DISTRIBUTION OF SPERM WHALE CATCHES IN THE
SOUTHERN INDIAN OCEANSABURO MACHIDA*
Whales Research Institute, Tokyo

ABSTRACTOver 6,000 sperm whales were caught by Japanese antarctic whaling expeditions in the southern Indian Ocean bounded by latitude 30° -50°S andlongitude 20°-l45°E on the way to and from the antarctic whaling grounds
in the seasons of 1957/58-1972/73. Most catches were made intensively in
November and December before the baleen whale seasons.
The distribution of the species in the area concerned is discussed in relation to the surface temperature field. The relationship between the heavy
catches of the animals and the Subtropical Convergence was found. Spermwhale concentrations are restricted in the convergence region and in temperate waters north of it. They are distributed up to about 41°S in the southwestern, southcentral, and southeastern Indian Ocean and about 47°S south ofAustralia. Virtually no females occur in colder waters south of the convergence region.
INTRODUCTION
Sperm whales have been caught by Japanese antarctic whaling expeditions in middle latitudes in the southern Indian Ocean on the way to and from the antarctic region in the Antarctic Ocean since the 1957/58 season.
There are very few reports about the distribution of sperm whales in pelagic
waters in the Indian Ocean. Especially in the southern part of the ocean only verysmall catches of the species were made by the American whaleships mainly in nineteenth century (Townsend, 1937) and only a few animals were observed by research
and merchant vesseles (Brown, 1957; Slijper et al., 1964). On the other hand we
can see the distribution of the species in the area concerned in the charts by Kasuya(1964), Ohsumi and Nasu (1968), and Berzin (1972), which were mapped basedon the materials from Japanese and Soviet antarctic whaling expeditions respectively. However, the practical study of the sperm whale distribution and thegrounds for the species in relation to the oceanographic conditions is rather scarce.
In any programme of whale research aimed at the reasonable exploitation of
a population a knowledge of the distribution of the animals concerned is invaluable.
In this present report the distribution of the sperm whale catches in the southern
Indian Ocean bounded by latitude 30°-50°S and longitude 20°-145°E has been

* Present address: Japan Marine Fishery Resource Research Center, Tokyo.
Sci. Rep. Whales Res. Inst.,

No. 27, 1975, 141-157.

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MACHIDA

described in relation to the surface temperature field, using the materials fromJapanese antarctic whaling expeditions in the seasons of 1957/58-1972/73.
RESULTSJapanese antarctic whaling expeditions had caught sperm whales heavily in middle
latitudes in the southern Indian Ocean from 1957/58 to 1972/73 (Table 1). Though
the sperm whale catches were made during the warmer months of November-April,most animals were actually caught in November before the baleen whale seasons.
A few catches of the animals were also made at the beginning of December and fromthe end of March to April again after carrying out catching for baleen whales.
During the mid summer (January-February), at the height of catching for baleen
whales, only very few sperm whales were caught.
TABLE 1. THE SEASONAL AND MONTHLY CATCHES OF SPERM WHALES BY THE
JAPANESE ANTARCTIC WHALING EXPEDITIONS IN THE SOUTHERN INDIAN
OCEAN FROM 1957/58 TO 1972/73. RIGHT FIGURES: FEMALES
SeasonNov.

1957/58
58/59
59/60
60/61
61/62
62/63
63/64
64/65
65/66
66/67
67/68
68/69
69/70
70/71
71/72
72/73

25

Total

Dec.

Jan.

Feb.

Apr.

Mar.

