on some occasions.
Among the four species known as the members of the family Platanistidae,
only the Ganges river dolphin is believed to be blind and has a distinct swellingwall on the maxillary bones. Examination with a flashlight on and off at 10 cm
distant from the dolphin's eyes, showed no sign of reaction. Of course anatomicaland histological studies on those dolphins have been carrying on until present day,but the results have not been completed yet. Because of this species of dolphinsare supposed to be blind, we consider that they must rely much more on the guidanceof the underwater sound than the other dolphins with clear eyesight do.
An address about the experiment was given by M. Nishiwaki at the Seventh Annual Conference
on Biological Sonar and Diving Mammals held at the Stanford Research Institute on October 23, 1970.
Although Proceedings of the conference will be published, this report have to claim the originality.
* Faculty of Fisheries, Nagasaki University, Nagasaki.
** Ocean Research Institute, University of Tokyo, Tokyo.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971. 123-128.

MIZUE, NISHIWAKI AND TAKEMURA

124

METHOD OF THE STUDY

An indoor freshwater pool was set at a quiet place in the pine tree forest near by
Kamogawa Beach, about 60 miles distant from Tokyo. The pool was 7 m long,
4 m wide and 2 m deep. Inside of the pool was covered with plastic. The pool
was heat and sound proofed by the method of stuffing artificial fiber wool between
the cement base and the plastic cover. ·water and air temperature was kept constantly about 23°C.
As the pool had been so prepared that four individuals of Platanista and those of
two lnia were kept in it. Sex and body length of those were:

Platanista

No. 1
No. 2
No. 3
No. 4
No. 1
No. 2

"
"
Inia"

"

118 cm
121
127
126
210
203

female""male"
femaleAfter the dolphins had grown accustomed to the pool, recording of the underwater sound was carried out.
~lnia

~

Platanista~,;------~l.. (f:'-

'~

~

~~

~-=-

~

lL-----~

Fig. 1.

Situation of the pool, the Ganges river dolphins were in.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

UNDE
R』YATERSOUNDSOFPLATAJVISTA

1
25

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i
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heunderwaters
oundemitte
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. Thes
ound
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MIZUE, NISHIWAKI AND TAKEMURA

126

2. Pre-amplifier, Style St-65, the Oki Electronics Industry Co., Ltd. made.
3. Tape Recorder, Style No. 3, Nagura Electric Co., Ltd. made.
4. Sonargraph, Style SG-04Al, Rion Co., Ltd. made.
Performance of those apparatuses is shown in Fig. 4.
10o~-~-/-7~--~~-=----=-=--~_....,,,.,=----=~~,-.-:::~-:r-c A

~

Iii

D

-20

~ -llOl:~-~i ! ~+16' i ! ~+ilf i ! ~+il:i•

E

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FREQUENCY (Hz)Fig. 4.

Performance of the apparatus.

RESULT AND DISCUSSION

1. Clicks: The Ganges river dolphins emitted cricks frequently. It was easily
presumed that the sound was emitted and received as a sense of echo-location.
Repetition rate of this sound was varied each time as indicated in Figs. 1
and 2 of Plate I. It was five times per second for the most seldom and 100 times
for the most frequent. The frequent emittions seem to have been aiming at near by
objects and the seldom emittions seem to have been aiming at distant objects. Thisphenomenon is equal to the dolphins at sea.
It is characteristic of this species, clicks went up to a fairly high wave frequency,
which is never reached by the sea dolphins. With our apparatus, as high as 20KHz
wave frequency was recorded. However, it is presumed that higher frequency
than that can be emitted by this species of dolphins. Shown in Fig. 3 of Plate I.
2. Bursts: Although sea dolphins too emit the bursting sound out. It seems
there is no special meaning with it. While this species of dolphins emitted bursts
not only once but multiple times at a time as usual. Frequency of this sound emittion is next to that of clicks though far less than the latter.
By the Ganges river dolphin, this sound seems to be used as a means of communication as well as following mentioned "twittering" sound. Sonargram of thissound is shown in Fig. 4 of Plate I. Observing the Ganges river dolphins in wildor in the pool, they seemed not to have lived in school but were swimming solitary
to and for in the river or in the pool. Communication between one another seemed
to have been rather infrequently. Need of communication is far more among sea
dolphins than by the solitary individuals.
3. Twitters: This is a sound heard like twittering of birds to human ears;
it is quite different from burstings. But, generally, there is no difference between
the two if the patterns of them appeared in the sonargram were analized. Bursts
continued about 0.4 seconds, comparatively longer period of a time, while twittersSci. Rep. Whales Res. Inst.,
No. 23, 1911.

UNDERWATER SOUNDS OF PLATANISTA

127

continued only about 0.1 second. This sound also seemed to be a means of communication. Sonargram of this is shown in Fig. 5 of Plate I.
4. Whistles: This species of dolphins emitted few whistles which are said tobe pure tone. How seldom the Ganges river dolphins whistles! Among sea dolphins,
the false killer whale (Pseudorca crassidens) whistles very often and the bottle-nosed
dolphin ( Tursiops gilli) seems to do conversation by the help of this whistles. However, we can hardly admit that the Ganges river dolphins are able to converse bymeans of their whistles. This sound may be emitted spontaneously by the Ganges
river dolphin. Sonargram of this is shown in Fig. 6 of Plate I.
5. Stratiform sound: In the sonargram, it was found a group of sounds whichwere appeared in parallel laminations. As it is well known, many species of sea
dolphins emit this stratiform sound spontaneously at times of mating, menacing
others of taking food etc. The Ganges river dolphins sometimes emitted a soundlike mewing of a pussy and some other times a sound like a creaking boat. The
sonargram indicated these in the patterns of stratiform sound. ·watkins (1967)
considered this type of sound to be a very quick repetition of clicks.
Fig. 1 of Plate II shows this type of sound playback at the natural speed oftape-rotation. Fig. 2 of Plate II show5 the same sound at half rotation speed,that is, the wave frequency was reduced in half cycle. At this speed, the pattern
still shows parallel laminations. However, as in Fig. 3 of Plate II, when taperotation was reduced to 1/4 at speed, analysis of the sound did not appear in parallel
laminations. It appeared in the typical clicks pattern. The opinion of Watkins
was proved.
But on the other hand, the sound similar to mewing of pussy did not appear
in the clicks pattern, even when the speed was reduced to 1/4 (Fig. 5 of Plate II),or even to 1/12 as shown in Fig. 6 of Plate II. It did not appear in the clicks pattern.
The sound of this type is emitted by various species of dolphins very often and thesound of the killer whale (Orcinus orca) is almost always of this type. We came toconclude that this type of sound of parallel laminations must have been different
from what Watkins wrote about. It is yet unknown whether these sounds were
spontaneously emitted or not.
In the following, above mentioned variety of sounds are shown in the rate of
frequency.
Clicks . .
87%
Bursts . .
5%Twitters 3%
Whistles 1%
Stratiform sounds (parallel laminations)4%
Total . . . . . . . . . . . . . .
.100%
ACKNOWLEDGEMENT\\Te extend our sincere appreciation to the stuff of the Kamogawa Sea ·world forgiving us convenience to have kept and have studied the Ganges river dolphins.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

