DISTRIBUTION AND MIGRATION OF TWO SPECIESOF STENELLA IN THE PACIFIC COAST
OF JAPANNOBUYUKI MIYAZAKITOSHYO KASUYAAND
MASAHARU NISHIWAKI
Ocean Research Institute, University of Tokyo, Tokyo

ABSTRACTDistribution and migration of Stenella coeruleoalba and Stenella attenuata in
the Pacific coast of Ja pan were studied basing on the fishing data and the sighting data, and the relationship between them and the marine environment
was discussed. S. coeruleoalba and S. attenuata are distributed in the pelagic andcoastal waters influenced by the warm Kuroshio current. S. attenuata is
distributed in slightly warmer waters than S. coeruleoalba is. Their range ofdistribution seems to extend up to 46°N in summer season and retreats to
33°N in winter. The concentration of these species in the northern boundaryof the Kuroshio current is suggested.
INTRODUCTION
At least three species of Stenella are known from Japanese coastal waters. They
are the spinner dolphin S. cf. longirostris (Mizue et al., 1964), the spotted dolphin(Mizue et al., 1962, Nishiwaki et al., 1965) and the blue white dolphin (Okada,
1936, Ogawa, 1936). The first is rare and only known from the southern partof Japan, and the color pattern of these are very similiar to S. cf. longirostris described by Perrin (1972) from Hawaiian waters. The other two species are fairly
common and have been the object of the commercial hunting at several places on
the Pacific coast of Japan. These two species are caught at Taiji (33° 36' N,
135° 56' E) on the coast of Kii Peninsula, at Arari (34° 48' N, 138° 46' E) on thewest coast oflzu Peninsula, and at Kawana (34° 57' N, 139° 08' E) and Futo (34°
52' N, 139° 06' E) on the east coast of Izu Peninsula. The fishermen at Taiji huntthe dolphin with hand harpoon, or with hand harpoon and shot gun off the coastof Kii Peninsula, but they have introduced the driving method since 1973. The
people at Arari had captured the various species of dolphins in Suruga Bay withdriving method, but the operation has almost ceased since 1962. The two villages
on the east coast of Izu Peninsula operate the dolphin hunting with driving methodin Sagami Bay and the waters around Oshima Island (Tobayama, 1969, Kasuya,1972). Details of dolphin fishing is described by Ohsumi (1972).
Sci. Rep. Whales Res. Inst.,
No. 26, 1974, 227-243

228

MIYAZAKI, KASUY A AND NISHIWAKI

Tobayama (1969) analyzed the catch statistics of the two fishermen's cooperative unions at Kawana and Fu to, and suggested the influence of the marine topography in the formation of the fishing ground. Howeven, Kasuya (1972) suggested another factor the inflow of warm water into Sagami Bay. Ohsumi (1972)
analyzed the official statistics of dolphin fishing prepared by the Ministry of Agriculture and Forestry, and showed an estimated migration route of blue white dolphin.
This study intends to analyze the distribution and migration of Stenella coeruleoalba and of Stenella attenuata. This analysis is based on the catch records of thefishermen's cooperative unions and sighting records of these species collected by us
or reported by various authors.
10'

20·

30'

40'

50'

140 °

Sagmi Bay1 1
( 8 )( 9)31(8) ( 4)I z u °KawanaPen.
2 1 3 2(3) (3) (11 )(13)
14 5 2(22)(12) (9)3 3 10 2(R10)(31x1s)
11

50'

4

. (62)(32)
Oshima
2

~

(47)

40'
Fig. I. The number of schools of Stenella spp. sighted by the scouting boats in 3.3'
(6.1 km) squares during 8 seasons from 1964-'65 to 1973-'74. Numerals inparenthesis indicate the number of schools per 10 7 nautical miles of scouting.
(For Sagmi Bay read Sagami Bay)

MATERIALS

The statistics were collected by Miyazaki from four fishermen's cooperative unions.
The data collected at Taiji covers ten years from 1963 to 1972. Some of thestatistics were provided by Dr. Kajihara. The distinction of the two species of Stenella
is made only in recent three years. In this district " Mairuka" and " Haukasu "indicate S. coeruleoalba and S. attenuata respectively. All of that catch were madewith hand harpoon, or hand harpoon and shot gun.
The data collected at Arari covers the catch of fourteen seasons from 1950 to1970, but there are only sporadic catches after 1962. S. coeruleoalba and S. attenuata
are recorded by the name "Mairuka" and" Hasunaga or Arari-iruka" respectively.
The various informations on the dolphin fishing in Sagami Bay were colSci. Rep. Whales Res. Inst.,