Total
25

62
391
1,750
1,194
254
309
20

7
187
960
684
7
47

302
458
45

137
305
9

4,810

2,343

46

18

8
22

5

-

1
3 27 -

13211
74
394 206
19
71
738

304

77

-

10 -

14 -

18

-

42

-

29
1
64
60
48
5
159
83

449

29
76 105 36
2

2

210

36

29
20
203
630
1,798
1, 199
414
417
69

7
223
962
684
7
52

315
687
439
71

137
379
215
19

6,326

2,685

Fig. 1 shows the relation between the number of sperm whales and surface
temperatures. It can be readily seen from the figure that the catches of the animals
in November, when most catches were made, have relations with temperature. A
large quantity of catches were made in the relatively limited range from 12° to l6°C
with a peak at l 4°C though the whales occur in the wide range of -1° to 23°C.
On the other hand, in other months, when few sperm whales were caught, therelationship between the catch and temperature can not be seen as well as that inNovember.
Fig. 2 shows the distribution of sperm whale catches in the southern Indian
Ocean from November to April in the seasons of 1957/58-1972/73. Most of theSci. Rep. Whales Res. Inst.,
No. 27, 1975.

DISTRIBUTION OF SPERM WHALE CATCHES

143

catches were made in the central part of the area in November. The southern halfof the favorite grounds is located in shallow waters around Newamsterdam Island(about 37°50'S and 77°30'E) and Saint Paul Island (about 38°40'S and 77°35'E).
The second large catches of the species, which were almost carried out at the beginning of December, are made off southwestern Australia. In the western part of
the area, the distribution of the catches are widely scattered and the extent of thefavorite haunts were hardly encountered though the total number of sperm whale
catches in the area concerned are rather large. In general a large quantity ofcatches of sperm whales was distributed in the warmer waters north of 40° to 41°S.
It is well known that the sperm whale has some social schools. We can not,of course, find out the accurate composition of the schools caught from the catchrecords but the catches of females, with which some large-scale social schools arecomposed, are available. As females have been also caught by Japanese antarctic
whaling fleets in middle latitudes in the southern Indian Ocean the catch location
are presented here.
The relationship between the nature of female sperm whales and oceanographic condition is shown in Fig. 3, which gives the one between the monthly
catch of females and the surface temperatures. Though females were frequently
encountered in l0°-23°C, the catches increased abruptly (from 19 to 277 animals)
in temperate waters from 11° to l2°C. A large number of the female catches weremade in November, and they occurred in waters between 12° and 19°C with apeak at l4°C. During December, probably at the beginning of the month, several
females were caught was made in warmer waters (14° to 20°C) than during November. In addition only a few females were caught in warmer temperatures than
17°C in March-April.
Fig. 4 shows the distribution of the female catches, most of which were also
captured in November to the beginning of December and a slight catch again in
March to April. Furthermore most females were caught in the southcentral Indian Ocean and some animals also caught off southwestern Australia. No females
were caught south of 42°S in the southern Indian Ocean except in the eastern extremity south of southeastern Australia, where several females were encountered as
far south as about 4 7°S.
DISCUSSION

Sperm whales are caught heavily in lower latitudes north of about 41°S (Fig. 2),
especially in November, though the catches are carried out over the area concerned. The southern extremity of the heavy catch area seems to be corresponding
with a certain oceanographic condition. In Deacon's (1937) chart the Subtropical
Convergence, which is the boundary between the Subtropical and Subantarctic
Surface Waters, was drawn between about 39° and 43°S in the southern Indian
Ocean and between about 45° and 47°S south of Tasmania Island in the easternmost area of the ocean. According to Orren (1966) the convergence was foundto lie at 42°S ± 1° in the south western part of the ocean. In the southeastern IndianSci. Rep. Whales Res. Inst.,
No. 27, 1975.