MIZUE, NISHIWAKI AND TAKEMURA

128

Acknowledgement is made of the financial support of this investigation throughgrants from the Ministry of Education of Japan as a part of the Fund of Scientific
Investigation Abroad.
REFERENCESCALDWELL, M. C., D. K. CALDWELL and W. E. EVANS, 1962. Sound and behaviour of captive Amazon
freshwater dolphin, Inia geojfrensis. Cont. in Sci., 108: 1-24.
ScHEVILL, W. E. and W. A. WATKINS, 1962. Whale and porpoise voices. A phonograph record. 24 pp.
and a phonograph disk. Woods Hole, Mass.: Woods Hole Oceanographic Institution.
WATKINS, W. A., 1967. The harmonic interval fact or artifact in spectral analyses of pulse frain. Marine
Bioacoustics II: 15-43.

EXPLANATION OF PLATESUnderwater sound emitted by Ganges river dolphin.
PLATE I
Fig. I.
Fig. 2.
Fig. 3.
Fig. 4.
Fig. 5.
Fig. 6.

ClicksClicks.
Clicks.
Bursts.
Twitters.
Whistles.
PLATE II

Fig. 1.
Fig. 2.
Fig. 3.
Fig. 4.
Fig. 5.
Fig. 6.

Stratiform sound at natural speed of tape-rotation.
Stratiform sound in Fig. 1 reduced to half speed rotation.
Stratiform sound in Fig. 1 reduced to l /4 speed rotation.
Stratiform sound at natural speed of tape-rotation.
Stratiform sound in Fig. 4 reduced to 1/4 from natural rotation speed.
Stratiform sound in Fig. 4 reduced to lj12 from natural rotation speed.

Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

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FIRST RECORD OF MESOPLODON DENSIROSTRISFROM FORMOSATOSHIO KASUYA* AND MASAHARU NISHIWAKI*
ABSTRACTTwo records of female Mesoplodon densirostris are reported. Commentson the external character, skull and flipper of the younger specimen, and thaton mandible of the older female are made.

INTRODUCTION

The Blainville's beaked whale, Mesoplodon densirostris is one of the rare species of the
Odontoceti. Moore (1958) and McCann (1964) suggested that it distributes in thewarmer waters. In 1963, Galbreath reported the stranding of two M. densirostris at
Midway Islands in the central North Pacific, which is the first record in the North
Pacific.
Here, are reported two specimens from Formosa, which are the first record ofthis species from the western North Pacific.
REFERRED SPECIMENS

Followings, referred specimens, are kept in Ocean Research Institute, Univ. of Tokyo.
TK 245: Mandibles with teeth. Collected by M. Nishiwaki in Aug., 1968 at
the fish market in Pei-kan town (approximately 23°30'N, 120°25'E). Presumablyof adult female, no other data.
TK 256: Female in puberty stage, Body length 3.56 m. Collected by T.
Kasuya on April 20, 1968 at the fish market in Pei-kan town. Skull, mandibles
with teeth and left flipper were collected.
LOCALITY AND DISTRIBUTION

According to the manager of the fish market in Pei-kan, the whale, TK 256, wasbrought from Su-a6 (approximately 24°35'N, 121°50'E), on the north east coast of
Formosa. Mr. Hung-chia Yang of Taiwan Fisheries Research Institute informed usthat there are small fishing boats operating mostly with hand harpoons, and that
there has been no pelagic tuna boat, which occasionally catch Mesoplodon (McCann,
1963, 1964). So we consider that this specimen was caught off the east coast of
Formosa by some local fishermen with harpoon. This consideration is supported
by a deep injury at just right side of the base of dorsal fin (Plate II, Fig. 3.)
The other specimen TK 245 had been deserted out side the fish market. This

* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971. 129-137.

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f
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CALITYOf'OCCURRE/¥
Cヒ O
f'MESOPLODOND E
NS
IROST
RI
S
North Pa
c
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s
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l
b
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1
9
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p
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cimenT K2
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6
Formosa; P1
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、
。

LordH v
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l
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8)
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whalewass
upposedtobeca
ughtin thecoasta
lwatersofFormosa,butwehaveno
convinc
ing information.
hows the localities o[ 20 records of λ1
.d
e
n
s
i
r
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s
t
r
i
s
. The present
Table 1s
c
i
f
i
c.
s
pecimensarethel
atesttwo,and arethefirs
trecordfromth巴 westernNorthPa

1
9
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ss
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e
sseemstoi
nhabi
tin the warm er waters.
Asmentioned byMoore (tofNorth
The extended range of di
s
t
r
ibut
ion to t
h巴 north along the east coas
Americawil
lbe a resultoftheinfluenceoft
he GulfStream. O nthe ot
her hand,

e
n
s
i
r
o
s
t
r
i
sin thecoastofJapan. Though onewastherehasbeen noreco吋 ofM .d

1
938)
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e
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d
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n
t
i
f
i
e
c
lasM .
g
i
nk
g
od
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n
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w akiand K amiya, 1
t
i
onoft
hefutureoccurrenceoft
hi
sspec
i
e
sin t
he watersfrom northofFormos
ato
thecoast
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sofJapan is not un同 asonable
.
S
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7
1
.

131

MESOPLODON FROM FORMOSA

MORPHOLOGY
The external characters of the specimen TK 256, which is a 3.56 m long young
female, was observed. No corpus luteum or corpus albicans was found in the ovaries,
and diameter of the largest Graafian folicle was about 1 mm. Therefore this whale
was considered to be in puberty stage.
The external colouration of the darkly pigmented area was bluish black. However, the whale died several days before the observation, so the colouration will havechanged into darker as the common case of the cetaceans. The dorsal and lateralside of the animal was darkly pigmented, which faded gradually into the paler
area in the ventral. The throat and chest between two flippers were slaty gray. The
ventral area from umbilicus to anus was pure white. The anus, mammaly slit andgenital aperture were not pigmented. The tail peduncle and the both surfaces of
the tail flukes were darkly pigmented. Though the both sides of the flippers were
pigmented, the ventral surface was slightly paler. This pattern of the pigmentation
TABLE 2.

EXTERNAL MEASUREMENTS OF MESOPLODON DENSIROSTRISTK 256femaleMeasurements
I.