No. 26, 1974

DISTRIBUTION AND MIGRATION OF STENELLA

229

lected from the fishermen's cooperative unions at Kawana and Futo. They comprise the number of dolphins and schools, position of sighting, and the hours and thenumber of scouting boats engaged. The number of dolphins is known for thetwenty seasons from 1949-'50 season to 1973-'74 season. But the statistics are fragmental before the 1961-'62 season, and do not give the total number of dolphinsof the genus Stenella caught in Sagami Bay. The two species of Stenella are recorded separately since 1969-'70 season. The main fishing area in Sagami Bay isshown in Fig. 1. The total scouting hours of the four high speed, 20 knot at maximum, scouting boats were available for eight seasons from 1964-'65 to 1973-'74
season. This was used as the indicator of the fishing effort. These scouting boats
leave the harbor, if the weather is good, at 5 o'clock in the morning. And if theyfind a suitable school, they drive it into the harbor with the help of other slower boats.
They usually find the school before the noon, but they sometimes continue the scouting until 3 o'clock in the afternoon. The fishing season in Sagami Bay starts inthe autumn season (October) and ends in the winter of the next year (January).
The sighting records of Stenella coeruleoalba and Stenella attenuata were obtainedby Kasuya and Miyazaki through five cruises of the research vessel the Tanseimaru.
They are used together with the many sighting records and sporadic catches of these
species reported by various authors (Tables 1, 2).
Oceanographical data obtained through two cruises of the Tanseimaru in 1971
and 1972, and that reported by Japanese Meteorological Agency, Japanese Maritime
Safety Agency, Tokyo Metropolitan Fisheries Experiment Station, and Shizuoka Prefectural Fisheries Experiment Station were used in analyzing the relation between
the distribution of the dolphins and the environment.

ANALYSIS OF THE STATISTICS

Annual .fluctuation of catch
Fig. 2 shows the annual fluctuation of the catch of Stenella spp. in each fishingarea.
Though the statistics are imperfect before 1961-'62 season, it is suggested thatthe number of the dolphins caught in Sagami Bay shows rapid increase after thatseason. This seems to be related with the introduction of the high speed scouting
boats. After this year the amount of the catch increases to record the maximum
catch of 15,649 dolphins in 1965-'66 season. As the two fishermen's unions started
the cooperative operation in 1967-'68 season to control the market price, the numberof dolphins caught decreased to about one third of the maximum catch. But thechange of the mode of operation cannot explain all the annual fluctuation of thecatch. Because the number of dolphins caught per one scouting hour shows thefluctuation parallel with that of total number of catch (Fig. 3). It is suggested thatthe annual fluctuation of the catch will indicate that of the abundance of thedolphins migrating into the fishing ground. Fig. 4 shows the relation betwem theannual catch of Stenella spp. in Sagami Bay and the distance from Oshima Island to
Sci. Rep. Whales Res. Inst.,
No. 26, 1974

MIYAZAKI, KASUYA AND NISHIWAKI

230
4-

4

x10

x10

2

.c
u

0

0

u

1

'50
• Kawanoo Fut oe Ka wan a......
0. 50-51'60-61
SeasonFig. 2. The number of catch of Stenella coeruleoalba (left scale) and of Stenella attenuata(right scale) at each fishing ground. Solid line indicate S. coeruleoalba, and broken
line S. attenuata.

x 103
15

.c 1 0

u.i
::i

u

5

0

u

a.:
u

5

'
0

0
'61·'62'69•70'65-'66'73'74

SeasonFig. 3. The number of catch and the catch per one scouting hour (C. P. U. E.)
of Stene/la spp. in Sagami Bay. Closed circle and solid line indicate the catch, andopen circle and broken line catch per one scouting hour.
Sci. Rep. Whales Res. Inst.,