144

MACHIDA

Ocean the convergence region was shown in latitudes from about 39° to 42°S in
Burling's (1961) chart. Rochford (1962) illustrated the South Transitional Zone
schematically, that is the transitional zone between the Subtropical and Subantarctic
Zones, which locates between about 35° and 40°S in the southeastern Indian Ocean.
In addition the Japanese whaling fleet also crossed the convergence region in nearlysame latitudes in the southeastern Indian Ocean (Machida, 1974, a, b, unpublisheddata). On the other hand, in the southcentral part of the ocean, according to
Deacon (1937) the surface temperature observations by the rv Valdivia and Gauss
show that the convergence lies between 40° and 41°S in about 76°E. The rv
Anton Brunn crossed the Subtropical Convergence at about 40°S, 75°E in April(Uda and Nakamura, 1973). Deacon's (1963) examination of mean monthly
temperatures of I-degree squares by Doneke (1938), though little is reported about
the seasonal variation of the convergence, suggests that its variations of the position
are rather small, of the same order as these of the Antarctic Convergence. Taking
account into these knowledge of the Subtropical Convergence it is evident that
good catches of sperm whales are related to the convergence region.
According to Fig. 1 the relationship between the good catches of sperm whales
and the Subtropical Convergence will be confirmed. A large quantity of the catches
were made in the range from 12° to 16°C with a peak at l4°C during November,when is outside the baleen whale seasons. Deacon (1963) described that the Subtropical Convergence is generally given in a close distribution of the surface isotherms of 10°-l4°C in winter and l4°-18°C in summer. Though he divided ayear into two seasons, winter and summer, November should be rather grouped
into the transitional season from winter to summer. There, however, are very few
reports on the Subtropical Convergence except the summer season. In the southeastern Indian Ocean (around 40.5°S and 108°E) a Japanese antarctic whaling fleet
crossed the convergence region from 13.5° to 10.4°C in the middle of November(Machida, 1974b). The range of temperature may be classified into the wintercategory according to Deacon's (1963) criterion. November, however, should begrouped into the warmer month or rather into the transitional season from winterto summer, i.e. spring. Simply taking account of the Deacon's (1963) generalcriterion about the Subtropital Convergence in the transitional season from winterto summer it probably lie in the range between 12° and l6°C, which are themeadian of the range corresponding with the convergence in winter and in summer
respectively. In November a large number of sperm whales, as mentioned above,were caught in these temperatures.
On the other hand a slight catch at the beginning of December, of which thegreat majority of the catches were made off southwestern Australia, appears to becorresponding to warmer waters than 14°C. The warmer temperatures than l4°C
are included into the summer category of Deacon's (1963) criterion of the Subtropical Convergence and coincident with the range which corresponds to the convergenceregion in December (Machida, unpublished data).
Though in the southern Indian Ocean only very small catches of sperm whales
were made mainly in the nineteenth century (Townsend, 1937) and only a few animals
Sci. Rep. Whales Res. Inst.,
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DISTRIBUTION OF SPERM WHALE CATCHES

145

were sighted by research and merchant vesseles (Brown, 1957: Slijper et al., 1964),
Kasuya (1964) and Ohsumi and Nasu (1968) illustrated the sperm whale distributionin pelagic waters of the southern Indian Ocean from catch records of Japaneseantarctic whaling expeditions. In addition Berzin (1972) charted the distribution of the species in the area concerned based on the recent materials from Soviet
pelagic whaling expeditions with previous works. In these charts it is evident
that the heavy catches of sperm whales are located around the Subtropical Convergence in the southern Indian Ocean during October-March. He describedfurthermore that large concentrations were noted north of Newamsterdam andSaint Paul Islands. A heavy catch of the animals by Japanese fleets was also
made from in shallow waters around both two islands to north. The large catches
was also illustrated off Southwestern Australia as the favourable grounds in thecharts by Townsend (1937), Gilmore (1959), Mackintosh (1965), Berzin (1972), andothers.
The southern extremity of the good catches of sperm whales seems to reflect
the concentrations of the large-scale schools of the species. According to Gaskin(1970), Ohsumi (1971), and others the sperm whale has the distinct social structureof various types of school, i.e. the nursely schools, the harem schools, the immature
mixed sex schools (the juveniel schools), the bachelor schools, the bull school (malepairs) and the lone bull (solitary bull). Of which the nursely, harem and juveniel
schools are composed of a large number of females. In the short period before thebaleen whale seasons catching for sperm whales will be occupied in waters inhabitingthese schools. We can not, of course, find out the accurate category of the social
structure of the species from the catch recrods but the females are recorded in thecatch logs. It is quite possible to suppose the location of the large-scale schools
from that of females, therefore. The distribution of the female catches shownin Fig. 4 may suggest the distribution pattern of the major schools of the species
which are restricted in the Subtropical Convergence.
The females and the youngs are generally accepted being limited to the regions
between about 40°N and 40°S (Slijper, 1962). Gilmore's (1959) charts show thatfemales are limited by the isotherm of 20°C, which seems to be more or less the range
as the convergence. Kasuya ( 1964), who charted the seasonal distribution of maleand female sperm whales in the rectangles by latitude 1° and longitude 5°, using thepart of the same materials as that in this report, assumed that the southern limit of
the female distribution in the southern Indian Ocean is 40°-45°S in latitude andthat the range is roughly corresponding with the Subtropical Convergence. On
the other hand Nasu (1969) pointed out that the southern range of females wascorresponding with the Australasian Subantarctic Front, which is located in theregion between the Subtropical and Antarctic Convergences (Burling, 1961) basedon the distribution of female sperm whales by Ohsumi and Nasu (1968). They
charted the distribution of the female catches in ten degree squares by using the partof the same materials as that in Kasuya (1964) and in this report. Clarke (1972)
studied the stomach contents of sperm whales caught off Durban (South Africa) andreported that few antarctic cephalopod beaks were found from females and small-sized
Sci. Rep. Whales Res. Inst.,
No. 27, 1975.