2.
3.
4.
5.
6.
7.

8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.

,-------'~

Total length, tip of upper jaw to tail notch
356cm
Length from tip of upper jaw to nostril
46
51
Length from tip of upper jaw to center of eye
32
Length from tip of upper jaw to angle of gape
Length from tip of upper jaw to anterior
94
insertion of flipper
133
Length from tip of upper jaw to tip of flipper
Length from tip of upper jaw to anterior endof throat groove
L. 24
R. 20
L. 34
Length of throat groove
R. 39
Length from tail notch to center of anus
87
Length from tail notch to center100of reproductive aperture169
Length from tail notch to umbilicus
Length from tail notch to anterior insertion145
of dorsal fin
120
Length from tail notch to tip of dorsal fin
Length from tail notch to anterior insertion
28
of tail flukes
80
Tail flukes, total spreadjg
Dorsal fin, height
28
Dorsal fin, length of baseFlipper, straight length from anterior
41
insertion to tip
Flipper, anterior insertion to tip along the42
anterior edge
30
Flipper, straight length from axilla to tip
12Flipper, greatest width* Annisquan specimen, misidentified as 11.1. bidens.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

100 %
12.9
14.3
9.0

Allen
(1906)
female*Guiler(1966)
male

Raven(1942)
male

401 cm

412cm

-%

-%

439 cm
11. 7
13.9

25.3

23.1

20.4

26.5

29.6

36.3
52.5

8.5

26.4
37.4
6.7
5.6
9.6
11.0
24.4

6.3

25.9

28.1
47.5
40.7
33.7
7.9
22.5
5.3
7.9
11.5
11.8
8.4
3.4

26.5

23.4

23.7

KASUYA AND NISHIWAKI

132

nearly coincides with that reported by Allen (1906).
The external measurements of TK 256 and those of other individuals of M.
densirostris reported by Allen (1906), Raven (1942) and Guiler (1966) are shown in
Table 1. The measurements of these 4 individuals fit fairly well.
As seen in Plate II, the mandibular tooth does not erupt and the swelling of
the posterior part of the mandible is not so conspicuous as reported by Andrews(1914), Raven (1942) and McCann (1963). This difference is considered to depend on sex and age, especially on the former.
The dorsal fin was nearly triangular and the tip is pointed to the posterior,which resembles more to that of Raven (1942) than that of Andrews (1914). The
flippers and the tail flukes showed no significant difference from those of otherziphioid whales.
As seen in Plate I, the genital aperture and the anus are situated in a continual groove.
OSTEOLOGY

Mandible The specimens TK 245 and TK 256 were collected on separate occasions.
The mandibles show similar diagnostic features of relative position of the tooth andsymphysis, of plateau like elevation of the upper edge of the mandibles around thealveolus, and of the shape of mandibular tooth. Because of above resemblance,these two specimens are considered to be of same species. However, there are somedifferences between the two specimens. In TK 245 the mandibular length is about

TABLE 3.

SKULL DIMENSIONS OF M. DENSIROSTRJS

Measurements
I.
2.
3.
4.
5.
6.
7.
10.
12.
13.
14.

17.
21.
34.
35.
37.
44.
46.

Total (condylo-basal) length
Rostrum, length from level of base of antorbital notches
Rostrum, width between base of antorbital notches
Rostrum, width at midlength
Rostrum, depth at midlength
Rostrum, least breadth proximal to midlength
Rostrum, depth at same point
Breadth of premaxillae at expanded proximal ends
Least breadth of premaxillae opposite anterior nares
Breadth of premaxillae opposite pemaxillary foramina
Least distance between the posterodorsal margins of themaxillary foramina
Distance between posterior border of maxillary foramen
and anterior extremity of maxillary protuberance
Breadth of anterior nares
Length of vomer visible on palate
Width at centers of orbits
Width on zygomatic processes of squamosals
Width of occipital condyles
Height, vertex to inferior border of pterigoids

TK 256

Range of Sample
M. densirostris size

725mm
63.7%
22.3
5.6
7.0
6.1
8.8
16.6
12.6
11.2

665-770 mm
60-64%
24-28
8-9
9-11
6-8
11-12
16-20
12-16
8-9

4
4
4
4
3
2
2
4
4
4

8.4

6-9

4

9.0
5.9
13.0
37.2
38.1
11.4
33.8

8-10
4-6
30-31
40-47
40-48
14-15
39-43

4
4
2
4
3
4
4

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

MESOPLODON FROM FORMOSA

133

6 cm longer than that of TK 256 and the plateau around the alveolus is more prominent in TK 245.
Differences are also found in the shape and size of the teeth (Plate IV and
Table 4). The pulp cavity of TK 245 is partly closed but that of TK 256 is still
perfectly open. The number of growth ridges on the surface of cement, whichreflect periodical growth of the tooth, is counted 11 and 8 respectively. If annual
accumulation of the growth layers is accepted as in the case of the sperm whale(Ohsumi et al, 1963), the age of TK 245 and TK 256 are considered to be about 10
and 7 years old respectively. Accordingly, it is considered that several morphological differences between the two mandibles are due to the difference of age ofthe animals. As mentioned in the former chapter, TK 256 is a female in puberty
stage, so TK 245 is probably a newly matured animal. The condition of thelatter tooth, which is small and almost perfectly concealed in the alveolus, suggests
this individual to be female.
The mandibular teeth of the present specimens are laterally compressed, andsituated far behind the posterior end of mandibular symphysis and on the low plateau.
The lateral view shapes an acute-angled triangle, and the anterior edge is slightly
shorter than the posterior. The long axis of the tooth is inclined to the anterior
direction, but the tip pointed nearly upward. At the top of the tooth, slightly
posterior to the center, there is a small denticle which remains perfect because of theunerupted condition of the tooth. These diagnostic features coincide only with
Mesoplodon densirostris among the known species of the genus Mesoplodon. Especiallythe shape of the tooth coincides with that of the formerly reported female specimens(Allen 1906, Raven 1942, private letter of]. C. Besharse on Midway specimens).
Skull The skull is collected only from TK 256. Several important measurementsof the skull are shown in Table 3 with those of the M. densirostris in Moore (1958).
Though, it shows that the present specimen has slender rostrum, most of the measurements fit with those of the other specimens.
On the present specimen, the length of vomer visible on palate is only 13% of
total length of skull while the corresponding measurements of the two other specimens
are 30 and 31 %. This part is easily influenced by the condition of the maxillae, so
the length ofvomer visible on palate will not be an important taxonomical character.
On the dorsal view, the mesorostral cartilage is not ossified. The maxillary
prominences are low and the prominential notches are shallow. Maxillary foramina
opens forwardly in the bottom of the narrow parallel grooves. The lacrimal isvisible at the bottom of antorbital notch. The lateral edges of the expansion of themaxillae above the temporal fossa are nearly straight and they open anteriorly.
There is a deep notch between the supra narial crests formed by maxillae, premaxillae and frontals (Plate III, top and bottom). As pointed out by Moore (1966) thelateral margins of the left spiracular plate is horizontal in the profile. These characters well coincide with those of other M. densirostris.
Flipper The left flipper of TK 256 was collected. Its phalangeal formula is
I: 1, II: 5, III: 6, IV: 4, V: 2.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

134

KASUYA AND NISHIWAKITABLE 4.