No. 26, 1974

DISTRIBUTION AND MIGRATION OF STENELLA

231

the nearest border of the Kuroshio current from October to December Qapanese
Maritime Safety Agency, 1961-'71). As the surface water temperature is highlyvariable by the effect of the meteorology or of the tide, the position of the l5°C
isothermal at the depth of 200 m was used as the indicator of the position of theKuroshio current. It is clear in Fig. 4 that the catch of Stenella spp. in Sagami Bay
has the negative correlation with the distance of the Kuroshio current from themain fishing area. This means that in the years when the Kuroshio current situatesclose to Sagami Bay, there migrates many dolphins of the genus Stenella. The catchor catch per unit effort changes affected by the abundance of the migrating dolphins.
Though the two species of Stenella are recorded separately in the statistics only inthe seasons from 1969-'70 to 1973-'74 season, as the catch of S. attenuata comprises
4,956 individuals or 16. l % of the total catch of Stenella spp. in Sagami Bay in theseseason, it is reasonable to expect the catch of S. attenuata even in the preceding years.
3

x 10
15

0

'65
0

'66

0

10

'61

..c

•

0

•
'70'67

u

0

'63

'62

Cl

0

u

5

'64

•

. 68

•

•

'69

'71

0
0

20

40

60

80

Distance(mile)
Fig. 4. Relationship between the number of catch of Stenella spp. in Sagami Bay,and the distance (nautical mile, 1.85 km) from Oshima Island to the 15°0 isothermal line at the depth of 200 m. Closed circle indicates cooperative operationand open circle competitional operation. The numerals indicate the starting
year of the season.

The catch of Stenella spp. in Suruga Bay was high until the early 1950's(see Arari in Fig. 2). But they had almost finished the operation since 1962. Thisage coincides with the time when the catch in Sagami Bay increased rapidly.
The other shorter cycle of annual fluctuation of the catch is expected to be affectedby the oceanographical conditions as in the case of Sagami Bay. Though Nishiwaki et al. ( 1965) reported the information from the fishermen's telling that the catchof S. attenuata in 1959 or in 1964 was the first case for them to catch this species. It is
Sci. Rep. Whales Res. Inst.,

No. 26, 1974

232

MIYAZAKI, KASUYA AND NISHIWAKI

difficult to trust their telling at the following two aspects. At first, after that year
the capture of several schools of S. attenuata within short period were reported fromthe village (Nishiwaki et al., 1965), and secondly the catch of S. coeruleoalba and S.
attenuata in the village seems to have been recorded by the different vernacular names
mentioned before.
The catch statistics off Kii Peninsula shown in Fig. 2 do not include the catchby driving method as it was started in 1973. The general trend of the catch of
Stenella is gradually increasing in recent years. The statistics of two kinds ofStenella were recorded separately only in the recent three seasons. As the result of
the difference of the price between two species in this local district, the fishermen
prefer S. coeruleoalba. So, the catch of S. attenuata in the recent three years was only
63 animals or 1.8 % of the total number of the catch of the two species. This ratio
is lower than that of the catch in Sagami Bay.

Seasonal fluctuation of catch
In Sagami Bay the fishing season starts in late September, and ended in theformer years in January or in early February but in recent years it ends in late
December (Figs. 5 and 6). Fig. 6 shows the difference of the fishing season of the
x10

3

x10

10

2

w

u

2
=i x10

5

5

1 0:

u

u

0

\

w

\...
0
Oct.

Nov.

Dec.
Season

Jan.

0

Feb.

Fig. 5. The seasonal changes of the catch of Stenella spp., of the catch per one
scouting hour (C.P.U.E.), and of the scouting hours (effort) in Sagami Bay.
8 seasons from 1964-'65 to 1973-'74 season are combined. Closed circle andsolid line indicate C.P.U.E., closed circle and chain line the total amount ofeffort, and open circle and broken line the catch.

two species. Though the season of S. attenuata seems to start almost at the same
season with that of S. coeruleoalba, the peak of the catch comes in early November andthe season ends by late November. On the other hand the peak of the catch of
Sci. Rep. Whales Res. Inst.,

No. 26, 1974

233

DISTRIBUTION AND MIGRATION OF STENELLA

S. coeruleoalba is in late November about one month later than that of S. attenuata.
The decrease of the catch of S. coeruleoalba in late October and early November
will be the effect of the catch of S. attenuata.
x 10

3

x1Q3

10

3

2
5

0
x10 2

0
3
x 1
10

o

2
0

.>::.

.>::.

u

u

5
0

0

0

u

u
0
x10

0
2
x 10
10

2
5

\

\
\

0------0.. ...

0

J

F

/'' ....

-M

/ /

/

' .,,_\\\,.......