146

MACHIDAmales though larger males having antarctic cephalopod beaks in large number.
From this fact he suggests that females and small-sized males do not go far south
through the Subtropical Convergence. I may take that the southern range offemale sperm whales in the southern Indian Ocean is corresponding with the Subtropical Convergence as far as I discuss the distribution of the female catches andthe surface temperatures in Fig. 3 and 4.
On the other hand there is really several records that the female and young
sperm whales occurred in higher latitudes beyond the Subtropical and Antarctic
Convergences. Salvenson (1915) illustrated one female caught off South Gergia(about 55°S). In the southern Indian Ocean several schools of small-sized sperm
whales, which seemed to be composed of females and youngs, were observed at theend of January at 59°S, 65°E and at 58°30'S, 71°E, respectively (Ivanov, 1972).
Fourteen females were caught at the end of January south of Herd Island (about
56°S) (lvashin and Budylenko, 1970). Though these observations and records
suggests that some females and youngs are tolerable to cold waters south of the
Subtropical Convergence and/or furthermore through the Antarctic Convergence,these are rather scarce and I may regarde them as strugglers.

REFERENCESBERZIN, A. A., 1971. The sperm wha/,e (Eng. transl. by A. V. Yablokov, IPST, Jerusalem, 1972, 394 pp.).
BROWN, S. G., 1957. Whales observed in the Indian Ocean. Mar. Obsr., 27: 157-165.
BURLING, R. W., 1961. Hydrology of circumpolar waters south of New Zealand. N.
Dep. sci. indust.
Res. Bull., 143 (N. Z· oceano. Inst. Mem., 10), 66 pp.
CALDWELL, D. K., CALDWELL, M. C., and D. W. RrcE, 1966. Behaviour of the sperm whale, Physetercatodon L. Whales, Dolphins, and Porpoises (ed. K. S. Norris), 677-717.
CLARKE, M. R., 1972. New technique for the study of sperm whale migration. Nature, 238: 405-406.
DEACON, G. E. R., 1937. Hydrology of the Southern Ocean. Discovery Rep., 15: 1-124.
DEACON, G.E.R., 1963. The Southern Ocean. The Sea 2 (ed. M. N. Hill), 281-296.
DEACON, G.E.R., 1966. Subtropical Convergence. The Encyclopedia of Oceanography (ed. R. W. Fairbridge),
884-885.
GASKIN, D. E., 1970. Composition of schools of sperm whales Physeter catodon Linn. east of New Zealand.
N. Z· Jl. Mar. Freshwat. Res., 4(4): 456-471.
IVANOV, A. P., 1972. Small-sized sperm whales in the Anatrctic. (Jap. transl. by H. Sakiura, Geiken Tsushin,
282: 14)lvAsHIN, M. V., and BuDYLENKO, G. A., 1970. Female sperm whales in the Antarctic? (cited from A. P.
Ivanov, 1972)
KASUYA, T., 1964. Report of biological investigations of whales caught by Japanese antarctic whaling expeditions in
the 1963/64 season. Whales Res. Inst., Tokyo, 79 pp. (in Japanese)
MACHIDA, S., 1974a. Geographical positions of the major oceanographic fronts observed by whale sighting
boat in the Australasian Antarctic in the 1972/73 season. Geiken Tsushin, 269: 1-5. (in Japanese)
MACHIDA, S., 1974b. Temperature observations by the whaling factory 'Chiyo Maru' and whale catcher'Katsu Maru No. 3' on the way to and from the Antarctic in the 1973/74 season. Geiken Tsushin, 275:
51-54. (in Japanese)
MACHIDA, S., (unpublished data) Subtropical Convergence, Subantarctic Front, and Antarctic Convergence observed by Japanese Antarctic Icebreaker' Fuji'.
NAsu, K., 1969. Oceanography in the southern limit of habitat of southern bluefin tuna. Bull. Jap. Soci.
Fish. Oceano., 15: 19-26. (in Japanese)z.