SKULL DIMENSIONS OF MESOPLODON DENSIROSTRIS FROM FORMOSA

Measurements

1.
2.
3.
4.
5.

6.
7.
8.
9.
10.
11.
12.
13.
14.
15.

16.
17.
18.
19.

20.

TK 245...------"'------..

percentage
of totallength*percentage
of total
mm
length*mm

Total (condylo-basal) length
Rostrum, length from level of base of antorbital notches
Rostrum, width between base of antorbital notches
Rostrum, width at midlength
Rostrum, depth at midlength
Rostrum, least breadth proximal to midlength
Rostrum, depth at the same point
Rostrum, width between prominential notches
Breadth of premaxillae at midlength of rostrum
Breadth of premaxillae at expanded proximal ends
Greatest breadth of premaxillae in front of anterior nares
Least breadth of premaxillae opposite anterior nares
Breadth of premaxillae opposite premaxillary foramina
Least distance between the posterodorsal margins of themaxillary foramina
Least distance between premaxillary foramina
L.
Least distance between maxillary and premaxillary
foramina
R.
Distance between posterior border of maxillary foramenL.
and anterior extremity of maxillary protuberance
R.
Length of nasal suture line (anteroposterior)
Length of nasal at the vertex of skull

TK 256,---/'-------

L.
R.

725
462
162
41
51
44
64

95
27
120

96
91

81

61
37
14
11
65
63
14
13
23
26
43

33.

Greatest breadth of nasals at the vertex of skull
Breadth of anterior nares
Breadth of posterior nares immediately behind pterigoid
processes
69
Length from tip of rostrum to prominential notch (median)436
Length from tip of rostrum to bottom of maxillary notches
472
Length from tip of rostrum to anterior end of vomer
183
Length from tip of rostrum to anterior marginof anterior nares
542
Length from tip of rostrum to nasal vertex
587
Length from tip of rostrum to madial suture lineof posterior end of pterygoids
551
Length from tip of rostrum to level of antorbital
processes of maxillae
461
Length from tip of rostrum to occipitofrontal vertex
607
Length from tip of rostrum to posterior median endof maxillae on palate
462
Length from tip of rostrum to most anterior pointof palatines
333
Length of premaxilla
L. 616

34.
35.
36.

Length of vomer visible on palate
Breadth across centers of orbits
Breadth across postorbital processes

21.
22.
23.

24.
25.
26.
27.
28.
29.
30.
31.
32.

R. 62094
270
Ca. 289

100.0
63.7
22.3
5.6
7.0
6.1
8.8
13. l
3.7

16.6
13.2
12.6
11.2
8.4
5.1
1.9
1.5
9.0
8.7
1. 9
1.8
3.2
3.6

5.9
9.5
60.1
65. l
25.2
74.8
81.0

76.0
63.6
83.7
63.7

45.9
85.0
85.5
13.0
37 .2
39.9
Continued ...

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

135

MESOPLODON FROM FORMOSATABLE 4.

Continued.

Measurements
37.
38.
39.
40.

Breadth across zygomatic processes
Breadth across posterior margins of temporal fossae
Diameter of orbit (antero-posterior)
Length of temporal fossa

41.

Depth of temporal fossa

42.
43.
44.
45.

Length of tympanic bone
Greatest breadth of tympanic bone
Breadth of occipital condyles
Length of occipital condyle

46.
47.
48.
49.

Breadth of foramen magnum
Height vertex to inferior border of pterygoids
Length of mandible (median)
Length of mandibular ramus

50.

Length of mandibular symphysis

51.

Distance from anterior end of mandible to coronoid
process

52.

Distance from anterior end of mandible to angle

53.

Distance from anterior end of mandible to anterior
lip of alveolus

54.

Distance from anterior end of mandible to posterior
lip of alveolus

55.

Depth of mandible at posterior lip of alveolus

56.

Depth between angle and coronoid process

57.
58.
59.
60.

Breadth across mandibular condyles
Length of tooth
Breadth of tooth (antero-posterior)
Breadth of tooth (transverse)

TK 256

TK 245~,....------"'-...,

percentage
of totallength*percentage
of total
mm length*

mm
276
186
R. 95
L. 80
R. 83
L. 62
R. 64
R. 54
R. 40
83
L. 63
R. 61
33
248
615
L. 625
R. 623L. 159R. 160L. 604
R. 607
L. 629R. 632
L. 253
R. 252
L. 278
R. 278
L. 73
R. 73
L. 114
R. 113
240
L. 51
39
10

38.1
25.7
13.1
11.0
11.4
8.6
8.8
7.0
5.5
11.4
8.7
8.8
4.6
33.8
84.8
100.0
100.0
25.4
25.7
96.6
97.4
100.6
101.4
40.5
40.4
44.5
44.6
11. 7
11. 7
18.2
18.1
33.1
8.2
6.2
1.6

681

100.0

206

30.2

664

97.5

299
296
326
325
86
87

43.9
43.5
47.9
47.7
12.6
12.8

L. 57

8.4
7.0
1.8

L. 48
L. 12

* Measurements of mandibles are shown in the percentage of length of mandible

ACKNOWLEDGEMENTGreatest thanks are due to Mr. Hung-cha Yang of Taiwan Fisheries ResearchInstitute. He kindly accompanied us to the Pei-kan fish market and helped us incollecting the present specimens and the information. Prof. Kazuhiro Mizue of theNagasaki University and Dr. Joseph C. Besharse of the Southern Illinois University
are acknowledged. Prof. K. Mizue kindly carried one of our specimen to Japan,
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