0

A

M

A
J
J
Se a son

s

0

N

D

J

Fig. 6. The seasonal fluctuations of the catch of Stenella coeruleoalba and Stenella
attenuata at each fishing ground. Closed circle, solid line and left scale indicate S.
coeruleoalba, and open circle, broken line and right scale S. attenuata. Top:
Sagami Bay, Middle: Suruga Bay, B::ittom: Off Kii Peninsula.

The seasonal fluctuation of the catch per scouting one hour in Sagami Bay isshown in Fig. 5. The fluctuation shows three peaks, the first in early October,second in late November, and the third in late December or in early January. At
the beginning of the season, they often start the catch after obtaining the informationof sighting by other fishing vessels. And in the late December and early January
the scouting effort decreases, because the fishermen spend the time for the new year
festival or for its preparation. These two factors affect the catch per one scouting
hour and keep it high. Accordingly, the first and the last peaks are supposed not
to reflect the real abundance of the dolphins. The real peak of the migration of
S. coeruleoalba in Sagami Bay is considered to be in the late November, and that
Sci. Rep. Whales Res. Inst.,
No. 26, 1971:

234

MIYAZAKI, KASUYA AND NISHIWAKIof S. attenuata is in late October.
In Suruga Bay the catch of Stenella spp. was made in any season of the year, but
the peaks of S. coeruleoalba caught are in the seasons from April to July and from
December to January. The former peak is not observed in Sagami Bay, and thelatter is about one month later than the corresponding peak in Sagami Bay. The
spring peak of S. attenuata in Suruga Bay seems to arrive later than that of S.
coeruleoalba.
Fig. 6 shows the seasonal fluctuation of catch of two species of Stenella off Kii
Penisula. Though the catch of Stenella spp. in this area is made in any season of
the year, the peak of S. coeruleoalba are in the seasons from April to July and from
October to March. The former will correspond to that of Suruga Bay, and the latterto the winter fishing seasons in other grounds. The winter peak of S. coeruleoalba
arrives slightly later in the southern area than the northern. Similar feature isobserved also in S. attenuata. The catch representing the spring peak of S. attenuata
is too small to discuss the difference of the season. The fishermen say that thefishing ground in March becomes too far from the coast to operate the dolphin
fishing. This will be one of the reason of the smaller catch in spring season.
GEOGRAPHICAL DISTRIBUTION

All the available records of sighting or of sporadic catch of S. coeruleoalba and S.
attenuata in the Pacific coast of Japan are plotted in Fig. 7. The origin of these records are shown in Tables 1 and 2. The l 7°C isothermal line shows the surface water
TABLE 1.
No.

LIST OF RECORDS OF SPORADIC CATCH OF STENELLA SPP. IN
THE WESTERN NORTH PACIFIC.
Position

Date

AuthorComments

Ogawa, 1936

Purchased at the market

Okada, 1936

Purchased at the market

Okada, 1936

Possibly caught on Izu coast

Okada, 1936
Okada, 1936
Higashikawa
et al., 1966

Purchased at the market
Possibly caught on Izu coast

Ogawa, 1936

Purchased at the market

S. coeruleoalba

IX

'34

2
3

21

4
5

27
4

II
II

'35

6

26

I

'64

'35

Off Choshi(35°44'N, 140°52'E)
Off Onahama(36°53'N, 140°52'E)
Shimizu fish market(35°00'N, 130°30'E)
Off Choshi
Shimizu fish market
Kokufu(34°20'N, 136°52'E)

Stranded

S. attenuata

7

12

VIII

'35

8

20

x

'61

9

VIII

Nagasaki fish market(32°40'N, 129°50'E)
Arikawa(33°00'N, 129°06'E)
OnahamaMizue et al.,1962
Kasuya, 1972

Driven intemperature in the warmest and coldest months of 1970. This figure shows thatthe distribution of these species is not restricted in the coastal waters, but extends
into the offshore waters. The northernmost records in the summer season are beSci. Rep. Whales Res. Inst.,
No. 26, 1974

DISTRIBUTION AND MIGRATION OF STENELLA

235

tween 44°N and 46°N. This range approximately coincides to the 17°0 isothermalline in the summer season. Though the northern range of the two species in winterseason is not clearly indicated, it is suggested that they are distributed south of 17°0
isothermal line.
TABLE. 2.

No.

LIST OF SIGHTING RECORDS OF STENELLA SPP. IN THE
WESTERN NORTH PACIFIC.