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No. 27, 1975.

DISTRIBUTION OF SPERM WHALE CATCHES

147

0HSUMI, S., and NAsu, K., 1968. Range of habitat of the female sperm whale with reference to oceanographic structure. (cited from K. Nasu, 1968)
0HSUMI, S., 1971. Some investigations on the school structure of sperm whale. Sci. Rep. Whales Res. Inst.,

23: 1-25.
ORREN, M. R., 1966.

Hydrology of the south west Indian Ocean. Invest. Rep. Div. Sea. Fish. S. Afr., 55: 136.
ROCHFORD, M. R., 1962. Hydrology of the Indian Ocean II. Aust. J. mar. Freshw. Res., 13: 226-251.
SALVESON, T. E., 1915. The whale fisheries of the Falkland Islands and dependencies. (cited from D. K.
Caldwell et al., 1966)
SLIJPER, E.J., VAN UTRECHT, W. L., and C. NAAKTGEBOEN, 1964. Remarks on the distribution and migration of whales observations from Netherlands ships. Bijdr. Dierkunde, 34, 93 pp.
TOWNSEND, C. H., 1935. The distribution of certain whales as shown by logbook records of American whaleships. .<:,oologica, 19: 1-50.
UDA, M., and NAKAMURA, Y., 1973. Hydrography in relation to tuna fisheries in the Indian Ocean. Spl.
Puhl. Mar. Biol. Ass. India, 1973, 276-292.

Sci. Rep. Whales Res. Inst.,

No. 27, 1975.

148

MACHIDA2x10

Nov.-Apr.

12
10

~8
:::J

Iii

u

..... 6

Q)

.0

E

:i. 4

0 2 4 6 8 10 12 14 16 18 20 22
Surface Temperature (°C)
2
x 10

12

Nov.

10
8

6

.....

Q)

~ 0 L....c:::i.........r::==--...L--=~-------='-~~
1~~--------"'--:--Dec.

1..--tL[--~-=='-='---'==J'""J...=-'~----J-a_n_.
Feb.

Mar.

[

~~[_ _ ___,,==-~oJ.....Ln~·~·n=-~n..L...J.~_._._,,,=---<=-=-~A~~...__r.
0
Fig. I.

2 4 6 8 10 12 14 16 18 20 22
Surface Temperature (~C)

Catches of sperm whales and surface temperatures in November-April(1957/58-1972/73)
Sci. Rep. Whales Res. Inst.,
No. 27, 1975.

149

DISTRIBUTION OF SPERM WHALE CATCHES
Fig. 2(a). Distribution of sperm
whale catches in NovemberApril (1957/58-1972/73). The
fine line represents the contourof 1,500 fathoms.

••

• •
o·•

1 -15

•

.• . 0•• 16-30• 31 -45

•

• 46-

•

·~·
.....• • :··• • •. ......
..
.

.•. •

.

.·•

• • • •••••

2~0____.__·_·~·-·-·__,_·____4~0---'-----''----~0----6'8°

• •

..•••
.

. • . •..
.

••

••

•

.

•••••
.

