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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