136

KASUYA AND NISHIWAKI

and Dr. ]. C. Besharse sent us the information and important photographs of the
Midway specimens with information, which were very useful for our study.
REFERENCES
ALLEN, G. M., 1906. Sowerby's whale on the American coast. Amer. .Naturalist, 40: 357-370.
ANDREWS, R. C., 1914. Notice of a rare ziphioid whale, Mesoplodon densirostris, on the New Jersey coast.
Proc. Acad. .Nat. Sci. Philadelphia, 66: 437-440.
GALBREATH, E. C., 1963. Three beaked whales stranded on the Midway Islands, central Pacific Ocean. ].
Mammalogy, 44(3): 422-423.
GmLER, E. R., 1966. A stranding of Mesoplodon densirostris in Tasmania. J. Mammalogy, 47(2): 326-327.
McCANN, C., 1963. Occurrence of Blainville's beaked-whale [Mesoplodon densirostris (BLAINVILLE)] in the
Indian Ocean. ]. Bombay .Nat. Hist. Soc., 60(3): 727-730.
McCANN, C., 1964. A further record ofB!ainville's beaked whale, Mesoplodon densirostris (BLAINVILLE), fromthe Indian Ocean. J. Bombay .Nat. Hist. Soc., 61(1): 179-181.
MooRE, J.C., 1958. A beaked whale from the Bahama Islands and comments on the distribution of
Mesoplodon densirostris. Amer. Mus . .Novitates, 1897: 1-12.
MooRE, J. C., 1966. Diagnoses and distribution of beakes whales of the genus Mesoplodon known from North
American waters. Whales, dolphins, and porpoises: 32-61. K. S. Norris (ed). Berkley and Los Angeles,
University of California Press.
MOORE, J. C .. 1968. Relationships among the living genera of beaked whales with classification, diagnoses
and keys. Fieldiana (:(oology ), 53 (4): 209-298.
NISHIWAKI, M. and T. KAMIYA, 1958. A beaked whale lvlesoplodon stranded at Oiso beach, Japan. Sci. Rep.
Whales Res. Inst., 13: 53-83, PLs. I-XVII.
OGAWA, T., 1938. Studen i.iber die Zahnwale inJapan, insbesondere i.iber die vier bei uns bisher unbekanten
Gattungen Tursiops, Steno, Pseudorca und Mesoplodon. Arb. Anotomischen Inst. Kaiserlich-Japanischen Univ.
Sendai, 21: 173-218, PLs. I-XIV.
0HSUMI, S., T. KAsUYA and M. N1smwAKI, 1963. Accumulation rate of dentinal growth layers in the maxillary tooth of the sperm whale. Sci. Rep. Whales Res. Inst., 17: 15-35, PLs. I-VII.
ORR, R. T., 1953. Beaked whale (Mesoplodon) from California, with comments on taxonomy. ]. Mammalogy, 34(2): 239-249.
RAVEN, H. C., 1942. On the structure of Mesoplodon densirostris, a rare beaked whale. Bull. Amer. Mus . .Nat.
Hist., 80(2): 23-50.
TRUE, F. W., 1910. An account of the beaked whales of the Family Ziphiidae in the collection of the UnitedStates National Museum, with remarks on some specimens in other American Museum. Bull. U.S . .Nat.
Mus., 73: 1-89.
ULMER, F. A., 1941. Mesoplodon mirus in New .Jersey, with additional notes on the New .Jersey M. densirostris,
and a list and key to the Ziphoid whales of the Atlantic coast of North America. Proc. Acad . .Nat. Sci.
Philadelphia, 93: 107-122.

Sci. Rep. Whales Res. Inst.,.No. 23, 1971.

MESOPLODON FROM FORMOSAEXPLANATION OF PLATESPLATE I
Fig. 1.
Fig. 2.
Fig. 3.

Throat region of M. densirostris, TK 256.
Ventral aspect of thoracic region of the same specimen.
Ventral aspect of tail region of the same specimen.
PLATE II

Fig. 1. Lateral aspect of head region of M. densirostris, TK 256.
Fig. 2. Ventral aspect of tail flukes of the same specimen.
Fig. 3. Dorsal fin of the same specimen seen from the right side.
of dorsal fin will have been caused by hand harpoon.
Fig. 4. Ventral aspect ofleft flipper of the same specimen.

A wound slightly below the base

PLATE III
Dorsal, lateral, ventral and posterior (top to bottom) aspects of the skull of M. densirostris, TK 256.
PLATE IV
Fig. I. Dorsal and lateral aspects of the mandible of M. densirostris, TK 256. White mark indicatesthe position of the tip of the mandibular tooth.
Fig. 2. Dorsal and lateral aspects of the mandible of M. densirostris, TK 245. White mark indicates the same with Fig. 1.
PLATE V
Fig. 1.

Outer, ventral and posterior (top to bottom) aspects of the left mandibular tooth of M.
densirostris, TK 256.
Fig. 2. Outer, ventral and posterior (top to bottom) aspects of the left mandibular tooth of M.
densirostris, TK 245.

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

137

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A RARE DOUBLE MONSTER OF DOLPHIN,
STENELLA CAERULEOALBAAKITO KAWAMURA AND KYOJI KASHITA*
Kawana, a village on the east coast of Izu Peninsula and located some 90 km south\·vest from Tokyo, is famous with dolphin hunting where several thousands of small
cetaceans are caught every year by means of 'Oikomi-driving '. This whaling
method is somewhat alike to that followed by Malaitan natives of Solomon Islands(Dawbin, 1966). Almost all the cetaceans caught there are used exclusively for
local consumption in Kawana and its environs.
During the course of examining whale body of S. caeruleoalba in the field at
Kawana village on November 26, 1970, one of the authors (Kashita) found verysmall but an abnormaly shaped foetuses among many normal ones. On closer
examination it was proved later to be a kind of double monster which was apparently
attributable to monovulation. The foetuses have one head with two body trunks
below the shoulder (Plate I).
A fairly big swarms of the dolphins had been driven into the Kawana Porton November 22, and kept alive there, and this foetuses were found among the
one-day-catch of November 26. The number of dolphins caught on that day was
1,532 animals in total which were consisted of 1,262 larger sized individuals and270 smaller ones. The composition of those animals by their state of maturity
was not known. It could, however, be reasonably approximated from the previous
study that both pregnant and lactating females occupy more than 40 percent amongwhole animals caught in mid-November of 1968 (Tobayama, 1970). The motherof this foetuses was 195 cm in total length, and showed no unusual appearance orcharactors both in the outside look and internal organs. The features of ovaries,
the number of corpus albicans and corpus luteum were not observed. The estiated age of the mother would be about 3 years from the body length by applying it
to growth curve obtained previously (Kasuya, 1970).
The general characters observed in this double monster were as follows : The
body lengths along transverse axis are 16.8 and 17.2 mm respectively. The facial
region in ventral view is much broader at the eye level than normal foetuses ofabout same length. The breadth is 5.6 mm in the former and 4.2 mm in the latter
while the distance between eyes is 3.1 and 3.4 mm respectively. The eyes areclearly visible, and the external nasal pits, Fovea nasalis, are distinctly seen on a levelslightly below the eyes. There is mouth cleft just below the nasal pits. External
ear opening is obscure. Maxillary process, lower jaw are distinguishable. Distance between nasal pits and mouth cleft is considerable. A slight neck-flexure
is visible, which seems as one of the distinct differences from that of normal foetuses.
Two pairs of fore-limbs and rudimental processes of hind-limbs on the side of genital* College of Agriculture & Veterinary Medicine, Nihon University, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 23. 1971. 139-140.