Date

PositionTime

S. coeruleoalba
11
1
VIII
31
2
VIII
3
9
IX
4
8
VIII
5
18
VIII
13
IX
6
15
IX
7
22
IX
8
9
22
XI
10
21
XI
21
11
XI
19
12
13
19
14
19
15
21
I
16
5
II
17
24
x
18
8
x
19
8
x
11
20
x
21
10
II
22
JO
II
23
10
II

'51
'51
'51
'54
'54
'54
'54
'70
'70
'71
'71
'72
'72
'72
'72
'72
'72
'73
'73
'73
'74
'74
'74

Nemuro Bay
Ekacherina Bay
Laperyza Bay
38°18'N, 148°50'E
39°04'N, 153°30'E
41°28'N, 153°03'E
44°34'N, 149°5l'E
34°3l'N, 139°35'E
34°35'N, 139°38'E
34°48'N, 141°07'E
34°52'N, 141°05'E
29°36'N, 140°38'E
29°32'N, 140°42'E
29°07'N, 141°ll'E
26°39'N, 142°28'E
20°17'N, 152°12'E
34°52'N, 141°05'E
34°48'N, 139°54'E
34°44'N, 139°47'E
35°02'N, 139°18'E
32°05'N, 132°12'E
32°52'N, 133°08'E
31°28'N, 134°09'E

13: 45
14: 2011 : 10
10: 3608: 0509: 26
12: 1807: 55
11: 46
15: 34
10: 00
11: 2508: 0007: 00
12: 00
16: 40S. attenuata
24
10
25
22
26
22
27
22
28
7
29
7
30
8
31
23
32
23
33
24

'67
'72
'72
'72
'72
'72
'72
'73
'73
'73

26°40'N, 124°50'E
25°55'N, 143°38'E
25°32'N, 142°00'E
25°22'N, 142°43'E
23°30'N, 151°42'E
23°35'N, 151°35'E
24°05'N, 149°09'E
31°28'N, 134°36'E
32°03'N, 135°0l'E
33°19'N, 137°52'E

06: 40
09: 41
11: 22
12: 23
16: JO
16: 0006: 40
11: 0005: 05

XII
I

II
II
II

v
v
v

Surfacetemperature(°C)

Schoolsize

Author

150
50
20-30
2,000
400
150-200

Sleptsov, 1961

22.7
22.7
20.6

10
1,000
60-70

Present data

19.8
19.8
21.4
21. 7
25.5
20.5
24. 7
25.4
23.1

50
30
100
10
30
200
50
500-1,000
20-30
50-60
100
20

Masaki, 1972

22.2
21.9
21.4
24.3
24.5
24.8
19.0
19.0
16.8

50
50
50
20-30
20-30
20-30
30

Present data

Masaki, 1972

Present data

5

The similar feature is also observed in the water temperature at the positionsof sighting collected by us or reported by various authors (Table 2). The 32 records
of water temperature at the sighting position of S. coeruleoalba and the 9 records atthe sighting position of S. attenuata are in the range between 16.8°0 and 26.0°0.
Sci. Rep. Whales Res. Inst.,
No. 26, 1974

MIYAZAKI, KASUYA AND NISHIWAKI

236

These informations suggest that the two kinds of the dolphins are distributed, inthe western North Pacific, in the waters influenced by the Kuroshio current. Fig. 8
shows the oceanographical structure and the positions of sighting of S. coeruleoalba.
The schools of this species seems to be concentrated near the area where the warm
water intrudes into the colder water at the periphery of the Kuroshio current.
Similar oceanographical structure is observed at the southeast entrance of Sagami
Bay in the winter season (Kasuya, 1972; Miyazaki et al., 1973 ), and at the southeast

130°E

150°E

140°E

50°N

•9
40° N

•8

17°C On 1-1 O Mar.

30°N

~·1
0

•1 0

12
0

0

1

1 1
0

2

Oo

22

20°N
Fig. 7. Map showing the geographical distribution of Stenella coeruleoalba and Stenella
attenuata. The numerals by the symbol indicate the month of sighting or collecting. A; Arari, F; Futo, K; Kawana, T; Taiji. The l7°C isothermallines
are for 1970 (Japanese Meteorological Agency).