•

..
•

••

60

100

80

• • •

•

.......

...._~--~~

100
Sci. Rep. Whales Res. Inst.,
No. 27, 1975.

......

~~.......

~~~~--~~..__~__.---~

120~~"'!'lo

140

150

MACHIDA• •••Fig. 2(b) Distribution of sperm
whale catches in November(1~57/88-1972/73).

1 -15• 16 - 30

••
•

•

•

.•

• 0

• 31 -45
• 46-

0

40

20

• •

•

·•••...••
••

40

•

Sci. Rep. Whales Res. Inst.,
No. 27, 1975.

151

DISTRIBUTION OF SPERM WHALE CATCHES

Fig. 2(c). Distribution of sperm
whale catches in December( 1957/58-1972/73).

1 -15• 16 - 30• 31 -45
• 46-

40

0

20

40

•
40

60

eo

•

Sci. Rep. Whales Res. Inst.,
No. 27, 1975.

152

MACHIDA30
70E 45s

50 40
135E 40

0

s

\)~
20

•

45
50

40

60

Fig. 2(d). Distribution of sperm whale catches in January (1957/58-1972/73).

1 - 15• 16 -30• 31 -45
• 46-

0

40

0

\> ~~..
.

020
Fig. 2(e).

40Distribution of sperm whale catches in February (1957/58-1972/73).

1 - 15• 16 -30• 31 -45• 46Sci. Rep. Whales Res. Inst.,
No. 27, 1975.

153

DISTRIBUTION OF SPERM WHALE CATCHES

Fig. 2(f). Distribution of sperm
whale catches in March (1957/
58-1972/73).

1 -15• 16 -30• 31 -45
• 46-

•

•

.'1

••

0

·•
80

60

10

Fig. 2(g). Distribution of sperm
whale catches in April (1957/
58-1972/73).

1 -15• 16 -30• 31 -45
• 46-

•
0

•

••
• •

Sci. Rep. Whales Res. Inst.,
No. 27, 1975.

40•

MACHIDA

154

2

Nov.-Apr.

x10...... 6
.c
Ol
:::J

~ 4
s...

<l1

..a

E
2
:::J

z

8 10 12 14 16 18 20 22
Surface Temperature (°C)
2

x10

Nov.

6

......

4

.c

Ol

~ 2

u

I...

~ 0 L-----l=------L.1_...J__~ 1L~r~----c=-...J.....1-.L-1---'--o-e_c_.
s:iDr-ifMar.

~~[~~~-c:~=--~~..__A~::~·
8 10 12 14 16 18 20 22
Surface Temperature (°C)
Fig. 3. Monthly catches of female sperm whales and the surface temperatures (1957/
58-1972/73).

Sci. Rep. Whales Res. Inst.,
No. 27, 1975.

155

DISTRIBUTION OF SPERM WHALE CATCHES

Fig. 4(a). Distribution of female
sperm whale catches in November-April (1957/58-1972/
73).

1 -15
• 16 -30• 31 -45
• 46-

•

•

•• ••••••••••

Sci. Rep. Whales Res. Inst.,
No. 27, 1975.

40

MACHIDA

156.--~..,.....~..........-=,,.,..,.--..----i....-~-r--...--.--~--r~--,30

•

•

o·

Fig. 4(b ). Distribution of female
sperm whale catches in November (1957/58-1972/73) .

1 -15• 16 -30• 31 -45
• 46-

•••
• •
•

• ••• •.
••• • -~.
••.I. • •

••

•••

•

40

Sci. Rep. Whales Res. Inst.,
No. 27, 1975.

DISTRIBUTION OF SPERM WHALE CATCHES

Fig. 4(c).
73).

157

Distribution of female sperm whale catches in December (1957/58-1972/

1 -15• 16 -30• 31 -45
• 46-

A A.
A. .
A.
A.

~

0

0

Fig. 4(d). Distribution offemale sperm whale catches in March and April (1957 /581972/73). M: March A: April

1 -15• 16 -30• 31 -45• 46Sci. Rep. Whales Res. Inst.,
No. 27, 1975.