KAWAMURA AND KASHITA

140

member are distinct. Tails are conical in shape with obscure constrictions of muscle
plates. Umbilical cords are quite massive and distinct so as to fill the cavity formedby confronting two bodies along with the dark brown colored evaginations ofinternalorgans such as heart and liver. Pigmentation in the skin is not developed yet.
Comparing these characters with those of normal foetuses collected on thesame day at Kawana, and with another species of dolphins, Lagenorhynchus acutus or
Phocaena communis (Guldberg and Nansen, 1894), there seems no distinct differences between them except lateral appearance ; the double monster twins showedmuch slighter neck-flexure than the normal ones although it would be almost usual
when the double monster was seen dorsi-lateraly. It therefore seems that thoseunusual appearance is supposedly caused by the fusing due to twisting of the bodies
at their shoulder.
There have been reported at least two instances of Siamese twins and one double
monster in cetaceans : the first report is a double monster of 3 feet foetus of 72 feet fin
whale which was caught and found in Leith Harbor, South Georgia in 1946 (Intern.
Whal. Statis., 1949; Vangstein, 1971,person. com. ), the second one is southern sei whale(Kawamura, 1969), and then humpback whale very recently (Zemsky and Budylenko, 1970). The instances ofsei and humpback whales are complete Siamese twins
so-called equal conjoined twins ofthoracopagus, and those of fin whale seems to be akind of hemididymus or double monster, viz., two headed twins with one bodytrunk. All the twins having been reported were the only cases of baleen whales.
The double monster reported here would be the first record in toothed whales,and double monster of cephalopagus, the type of this foetuses which have two dody
trunks with one head, must be also the first instance throughout the order cetacea.
REFERENCES
DAwBrN, W. H., 1966. Porpoises and porpoise hunting in Malaita. Aust. Nat. Hist., 15: 107-211.
GuLDBERG, G. and F. NANSEN, 1894. On the development and structure of the whale. Bergens Mus., V. Bergen,
70+vii.
INTERNATIONAL WHALING STATISTICS, 20, 1949. Oslo.
KASUYA, T., 1970. Growth and age determination of blue white dolphin, Stene/la caeruleoalba. Geiken Tsushin,
228: 4-5. (in Japanese)
KAWAMURA, A., 1969. Siamese twins in the sei whale Balaenoptera horealis Lesson. Nature, 221: 490-491.
ToBAYAMA, T., 1970. On the school of marine mammals. Cetacea. Geiken Tsushin, 228: 2-3.
(in Japanese)ZEMSKY, V. A. and G. A. BuDYLENKO, 1970. Siamese twins of humpback whale. Trans. AtlantNIRO, 24:
225-230.
EXPLANATION OF PLATE

Fig. I.
Fig. 2.
Fig. 3.
Fig. 4.

The foetal double monster of Stene/la caeruleoalba
Ventral view (ea. X 3.1)
Dorsal view (ea. X 3.1)
Ventro-lateral view (ea. x 3.1)
Lateral views of the double monster (left) and the mormal foetus of about same bodylength (right). (ea. X 2.9)
Sci. Rep. Whales Res. Inst.
No. 25, 1971.

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FATTY ACID COMPONENTS OF GANGES RIVER
DOLPHIN OIL
HIDEO TSUYUKI* AND SHINGO ITOH*
ABSTRACTThe purpose of the present work is an examination of chemical components of Ganges river dolphin oil by TLC, CC, and GLC.
The analysis by TLC and CC showed the presence of triglycerides,
phospholipids, sterol esters, diglycerides, hydrocarbons, monoglycerides,
sterols and free fatty acids. A substantial part in all fractions was 80.6% of
triglycerides fraction contained a small amount of free fatty acids.
The analysis by GLC showed the presence of fatty acids with chain lengths
from 10 to 22 carbon atoms and with zero to six double bonds. The Ganges
river dolphin oil was found to be rich in unsaturated fatty acids (72. 73%),
particularly octadecamonoenoic (32.30%) and hexadecamonoenoic (24.47%).
On the other hand, saturated fatty acids were contained in small amounts(27.27%) in Ganges river dolphin oil.

INTRODUCTION

Although we have reported on the fatty acid composition of the oil of Finless porpoise (Tsuyuki and Itoh, 1969a) and Many-toothed pilot whale (Tsuyuki and Itoh,l 969b) which are cetaceans in salt-water, the literatures on the oil of fresh-watercetaceans are few.
Expedition of the Ganges river dolphin (Platanista gangetica) was done in East
Pakistan on the various field of study from Oct. 1969 through March 1970 organized
by Prof. M. Nishiwaki of the Ocean Research Institute, University of Tokyo.
The materials were brought us through Prof. M. Nishiwaki.
This study is reported as a part of the examination of Platanistidae which has
been continuing to date by organized Japanese scientists.
It was a pleasure for us to join in the study.
MATERIAL AND METHODS

Material
Ganges river dolphin used in the present investigation was caught at the Ganges
River in East Pakistan, in January 1970 by Prof. Dr. Nishiwaki. Then sample oil
was extracted by boiling the blubber of Ganges river dolphin with water. The
chemical properties of sample oil are shown in Table 1.

* Department of Food Engineering, College of Agriculture & Veterinary Medicine, Nihon University.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971. 141-147

TSUYUKI AND !TOH

142

TABLE !.