Sci. Rep. Whales Res. Inst.,
No. 26, 1974

237

DISTRIBUTION AND MIGRATION OF STENELLA

area of Suruga Bay in winter and spring dolphin fishing season (Fig. 9). These
places coincide with the important fishing ground of the dolphins. Though thespecies was not identified, there is observed in October and December a peak of
landing of dolphins at the Choshi fish market (35°44' N, 140°52' E). This peak will
140°E

141° E

140 E

141°E

20'

35'N

40'

,....,, .........
'I

>\

,,-

'-)

\

}

"

e e

pp

On19-25 Nov.1971
20'

I

Fig. 8. The oceanographical condition and the sighting position of the dolphin
obtained through 2 cruises of the Tanseimaru. S; Stenella coeruleoalba, L; Lagenor-hynchus, T; Tursiops, D; Delphinidae, P; sperm whale, G; Globicephala, R;
Grampus, M; minke whale, Z; Zyphiidae. Solid line indicate surface water isothermal line, and broken line the 200 m depth.

40'

40'

20'

/

20'

40'

20'

21°
/

2:(o

Fig. 9. The oceanographical condition in Suruga Bay in 1967. Solid line indicatessurface water temperature. (Shizuoka Fisheries Experiment Station, 1967).

Sci. Rep. Whales Res. Inst.,
No. 26, 1974

238

MIYAZAKI, KASUYA AND NISHIWAKI

probably represent the catch of Stenella spp. in the waters off Choshi, where the similar intrusion of warm water is observed (Fig. 8). It is interesting to note that there
occurs no intrusion of warm warter in the spring at the southeast entrance ofSagami Bay, and that this area has no spring dolphin fishing season.
DISCUSSION

Hubbs et al., (1973) summarized all known records of S. coeruleoalba in the North Pacific, and showed that this species is distributed continuously from the west coast of
North America to the central tropical Pacific. The sighting records reported by
Masaki (1972) now suggest that the continuity of the distribution can be extended
to the Japanese coastal waters. But this does not necessarily mean that S.
coeruleoalba in the both sides of the North Pacific belongs to one population. It will
be more reasonable to expect several separate populations in the North Pacific.
Stenella spp. and probably other tropical or subtropical dolphins seem to concentrate at the area where the warm water at the periphery of the Kuroshio current
intrudes into the colder water as suggested by Kasuya (1972) and shown on large
cetaceans by Uda (1954). This assumption can explain the mechanism concerning
the formation of the several fishing grounds and fishing season. We don't deny
all the possibility where the concentration of dolphins occurs on the steep slope
along the continental shelf (Tobayama 1969). But this hypothesis can not explain
the presence of the fishing ground near Choshi, because the sea floor off Choshi isflat and shallow.
The winter peaks for S. coeruleoalba and S. attenuata are observed in the earlier
season in Sagami Bay at the north, and off Kii Peninsula at the south they delay forabout one month. The time lag between Sagami Bay and Suruga Bay in closer
distance is larger than that between Suruga Bay and Kii Peninsula in larger distance.
This suggests that the time lag is related to the speed of the seasonal change of theoceanographical conditions or the seasonal movement of the area where the northernboundary of the Kuroshio current crosses the coastal waters. The spring peak observed in the catch at Taiji (Kii Peninsula) and Arari (Suruga Bay) will correspondto the northbound movement of the northern boundary of the Kuroshio current
and that of dolphins induced by it. These features of the seasonal migration of thedolphins are close to that suggested by Ohsumi (1972). But it must be noted thatthe migration of these dolphins seems to be the shift of the area of the higher densityof dolphins resulting in the expansion or retreat of the range of the distribution.
Compared with the peaks of S. coeruleoalba, the winter peak of S. attenuata arrives
earlier and the spring peak later. This indicates that S. attenuata lives in the warmer
waters and possibly in the lower latitudes than S. coeruleoalba does.
As the catch of the two species of the dolphins are strongly affected by the annual fluctuation of the Kuroshio current, it was impossible to analyze the fluctuation of the population based on the fishing statistics covering only a short period.

Sci. Rep. Whales Res. Inst.,
No. 26, 1974

DISTRIBUTION AND MIGRATION OF STENELLA

239

ACKNOWLEDGEMENTS

Sincere thanks are due to the members of the fishermen's cooperative unions at
Kawana, Futo, Arari, and Taiji, who are very helpful in collecting the data. We
extend our hearty thanks to the members of the Tanseimaru, who kindly supported
us in studying the dolphins on the vessel.
Dr. T. Kajihara and Dr. K. Numachi of The Ocean Research Institute, and
Mr. R. L. Brownell of The Smithsonian Institution are acknowledged for their cooperation and the valuable suggestions.