PROPERTIES OF GANGES RIVER DOLPHIN OIL

nn'o
Acid value
Iodine value (Wijs)
Saponification value
Unsaponifiable matter (o/o)

1.4635
1.3
104.4
195.3
I.OJ

Thin-layer chromatograplry
TLC was carried out qualitatively according to the method of Doizaki andZieve (1962). Commercially available silica gel (Wakogel B-5, Wako Pure Chemical Industries, Ltd. in Tokyo) was applied in 0.25 mm thickness on 5 x 20 cm glass
plate. The plate was dried in air for 15 min after spreading, and activated for
1 hr at 110° just before use. The sample oil was applied on 1.5 cm place from thebottom of the plate with a capillary tube. The chromatograms were developed in
the glass chamber saturated with petroleum ether-ethyl ether-glacial acetic acid,90: 10: 1 (v/v/v). The developed plate was sprayed with 50% solution of sulfuric
acid in water, and the separated spots were identified by comparison with the eachstandard mixture which was developed by the same procedure.
Silicic acid column chromatography
To separate Ganges river dolphin oil quantitatively, silicic acid column chromatography was carried out according to the modified method of Barron and
Hanahan (1958). A glass column (height 70 cm, ID 20 mm) was packed with 60 g
silicic acid (Wakogel C-200, Wako Pure Chemical Industries, Ltd. in Tokyo) prepared by activation at 120° for 1 hr and washing with hexane. 0.526 g of sample oil
was placed on the column as 10% solution in hexane, and constituents in sample oil
were eluted. Also the flow rate was adjusted to 1.5-1.8 ml/min, and then eachfraction was respectively collected in amount of 20 ml. The solvent mixture wasreplenished from a reservoir filled consecutively with 120 ml of hexane, 180 ml of 15%
benzen in hexane, 660 ml of 5% ether in hexane, 320 ml of 15% ether in hexane,
280 ml of 30% ether in hexane, 240 ml of 90% ether in hexane and 320 ml of 20%
methanol in ether. Each fraction was identified by chromatographed known
compounds on silicic acid column by the same procedure.
Preparation ef methyl ester
Fatty acid methyl ester was prepared with boron triftuoride-methanol reagent
according to Duron and Nowotny (1963). 100 mg of Ganges river dolphin oil wasadded 10 ml of boron triftuoride-methanol reagent (140 g BF 3 per liter of methanol)
under nitrogen atmosphere, and the conical beaker was closed with the screw cap.
Then, the beaker was heated in a boiling water bath for 45 min. After the reaction,
the ester was extracted by adding 2 volumes of ethyl ether, so 1 volume of water andshaking. The ethyl ether solution was dehydrated with anhydrous sodium sulfate
and then evaporated. Finally the methyl ester was obtained in amount of 92 mg.
Sci. Rep. Whales Res. Inst.,
No. 23, 197!.

GANGES RIVER DOLPHIN OIL

143

Gas-liquid chromatography
GLC was analyzed with a Shimadzu Gas Chromatograph Model GC-lC using
a flame ionization attachment. A 180 cm long, 3 mm ID, U shaped stainless steel
column was packed with Shimalite W (60-80 mesh), coated with 10% diethylene
glycol succinate (commercially available DEGS made by Shimadzu Seisakusho
Ltd, in Kyoto). Column temperature was kept constantly at 200°, and temperature
at injection port and detector block were respectively 275° and 240°. Flow rates
for air, nitrogen as carrier and hydrogen were 600, 70 and 75 ml/min respectively.
Chromatographic peaks were identified either by comparison of retention
times with those of standards or from a graph representing the relationship between
log retention time and the number of carbon atoms by applying the methods ofAckman (1963), Nelson and Freeman (1960).
Each peak was quantitated by the method of Ettre and Kabot (1963). All
fatty acids were calculated as weight percentages of the total known fatty acids
present.
RESULTS AND DISCUSSION

Fig. 1 shows the fractionation of Ganges river dolphin oil by a TLC plate qualitatively. The obtained fractions were from above, as follows: hydrocarbons, sterolesters, triglycerides, free fatty acids, sterols, diglycerides, monoglycerides and phos-

crn

Cl

0

2

10

5

0
0

3

5

6

7

Fig. I. Thin-layer chromatogram of Ganges river dolphin oil.
I. Hydrocarbons
5. Sterols
2. Sterol esters
6. Diglycerides
3. Triglycerides
7. Monoglycerides
4. Free fatty acids
8. Phospholipids

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

144

TSUYUKI AND ITOH

100

80

bi>

E

60

_::

·c;

0

.....

.c

bO

~

40

2

20

0

3

20

4

40

6

60

7

80

100

Fraction number
Fig. 2.
No.
I

2
3
4
5
6
7

Separation of Ganges river dolphin oil by silicic acid column.
Fraction
Eluting solvent
Hydrocarbons
HexaneSterol esters
15% benzen in hexane
5% ether in hexane
Triglicerides & free fatty acids
Sterols
15% ether in hexane
Diglycerides
30% ether in hexane
90% ether in hexane
Monoglycerides
20% methanol in ether
Phospholipids

pholipids. It was seemed that triglycerides fraction was contained in sample oil atthe largest quantity as compared to other fractions, because of the spot color was
darker than others. The seven fractions except triglycerides seem to be contained
respectively only trace amount as compared to triglycerides fraction.
Fig. 2 shows the fractionation of Ganges river dolphin oil by a silicic acidcolumn quantitatively. The seven fractions were eluted as follows: hydrocarbons,sterol esters, triglycerides and free fatty acids, sterols, diglycerides, monoglycerides,
and phospholipids. The largest proportion was 80.6% as triglycerides and freefatty acids fraction, and other proportions were as follows: 4.9% phospholipids,
4.1 % sterol esters, 3.2% diglycerides, 2.8% hydrocarbons, 2.5% monoglycerides and1.9% sterols.
Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

GANGES RIVER DOLPHIN OIL
TABLE 2.

145

FATTY ACID COMPONENTS OF GANGES RIVER DOLPHIN OIL

No. ofcarbon atoms

No. ofdouble bonds

Weightper cent

No. ofcarbon atoms

No. ofdouble bondWeightper cent

12
12
14
14
14
16
16
16
16
18
18
18

0

0.39
0.09
4.89
2.35
1.40
18.11
24.47
1.32
l. 71
1.27
32.30
4.65

18
18
20
20
20
20
20
20
22
22
22
22

3
4
0

0.43
0.24
2.51
0.54
0.11
0.29
0.98
0.42
0.10
0.53
0.41
0.49

l

0
2
0
2
3
0
l

2

l

2
3
4
5

0
4
5

6

TABLE 3. A COMPARISON OF SATURATED AND UNSATURATEDFATTY ACIDS OF GANGES RIVER DOLPHIN OIL
Weight per cent of total fatty acids
No. ofcarbon atoms

Saturated

Unsaturated

Total

12
14
16
18
20
22
Total

0.39
4.89
18.11
1.27
2.51
0.10
27.27

0.09
3.75
27.50
37.62
2.34
1.43
72.73

0.48
8.64
45.61
38.89
4.85
1.53
100.00From the results of thin layer chromatogram and column chromatogram, it
was found that Ganges river dolphin oil was approximately consisted of triglycerides.
Table 2 shows the fatty acid components of Ganges river dolphin oil by quantitative GLC analysis. There were 24 kinds of fatty acids, having from 12 to 22
carbon atoms. The majority were hexadecanoic, hexadecamonoenoic and octadecamonoenoic fatty acids, because of the total of the above three fatty acids held really
74.88% of the total fatty acids. The next prominents were tetradecanoic, tetradecamonoenoic and octadecadienoic fatty acids. On the other hand, the total proportion of other fatty acids was slightly 9.72%. In comparison with saturated andunsaturated fatty acids, the proportion of total saturated fatty acids was 27.27%, andthose of total unsaturated fatty acids was 72. 73%, as shown in Table 3. Moreover,to compare with the proportion of each carbon numbers, the most prominent was
45.61 % of 16 carbon atoms fatty acids, and the next was 38.89% of 18 carbon atoms
fatty acids. The rest were as follows: 8.64% 14 carbon atoms, 4.85% 20 carbon
atoms, 1.53% 22 carbon atoms and 0.48% 12 carbon atoms.
Finally, the principal ingredient of Ganges river dolphin oil was triglycerides,
and main fatty acid components of sample oil were hexadecanoic, hexadecamonoenoic and octadecamonoenoic.
Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

146

TSUYUKI AND ITOH

SUMMARY

1. The fractionation of Ganges river dolphin oil was done by thin layer
chromatography and silicic acid chromatography. The largest fraction was triglycerides and free fatty acids, and its proportion was 80.6%. The other proportions
were as follows: phospholipids 4.9%, sterol esters 4.1 %, diglycerides 3.2%, hydrocarbons 2.8%, monoglycerides 2.5%, and sterols 1.9%.
2. Fatty acid components of Ganges river dolphin oil were analyzed by gasliquid chromatography.
The results obtained were as follows:
Total saturated fatty acids
27.27%;
dodecanoic
0.39%
tetradecanoic
4.89%
hexadecanoic
18.11 %
octadecanoic
1.27%
eicosanoic
2.51 %
docosanoic
0.10%
Total unsaturated fatty acids
72.73%;
dodecamonoenoic
0.09%
tetradecamonoenoic
2.35%
te'.radecadienoic
1.40%
hexadecamonoenoic
24.47%
hexadecadienoic
1.32%
hexadecatrienoic
1. 71 %
octadecamonoenoic
32.30%
octadecadienoic
4.65%
octadecatrienoic
0.43%
octadecatetraenoic
0.24%
eicosamonoenoic
0.54%
eicosadienoic
0.11 %
eicosatrienoic
0.29%
eicosatetraenoic
0.98%
eicosapentaenoic
0.42%
docosatetraenoic
0.53%
docosapentaenoic
0.41 %
docosahexaenoic
0.49%
REFERENCES
R. G., 1963. Structural correlation of unsaturated fatty acid esters by graphycal comparison ofgas-liquid chromatographic retention times on a polyester substrate. J. Am. Oil Chemists' Soc., 40:
558-564.
BARRON E.J. and D.J. HANAHAN, 1958.
Silicic acid chromatography of the neutral lipides of rat liver, beefliver, and yeast. J. Biol. Chem., 231: 493-503.
DorzAKI, W. M. and L. ZmvE, 1962. Rapid thin-layer chromatographic separation of phospholipids and
AaKMAN,

Sci. Rep. Whales Res. Inst.,
No. 23, 1971.

GANGES RIVER DOLPHIN OIL

147

neutral lipids of serum. ]. Biol. Chem., 3: 138-140.
DuRoN, 0. S. and A. NowoTNY, 1963. Microdetermination oflongchain carboxylic acids by transesterification with boron trifluoride. Anal. Chem., 35: 370-372.
ETTRE, L. S. and F.J. KABOT, 1963. Relative response of fatty acid methyl esters on the flame ionization
detector. J. Chromatog., 11: 114-116.
NELSON, G. J. and N. K. FREEMAN, 1960. Phospholipide and phospholipide-fatty acid component of humanserum lipoprotein fraction. J. Biol. Chem., 235: 578-583.
TsuYUKI, H. and S. lToH, 1969a. Fatty acid composition offinless porpoise oil. Sci. Rep. Whales Res. Inst.,
21: 131-135.
TsuYUKI, H. and S. I TOH, l 969b. Fatty acid composition of Many toothed pilot whale oil. Sci. Rep. Whales
Res. Inst., 21: 137-141.

Sci. Rep. Whales Res. Inst.,

No. 23, 1971.

THE SCIENTIFIC REPORTS OF THE WHALES RESEARCHINSTITUTE, TOKYO, JAPANNUMBER 1, JUNE 1948
Akiya, S. and Tejima, S. Studies on digestive enzyme in whale. 3-7
Akiya, S. Ishikawa, Y., Tejima, S. and Tanazawa, T. Studies on tryptase from a whale (Balaenoptera borealis

L.).

8-10

Akiya, S., Tejima, S. and Ishikawa, Y. Studies on the 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 whale 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 B 2 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 of kitol 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 of histidine 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 of kitol. 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 of kitol (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 of5-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 (Prodelphinus 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) Blood 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. Ill. Relation between movement
and water temperature of the sea. 79-87
Omura, H., Fujino, K. and Kimura, S. Beaked whaleBerardius bairdi ofJapan, with notes of,(,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
Ohta, 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 North 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 Architeuthis. 139-151
I wai, 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 of Japan. 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 of cetacea. 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 boundaryof water masses. 209-224
Abe, T. Notes on fishes from the stomachs of whales taken in the Antarctic. I. Xenoryttus 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 Mesoplodon stranded at Oiso beach, Japan. 53-83
Nishiwaki, M. and Randa, 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 of Japan. 1-33
Nishiwaki, M. and Kamiya, T. Mesoplodon stejnegeri from the coast of Japan. 35-48
Nishiwaki, 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 1311 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 ofcetacea. 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. lmmunogenetic 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 of Japan. 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
Ichihara, T. Prenatal dead foetus of baleen whales. 47-60
Nishiwaki, M. Mesoplodon bowdoini stranded at Akita beach, Sea of Japan. 61-77
Nishiwaki, M. Observation on two mandibles of Mesoplodon. 79-82
Sinclair, John. An early dolphin embryo (Stenella caeruleoalbus) in serial sections. 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 maxillary 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
N emoto, 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 N aruse, 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 attenuata were caught andkept at Ito, Japan. 65-90
Nakajima, M. and Nishiwaki, M. The first occurrence of a porpoise (Electra electra) in Japan. 91-104
Hosokawa, H. and Kamiya, T. Sections of the 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. Thysanoessa 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. Externarmeasurements and weight ofa southern elephant seal. 211-212
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 of varginal band in the fin, sei, and blue whales. 85-94
Hosokawa, H., lgarashi, S., Kamiya, T. and Hirosawa, K. Morphological characteristics and myelinizationof acoustic system in the dolphins (Stenella caeruleoalba). 95-123
Mol, 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., lchihara, 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
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
Nemoto, T. and Yoo, K. I.

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. 141-14 7

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