Sci. Rep. Whales Res. Inst.,
No. 26, 1974

MIYAZAKI, KASUYA AND NISHIWAKI240

REFERENCES
HmASHIKAWA, S., H. KITAMURA, Y. MoTOMURA, K. YAMAMOTO, and T. KATAOKA, 1966. Dolphins in
Mie prefecture. Mu Seibutsu 16: 49-52. (in Japanese)
HUBBS, C. L., W. F. PERRIN, and K. C. BALCOMB, 1973. Stenella coeruleoalba in the eastern and central
Pacific. J. Mamm., 54(2): 549-552.
JAPANESE MARINTIME SAFETY AGENCY, 1961-1971. State of the Adjacent Seas of Nippon. Vol. 2-4. Tokyo.
KASUYA, T., 1971. Consideration of distribution and migration of toothed whales off the Pacific coastof Japan based upon aerial sighting record. Sci. Rep. Whales Res. Inst., 23: 37-66.
KASUYA, T., 1972. Growth and reproduction of Stenella caeruleoalba based on the age determination bymeans of dentinal growth layers. Sci. Rep. Whale Res. Inst., 24: 57-79.
KAsUYA, T., N. MIYAZAKI, and W. H. DAWBIN, 1974. Growth and reproduction of Stenella attenuata in
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MASAKI, M., 1972. Tagging investigation of whale in Ogasawara and Mariana Islands. Geiken Tsushin,
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MIYAZAKI, N., T. KusAKA, and M. NISHIWAKI, 1973. Food of Stenella caeruleoalba. Sci. Rep. Whales Res. Inst.,

25: 265-275.
MIZUE, K., and K. YosHmA, 1962. Studies on the little toothed whales in the west sea area of Kyusyu
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Nagasaki Pref. Bull. Fae. Fish. Nagasaki Univ., 13: 1-8. (in Japanese)
MIZUE, K., K. YosHIDA, and S. SONODA, 1964. Studies on the little toothed whales in the west sea areaof Kyusyu X. About Prodelphinus sp. so-called "Hashinaga iruka" in Japan caught in the sea areaaround Goto Is. Nagasaki Pref. Bull. Fae. Fish. Nagasaki Univ., 17: 10-24. (in Japanese)
NisHIWAKI, M. and T. Yagi, 1953. On the age and the growth of teeth in a dolphin (Prodelphinus caeruleoalbus). Sci. Rep. Whales Res. Inst., 8: 133-146.
NISHIWAKI, M., M. NAKAJIMA, and T. KAMIYA, 1965. A rare species of dolphin (Stenella attenuata) from
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OGAWA, T., 1936. Studien iiber die Zahnwale in Japan. Botany and Zoology, 4(8): 1337-1344. (inJapanese)
0HSUMI, S., 1972. Catch of marine mammals, mainly of small cetaceans, by local fisheries along the coastof Japan. Bull. Far Seas Fish. Res. Lab., 7: 137-166.
OKADA, Y., 1936. A study of Japanese Delphinidae. Sci. Rep. Tokyo Bunrika Daigaku. Sect. B., 3(44-45): 1-16.
PERRIN, W. F., 1972. Color patterns of spinner porpoises (Stenella cf. S. longirostris) of the ea~tern Pacificand Hawaii, with comments on delphinid pigmentation. Fish. Bull., U.S., 70(3): 983-1003.
SAMPSON, W. F., 1970. Stenella eoeruleoalba in the northern Pacific Ocean. J. Mamm., 51(4) 809.
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ToBAYAMA, T., 1969. School size and its fluctuation in the catch of Stenella eoeruleoalba in Sagami Bay.
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Sci. Rep. Whales Res. Inst.,
No. 26, 1974

241

DISTRIBUTION AND MIGRATION OF STENELLAAPPENDIX I. THE NUMBER OF CATCH OF STENELLA COERULEOALBA AND
STENELLA ATTENUATA (IN PARENTHESES) IN ARARI.
Jan.

1950

60

1951
1952

2, 194
245

Feb.

Mar.

Apr.

May

June

July

10

4,794

3,293

47

93

1,321

1,990

1,231
(1)
826
1,321

(25)
88

19

759
(6)

62

125

1953
1954
1955

53

1956

1,390

69

1957

261

102

274

1958
1959

1,274
4, 117

79

151
76

Sep.

Aug.

Oct.

Nov.

646
11
153
(65)

245
69
611

48

68
(257)

275

(188)

1960
1961
1968
1970
Total

1,440

63
671
(83)
67

151

613

11

63 613
(188)

11

90
9,745

1,565

281
(25)

6,384

41
6,584
(6)

5, 104 1,180
(341)
(6'5)

67

Dec.

Total

4,236 13' 671(1)2,469 9,664
4,050 5,627
(25)
1,081
(71)
298
2,483 2,552
(15)
(15)
3,634 5,752(188)
1, 771 2, 751
(257)
1,567
6,304
(83)
67
775
90
41
18,643 50,240
(640)
(15)

APPENDIX II. THE NUMBER OF CATCH OF STENELLA COERULEOALBA AND
STENELLA ATTENUATA (IN PARENTHESES) IN TAIJI.
Jan.

Feb.

Mar.

Apr.

May

1963
1964
1965
1966
1967
1968
1969
1970

16
252
207
129
336
175
77
331

30
247
138
177
206
112
3
81

34
162
29
15
29
4

18
25
17
12
29
42
3
3

46
11

1971

423
(1)
288
(2)
2,234
(3)

178

11

1972
Total

28
(3)
1,200
(3)

Sci. Rep. Whales Res. Inst.,
No. 26, 1974

2
286

(1)
1
150
(11)

June July Aug. Sep. Oct.

4
1
14

2
3

4

Nov.

Dec.

Total

3
5
(1)
35
(3)
5

63
93
78
7
97
6
74
114
(8)
327
(19)
68

120
131
121
77
105
27
237
444
(5)
730
(19)
239

104
(4)

927
(27)

2,231
(14)

331
934
642
422
819
400
499
997
(14)
1, 717
(37)
700
(12)
7,461
(63)

9
30

5
16
33
90
7
5
(4)
30
(3)
227
(7)

12
8

4

8
39
(4)
87
(4)

7

5

3

242

MIYAZAKI, KASUYA AND NISHIWAKIAPPENDIX III.

THE NUMBER OF CATCH OF STENELLA COERULEOALBA

Sep.
E
1949-'50
1950-'51
1951-'52
1952-'53
1953-'54
1954-'55
1955-'56
1056-'57
1957-'58
1958-'59
1959-'60
1960-'61
1961-'62
1962-'63
1963-'64
1964-'65
1965-'66
1966-'67
1967-'68
1968-'69
1969-'70

M

Nov.

Oct.
L

E

M

L

E

1,035

374

71

275
283
268
183
686
116
1,634
404

510

364

862
717
237

99
820
50
101
1,324

158
453
351
248
191

169

510
401

293

603
(881)

1971-'72

1,310
(159)
517

1972-'73

503

1,117

1973-'74

1,140

512

3,969
(159)

4,849

470

29

1970-'71

Total
*:

M

L

408

131

408

131

102
(213)
143
(786)
6,011
(1, 880)

11
145
(435)
0
(1, 657)
25
631
(189)
116
(376)
5, 151(2' 657)

162
952
160
173
1,229
251
162
1,643
1,840

279
310
210
1,903
1, 187
389
1,445
2,768
1,203
2,325
1,345
355

314

2, 197

776
815
(260)
3,277

4,067

12,335(260)

20,471

488

The total catch at Futo and Kawana, but only the catch at Futo is given by month.

Sci. Rep. Whales Res. Inst.,
No. 26, 1974

DISTRIBUTION AND MIGRATION OF STENELLA

243

AND STEJ'iELLA ATTENUATA (IN PARENTHESES) IN KAWANA AND FUTO.

Jan.

Dec.

Feb.
Total

E

M

L

E

M

L

E

327
1,515

168
605
3,248
1,477
467
135
3,253
504
948
389

148

2,755

146
6,257
1,401
637
1,084
843
1,500
542

973
452
160
68
0
2,846
1,675
1,967
50
131

903

1,094

1,805

100

378
870
738
892
107
62

47
420
229
119
533
109

129
612
106
36
74
56
33
24

1,557

1,070

69

4,534

459

975

148

15,597

13,609

L

735
1,515
2,235

2,235

1,127

M

11, 651

Sci. Rep. Whales Res. Inst.,
No. 26, 1974

9,386

69

4, 1482,876
2,569
10,5898,269
8,535
6, 103
15,649*14,351*8, 1984,626
3, 130(435)
5,307(2,697)
3,315
(0)
7,235
(662)
6,799
(1,162)
118,939(4,956)